fix checks that operations cannot be performed on slaves; also, allow read operations on

--slave instances (but not repl pair nonmasters)

8 files changed, 21 insertions, 13 deletions

diff --git a/db/db.cpp b/db/db.cpp
index 4ac096696ab..3fdfdbb2625 100644
--- a/db/db.cpp
+++ b/db/db.cpp
@@ -360,7 +360,7 @@ namespace mongo {
         bool is32bit = sizeof(int*) == 4;
 
         log() << "Mongo DB : starting : pid = " << pid << " port = " << port << " dbpath = " << dbpath
-              <<  " master = " << master << " slave = " << slave << "  " << ( is32bit ? "32" : "64" ) << "-bit " << endl;
+              <<  " master = " << master << " slave = " << (int) slave << "  " << ( is32bit ? "32" : "64" ) << "-bit " << endl;
 
         show_32_warning();
 
@@ -670,7 +670,7 @@ int main(int argc, char* argv[], char *envp[] )
             master = true;
         }
         if (params.count("slave")) {
-            slave = true;
+			slave = SimpleSlave;
         }
         if (params.count("source")) {
             /* specifies what the source in local.sources should be */
diff --git a/db/dbcommands.cpp b/db/dbcommands.cpp
index 0c72bdf5319..0a57387e1c2 100644
--- a/db/dbcommands.cpp
+++ b/db/dbcommands.cpp
@@ -630,7 +630,8 @@ namespace mongo {
             return false;
         }
         virtual bool slaveOk() {
-            return false;
+			// ok on --slave setups, not ok for nonmaster of a repl pair (unless override)
+            return slave == SimpleSlave;
         }
         virtual bool slaveOverrideOk() {
             return true;
diff --git a/db/instance.cpp b/db/instance.cpp
index a63799a8cbf..959460e0a7c 100644
--- a/db/instance.cpp
+++ b/db/instance.cpp
@@ -41,7 +41,7 @@ namespace mongo {
 #define LOGSOME if( ++nloggedsome < 1000 || nloggedsome % 100 == 0 )
 
     bool quota = false;
-    bool slave = false;
+    SlaveTypes slave = NotSlave;
     bool master = false; // true means keep an op log
     extern int curOp;
     bool autoresync = false;
@@ -377,9 +377,6 @@ namespace mongo {
                 }
             }
 
-            // Check before setClient() to avoid creating ns unnecessarily.
-            uassert( "not master", isMasterNs( q.ns ) || (q.queryOptions & Option_SlaveOk) || strstr( q.ns, ".$cmd" ) );
-            
             setClient( q.ns );
             Top::setRead();
             strncpy(currentOp.ns, q.ns, Namespace::MaxNsLen);
diff --git a/db/query.cpp b/db/query.cpp
index 7051ad68fb3..7fdf3197bdd 100644
--- a/db/query.cpp
+++ b/db/query.cpp
@@ -1355,8 +1355,12 @@ namespace mongo {
             
             AuthenticationInfo *ai = authInfo.get();
             uassert("unauthorized", ai->isAuthorized(database->name.c_str()));
-            
-            uassert( "not master", isMaster() || (queryOptions & Option_SlaveOk) );
+
+			/* we allow queries to SimpleSlave's -- but not to the slave (nonmaster) member of a replica pair 
+			   so that queries to a pair are realtime consistent as much as possible.  use setSlaveOk() to 
+			   query the nonmaster member of a replica pair.
+			*/
+            uassert( "not master", isMaster() || (queryOptions & Option_SlaveOk) || slave == SimpleSlave );
 
             BSONElement hint;
             BSONObj min;
diff --git a/db/repl.cpp b/db/repl.cpp
index d00da01dd6a..05b8673cc70 100644
--- a/db/repl.cpp
+++ b/db/repl.cpp
@@ -1651,9 +1651,12 @@ namespace mongo {
         }
 
         if ( slave || replPair ) {
-            if ( slave )
+            if ( slave ) {
+				assert( slave == SimpleSlave );
                 log(1) << "slave=true" << endl;
-            slave = true;
+			}
+			else
+				slave = ReplPairSlave;
             boost::thread repl_thread(replSlaveThread);
         }
 
diff --git a/db/repl.h b/db/repl.h
index dfba8185670..10ebc67de85 100644
--- a/db/repl.h
+++ b/db/repl.h
@@ -41,7 +41,9 @@ namespace mongo {
 
     class DBClientConnection;
     class DBClientCursor;
-    extern bool slave;
+	// --slave = SimpleSlave
+	typedef enum { NotSlave=0, SimpleSlave, ReplPairSlave } SlaveTypes;
+	extern SlaveTypes slave;
     extern bool master;
     extern int opIdMem;
     
diff --git a/db/replset.h b/db/replset.h
index 686c71157e2..71b94f33f8e 100644
--- a/db/replset.h
+++ b/db/replset.h
@@ -112,7 +112,7 @@ namespace mongo {
     inline bool isMaster( const char *client = 0 ) {
         if ( !client )
             client = database->name.c_str();
-        if ( replAllDead ) {
+        if ( replAllDead || slave ) {
             return strcmp( client, "local" ) == 0;
         }
 
diff --git a/shell/db.js b/shell/db.js
index be5150bdbb4..0272baf9dff 100644
--- a/shell/db.js
+++ b/shell/db.js
@@ -239,6 +239,7 @@ DB.prototype.help = function() {
     print("DB methods:");
     print("\tdb.auth(username, password)");
     print("\tdb.getMongo() get the server connection object");
+	print("\tdb.getMongo().setSlaveOk() allow this connection to read from the nonmaster member of a replica pair");
     print("\tdb.getSisterDB(name) get the db at the same server as this onew");
     print("\tdb.getName()");
     print("\tdb.getCollection(cname) same as db['cname'] or db.cname");