SERVER-6908 Don't pass strings by value

Change lots of code to take <string> arguments by const ref instead
of by value; minor changes to surrounding code.

92 files changed, 274 insertions, 222 deletions

diff --git a/src/mongo/bson/bson-inl.h b/src/mongo/bson/bson-inl.h
index c6634b1e14c..cbe547bb6cf 100644
--- a/src/mongo/bson/bson-inl.h
+++ b/src/mongo/bson/bson-inl.h
@@ -916,9 +916,9 @@ dodouble:
     }
 
     // used by jsonString()
-    inline std::string escape( std::string s , bool escape_slash=false) {
+    inline std::string escape( const std::string& s , bool escape_slash=false) {
         StringBuilder ret;
-        for ( std::string::iterator i = s.begin(); i != s.end(); ++i ) {
+        for ( std::string::const_iterator i = s.begin(); i != s.end(); ++i ) {
             switch ( *i ) {
             case '"':
                 ret << "\\\"";
diff --git a/src/mongo/bson/bson.h b/src/mongo/bson/bson.h
index a26ba09f784..2c8d61bd3da 100644
--- a/src/mongo/bson/bson.h
+++ b/src/mongo/bson/bson.h
@@ -84,7 +84,7 @@ namespace mongo {
         throw bson::assertion( msgid , s );
     }
 
-    inline void uassert(unsigned msgid, std::string msg, bool expr) {
+    inline void uassert(unsigned msgid, const std::string& msg, bool expr) {
         if( !expr )
             uasserted( msgid , msg );
     }
@@ -94,7 +94,7 @@ namespace mongo {
     MONGO_COMPILER_NORETURN inline void msgasserted(int msgid, const std::string &msg) {
         msgasserted(msgid, msg.c_str());
     }
-    inline void massert(int msgid, std::string msg, bool expr) {
+    inline void massert(int msgid, const std::string& msg, bool expr) {
         if(!expr) {
             std::cout << "assertion failure in bson library: " << msgid << ' ' << msg << std::endl;
             throw bson::assertion( msgid , msg );
diff --git a/src/mongo/bson/oid.cpp b/src/mongo/bson/oid.cpp
index 15bc15f6502..ef82e525422 100644
--- a/src/mongo/bson/oid.cpp
+++ b/src/mongo/bson/oid.cpp
@@ -157,7 +157,7 @@ namespace mongo {
         }
     }
 
-    void OID::init( string s ) {
+    void OID::init( const std::string& s ) {
         verify( s.size() == 24 );
         const char *p = s.c_str();
         for( int i = 0; i < 12; i++ ) {
diff --git a/src/mongo/bson/oid.h b/src/mongo/bson/oid.h
index 62732a67ab4..36db5380e55 100644
--- a/src/mongo/bson/oid.h
+++ b/src/mongo/bson/oid.h
@@ -79,7 +79,7 @@ namespace mongo {
         void initSequential();
 
         /** init from a 24 char hex string */
-        void init( std::string s );
+        void init( const std::string& s );
 
         /** Set to the min/max OID that could be generated at given timestamp. */
         void init( Date_t date, bool max=false );
diff --git a/src/mongo/client/connpool.h b/src/mongo/client/connpool.h
index 4e8e8dcd35f..b785e9d04f6 100644
--- a/src/mongo/client/connpool.h
+++ b/src/mongo/client/connpool.h
@@ -152,7 +152,7 @@ namespace mongo {
         DBClientBase* _finishCreate( const string& ident , double socketTimeout, DBClientBase* conn );
         
         struct PoolKey {
-            PoolKey( string i , double t ) : ident( i ) , timeout( t ) {}
+            PoolKey( const std::string& i , double t ) : ident( i ) , timeout( t ) {}
             string ident;
             double timeout;
         };
diff --git a/src/mongo/client/distlock.cpp b/src/mongo/client/distlock.cpp
index 7345a692168..5413cbc6e10 100644
--- a/src/mongo/client/distlock.cpp
+++ b/src/mongo/client/distlock.cpp
@@ -79,7 +79,9 @@ namespace mongo {
             : _mutex( "DistributedLockPinger" ) {
         }
 
-        void _distLockPingThread( ConnectionString addr, string process, unsigned long long sleepTime ) {
+        void _distLockPingThread( ConnectionString addr,
+                                  const std::string& process,
+                                  unsigned long long sleepTime ) {
 
             setThreadName( "LockPinger" );
 
@@ -216,7 +218,10 @@ namespace mongo {
 
         }
 
-        void distLockPingThread( ConnectionString addr, long long clockSkew, string processId, unsigned long long sleepTime ) {
+        void distLockPingThread( ConnectionString addr,
+                                 long long clockSkew,
+                                 const std::string& processId,
+                                 unsigned long long sleepTime ) {
             try {
                 jsTimeVirtualThreadSkew( clockSkew );
                 _distLockPingThread( addr, processId, sleepTime );
diff --git a/src/mongo/client/distlock.h b/src/mongo/client/distlock.h
index 70aa3bd158c..92df434df1a 100644
--- a/src/mongo/client/distlock.h
+++ b/src/mongo/client/distlock.h
@@ -218,7 +218,7 @@ namespace mongo {
     	    return *this;
     	}
 
-        dist_lock_try( DistributedLock * lock , string why )
+        dist_lock_try( DistributedLock * lock , const std::string& why )
             : _lock(lock), _why(why) {
             _got = _lock->lock_try( why , false , &_other );
         }
diff --git a/src/mongo/client/syncclusterconnection.cpp b/src/mongo/client/syncclusterconnection.cpp
index d09c4be3d02..0b5e1150e3b 100644
--- a/src/mongo/client/syncclusterconnection.cpp
+++ b/src/mongo/client/syncclusterconnection.cpp
@@ -42,19 +42,19 @@ namespace mongo {
             _connect( i->toString() );
     }
 
-    SyncClusterConnection::SyncClusterConnection( string commaSeperated, double socketTimeout)  : _mutex("SyncClusterConnection"), _socketTimeout( socketTimeout ) {
-        _address = commaSeperated;
+    SyncClusterConnection::SyncClusterConnection( string commaSeparated, double socketTimeout)  : _mutex("SyncClusterConnection"), _socketTimeout( socketTimeout ) {
+        _address = commaSeparated;
         string::size_type idx;
-        while ( ( idx = commaSeperated.find( ',' ) ) != string::npos ) {
-            string h = commaSeperated.substr( 0 , idx );
-            commaSeperated = commaSeperated.substr( idx + 1 );
+        while ( ( idx = commaSeparated.find( ',' ) ) != string::npos ) {
+            string h = commaSeparated.substr( 0 , idx );
+            commaSeparated = commaSeparated.substr( idx + 1 );
             _connect( h );
         }
-        _connect( commaSeperated );
+        _connect( commaSeparated );
         uassert( 8004 ,  "SyncClusterConnection needs 3 servers" , _conns.size() == 3 );
     }
 
-    SyncClusterConnection::SyncClusterConnection( string a , string b , string c, double socketTimeout)  : _mutex("SyncClusterConnection"), _socketTimeout( socketTimeout ) {
+    SyncClusterConnection::SyncClusterConnection( const std::string& a , const std::string& b , const std::string& c, double socketTimeout)  : _mutex("SyncClusterConnection"), _socketTimeout( socketTimeout ) {
         _address = a + "," + b + "," + c;
         // connect to all even if not working
         _connect( a );
@@ -146,7 +146,7 @@ namespace mongo {
         return DBClientBase::getLastErrorDetailed(fsync,j,w,wtimeout);
     }
 
-    void SyncClusterConnection::_connect( string host ) {
+    void SyncClusterConnection::_connect( const std::string& host ) {
         log() << "SyncClusterConnection connecting to [" << host << "]" << endl;
         DBClientConnection * c = new DBClientConnection( true );
         c->setSoTimeout( _socketTimeout );
diff --git a/src/mongo/client/syncclusterconnection.h b/src/mongo/client/syncclusterconnection.h
index 3907f7e50a0..02cc864bed4 100644
--- a/src/mongo/client/syncclusterconnection.h
+++ b/src/mongo/client/syncclusterconnection.h
@@ -51,7 +51,10 @@ namespace mongo {
          */
         SyncClusterConnection( const list<HostAndPort> &, double socketTimeout = 0);
         SyncClusterConnection( string commaSeparated, double socketTimeout = 0);
-        SyncClusterConnection( string a , string b , string c, double socketTimeout = 0 );
+        SyncClusterConnection( const std::string& a,
+                               const std::string& b,
+                               const std::string& c,
+                               double socketTimeout = 0 );
         ~SyncClusterConnection();
 
         /**
@@ -114,7 +117,7 @@ namespace mongo {
                                                 const BSONObj *fieldsToReturn, int queryOptions, int batchSize );
         int _lockType( const string& name );
         void _checkLast();
-        void _connect( string host );
+        void _connect( const std::string& host );
 
         string _address;
         vector<string> _connAddresses;
diff --git a/src/mongo/db/client.cpp b/src/mongo/db/client.cpp
index 11216632fa1..a1527802e37 100644
--- a/src/mongo/db/client.cpp
+++ b/src/mongo/db/client.cpp
@@ -186,7 +186,7 @@ namespace mongo {
     }
 
     BSONObj CachedBSONObj::_tooBig = fromjson("{\"$msg\":\"query not recording (too large)\"}");
-    Client::Context::Context( string ns , Database * db, bool doauth ) :
+    Client::Context::Context( const std::string& ns , Database * db, bool doauth ) :
         _client( currentClient.get() ), 
         _oldContext( _client->_context ),
         _path( mongo::dbpath ), // is this right? could be a different db? may need a dassert for this
@@ -200,7 +200,7 @@ namespace mongo {
         checkNsAccess( doauth );
     }
 
-    Client::Context::Context(const string& ns, string path , bool doauth, bool doVersion ) :
+    Client::Context::Context(const string& ns, const std::string& path , bool doauth, bool doVersion ) :
         _client( currentClient.get() ), 
         _oldContext( _client->_context ),
         _path( path ), 
@@ -215,7 +215,7 @@ namespace mongo {
     /** "read lock, and set my context, all in one operation" 
      *  This handles (if not recursively locked) opening an unopened database.
      */
-    Client::ReadContext::ReadContext(const string& ns, string path, bool doauth ) {
+    Client::ReadContext::ReadContext(const string& ns, const std::string& path, bool doauth ) {
         {
             lk.reset( new Lock::DBRead(ns) );
             Database *db = dbHolder().get(ns, path);
@@ -253,7 +253,7 @@ namespace mongo {
         //       it would be easy to first check that there is at least a .ns file, or something similar.
     }
 
-    Client::WriteContext::WriteContext(const string& ns, string path , bool doauth ) 
+    Client::WriteContext::WriteContext(const string& ns, const std::string& path , bool doauth ) 
         : _lk( ns ) ,
           _c( ns , path , doauth ) {
     }
diff --git a/src/mongo/db/client.h b/src/mongo/db/client.h
index c2142115ca5..717d2344f26 100644
--- a/src/mongo/db/client.h
+++ b/src/mongo/db/client.h
@@ -168,7 +168,7 @@ namespace mongo {
          */
         class ReadContext : boost::noncopyable { 
         public:
-            ReadContext(const string& ns, string path=dbpath, bool doauth=true );
+            ReadContext(const std::string& ns, const std::string& path=dbpath, bool doauth=true );
             Context& ctx() { return *c.get(); }
         private:
             scoped_ptr<Lock::DBRead> lk;
@@ -181,13 +181,13 @@ namespace mongo {
         class Context : boost::noncopyable {
         public:
             /** this is probably what you want */
-            Context(const string& ns, string path=dbpath, bool doauth=true, bool doVersion=true );
+            Context(const string& ns, const std::string& path=dbpath, bool doauth=true, bool doVersion=true );
 
