SERVER-18131 Clean up LastError.

Makes LastError a decoration on Client.  Removes behavior that was specific to
the dbKillCursors wire protocol message into the processing for that message,
and out of last error.  Simplifies lifetime of LastError.  It always exists on
Clients, so there's no checking for its existence, and no passing it around
through parts of the networking library.

1 files changed, 60 insertions, 90 deletions

diff --git a/src/mongo/db/lasterror.h b/src/mongo/db/lasterror.h
index 5b04b69a57a..55a04c8334d 100644
--- a/src/mongo/db/lasterror.h
+++ b/src/mongo/db/lasterror.h
@@ -29,16 +29,13 @@
 
 #pragma once
 
-#include <boost/noncopyable.hpp>
-#include <boost/thread/tss.hpp>
 #include <string>
 
+#include "mongo/db/client.h"
 #include "mongo/db/jsobj.h"
-#include "mongo/bson/oid.h"
 
 namespace mongo {
     class BSONObjBuilder;
-    class Message;
 
     static const char kUpsertedFieldName[] = "upserted";
     static const char kGLEStatsFieldName[] = "$gleStats";
@@ -46,107 +43,80 @@ namespace mongo {
     static const char kGLEStatsLastOpTimeTermFieldName[] = "lastOpTimeTerm";
     static const char kGLEStatsElectionIdFieldName[] = "electionId";
 
-    struct LastError {
-        int code;
-        std::string msg;
-        enum UpdatedExistingType { NotUpdate, True, False } updatedExisting;
-        // _id field value from inserted doc, returned as kUpsertedFieldName (above)
-        BSONObj upsertedId;
-        long long nObjects;
-        int nPrev;
-        bool valid;
-        bool disabled;
-        void raiseError(int _code , const char *_msg) {
-            reset( true );
-            code = _code;
-            msg = _msg;
-        }
-        void recordUpdate( bool _updateObjects , long long _nObjects , BSONObj _upsertedId ) {
-            reset( true );
-            nObjects = _nObjects;
-            updatedExisting = _updateObjects ? True : False;
-            if ( _upsertedId.valid() && _upsertedId.hasField(kUpsertedFieldName) )
-                upsertedId = _upsertedId;
-
-        }
-        void recordDelete( long long nDeleted ) {
-            reset( true );
-            nObjects = nDeleted;
-        }
-        LastError() {
-            reset();
-        }
-        void reset( bool _valid = false ) {
-            code = 0;
-            msg.clear();
-            updatedExisting = NotUpdate;
-            nObjects = 0;
-            nPrev = 1;
-            valid = _valid;
-            disabled = false;
-            upsertedId = BSONObj();
-        }
+    class LastError {
+    public:
+        static const Client::Decoration<LastError> get;
 
         /**
-         * @return if there is an err
+         * Resets the object to a newly constructed state.  If "valid" is true, marks the last-error
+         * object as "valid".
          */
-        bool appendSelf( BSONObjBuilder &b , bool blankErr = true );
-
-        struct Disabled : boost::noncopyable {
-            Disabled( LastError * le ) {
-                _le = le;
-                if ( _le ) {
-                    _prev = _le->disabled;
-                    _le->disabled = true;
-                }
-                else {
-                    _prev = false;
-                }
-            }
+        void reset(bool valid = false);
 
-            ~Disabled() {
-                if ( _le )
-                    _le->disabled = _prev;
-            }
+        /**
+         * when db receives a message/request, call this
+         */
+        void startRequest();
 
-            LastError * _le;
-            bool _prev;
-        };
+        /**
+         * Disables error recording for the current operation.
+         */
+        void disable();
 
-        static LastError noError;
-    };
+        /**
+         * Sets the error information for the current operation, if error recording was not
+         * explicitly disabled via a call to disable() since the call to startRequest.
+         */
+        void setLastError(int code, std::string msg);
 
-    extern class LastErrorHolder {
-    public:
-        LastErrorHolder(){}
-        ~LastErrorHolder();
+        void recordInsert(long long nObjects);
 
-        LastError * get( bool create = false );
-        LastError * getSafe();
-        LastError * _get( bool create = false ); // may return a disabled LastError
+        void recordUpdate(bool updateObjects, long long nObjects, BSONObj upsertedId);
 
-        void reset( LastError * le );
+        void recordDelete(long long nDeleted);
 
-        /** ok to call more than once. */
-        void initThread();
+        /**
+         * Writes the last-error state described by this object to "b".
+         *
+         * If "blankErr" is true, the "err" field will be explicitly set to null in the result
+         * instead of being omitted when the error string is empty.
+         *
+         * Returns true if there is a non-empty error message.
+         */
+        bool appendSelf(BSONObjBuilder &b, bool blankErr) const;
 
-        void release();
+        bool isValid() const { return _valid; }
+        int const getNPrev() const { return _nPrev; }
 
-        /** when db receives a message/request, call this */
-        LastError * startRequest( Message& m , LastError * connectionOwned );
+        class Disabled {
+        public:
+            explicit Disabled(LastError* le) : _le(le), _prev(le->_disabled) {
+                _le->_disabled = true;
+            }
 
-        // used to disable lastError reporting while processing a killCursors message
-        // disable causes get() to return 0.
-        LastError *disableForCommand(); // only call once per command invocation!
-    private:
-        boost::thread_specific_ptr<LastError> _tl;
+            ~Disabled() {
+                _le->_disabled = _prev;
+            }
 
-        struct Status {
-            time_t time;
-            LastError *lerr;
+        private:
+            LastError * const _le;
+            const bool _prev;
         };
-    } lastError;
 
-    void setLastError(int code , const char *msg);
+        static LastError noError;
+
+    private:
+        enum UpdatedExistingType { NotUpdate, True, False };
+
+        int _code = 0;
+        std::string _msg = {};
+        UpdatedExistingType _updatedExisting = NotUpdate;
+        // _id field value from inserted doc, returned as kUpsertedFieldName (above)
+        BSONObj _upsertedId = {};
+        long long _nObjects = 0;
+        int _nPrev = 1;
+        bool _valid = false;
+        bool _disabled = false;
+    };
 
 } // namespace mongo