             /** note: this does not call finishInit -- i.e., does not call 
                       shardVersionOk() for example. 
                 see also: reset().
             */
-            Context( string ns , Database * db, bool doauth=true );
+            Context( const std::string& ns , Database * db, bool doauth=true );
 
             // used by ReadContext
             Context(const string& path, const string& ns, Database *db, bool doauth);
@@ -237,7 +237,7 @@ namespace mongo {
 
         class WriteContext : boost::noncopyable {
         public:
-            WriteContext(const string& ns, string path=dbpath, bool doauth=true );
+            WriteContext(const string& ns, const std::string& path=dbpath, bool doauth=true );
             Context& ctx() { return _c; }
         private:
             Lock::DBWrite _lk;
diff --git a/src/mongo/db/commands/group.cpp b/src/mongo/db/commands/group.cpp
index 9fbd56d8a4b..61adfc9efc7 100644
--- a/src/mongo/db/commands/group.cpp
+++ b/src/mongo/db/commands/group.cpp
@@ -47,11 +47,17 @@ namespace mongo {
             return obj.extractFields( keyPattern , true ).getOwned();
         }
 
-        bool group( string realdbname , const string& ns , const BSONObj& query ,
-                    BSONObj keyPattern , string keyFunctionCode , string reduceCode , const char * reduceScope ,
-                    BSONObj initial , string finalize ,
-                    string& errmsg , BSONObjBuilder& result ) {
-
+        bool group( const std::string& realdbname,
+                    const std::string& ns,
+                    const BSONObj& query,
+                    BSONObj keyPattern,
+                    const std::string& keyFunctionCode,
+                    const std::string& reduceCode,
+                    const char * reduceScope,
+                    BSONObj initial,
+                    const std::string& finalize,
+                    string& errmsg,
+                    BSONObjBuilder& result ) {
 
             auto_ptr<Scope> s = globalScriptEngine->getPooledScope( realdbname );
             s->localConnect( realdbname.c_str() );
diff --git a/src/mongo/db/commands/mr.cpp b/src/mongo/db/commands/mr.cpp
index de2113d0fc0..7f69a847398 100644
--- a/src/mongo/db/commands/mr.cpp
+++ b/src/mongo/db/commands/mr.cpp
@@ -37,7 +37,7 @@ namespace mongo {
 
         AtomicUInt Config::JOB_NUMBER;
 
-        JSFunction::JSFunction( string type , const BSONElement& e ) {
+        JSFunction::JSFunction( const std::string& type , const BSONElement& e ) {
             _type = type;
             _code = e._asCode();
 
diff --git a/src/mongo/db/commands/mr.h b/src/mongo/db/commands/mr.h
index e547f475dc7..76ef7091ff9 100644
--- a/src/mongo/db/commands/mr.h
+++ b/src/mongo/db/commands/mr.h
@@ -72,7 +72,7 @@ namespace mongo {
             /**
              * @param type (map|reduce|finalize)
              */
-            JSFunction( string type , const BSONElement& e );
+            JSFunction( const std::string& type , const BSONElement& e );
             virtual ~JSFunction() {}
 
             virtual void init( State * state );
diff --git a/src/mongo/db/dbwebserver.cpp b/src/mongo/db/dbwebserver.cpp
index f427d24cf80..67d7746b18f 100644
--- a/src/mongo/db/dbwebserver.cpp
+++ b/src/mongo/db/dbwebserver.cpp
@@ -373,7 +373,7 @@ namespace mongo {
     public:
         FavIconHandler() : DbWebHandler( "favicon.ico" , 0 , false ) {}
 
-        virtual void handle( const char *rq, string url, BSONObj params,
+        virtual void handle( const char *rq, const std::string& url, BSONObj params,
                              string& responseMsg, int& responseCode,
                              vector<string>& headers,  const SockAddr &from ) {
             responseCode = 404;
@@ -387,7 +387,7 @@ namespace mongo {
     public:
         StatusHandler() : DbWebHandler( "_status" , 1 , false ) {}
 
-        virtual void handle( const char *rq, string url, BSONObj params,
+        virtual void handle( const char *rq, const std::string& url, BSONObj params,
                              string& responseMsg, int& responseCode,
                              vector<string>& headers,  const SockAddr &from ) {
             headers.push_back( "Content-Type: application/json;charset=utf-8" );
@@ -439,7 +439,7 @@ namespace mongo {
     public:
         CommandListHandler() : DbWebHandler( "_commands" , 1 , true ) {}
 
-        virtual void handle( const char *rq, string url, BSONObj params,
+        virtual void handle( const char *rq, const std::string& url, BSONObj params,
                              string& responseMsg, int& responseCode,
                              vector<string>& headers,  const SockAddr &from ) {
             headers.push_back( "Content-Type: text/html;charset=utf-8" );
@@ -491,7 +491,7 @@ namespace mongo {
             return _cmd(cmd) != 0;
         }
 
-        virtual void handle( const char *rq, string url, BSONObj params,
+        virtual void handle( const char *rq, const std::string& url, BSONObj params,
                              string& responseMsg, int& responseCode,
                              vector<string>& headers,  const SockAddr &from ) {
             string cmd;
diff --git a/src/mongo/db/dbwebserver.h b/src/mongo/db/dbwebserver.h
index bdbcba2c07d..04715963249 100644
--- a/src/mongo/db/dbwebserver.h
+++ b/src/mongo/db/dbwebserver.h
@@ -39,7 +39,7 @@ namespace mongo {
         virtual bool requiresREST( const string& url ) const { return _requiresREST; }
 
         virtual void handle( const char *rq, // the full request
-                             string url,
+                             const std::string& url,
                              BSONObj params,
                              // set these and return them:
                              string& responseMsg,
diff --git a/src/mongo/db/dur.cpp b/src/mongo/db/dur.cpp
index 978c4bea9eb..b83957bfc32 100644
--- a/src/mongo/db/dur.cpp
+++ b/src/mongo/db/dur.cpp
@@ -217,7 +217,7 @@ namespace mongo {
             is created first, and the journal will just replay the creation if the create didn't
             happen because of crashing.
         */
-        void DurableImpl::createdFile(string filename, unsigned long long len) {
+        void DurableImpl::createdFile(const std::string& filename, unsigned long long len) {
             shared_ptr<DurOp> op( new FileCreatedOp(filename, len) );
             commitJob.noteOp(op);
         }
diff --git a/src/mongo/db/dur.h b/src/mongo/db/dur.h
index ffacf90f591..9914264c83e 100644
--- a/src/mongo/db/dur.h
+++ b/src/mongo/db/dur.h
@@ -34,7 +34,7 @@ namespace mongo {
                 is created first, and the journal will just replay the creation if the create didn't
                 happen because of crashing.
             */
-            virtual void createdFile(string filename, unsigned long long len) = 0;
+            virtual void createdFile(const std::string& filename, unsigned long long len) = 0;
 
             /** Declarations of write intent.
 
@@ -168,7 +168,7 @@ namespace mongo {
             void* writingAtOffset(void *buf, unsigned ofs, unsigned len) { return buf; }
             void* writingRangesAtOffsets(void *buf, const vector< pair< long long, unsigned > > &ranges) { return buf; }
             void declareWriteIntent(void *, unsigned);
-            void createdFile(string filename, unsigned long long len) { }
+            void createdFile(const std::string& filename, unsigned long long len) { }
             bool awaitCommit() { return false; }
             bool commitNow() { return false; }
             bool commitIfNeeded(bool) { return false; }
@@ -182,7 +182,7 @@ namespace mongo {
             void* writingAtOffset(void *buf, unsigned ofs, unsigned len);
             void* writingRangesAtOffsets(void *buf, const vector< pair< long long, unsigned > > &ranges);
             void declareWriteIntent(void *, unsigned);
-            void createdFile(string filename, unsigned long long len);
+            void createdFile(const std::string& filename, unsigned long long len);
             bool awaitCommit();
             bool commitNow();
             bool aCommitIsNeeded() const;
diff --git a/src/mongo/db/durop.cpp b/src/mongo/db/durop.cpp
index dae10f0cbbc..b0039c93b74 100644
--- a/src/mongo/db/durop.cpp
+++ b/src/mongo/db/durop.cpp
@@ -82,7 +82,7 @@ namespace mongo {
             _deleteDataFiles(_db.c_str());
         }
 
-        FileCreatedOp::FileCreatedOp(string f, unsigned long long l) :
+        FileCreatedOp::FileCreatedOp(const std::string& f, unsigned long long l) :
             DurOp(JEntry::OpCode_FileCreated) {
             _p = RelativePath::fromFullPath(f);
             _len = l;
diff --git a/src/mongo/db/durop.h b/src/mongo/db/durop.h
index 9ab1bfcbede..77b2a8a34f8 100644
--- a/src/mongo/db/durop.h
+++ b/src/mongo/db/durop.h
@@ -78,7 +78,7 @@ namespace mongo {
         public:
             FileCreatedOp(BufReader& log);
             /** param f filename to create with path */
-            FileCreatedOp(string f, unsigned long long l);
+            FileCreatedOp(const std::string& f, unsigned long long l);
             virtual void replay();
             virtual string toString();
             virtual bool needFilesClosed();
@@ -93,7 +93,7 @@ namespace mongo {
         class DropDbOp : public DurOp {
         public:
             DropDbOp(BufReader& log);
-            DropDbOp(string db) :
+            DropDbOp(const std::string& db) :
                 DurOp(JEntry::OpCode_DropDb), _db(db) { }
             virtual void replay();
             virtual string toString() { return string("DropDbOp ") + _db; }
diff --git a/src/mongo/db/extsort.cpp b/src/mongo/db/extsort.cpp
index 982555ce8c1..4629873f4e6 100644
--- a/src/mongo/db/extsort.cpp
+++ b/src/mongo/db/extsort.cpp
@@ -260,7 +260,7 @@ namespace mongo {
 
     // -----------------------------------
 
-    BSONObjExternalSorter::FileIterator::FileIterator( string file ) {
+    BSONObjExternalSorter::FileIterator::FileIterator( const std::string& file ) {
 #ifdef _WIN32
         _file = ::_open( file.c_str(), _O_BINARY | _O_RDWR | _O_CREAT , _S_IREAD | _S_IWRITE );
 #else
diff --git a/src/mongo/db/extsort.h b/src/mongo/db/extsort.h
index a1107fa9426..853c02283ca 100644
--- a/src/mongo/db/extsort.h
+++ b/src/mongo/db/extsort.h
@@ -62,7 +62,7 @@ namespace mongo {
 
         class FileIterator : boost::noncopyable {
         public:
-            FileIterator( string file );
+            FileIterator( const std::string& file );
             ~FileIterator();
             bool more();
             Data next();
@@ -124,7 +124,7 @@ namespace mongo {
 
         void _sortInMem();
 
-        void sort( string file );
+        void sort( const std::string& file );
         void finishMap();
 
         BSONObj _order;
diff --git a/src/mongo/db/geo/core.h b/src/mongo/db/geo/core.h
index 32d62bdc1dd..25a2f3b9239 100644
--- a/src/mongo/db/geo/core.h
+++ b/src/mongo/db/geo/core.h
@@ -341,7 +341,7 @@ namespace mongo {
             return n;
         }
 
-        GeoHash operator+( string s ) const {
+        GeoHash operator+( const std::string& s ) const {
            return operator+( s.c_str() );
         }
 
diff --git a/src/mongo/db/helpers/dblogger.h b/src/mongo/db/helpers/dblogger.h
index 4d6ee6d78c4..52d5e4db646 100644
--- a/src/mongo/db/helpers/dblogger.h
+++ b/src/mongo/db/helpers/dblogger.h
@@ -25,7 +25,7 @@ namespace mongo {
         bool _inited;
     public:
         const string _ns;
-        DBLogger(string ns) : _inited(false), _ns(ns) { }
+        DBLogger(const std::string& ns) : _inited(false), _ns(ns) { }
     };
 
 }
diff --git a/src/mongo/db/index_update.cpp b/src/mongo/db/index_update.cpp
index fcb36f3ba46..c1acd9ba0c1 100644
--- a/src/mongo/db/index_update.cpp
+++ b/src/mongo/db/index_update.cpp
@@ -479,7 +479,7 @@ namespace mongo {
     };
 
     // throws DBException
-    void buildAnIndex(string ns, NamespaceDetails *d, IndexDetails& idx, int idxNo, bool background) {
+    void buildAnIndex(const std::string& ns, NamespaceDetails *d, IndexDetails& idx, int idxNo, bool background) {
         tlog() << "build index " << ns << ' ' << idx.keyPattern() << ( background ? " background" : "" ) << endl;
         Timer t;
         unsigned long long n;
diff --git a/src/mongo/db/index_update.h b/src/mongo/db/index_update.h
index 128889e7d17..81a777d3b2b 100644
--- a/src/mongo/db/index_update.h
+++ b/src/mongo/db/index_update.h
@@ -30,7 +30,11 @@ namespace mongo {
     // Build an index in the foreground
     // If background is false, uses fast index builder
     // If background is true, uses background index builder; blocks until done.
-    void buildAnIndex(string ns, NamespaceDetails *d, IndexDetails& idx, int idxNo, bool background);
+    void buildAnIndex(const std::string& ns,
+                      NamespaceDetails *d,
+                      IndexDetails& idx,
+                      int idxNo,
+                      bool background);
 
     // add index keys for a newly inserted record 
     // done in two steps/phases to allow potential deferal of write lock portion in the future
diff --git a/src/mongo/db/memconcept.cpp b/src/mongo/db/memconcept.cpp
index d41afcbf2a3..3d3ebe72032 100644
--- a/src/mongo/db/memconcept.cpp
+++ b/src/mongo/db/memconcept.cpp
@@ -86,7 +86,7 @@ namespace mongo {
 
 #if 0 && defined(_DEBUG)
         bool d = false;
-        void is(void *p, concept c, string description, unsigned len) {
+        void is(void *p, concept c, const std::string& description, unsigned len) {
             DDD( log() << "is  " << p << ' ' << c.toString() << ' ' << description << ' ' << len << endl; )
             C &node = map.find(p);
             node.p = p;
diff --git a/src/mongo/db/mongommf.cpp b/src/mongo/db/mongommf.cpp
index 0ece3125291..c68dcfb61b0 100644
--- a/src/mongo/db/mongommf.cpp
+++ b/src/mongo/db/mongommf.cpp
@@ -155,7 +155,7 @@ namespace mongo {
     extern string dbpath;
 
     // here so that it is precomputed...
-    void MongoMMF::setPath(string f) {
+    void MongoMMF::setPath(const std::string& f) {
         string suffix;
         string prefix;
         bool ok = str::rSplitOn(f, '.', prefix, suffix);
@@ -168,14 +168,14 @@ namespace mongo {
         _p = RelativePath::fromFullPath(prefix);
     }
 
-    bool MongoMMF::open(string fname, bool sequentialHint) {
+    bool MongoMMF::open(const std::string& fname, bool sequentialHint) {
         LOG(3) << "mmf open " << fname << endl;
         setPath(fname);
         _view_write = mapWithOptions(fname.c_str(), sequentialHint ? SEQUENTIAL : 0);
         return finishOpening();
     }
 
-    bool MongoMMF::create(string fname, unsigned long long& len, bool sequentialHint) {
+    bool MongoMMF::create(const std::string& fname, unsigned long long& len, bool sequentialHint) {
         LOG(3) << "mmf create " << fname << endl;
         setPath(fname);
         _view_write = map(fname.c_str(), len, sequentialHint ? SEQUENTIAL : 0);
diff --git a/src/mongo/db/mongommf.h b/src/mongo/db/mongommf.h
index d3c761c32a3..3d6324443c6 100644
--- a/src/mongo/db/mongommf.h
+++ b/src/mongo/db/mongommf.h
@@ -36,7 +36,7 @@ namespace mongo {
         virtual void close();
 
         /** @return true if opened ok. */
-        bool open(string fname, bool sequentialHint /*typically we open with this false*/);
+        bool open(const std::string& fname, bool sequentialHint /*typically we open with this false*/);
 
         /** @return file length */
         unsigned long long length() const { return MemoryMappedFile::length(); }
@@ -50,7 +50,7 @@ namespace mongo {
            @param sequentialHint if true will be sequentially accessed
            @return true for ok
         */
-        bool create(string fname, unsigned long long& len, bool sequentialHint);
+        bool create(const std::string& fname, unsigned long long& len, bool sequentialHint);
 
         /* Get the "standard" view (which is the private one).
            @return the private view.
@@ -101,7 +101,7 @@ namespace mongo {
         RelativePath _p;   // e.g. "somepath/dbname"
         int _fileSuffixNo;  // e.g. 3.  -1="ns"
 
-        void setPath(string pathAndFileName);
+        void setPath(const std::string& pathAndFileName);
         bool finishOpening();
     };
 
diff --git a/src/mongo/db/oplogreader.h b/src/mongo/db/oplogreader.h
index 93c4bcdc156..8a61aeaa250 100644
--- a/src/mongo/db/oplogreader.h
+++ b/src/mongo/db/oplogreader.h
@@ -34,7 +34,7 @@ namespace mongo {
         }
 
         /* ok to call if already connected */
-        bool connect(string hostname);
+        bool connect(const std::string& hostname);
 
         bool connect(const BSONObj& rid, const int from, const string& to);
 
diff --git a/src/mongo/db/pdfile.cpp b/src/mongo/db/pdfile.cpp
index 64e86613296..0c424f01677 100644
--- a/src/mongo/db/pdfile.cpp
+++ b/src/mongo/db/pdfile.cpp
@@ -1625,7 +1625,7 @@ namespace mongo {
         }
     }
 
-    void dropDatabase(string db) {
+    void dropDatabase(const std::string& db) {
         log(1) << "dropDatabase " << db << endl;
         Lock::assertWriteLocked(db);
         Database *d = cc().database();
diff --git a/src/mongo/db/pdfile.h b/src/mongo/db/pdfile.h
index d1904f928b9..408640398dc 100644
--- a/src/mongo/db/pdfile.h
+++ b/src/mongo/db/pdfile.h
@@ -48,7 +48,7 @@ namespace mongo {
     class Cursor;
     class OpDebug;
 
-    void dropDatabase(string db);
+    void dropDatabase(const std::string& db);
     bool repairDatabase(string db, string &errmsg, bool preserveClonedFilesOnFailure = false, bool backupOriginalFiles = false);
 
     /* low level - only drops this ns */
diff --git a/src/mongo/db/pipeline/accumulator.cpp b/src/mongo/db/pipeline/accumulator.cpp
index b100154783f..993ec126504 100755
--- a/src/mongo/db/pipeline/accumulator.cpp
+++ b/src/mongo/db/pipeline/accumulator.cpp
@@ -36,18 +36,19 @@ namespace mongo {
         ExpressionNary() {
     }
 
-    void Accumulator::opToBson(
-        BSONObjBuilder *pBuilder, string opName,
-        string fieldName, bool requireExpression) const {
+    void Accumulator::opToBson(BSONObjBuilder *pBuilder,
+                               const std::string& opName,
+                               const std::string& fieldName,
+                               bool requireExpression) const {
         verify(vpOperand.size() == 1);
         BSONObjBuilder builder;
         vpOperand[0]->addToBsonObj(&builder, opName, requireExpression);
         pBuilder->append(fieldName, builder.done());
     }
 
-    void Accumulator::addToBsonObj(
-        BSONObjBuilder *pBuilder, string fieldName,
-        bool requireExpression) const {
+    void Accumulator::addToBsonObj(BSONObjBuilder *pBuilder,
+                                   const std::string& fieldName,
+                                   bool requireExpression) const {
         opToBson(pBuilder, getOpName(), fieldName, requireExpression);
     }
 
diff --git a/src/mongo/db/pipeline/accumulator.h b/src/mongo/db/pipeline/accumulator.h
index 4ca6c94b086..1c947c9ca84 100755
--- a/src/mongo/db/pipeline/accumulator.h
+++ b/src/mongo/db/pipeline/accumulator.h
@@ -32,7 +32,7 @@ namespace mongo {
         // virtuals from ExpressionNary
         virtual void addOperand(const intrusive_ptr<Expression> &pExpression);
         virtual void addToBsonObj(
-            BSONObjBuilder *pBuilder, string fieldName,
+            BSONObjBuilder *pBuilder, const std::string& fieldName,
             bool requireExpression) const;
         virtual void addToBsonArray(BSONArrayBuilder *pBuilder) const;
 
@@ -56,7 +56,7 @@ namespace mongo {
           @param opName the operator name
          */
         void opToBson(
-            BSONObjBuilder *pBuilder, string fieldName, string opName,
+            BSONObjBuilder *pBuilder, const std::string& fieldName, const std::string& opName,
             bool requireExpression) const;
     };
 
diff --git a/src/mongo/db/pipeline/builder.cpp b/src/mongo/db/pipeline/builder.cpp
index 8af427d8c9f..a85d75ce02f 100755
--- a/src/mongo/db/pipeline/builder.cpp
+++ b/src/mongo/db/pipeline/builder.cpp
@@ -46,7 +46,7 @@ namespace mongo {
         pBuilder->append(fieldName, d);
     }
 
-    void BuilderObj::append(string s) {
+    void BuilderObj::append(const std::string& s) {
         pBuilder->append(fieldName, s);
     }
 
@@ -71,7 +71,7 @@ namespace mongo {
     }
 
     BuilderObj::BuilderObj(
-        BSONObjBuilder *pObjBuilder, string theFieldName):
+        BSONObjBuilder *pObjBuilder, const std::string& theFieldName):
         pBuilder(pObjBuilder),
         fieldName(theFieldName) {
     }
@@ -101,7 +101,7 @@ namespace mongo {
         pBuilder->append(d);
     }
 
-    void BuilderArray::append(string s) {
+    void BuilderArray::append(const std::string& s) {
         pBuilder->append(s);
     }
 
diff --git a/src/mongo/db/pipeline/builder.h b/src/mongo/db/pipeline/builder.h
index 6b6a265aeea..e6a68a72a32 100755
--- a/src/mongo/db/pipeline/builder.h
+++ b/src/mongo/db/pipeline/builder.h
@@ -44,7 +44,7 @@ namespace mongo {
         virtual void append(int i) = 0;
         virtual void append(long long ll) = 0;
         virtual void append(double d) = 0;
-        virtual void append(string s) = 0;
+        virtual void append(const std::string& s) = 0;
         virtual void append(const OID &o) = 0;
         virtual void append(const Date_t &d) = 0;
         virtual void append(const OpTime& ot) = 0;
@@ -62,14 +62,14 @@ namespace mongo {
         virtual void append(int i);
         virtual void append(long long ll);
         virtual void append(double d);
-        virtual void append(string s);
+        virtual void append(const std::string& s);
         virtual void append(const OID &o);
         virtual void append(const Date_t &d);
         virtual void append(const OpTime& ot);
         virtual void append(BSONObjBuilder *pDone);
         virtual void append(BSONArrayBuilder *pDone);
 
-        BuilderObj(BSONObjBuilder *pBuilder, string fieldName);
+        BuilderObj(BSONObjBuilder *pBuilder, const std::string& fieldName);
 
     private:
         BSONObjBuilder *pBuilder;
@@ -86,7 +86,7 @@ namespace mongo {
         virtual void append(int i);
         virtual void append(long long ll);
         virtual void append(double d);
-        virtual void append(string s);
+        virtual void append(const std::string& s);
         virtual void append(const OID &o);
         virtual void append(const Date_t &d);
         virtual void append(const OpTime& ot);
diff --git a/src/mongo/db/pipeline/document_source.h b/src/mongo/db/pipeline/document_source.h
index 329564ac490..b5ae5c80ef5 100755
--- a/src/mongo/db/pipeline/document_source.h
+++ b/src/mongo/db/pipeline/document_source.h
@@ -625,7 +625,7 @@ namespace mongo {
           @param pAccumulatorFactory used to create the accumulator for the
                 group field
          */
-        void addAccumulator(string fieldName,
+        void addAccumulator(const std::string& fieldName,
                             intrusive_ptr<Accumulator> (*pAccumulatorFactory)(
                             const intrusive_ptr<ExpressionContext> &),
                             const intrusive_ptr<Expression> &pExpression);
diff --git a/src/mongo/db/pipeline/document_source_group.cpp b/src/mongo/db/pipeline/document_source_group.cpp
index 5b30b27f144..c84d73d16b6 100755
--- a/src/mongo/db/pipeline/document_source_group.cpp
+++ b/src/mongo/db/pipeline/document_source_group.cpp
@@ -119,7 +119,7 @@ namespace mongo {
     }
 
     void DocumentSourceGroup::addAccumulator(
-        string fieldName,
+        const std::string& fieldName,
         intrusive_ptr<Accumulator> (*pAccumulatorFactory)(
             const intrusive_ptr<ExpressionContext> &),
         const intrusive_ptr<Expression> &pExpression) {
diff --git a/src/mongo/db/pipeline/expression.cpp b/src/mongo/db/pipeline/expression.cpp
index 6cc54bdca21..912c251bc76 100644
--- a/src/mongo/db/pipeline/expression.cpp
+++ b/src/mongo/db/pipeline/expression.cpp
@@ -528,7 +528,7 @@ namespace mongo {
     }
 
     void ExpressionCoerceToBool::addToBsonObj(
-            BSONObjBuilder *pBuilder, string fieldName,
+            BSONObjBuilder *pBuilder, const std::string& fieldName,
             bool requireExpression) const {
         // Serializing as an $and expression which will become a CoerceToBool
         BSONObjBuilder sub (pBuilder->subobjStart(fieldName));
@@ -789,7 +789,7 @@ namespace mongo {
     }
 
     void ExpressionConstant::addToBsonObj(
-        BSONObjBuilder *pBuilder, string fieldName,
+        BSONObjBuilder *pBuilder, const std::string& fieldName,
         bool requireExpression) const {
         /*
           If we don't need an expression, but can use a naked scalar,
@@ -1278,7 +1278,7 @@ namespace mongo {
     }
 
     void ExpressionObject::addToBsonObj(
-        BSONObjBuilder *pBuilder, string fieldName,
+        BSONObjBuilder *pBuilder, const std::string& fieldName,
         bool requireExpression) const {
 
         BSONObjBuilder objBuilder (pBuilder->subobjStart(fieldName));
@@ -1391,7 +1391,7 @@ namespace mongo {
     }
 
     void ExpressionFieldPath::addToBsonObj(
-        BSONObjBuilder *pBuilder, string fieldName,
+        BSONObjBuilder *pBuilder, const std::string& fieldName,
         bool requireExpression) const {
         pBuilder->append(fieldName, fieldPath.getPath(true));
     }
@@ -1513,7 +1513,7 @@ namespace mongo {
     }
 
     void ExpressionFieldRange::addToBsonObj(
-        BSONObjBuilder *pBuilder, string fieldName,
+        BSONObjBuilder *pBuilder, const std::string& fieldName,
         bool requireExpression) const {
         BuilderObj builder(pBuilder, fieldName);
         addToBson(&builder);
@@ -2139,7 +2139,7 @@ namespace mongo {
     }
 
     void ExpressionNary::addToBsonObj(
-        BSONObjBuilder *pBuilder, string fieldName,
+        BSONObjBuilder *pBuilder, const std::string& fieldName,
         bool requireExpression) const {
         BSONObjBuilder exprBuilder;
         toBson(&exprBuilder, getOpName());
diff --git a/src/mongo/db/pipeline/expression.h b/src/mongo/db/pipeline/expression.h
index 49873f8d380..adbfc1826dc 100755
--- a/src/mongo/db/pipeline/expression.h
+++ b/src/mongo/db/pipeline/expression.h
@@ -95,7 +95,7 @@ namespace mongo {
             field specification;  See ExpressionConstant.
          */
         virtual void addToBsonObj(
-            BSONObjBuilder *pBuilder, string fieldName,
+            BSONObjBuilder *pBuilder, const std::string& fieldName,
             bool requireExpression) const = 0;
 
         /*
@@ -224,7 +224,7 @@ namespace mongo {
         // virtuals from Expression
         virtual intrusive_ptr<Expression> optimize();
         virtual void addToBsonObj(
-            BSONObjBuilder *pBuilder, string fieldName,
+            BSONObjBuilder *pBuilder, const std::string& fieldName,
             bool requireExpression) const;
         virtual void addToBsonArray(BSONArrayBuilder *pBuilder) const;
         virtual void addDependencies(set<string>& deps, vector<string>* path=NULL) const;
@@ -368,7 +368,7 @@ namespace mongo {
         virtual intrusive_ptr<const Value> evaluate(
             const intrusive_ptr<Document> &pDocument) const;
         virtual void addToBsonObj(
-            BSONObjBuilder *pBuilder, string fieldName,
+            BSONObjBuilder *pBuilder, const std::string& fieldName,
             bool requireExpression) const;
         virtual void addToBsonArray(BSONArrayBuilder *pBuilder) const;
 
@@ -445,7 +445,7 @@ namespace mongo {
             const intrusive_ptr<Document> &pDocument) const;
         virtual const char *getOpName() const;
         virtual void addToBsonObj(
-            BSONObjBuilder *pBuilder, string fieldName,
+            BSONObjBuilder *pBuilder, const std::string& fieldName,
             bool requireExpression) const;
         virtual void addToBsonArray(BSONArrayBuilder *pBuilder) const;
 
@@ -547,7 +547,7 @@ namespace mongo {
         virtual intrusive_ptr<const Value> evaluate(
             const intrusive_ptr<Document> &pDocument) const;
         virtual void addToBsonObj(
-            BSONObjBuilder *pBuilder, string fieldName,
+            BSONObjBuilder *pBuilder, const std::string& fieldName,
             bool requireExpression) const;
         virtual void addToBsonArray(BSONArrayBuilder *pBuilder) const;
 
@@ -617,7 +617,7 @@ namespace mongo {
         virtual intrusive_ptr<const Value> evaluate(
             const intrusive_ptr<Document> &pDocument) const;
         virtual void addToBsonObj(
-            BSONObjBuilder *pBuilder, string fieldName,
+            BSONObjBuilder *pBuilder, const std::string& fieldName,
             bool requireExpression) const;
         virtual void addToBsonArray(BSONArrayBuilder *pBuilder) const;
         virtual void toMatcherBson(BSONObjBuilder *pBuilder) const;
@@ -838,7 +838,7 @@ namespace mongo {
         virtual intrusive_ptr<const Value> evaluate(
             const intrusive_ptr<Document> &pDocument) const;
         virtual void addToBsonObj(
-            BSONObjBuilder *pBuilder, string fieldName,
+            BSONObjBuilder *pBuilder, const std::string& fieldName,
             bool requireExpression) const;
         virtual void addToBsonArray(BSONArrayBuilder *pBuilder) const;
 
diff --git a/src/mongo/db/pipeline/value.cpp b/src/mongo/db/pipeline/value.cpp
index ff75022a4fb..5ab0bd65c61 100644
--- a/src/mongo/db/pipeline/value.cpp
+++ b/src/mongo/db/pipeline/value.cpp
@@ -464,7 +464,7 @@ namespace mongo {
         }
     }
 
-    void Value::addToBsonObj(BSONObjBuilder *pBuilder, string fieldName) const {
+    void Value::addToBsonObj(BSONObjBuilder *pBuilder, const std::string& fieldName) const {
         BuilderObj objBuilder(pBuilder, fieldName);
         addToBson(&objBuilder);
     }
diff --git a/src/mongo/db/pipeline/value.h b/src/mongo/db/pipeline/value.h
index 293ba065fc1..6a99b673a70 100755
--- a/src/mongo/db/pipeline/value.h
+++ b/src/mongo/db/pipeline/value.h
@@ -185,7 +185,7 @@ namespace mongo {
         /*
           Add this value to the BSON object under construction.
         */
-        void addToBsonObj(BSONObjBuilder *pBuilder, string fieldName) const;
+        void addToBsonObj(BSONObjBuilder *pBuilder, const std::string& fieldName) const;
 
         /*
           Add this field to the BSON array under construction.
diff --git a/src/mongo/db/queryoptimizer.cpp b/src/mongo/db/queryoptimizer.cpp
index 849c8064c85..3e84483ea9b 100644
--- a/src/mongo/db/queryoptimizer.cpp
+++ b/src/mongo/db/queryoptimizer.cpp
@@ -95,7 +95,7 @@ namespace mongo {
                                const shared_ptr<const ParsedQuery> &parsedQuery,
                                const BSONObj &startKey,
                                const BSONObj &endKey,
-                               string special ) {
+                               const std::string& special ) {
         auto_ptr<QueryPlan> ret( new QueryPlan( d, idxNo, frsp, originalQuery, order, parsedQuery,
                                                special ) );
         ret->init( originalFrsp, startKey, endKey );
@@ -108,7 +108,7 @@ namespace mongo {
                          const BSONObj &originalQuery,
                          const BSONObj &order,
                          const shared_ptr<const ParsedQuery> &parsedQuery,
-                         string special ) :
+                         const std::string& special ) :
         _d(d),
         _idxNo(idxNo),
         _frs( frsp.frsForIndex( _d, _idxNo ) ),
diff --git a/src/mongo/db/queryoptimizer.h b/src/mongo/db/queryoptimizer.h
index 64a5e3a75a0..89c80241547 100644
--- a/src/mongo/db/queryoptimizer.h
+++ b/src/mongo/db/queryoptimizer.h
@@ -51,7 +51,7 @@ namespace mongo {
                                        shared_ptr<const ParsedQuery>(),
                                const BSONObj &startKey = BSONObj(),
                                const BSONObj &endKey = BSONObj(),
-                               string special="" );
+                               const std::string& special="" );
 
         /** Categorical classification of a QueryPlan's utility. */
         enum Utility {
@@ -120,7 +120,7 @@ namespace mongo {
                   const BSONObj &originalQuery,
                   const BSONObj &order,
                   const shared_ptr<const ParsedQuery> &parsedQuery,
-                  string special );
+                  const std::string& special );
         void init( const FieldRangeSetPair *originalFrsp,
                   const BSONObj &startKey,
                   const BSONObj &endKey );
diff --git a/src/mongo/db/repl.cpp b/src/mongo/db/repl.cpp
index 8520d3fe674..e93d608c742 100644
--- a/src/mongo/db/repl.cpp
+++ b/src/mongo/db/repl.cpp
@@ -491,7 +491,7 @@ namespace mongo {
     }
 
     /* grab initial copy of a database from the master */
-    void ReplSource::resync(string db) {
+    void ReplSource::resync(const std::string& db) {
         string dummyNs = resyncDrop( db.c_str(), "internal" );
         Client::Context ctx( dummyNs );
         {
@@ -1155,7 +1155,7 @@ namespace mongo {
         return true;
     }
     
-    bool OplogReader::connect(string hostName) {
+    bool OplogReader::connect(const std::string& hostName) {
         if (conn() != 0) {
             return true;
         }
diff --git a/src/mongo/db/repl.h b/src/mongo/db/repl.h
index f621262989c..8000fcc6506 100644
--- a/src/mongo/db/repl.h
+++ b/src/mongo/db/repl.h
@@ -94,7 +94,7 @@ namespace mongo {
     class ReplSource {
         shared_ptr<ThreadPool> tp;
 
-        void resync(string db);
+        void resync(const std::string& db);
 
         /** @param alreadyLocked caller already put us in write lock if true */
         void sync_pullOpLog_applyOperation(BSONObj& op, bool alreadyLocked);
diff --git a/src/mongo/db/repl/connections.h b/src/mongo/db/repl/connections.h
index 7254078ae34..22f2729d1fe 100644
--- a/src/mongo/db/repl/connections.h
+++ b/src/mongo/db/repl/connections.h
@@ -42,7 +42,7 @@ namespace mongo {
     class ScopedConn {
     public:
         /** throws assertions if connect failure etc. */
-        ScopedConn(string hostport);
+        ScopedConn(const std::string& hostport);
         ~ScopedConn() {
             // conLock releases...
         }
@@ -119,7 +119,7 @@ namespace mongo {
         }
     };
 
-    inline ScopedConn::ScopedConn(string hostport) : _hostport(hostport) {
+    inline ScopedConn::ScopedConn(const std::string& hostport) : _hostport(hostport) {
         bool first = false;
         {
             scoped_lock lk(mapMutex);
diff --git a/src/mongo/db/repl/health.h b/src/mongo/db/repl/health.h
index 0cb2f220d6f..52451a0c4c7 100644
--- a/src/mongo/db/repl/health.h
+++ b/src/mongo/db/repl/health.h
@@ -21,7 +21,13 @@
 namespace mongo {
 
     /* throws */
-    bool requestHeartbeat(string setname, string fromHost, string memberFullName, BSONObj& result, int myConfigVersion, int& theirConfigVersion, bool checkEmpty = false);
+    bool requestHeartbeat(const std::string& setname,
+                          const std::string& fromHost,
+                          const std::string& memberFullName,
+                          BSONObj& result,
+                          int myConfigVersion,
+                          int& theirConfigVersion,
+                          bool checkEmpty = false);
 
     struct HealthOptions {
         HealthOptions() :  
diff --git a/src/mongo/db/repl/heartbeat.cpp b/src/mongo/db/repl/heartbeat.cpp
index 875af670147..ee80eeee1a0 100644
--- a/src/mongo/db/repl/heartbeat.cpp
+++ b/src/mongo/db/repl/heartbeat.cpp
@@ -131,8 +131,13 @@ namespace mongo {
         }
     } cmdReplSetHeartbeat;
 
-    bool requestHeartbeat(string setName, string from, string memberFullName, BSONObj& result,
-                          int myCfgVersion, int& theirCfgVersion, bool checkEmpty) {
+    bool requestHeartbeat(const std::string& setName,
+                          const std::string& from,
+                          const std::string& memberFullName,
+                          BSONObj& result,
+                          int myCfgVersion,
+                          int& theirCfgVersion,
+                          bool checkEmpty) {
         if( replSetBlind ) {
             return false;
         }
diff --git a/src/mongo/db/repl/replset_commands.cpp b/src/mongo/db/repl/replset_commands.cpp
index 208601d59fd..a7dfa0c82c9 100644
--- a/src/mongo/db/repl/replset_commands.cpp
+++ b/src/mongo/db/repl/replset_commands.cpp
@@ -344,7 +344,7 @@ namespace mongo {
             return startsWith( url , "/_replSet" );
         }
 
-        virtual void handle( const char *rq, string url, BSONObj params,
+        virtual void handle( const char *rq, const std::string& url, BSONObj params,
                              string& responseMsg, int& responseCode,
                              vector<string>& headers,  const SockAddr &from ) {
 
diff --git a/src/mongo/db/repl/rs.cpp b/src/mongo/db/repl/rs.cpp
index 7045aedf1c0..9a7142cf8c7 100644
--- a/src/mongo/db/repl/rs.cpp
+++ b/src/mongo/db/repl/rs.cpp
@@ -54,7 +54,7 @@ namespace mongo {
         }
     }
 
-    void ReplSetImpl::sethbmsg(string s, int logLevel) {
+    void ReplSetImpl::sethbmsg(const std::string& s, int logLevel) {
         static time_t lastLogged;
         _hbmsgTime = time(0);
 
@@ -318,7 +318,10 @@ namespace mongo {
 
     /** @param cfgString <setname>/<seedhost1>,<seedhost2> */
 
-    void parseReplsetCmdLine(string cfgString, string& setname, vector<HostAndPort>& seeds, set<HostAndPort>& seedSet ) {
+    void parseReplsetCmdLine(const std::string& cfgString,
+                             string& setname,
+                             vector<HostAndPort>& seeds,
+                             set<HostAndPort>& seedSet ) {
         const char *p = cfgString.c_str();
         const char *slash = strchr(p, '/');
         if( slash )
diff --git a/src/mongo/db/repl/rs.h b/src/mongo/db/repl/rs.h
index e0425b42a6c..eeb79b1fd0b 100644
--- a/src/mongo/db/repl/rs.h
+++ b/src/mongo/db/repl/rs.h
@@ -294,14 +294,17 @@ namespace mongo {
         SP sp;
     };
 
-    void parseReplsetCmdLine(string cfgString, string& setname, vector<HostAndPort>& seeds, set<HostAndPort>& seedSet );
+    void parseReplsetCmdLine(const std::string& cfgString,
+                             string& setname,
+                             vector<HostAndPort>& seeds,
+                             set<HostAndPort>& seedSet);
 
     /** Parameter given to the --replSet command line option (parsed).
         Syntax is "<setname>/<seedhost1>,<seedhost2>"
         where setname is a name and seedhost is "<host>[:<port>]" */
     class ReplSetCmdline {
     public:
-        ReplSetCmdline(string cfgString) { parseReplsetCmdLine(cfgString, setname, seeds, seedSet); }
+        ReplSetCmdline(const std::string& cfgString) { parseReplsetCmdLine(cfgString, setname, seeds, seedSet); }
         string setname;
         vector<HostAndPort> seeds;
         set<HostAndPort> seedSet;
@@ -367,7 +370,7 @@ namespace mongo {
         char _hbmsg[256]; // we change this unlocked, thus not an stl::string
         time_t _hbmsgTime; // when it was logged
     public:
-        void sethbmsg(string s, int logLevel = 0);
+        void sethbmsg(const std::string& s, int logLevel = 0);
 
         /**
          * Election with Priorities
diff --git a/src/mongo/db/repl/rs_config.h b/src/mongo/db/repl/rs_config.h
index 945b422bc0f..a1e45f20edf 100644
--- a/src/mongo/db/repl/rs_config.h
+++ b/src/mongo/db/repl/rs_config.h
@@ -174,7 +174,7 @@ namespace mongo {
          */
         struct TagSubgroup : boost::noncopyable {
             ~TagSubgroup(); // never called; not defined
-            TagSubgroup(string nm) : name(nm) { }
+            TagSubgroup(const std::string& nm) : name(nm) { }
             const string name;
             OpTime last;
             vector<TagClause*> clauses;
diff --git a/src/mongo/db/repl/rs_initialsync.cpp b/src/mongo/db/repl/rs_initialsync.cpp
index eb56c634722..aa4104c4cff 100644
--- a/src/mongo/db/repl/rs_initialsync.cpp
+++ b/src/mongo/db/repl/rs_initialsync.cpp
@@ -67,7 +67,7 @@ namespace mongo {
     }
 
     /* todo : progress metering to sethbmsg. */
-    static bool clone(const char *master, string db, bool dataPass ) {
+    static bool clone(const char *master, const std::string& db, bool dataPass ) {
         CloneOptions options;
 
         options.fromDB = db;
diff --git a/src/mongo/db/restapi.cpp b/src/mongo/db/restapi.cpp
index 0f982b5fda8..da9a3fe48ef 100644
--- a/src/mongo/db/restapi.cpp
+++ b/src/mongo/db/restapi.cpp
@@ -49,7 +49,7 @@ namespace mongo {
                 url.find_last_of( '/' ) > 0;
         }
 
-        virtual void handle( const char *rq, string url, BSONObj params,
+        virtual void handle( const char *rq, const std::string& url, BSONObj params,
                              string& responseMsg, int& responseCode,
                              vector<string>& headers,  const SockAddr &from ) {
 
@@ -110,7 +110,11 @@ namespace mongo {
             responseMsg = ss.str();
         }
 
-        bool handleRESTQuery( string ns , string action , BSONObj & params , int & responseCode , stringstream & out ) {
+        bool handleRESTQuery( const std::string& ns,
+                              const std::string& action,
+                              BSONObj & params,
+                              int & responseCode,
+                              stringstream & out ) {
             Timer t;
 
             int html = _getOption( params["html"] , 0 );
@@ -208,7 +212,11 @@ namespace mongo {
         }
 
         // TODO Generate id and revision per couch POST spec
-        void handlePost( string ns, const char *body, BSONObj& params, int & responseCode, stringstream & out ) {
+        void handlePost( const std::string& ns,
+                         const char *body,
+                         BSONObj& params,
+                         int & responseCode,
+                         stringstream & out ) {
             try {
                 BSONObj obj = fromjson( body );
                 db.insert( ns.c_str(), obj );
diff --git a/src/mongo/s/config.cpp b/src/mongo/s/config.cpp
index fa3d43defce..966c977e6cc 100644
--- a/src/mongo/s/config.cpp
+++ b/src/mongo/s/config.cpp
@@ -427,7 +427,7 @@ namespace mongo {
         return ci.getCM();
     }
 
-    void DBConfig::setPrimary( string s ) {
+    void DBConfig::setPrimary( const std::string& s ) {
         scoped_lock lk( _lock );
         _primary.reset( s );
         _save();
@@ -711,7 +711,7 @@ namespace mongo {
     ConfigServer::~ConfigServer() {
     }
 
-    bool ConfigServer::init( string s ) {
+    bool ConfigServer::init( const std::string& s ) {
         vector<string> configdbs;
         splitStringDelim( s, &configdbs, ',' );
         return init( configdbs );
@@ -963,7 +963,7 @@ namespace mongo {
         }
     }
 
-    string ConfigServer::getHost( string name , bool withPort ) {
+    string ConfigServer::getHost( const std::string& name , bool withPort ) {
         if ( name.find( ":" ) != string::npos ) {
             if ( withPort )
                 return name;
diff --git a/src/mongo/s/config.h b/src/mongo/s/config.h
index 7286e829e4a..788683e82d3 100644
--- a/src/mongo/s/config.h
+++ b/src/mongo/s/config.h
@@ -164,7 +164,7 @@ namespace mongo {
             return _primary;
         }
 
-        void setPrimary( string s );
+        void setPrimary( const std::string& s );
 
         bool load();
         bool reload();
@@ -226,7 +226,7 @@ namespace mongo {
         */
         bool init( vector<string> configHosts );
 
-        bool init( string s );
+        bool init( const std::string& s );
 
         bool allUp();
         bool allUp( string& errmsg );
@@ -268,7 +268,7 @@ namespace mongo {
         bool checkConfigServersConsistent( string& errmsg , int tries = 4 ) const;
 
     private:
-        string getHost( string name , bool withPort );
+        string getHost( const std::string& name , bool withPort );
         vector<string> _config;
     };
 
diff --git a/src/mongo/s/d_migrate.cpp b/src/mongo/s/d_migrate.cpp
index 138081fe376..7cca533cd16 100644
--- a/src/mongo/s/d_migrate.cpp
+++ b/src/mongo/s/d_migrate.cpp
@@ -256,7 +256,7 @@ namespace mongo {
             _memoryUsed = 0;
         }
 
-        void start( string ns ,
+        void start( const std::string& ns ,
                     const BSONObj& min ,
                     const BSONObj& max ,
                     const BSONObj& shardKeyPattern ) {
@@ -650,7 +650,7 @@ namespace mongo {
     } migrateFromStatus;
 
     struct MigrateStatusHolder {
-        MigrateStatusHolder( string ns ,
+        MigrateStatusHolder( const std::string& ns ,
                              const BSONObj& min ,
                              const BSONObj& max ,
                              const BSONObj& shardKeyPattern ) {
diff --git a/src/mongo/s/grid.cpp b/src/mongo/s/grid.cpp
index 4f40b8dfc79..5c972a7f5f0 100644
--- a/src/mongo/s/grid.cpp
+++ b/src/mongo/s/grid.cpp
@@ -134,7 +134,7 @@ namespace mongo {
         return dbConfig;
     }
 
-    void Grid::removeDB( string database ) {
+    void Grid::removeDB( const std::string& database ) {
         uassert( 10186 ,  "removeDB expects db name" , database.find( '.' ) == string::npos );
         scoped_lock l( _lock );
         _databases.erase( database );
@@ -554,7 +554,7 @@ namespace mongo {
         _databases.clear();
     }
 
-    BSONObj Grid::getConfigSetting( string name ) const {
+    BSONObj Grid::getConfigSetting( const std::string& name ) const {
         scoped_ptr<ScopedDbConnection> conn( ScopedDbConnection::getInternalScopedDbConnection(
                 configServer.getPrimary().getConnString() ) );
         BSONObj result = conn->get()->findOne( ShardNS::settings, BSON( "_id" << name ) );
diff --git a/src/mongo/s/grid.h b/src/mongo/s/grid.h
index ba8886317bc..a3fd0c1cd5b 100644
--- a/src/mongo/s/grid.h
+++ b/src/mongo/s/grid.h
@@ -45,7 +45,7 @@ namespace mongo {
          * removes db entry.
          * on next getDBConfig call will fetch from db
          */
-        void removeDB( string db );
+        void removeDB( const std::string& db );
 
         /**
          * removes db entry - only this DBConfig object will be removed,
@@ -106,7 +106,7 @@ namespace mongo {
          * @param name identifies a particular type of configuration data.
          * @return a BSON object containing the requested data.
          */
-        BSONObj getConfigSetting( string name ) const;
+        BSONObj getConfigSetting( const std::string& name ) const;
 
         unsigned long long getNextOpTime() const;
         
diff --git a/src/mongo/scripting/engine.cpp b/src/mongo/scripting/engine.cpp
index 9da44fe9b3e..7be1b471f2d 100644
--- a/src/mongo/scripting/engine.cpp
+++ b/src/mongo/scripting/engine.cpp
@@ -342,7 +342,7 @@ namespace mongo {
 
     class PooledScope : public Scope {
     public:
-        PooledScope( const string pool , Scope * real ) : _pool( pool ) , _real( real ) {
+        PooledScope( const std::string& pool , Scope * real ) : _pool( pool ) , _real( real ) {
             _real->loadStored( true );
         };
         virtual ~PooledScope() {
diff --git a/src/mongo/scripting/engine_spidermonkey.cpp b/src/mongo/scripting/engine_spidermonkey.cpp
index 4909ddd9763..a69c526b371 100644
--- a/src/mongo/scripting/engine_spidermonkey.cpp
+++ b/src/mongo/scripting/engine_spidermonkey.cpp
@@ -335,7 +335,11 @@ namespace mongo {
             b.appendRegex( name , s.substr( 0 , end ) , s.substr( end + 1 ) );
         }
 
-        void append( BSONObjBuilder& b , string name , jsval val , BSONType oldType = EOO , const TraverseStack& stack=TraverseStack() ) {
+        void append( BSONObjBuilder& b,
+                     const std::string& name,
+                     jsval val,
+                     BSONType oldType = EOO,
+                     const TraverseStack& stack=TraverseStack() ) {
             //cout << "name: " << name << "\t" << typeString( val ) << " oldType: " << oldType << endl;
             switch ( JS_TypeOfValue( _context , val ) ) {
 
@@ -1857,7 +1861,7 @@ namespace mongo {
                            readOnlyRecv );
         }
 
-        void gotError( string s ) {
+        void gotError( const std::string& s ) {
             _error = s;
         }
 
diff --git a/src/mongo/shell/dbshell.cpp b/src/mongo/shell/dbshell.cpp
index 608c8ab77c7..0d8258b736a 100644
--- a/src/mongo/shell/dbshell.cpp
+++ b/src/mongo/shell/dbshell.cpp
@@ -243,7 +243,7 @@ void setupSignals() {
     set_terminate( myterminate );
 }
 
-string fixHost( string url , string host , string port ) {
+string fixHost( const std::string& url, const std::string& host, const std::string& port ) {
     //cout << "fixHost url: " << url << " host: " << host << " port: " << port << endl;
 
     if ( host.size() == 0 && port.size() == 0 ) {
@@ -264,10 +264,7 @@ string fixHost( string url , string host , string port ) {
         ::_exit(-1);
     }
 
-    if ( host.size() == 0 )
-        host = "127.0.0.1";
-
-    string newurl = host;
+    string newurl( ( host.size() == 0 ) ? "127.0.0.1" : host );
     if ( port.size() > 0 )
         newurl += ":" + port;
     else if ( host.find(':') == string::npos ) {
@@ -288,14 +285,14 @@ bool isOpSymbol( char c ) {
     return false;
 }
 
-bool isUseCmd( string code ) {
+bool isUseCmd( const std::string& code ) {
     string cmd = code;
     if ( cmd.find( " " ) > 0 )
         cmd = cmd.substr( 0 , cmd.find( " " ) );
     return cmd == "use";
 }
 
-bool isBalanced( string code ) {
+bool isBalanced( const std::string& code ) {
     if (isUseCmd( code ))
         return true;  // don't balance "use <dbname>" in case dbname contains special chars
     int curlyBrackets = 0;
diff --git a/src/mongo/util/assert_util.cpp b/src/mongo/util/assert_util.cpp
index b1c1d2321ca..49d1e7967d6 100644
--- a/src/mongo/util/assert_util.cpp
+++ b/src/mongo/util/assert_util.cpp
@@ -161,7 +161,7 @@ namespace mongo {
         throw MsgAssertionException(msgid, msg);
     }
 
-    NOINLINE_DECL void streamNotGood( int code , string msg , std::ios& myios ) {
+    NOINLINE_DECL void streamNotGood( int code , const std::string& msg , std::ios& myios ) {
         stringstream ss;
         // errno might not work on all systems for streams
         // if it doesn't for a system should deal with here
diff --git a/src/mongo/util/assert_util.h b/src/mongo/util/assert_util.h
index 8ae7ad8863f..c35911aa9e6 100644
--- a/src/mongo/util/assert_util.h
+++ b/src/mongo/util/assert_util.h
@@ -219,9 +219,9 @@ namespace mongo {
     enum { ASSERT_ID_DUPKEY = 11000 };
 
     /* throws a uassertion with an appropriate msg */
-    MONGO_COMPILER_NORETURN void streamNotGood( int code , std::string msg , std::ios& myios );
+    MONGO_COMPILER_NORETURN void streamNotGood( int code, const std::string& msg, std::ios& myios );
 
-    inline void assertStreamGood(unsigned msgid, std::string msg, std::ios& myios) {
+    inline void assertStreamGood(unsigned msgid, const std::string& msg, std::ios& myios) {
         if( !myios.good() ) streamNotGood(msgid, msg, myios);
     }
 
diff --git a/src/mongo/util/concurrency/msg.h b/src/mongo/util/concurrency/msg.h
index 6e8a3980246..6b1badd55e3 100644
--- a/src/mongo/util/concurrency/msg.h
+++ b/src/mongo/util/concurrency/msg.h
@@ -35,7 +35,7 @@ namespace mongo {
             /** send a message to the port */
             void send(lam);
 
-            Server(string name) : m("server"), _name(name), rq(false) { }
+            Server(const std::string& name) : m("server"), _name(name), rq(false) { }
             virtual ~Server() { }
 
             /** send message but block until function completes */
diff --git a/src/mongo/util/concurrency/race.h b/src/mongo/util/concurrency/race.h
index 71bf7fde5dd..d5add6abe52 100644
--- a/src/mongo/util/concurrency/race.h
+++ b/src/mongo/util/concurrency/race.h
@@ -48,7 +48,7 @@ namespace mongo {
                 if( --n != 0 ) fail();
             }
         public:
-            Block(string f, unsigned l) : n(0), ncalls(0), file(f), line(l) { }
+            Block(const std::string& f, unsigned l) : n(0), ncalls(0), file(f), line(l) { }
             ~Block() { 
                 if( ncalls > 1000000 ) { 
                     // just so we know if we are slowing things down
diff --git a/src/mongo/util/goodies.h b/src/mongo/util/goodies.h
index d2752dac72c..202d98920e1 100644
--- a/src/mongo/util/goodies.h
+++ b/src/mongo/util/goodies.h
@@ -82,7 +82,9 @@ namespace mongo {
         if ( strlen(str) < l ) return false;
         return strncmp(str, prefix, l) == 0;
     }
-    inline bool startsWith(string s, string p) { return startsWith(s.c_str(), p.c_str()); }
+    inline bool startsWith(const std::string& s, const std::string& p) {
+        return startsWith(s.c_str(), p.c_str());
+    }
 
     inline bool endsWith(const char *p, const char *suffix) {
         size_t a = strlen(p);
diff --git a/src/mongo/util/log.h b/src/mongo/util/log.h
index 15ab06dc0df..f983f71619d 100644
--- a/src/mongo/util/log.h
+++ b/src/mongo/util/log.h
@@ -94,7 +94,7 @@ namespace mongo {
             return LabeledLevel( _label + string("::") + label, _level );
         }
 
-        LabeledLevel operator+( string& label ) const {
+        LabeledLevel operator+( const std::string& label ) const {
             return LabeledLevel( _label + string("::") + label, _level );
         }
 
diff --git a/src/mongo/util/logfile.cpp b/src/mongo/util/logfile.cpp
index d5aa99ee743..23b3b597e19 100644
--- a/src/mongo/util/logfile.cpp
+++ b/src/mongo/util/logfile.cpp
@@ -57,7 +57,7 @@ namespace mongo {
 
 namespace mongo {
 
-    LogFile::LogFile(string name, bool readwrite) : _name(name) {
+    LogFile::LogFile(const std::string& name, bool readwrite) : _name(name) {
         _fd = CreateFile(
                   toNativeString(name.c_str()).c_str(),
                   (readwrite?GENERIC_READ:0)|GENERIC_WRITE,
@@ -147,7 +147,7 @@ namespace mongo {
 
 namespace mongo {
 
-    LogFile::LogFile(string name, bool readwrite) : _name(name) {
+    LogFile::LogFile(const std::string& name, bool readwrite) : _name(name) {
         int options = O_CREAT
                     | (readwrite?O_RDWR:O_WRONLY)
 #if defined(O_DIRECT)
diff --git a/src/mongo/util/logfile.h b/src/mongo/util/logfile.h
index e41ecc2f6ec..496b62c63e0 100644
--- a/src/mongo/util/logfile.h
+++ b/src/mongo/util/logfile.h
@@ -25,7 +25,7 @@ namespace mongo {
         /** create the file and open.  must not already exist.
             throws UserAssertion on i/o error
         */
-        LogFile(string name, bool readwrite = false);
+        LogFile(const std::string& name, bool readwrite = false);
 
         /** closes */
         ~LogFile();
diff --git a/src/mongo/util/md5.hpp b/src/mongo/util/md5.hpp
index dc061719747..8974751054f 100644
--- a/src/mongo/util/md5.hpp
+++ b/src/mongo/util/md5.hpp
@@ -50,7 +50,7 @@ namespace mongo {
         return digestToString( d );
     }
 
-    inline std::string md5simpledigest( string s ){
+    inline std::string md5simpledigest( const std::string& s ){
         return md5simpledigest(s.data(), s.size());
     }
 
diff --git a/src/mongo/util/mmap.cpp b/src/mongo/util/mmap.cpp
index bedbd70fb44..756f46e4c07 100644
--- a/src/mongo/util/mmap.cpp
+++ b/src/mongo/util/mmap.cpp
@@ -44,7 +44,7 @@ namespace mongo {
     /* Create. Must not exist.
     @param zero fill file with zeros when true
     */
-    void* MemoryMappedFile::create(string filename, unsigned long long len, bool zero) {
+    void* MemoryMappedFile::create(const std::string& filename, unsigned long long len, bool zero) {
         uassert( 13468, string("can't create file already exists ") + filename, ! boost::filesystem::exists(filename) );
         void *p = map(filename.c_str(), len);
         if( p && zero ) {
@@ -190,7 +190,7 @@ namespace mongo {
         mmfiles.insert(this);
     }
 
-    void MongoFile::setFilename(string fn) {
+    void MongoFile::setFilename(const std::string& fn) {
         LockMongoFilesExclusive lk;
         verify( _filename.empty() );
         _filename = fn;
diff --git a/src/mongo/util/mmap.h b/src/mongo/util/mmap.h
index 03be7b535e2..da5f28ef627 100644
--- a/src/mongo/util/mmap.h
+++ b/src/mongo/util/mmap.h
@@ -99,7 +99,7 @@ namespace mongo {
         virtual bool isMongoMMF() { return false; }
 
         string filename() const { return _filename; }
-        void setFilename(string fn);
+        void setFilename(const std::string& fn);
 
     private:
         string _filename;
@@ -142,7 +142,7 @@ namespace mongo {
         /** @return The MongoFile object associated with the specified file name.  If no file is open
                     with the specified name, returns null.
         */
-        MongoFile* findByPath(string path) {
+        MongoFile* findByPath(const std::string& path) {
             map<string,MongoFile*>::iterator i = MongoFile::pathToFile.find(path);
             return  i == MongoFile::pathToFile.end() ? NULL : i->second;
         }
@@ -185,7 +185,7 @@ namespace mongo {
         /* Create. Must not exist.
            @param zero fill file with zeros when true
         */
-        void* create(string filename, unsigned long long len, bool zero);
+        void* create(const std::string& filename, unsigned long long len, bool zero);
 
         void flush(bool sync);
         virtual Flushable * prepareFlush();
diff --git a/src/mongo/util/mmap_win.cpp b/src/mongo/util/mmap_win.cpp
index 55cdc1ddeb8..50936f637de 100644
--- a/src/mongo/util/mmap_win.cpp
+++ b/src/mongo/util/mmap_win.cpp
@@ -328,7 +328,10 @@ namespace mongo {
 
     class WindowsFlushable : public MemoryMappedFile::Flushable {
     public:
-        WindowsFlushable( void * view , HANDLE fd , string filename , boost::shared_ptr<mutex> flushMutex )
+        WindowsFlushable( void * view,
+                          HANDLE fd,
+                          const std::string& filename,
+                          boost::shared_ptr<mutex> flushMutex )
             : _view(view) , _fd(fd) , _filename(filename) , _flushMutex(flushMutex)
         {}
 
diff --git a/src/mongo/util/mongoutils/html.h b/src/mongo/util/mongoutils/html.h
index b9757e8997e..d1c96c549b1 100644
--- a/src/mongo/util/mongoutils/html.h
+++ b/src/mongo/util/mongoutils/html.h
@@ -37,7 +37,7 @@ namespace mongoutils {
         inline string _tr() { return "</tr>\n"; }
 
         inline string tr() { return "<tr>"; }
-        inline string tr(string a, string b) {
+        inline string tr(const std::string& a, const std::string& b) {
             stringstream ss;
             ss << "<tr><td>" << a << "</td><td>" << b << "</td></tr>\n";
             return ss.str();
@@ -48,10 +48,10 @@ namespace mongoutils {
             ss << "<td>" << x << "</td>";
             return ss.str();
         }
-        inline string td(string x) {
+        inline string td(const std::string& x) {
             return "<td>" + x + "</td>";
         }
-        inline string th(string x) {
+        inline string th(const std::string& x) {
             return "<th>" + x + "</th>";
         }
 
@@ -80,7 +80,7 @@ namespace mongoutils {
             return ss.str();
         }
 
-        inline string start(string title) {
+        inline string start(const std::string& title) {
             stringstream ss;
             ss << "<html><head>\n<title>";
             ss << title;
@@ -97,51 +97,53 @@ namespace mongoutils {
             return ss.str();
         }
 
-        inline string red(string contentHtml, bool color=true) {
+        inline string red(const std::string& contentHtml, bool color=true) {
             if( !color ) return contentHtml;
             stringstream ss;
             ss << "<span style=\"color:#A00;\">" << contentHtml << "</span>";
             return ss.str();
         }
-        inline string grey(string contentHtml, bool color=true) {
+        inline string grey(const std::string& contentHtml, bool color=true) {
             if( !color ) return contentHtml;
             stringstream ss;
             ss << "<span style=\"color:#888;\">" << contentHtml << "</span>";
             return ss.str();
         }
-        inline string blue(string contentHtml, bool color=true) {
+        inline string blue(const std::string& contentHtml, bool color=true) {
             if( !color ) return contentHtml;
             stringstream ss;
             ss << "<span style=\"color:#00A;\">" << contentHtml << "</span>";
             return ss.str();
         }
-        inline string yellow(string contentHtml, bool color=true) {
+        inline string yellow(const std::string& contentHtml, bool color=true) {
             if( !color ) return contentHtml;
             stringstream ss;
             ss << "<span style=\"color:#A80;\">" << contentHtml << "</span>";
             return ss.str();
         }
-        inline string green(string contentHtml, bool color=true) {
+        inline string green(const std::string& contentHtml, bool color=true) {
             if( !color ) return contentHtml;
             stringstream ss;
             ss << "<span style=\"color:#0A0;\">" << contentHtml << "</span>";
             return ss.str();
         }
 
-        inline string p(string contentHtml) {
+        inline string p(const std::string& contentHtml) {
             stringstream ss;
             ss << "<p>" << contentHtml << "</p>\n";
             return ss.str();
         }
 
-        inline string h2(string contentHtml) {
+        inline string h2(const std::string& contentHtml) {
             stringstream ss;
             ss << "<h2>" << contentHtml << "</h2>\n";
             return ss.str();
         }
 
         /* does NOT escape the strings. */
-        inline string a(string href, string title="", string contentHtml = "") {
+        inline string a(const std::string& href,
+                        const std::string& title="",
+                        const std::string& contentHtml = "") {
             stringstream ss;
             ss << "<a";
             if( !href.empty() ) ss << " href=\"" << href << '"';
diff --git a/src/mongo/util/mongoutils/str.h b/src/mongo/util/mongoutils/str.h
index 9859f92f673..35589468309 100644
--- a/src/mongo/util/mongoutils/str.h
+++ b/src/mongo/util/mongoutils/str.h
@@ -37,8 +37,6 @@ namespace mongoutils {
 
     namespace str {
 
-        typedef std::string string;
-
         /** the idea here is to make one liners easy.  e.g.:
 
                return str::stream() << 1 << ' ' << 2;
@@ -67,13 +65,15 @@ namespace mongoutils {
             }
             return true;
         }
-        inline bool startsWith(string s, string p) { return startsWith(s.c_str(), p.c_str()); }
+        inline bool startsWith(const std::string& s, const std::string& p) {
+            return startsWith(s.c_str(), p.c_str());
+        }
 
         // while these are trivial today use in case we do different wide char things later
         inline bool startsWith(const char *p, char ch) { return *p == ch; }
-        inline bool startsWith(string s, char ch) { return startsWith(s.c_str(), ch); }
+        inline bool startsWith(const std::string& s, char ch) { return startsWith(s.c_str(), ch); }
 
-        inline bool endsWith(string s, string p) {
+        inline bool endsWith(const std::string& s, const std::string& p) {
             int l = p.size();
             int x = s.size();
             if( x < l ) return false;
@@ -91,9 +91,9 @@ namespace mongoutils {
             const char *p = strchr(s, x);
             return (p != 0) ? p+1 : "";
         }
-        inline string after(const string& s, char x) {
+        inline std::string after(const std::string& s, char x) {
             const char *p = strchr(s.c_str(), x);
-            return (p != 0) ? string(p+1) : "";
+            return (p != 0) ? std::string(p+1) : "";
         }
 
         /** find string x, and return rest of string thereafter, or "" if not found */
@@ -101,30 +101,30 @@ namespace mongoutils {
             const char *p = strstr(s, x);
             return (p != 0) ? p+strlen(x) : "";
         }
-        inline string after(string s, string x) {
+        inline std::string after(const std::string& s, const std::string& x) {
             const char *p = strstr(s.c_str(), x.c_str());
-            return (p != 0) ? string(p+x.size()) : "";
+            return (p != 0) ? std::string(p+x.size()) : "";
         }
 
         /** @return true if s contains x
          *  These should not be used with strings containing NUL bytes
          */
-        inline bool contains(string s, string x) {
+        inline bool contains(const std::string& s, const std::string& x) {
             return strstr(s.c_str(), x.c_str()) != 0;
         }
-        inline bool contains(string s, char x) {
+        inline bool contains(const std::string& s, char x) {
             verify(x != '\0'); // this expects c-strings so don't use when looking for NUL bytes
             return strchr(s.c_str(), x) != 0;
         }
 
         /** @return everything before the character x, else entire string */
-        inline string before(const string& s, char x) {
+        inline std::string before(const std::string& s, char x) {
             const char *p = strchr(s.c_str(), x);
             return (p != 0) ? s.substr(0, p-s.c_str()) : s;
         }
 
         /** @return everything before the string x, else entire string */
-        inline string before(const string& s, const string& x) {
+        inline std::string before(const std::string& s, const std::string& x) {
             const char *p = strstr(s.c_str(), x.c_str());
             return (p != 0) ? s.substr(0, p-s.c_str()) : s;
         }
@@ -142,11 +142,11 @@ namespace mongoutils {
             }
             return ofs;
         }
-        inline int shareCommonPrefix(const string &a, const string &b)
+        inline int shareCommonPrefix(const std::string &a, const std::string &b)
         { return shareCommonPrefix(a.c_str(), b.c_str()); }
 
         /** string to unsigned. zero if not a number. can end with non-num chars */
-        inline unsigned toUnsigned(const string& a) {
+        inline unsigned toUnsigned(const std::string& a) {
             unsigned x = 0;
             const char *p = a.c_str();
             while( 1 ) {
@@ -163,32 +163,32 @@ namespace mongoutils {
             and R is empty.
             @return true if char found
         */
-        inline bool splitOn(const string &s, char c, string& L, string& R) {
+        inline bool splitOn(const std::string &s, char c, std::string& L, std::string& R) {
             const char *start = s.c_str();
             const char *p = strchr(start, c);
             if( p == 0 ) {
                 L = s; R.clear();
                 return false;
             }
-            L = string(start, p-start);
-            R = string(p+1);
+            L = std::string(start, p-start);
+            R = std::string(p+1);
             return true;
         }
         /** split scanning reverse direction. Splits ONCE ONLY. */
-        inline bool rSplitOn(const string &s, char c, string& L, string& R) {
+        inline bool rSplitOn(const std::string &s, char c, std::string& L, std::string& R) {
             const char *start = s.c_str();
             const char *p = strrchr(start, c);
             if( p == 0 ) {
                 L = s; R.clear();
                 return false;
             }
-            L = string(start, p-start);
-            R = string(p+1);
+            L = std::string(start, p-start);
+            R = std::string(p+1);
             return true;
         }
 
         /** @return number of occurrences of c in s */
-        inline unsigned count( const string& s , char c ) {
+        inline unsigned count( const std::string& s , char c ) {
             unsigned n=0;
             for ( unsigned i=0; i<s.size(); i++ )
                 if ( s[i] == c )
@@ -197,15 +197,15 @@ namespace mongoutils {
         }
 
         /** trim leading spaces. spaces only, not tabs etc. */
-        inline string ltrim(const string& s) {
+        inline std::string ltrim(const std::string& s) {
             const char *p = s.c_str();
             while( *p == ' ' ) p++;
             return p;
         }
 
         /** remove trailing chars in place */
-        inline void stripTrailing(string& s, const char *chars) {
-            string::iterator i = s.end();
+        inline void stripTrailing(std::string& s, const char *chars) {
+            std::string::iterator i = s.end();
             while( s.begin() != i ) {
                 i--;
                 if( contains(chars, *i) ) {
diff --git a/src/mongo/util/net/hostandport.h b/src/mongo/util/net/hostandport.h
index 11acf5def25..f1e6bba58bb 100644
--- a/src/mongo/util/net/hostandport.h
+++ b/src/mongo/util/net/hostandport.h
@@ -33,10 +33,10 @@ namespace mongo {
         /** From a string hostname[:portnumber]
             Throws user assertion if bad config string or bad port #.
         */
-        HostAndPort(string s);
+        HostAndPort(const std::string& s);
 
         /** @param p port number. -1 is ok to use default. */
-        HostAndPort(string h, int p /*= -1*/) : _host(h), _port(p) { 
+        HostAndPort(const std::string& h, int p /*= -1*/) : _host(h), _port(p) { 
             verify( !str::startsWith(h, '#') );
         }
 
@@ -172,7 +172,7 @@ namespace mongo {
         }
     }
 
-    inline HostAndPort::HostAndPort(string s) {
+    inline HostAndPort::HostAndPort(const std::string& s) {
         init(s.c_str());
     }
 
diff --git a/src/mongo/util/net/httpclient.cpp b/src/mongo/util/net/httpclient.cpp
index e94475a1940..d39f10dba69 100644
--- a/src/mongo/util/net/httpclient.cpp
+++ b/src/mongo/util/net/httpclient.cpp
@@ -29,11 +29,11 @@ namespace mongo {
 #define HD(x)
 
 
-    int HttpClient::get( string url , Result * result ) {
+    int HttpClient::get( const std::string& url , Result * result ) {
         return _go( "GET" , url , 0 , result );
     }
 
-    int HttpClient::post( string url , string data , Result * result ) {
+    int HttpClient::post( const std::string& url , const std::string& data , Result * result ) {
         return _go( "POST" , url , data.c_str() , result );
     }
 
diff --git a/src/mongo/util/net/httpclient.h b/src/mongo/util/net/httpclient.h
index 4f6dd0d718d..08cee82d5d2 100644
--- a/src/mongo/util/net/httpclient.h
+++ b/src/mongo/util/net/httpclient.h
@@ -59,12 +59,12 @@ namespace mongo {
         /**
          * @return response code
          */
-        int get( string url , Result * result = 0 );
+        int get( const std::string& url , Result * result = 0 );
 
         /**
          * @return response code
          */
-        int post( string url , string body , Result * result = 0 );
+        int post( const std::string& url , const std::string& body , Result * result = 0 );
 
     private:
         int _go( const char * command , string url , const char * body , Result * result );
diff --git a/src/mongo/util/net/listen.h b/src/mongo/util/net/listen.h
index 4b98045e5a7..2ce8398a79c 100644
--- a/src/mongo/util/net/listen.h
+++ b/src/mongo/util/net/listen.h
@@ -152,7 +152,7 @@ namespace mongo {
             scoped_lock lk( _mutex );
             _sockets->insert( sock );
         }
-        void addPath( string path ) {
+        void addPath( const std::string& path ) {
             scoped_lock lk( _mutex );
             _socketPaths->insert( path );
         }
diff --git a/src/mongo/util/net/miniwebserver.cpp b/src/mongo/util/net/miniwebserver.cpp
index c0d1bf24fc4..3888c059914 100644
--- a/src/mongo/util/net/miniwebserver.cpp
+++ b/src/mongo/util/net/miniwebserver.cpp
@@ -175,7 +175,7 @@ namespace mongo {
         }
     }
 
-    string MiniWebServer::getHeader( const char * req , string wanted ) {
+    string MiniWebServer::getHeader( const char * req , const std::string& wanted ) {
         const char * headers = strchr( req , '\n' );
         if ( ! headers )
             return "";
diff --git a/src/mongo/util/net/miniwebserver.h b/src/mongo/util/net/miniwebserver.h
index 7690dfa2f7a..2f7d68cf3a9 100644
--- a/src/mongo/util/net/miniwebserver.h
+++ b/src/mongo/util/net/miniwebserver.h
@@ -46,11 +46,11 @@ namespace mongo {
 
         static string parseURL( const char * buf );
         static string parseMethod( const char * headers );
-        static string getHeader( const char * headers , string name );
+        static string getHeader( const char * headers , const std::string& name );
         static const char *body( const char *buf );
 
         static string urlDecode(const char* s);
-        static string urlDecode(string s) {return urlDecode(s.c_str());}
+        static string urlDecode(const std::string& s) {return urlDecode(s.c_str());}
 
     private:
         void accepted(boost::shared_ptr<Socket> psocket, long long connectionId );
diff --git a/src/mongo/util/net/sock.h b/src/mongo/util/net/sock.h
index 436998e7a09..fc13017b97f 100644
--- a/src/mongo/util/net/sock.h
+++ b/src/mongo/util/net/sock.h
@@ -132,7 +132,7 @@ namespace mongo {
     public:
         const enum Type { CLOSED , RECV_ERROR , SEND_ERROR, RECV_TIMEOUT, SEND_TIMEOUT, FAILED_STATE, CONNECT_ERROR } _type;
         
-        SocketException( Type t , string server , int code = 9001 , string extra="" ) 
+        SocketException( Type t , const std::string& server , int code = 9001 , const std::string& extra="" ) 
             : DBException( (string)"socket exception ["  + _getStringType( t ) + "] for " + server, code ),
               _type(t),
               _server(server),
diff --git a/src/mongo/util/ntservice.cpp b/src/mongo/util/ntservice.cpp
index 92dfa7d8990..1eed0b7459b 100644
--- a/src/mongo/util/ntservice.cpp
+++ b/src/mongo/util/ntservice.cpp
@@ -40,7 +40,7 @@ namespace mongo {
     // returns true if the service is started.
     bool serviceParamsCheck(
             boost::program_options::variables_map& params,
-            const std::string dbpath,
+            const std::string& dbpath,
             const ntServiceDefaultStrings& defaultStrings,
             const vector<string>& disallowedOptions,
             int argc,
@@ -177,7 +177,7 @@ namespace mongo {
             const wstring& serviceDesc,
             const wstring& serviceUser,
             const wstring& servicePassword,
-            const std::string dbpath,
+            const std::string& dbpath,
             int argc,
             char* argv[]
     ) {
diff --git a/src/mongo/util/ntservice.h b/src/mongo/util/ntservice.h
index 4492c317e27..8ce43feeed3 100644
--- a/src/mongo/util/ntservice.h
+++ b/src/mongo/util/ntservice.h
@@ -32,7 +32,7 @@ namespace mongo {
     typedef bool ( *ServiceCallback )( void );
     bool serviceParamsCheck(
             boost::program_options::variables_map& params,
-            const std::string dbpath,
+            const std::string& dbpath,
             const ntServiceDefaultStrings& defaultStrings,
             const vector<string>& disallowedOptions,
             int argc,
@@ -50,7 +50,7 @@ namespace mongo {
                 const std::wstring& serviceDesc,
                 const std::wstring& serviceUser,
                 const std::wstring& servicePassword,
-                const std::string dbpath,
+                const std::string& dbpath,
                 int argc,
                 char* argv[]
         );
diff --git a/src/mongo/util/paths.h b/src/mongo/util/paths.h
index 5ba3c64d8ae..e7ca6d5d17c 100644
--- a/src/mongo/util/paths.h
+++ b/src/mongo/util/paths.h
@@ -39,7 +39,7 @@ namespace mongo {
 
         bool empty() const { return _p.empty(); }
 
-        static RelativePath fromRelativePath(string f) {
+        static RelativePath fromRelativePath(const std::string& f) {
             RelativePath rp;
             rp._p = f;
             return rp;
diff --git a/src/mongo/util/progress_meter.h b/src/mongo/util/progress_meter.h
index 50a1133a5cb..6da0c14fc0a 100644
--- a/src/mongo/util/progress_meter.h
+++ b/src/mongo/util/progress_meter.h
@@ -46,7 +46,7 @@ namespace mongo {
          */
         bool hit( int n = 1 );
 
-        void setUnits( std::string units ) { _units = units; }
+        void setUnits( const std::string& units ) { _units = units; }
         std::string getUnit() const { return _units; }
 
         void setTotalWhileRunning( unsigned long long total ) {
diff --git a/src/mongo/util/ramlog.cpp b/src/mongo/util/ramlog.cpp
index 12e8ba0921e..e61d78863f0 100644
--- a/src/mongo/util/ramlog.cpp
+++ b/src/mongo/util/ramlog.cpp
@@ -25,7 +25,7 @@ namespace mongo {
 
     using namespace mongoutils;
 
-    RamLog::RamLog( string name ) : _name(name), _lastWrite(0) {
+    RamLog::RamLog( const std::string& name ) : _name(name), _lastWrite(0) {
         h = 0; n = 0;
         for( int i = 0; i < N; i++ )
             lines[i][C-1] = 0;
@@ -47,7 +47,7 @@ namespace mongo {
         
     }
 
-    void RamLog::write(LogLevel ll, const string& str) {
+    void RamLog::write(LogLevel ll, const std::string& str) {
         _lastWrite = time(0);
 
         char *p = lines[(h+n)%N];
@@ -96,7 +96,7 @@ namespace mongo {
         return v[i];
     }
 
-    string RamLog::color(string line) {
+    string RamLog::color(const std::string& line) {
         string s = str::after(line, "replSet ");
         if( str::startsWith(s, "warning") || startsWith(s, "error") )
             return html::red(line);
@@ -161,7 +161,7 @@ namespace mongo {
     // static things
     // ---------------
 
-    RamLog* RamLog::get( string name ) {
+    RamLog* RamLog::get( const std::string& name ) {
         if ( ! _named )
             return 0;
 
diff --git a/src/mongo/util/ramlog.h b/src/mongo/util/ramlog.h
index d3d5c8fbb4e..889f4f6a4e2 100644
--- a/src/mongo/util/ramlog.h
+++ b/src/mongo/util/ramlog.h
@@ -23,7 +23,7 @@ namespace mongo {
 
     class RamLog : public Tee {
     public:
-        RamLog( string name );
+        RamLog( const std::string& name );
 
         virtual void write(LogLevel ll, const string& str);
 
@@ -31,7 +31,7 @@ namespace mongo {
 
         void toHTML(stringstream& s);
 
-        static RamLog* get( string name );
+        static RamLog* get( const std::string& name );
         static void getNames( vector<string>& names );
 
         time_t lastWrite() { return _lastWrite; } // 0 if no writes
@@ -39,7 +39,7 @@ namespace mongo {
     protected:
         static int repeats(const vector<const char *>& v, int i);
         static string clean(const vector<const char *>& v, int i, string line="");
-        static string color(string line);
+        static string color(const std::string& line);
 
         /* turn http:... into an anchor */
         static string linkify(const char *s);
diff --git a/src/mongo/util/text.cpp b/src/mongo/util/text.cpp
index 9308c0a333a..59592b9a49d 100644
--- a/src/mongo/util/text.cpp
+++ b/src/mongo/util/text.cpp
@@ -99,7 +99,7 @@ namespace mongo {
 
     }
 
-    bool isValidUTF8(string s) { 
+    bool isValidUTF8(const std::string& s) { 
         return isValidUTF8(s.c_str()); 
     }
 
diff --git a/src/mongo/util/text.h b/src/mongo/util/text.h
index 96f88285299..40ee2cbae2d 100644
--- a/src/mongo/util/text.h
+++ b/src/mongo/util/text.h
@@ -70,7 +70,7 @@ namespace mongo {
      * guarantee that the codepoints are valid.
      */
     bool isValidUTF8(const char *s);
-    bool isValidUTF8(std::string s);
+    bool isValidUTF8(const std::string& s);
 
     // expect that n contains a base ten number and nothing else after it
     // NOTE win version hasn't been tested directly