1 files changed, 158 insertions, 0 deletions
diff --git a/src/mongo/db/commands/distinct.cpp b/src/mongo/db/commands/distinct.cpp
new file mode 100644
index 00000000000..08c78308b35
--- /dev/null
+++ b/src/mongo/db/commands/distinct.cpp
@@ -0,0 +1,158 @@
+// distinct.cpp
+
+/**
+*
+*    This program is free software: you can redistribute it and/or  modify
+*    it under the terms of the GNU Affero General Public License, version 3,
+*    as published by the Free Software Foundation.
+*
+*    This program is distributed in the hope that it will be useful,
+*    but WITHOUT ANY WARRANTY; without even the implied warranty of
+*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+*    GNU Affero General Public License for more details.
+*
+*    You should have received a copy of the GNU Affero General Public License
+*    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+//#include "pch.h"
+#include "../commands.h"
+#include "../instance.h"
+#include "../clientcursor.h"
+#include "../../util/timer.h"
+
+namespace mongo {
+
+    class DistinctCommand : public Command {
+    public:
+        DistinctCommand() : Command("distinct") {}
+        virtual bool slaveOk() const { return true; }
+        virtual LockType locktype() const { return READ; }
+        virtual void help( stringstream &help ) const {
+            help << "{ distinct : 'collection name' , key : 'a.b' , query : {} }";
+        }
+
+        bool run(const string& dbname, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
+            Timer t;
+            string ns = dbname + '.' + cmdObj.firstElement().valuestr();
+
+            string key = cmdObj["key"].valuestrsafe();
+            BSONObj keyPattern = BSON( key << 1 );
+
+            BSONObj query = getQuery( cmdObj );
+
+            int bufSize = BSONObjMaxUserSize - 4096;
+            BufBuilder bb( bufSize );
+            char * start = bb.buf();
+
+            BSONArrayBuilder arr( bb );
+            BSONElementSet values;
+
+            long long nscanned = 0; // locations looked at
+            long long nscannedObjects = 0; // full objects looked at
+            long long n = 0; // matches
+            MatchDetails md;
+
+            NamespaceDetails * d = nsdetails( ns.c_str() );
+
+            if ( ! d ) {
+                result.appendArray( "values" , BSONObj() );
+                result.append( "stats" , BSON( "n" << 0 << "nscanned" << 0 << "nscannedObjects" << 0 ) );
+                return true;
+            }
+
+            shared_ptr<Cursor> cursor;
+            if ( ! query.isEmpty() ) {
+                cursor = NamespaceDetailsTransient::getCursor(ns.c_str() , query , BSONObj() );
+            }
+            else {
+
+                // query is empty, so lets see if we can find an index
+                // with the key so we don't have to hit the raw data
+                NamespaceDetails::IndexIterator ii = d->ii();
+                while ( ii.more() ) {
+                    IndexDetails& idx = ii.next();
+
+                    if ( d->isMultikey( ii.pos() - 1 ) )
+                        continue;
+
+                    if ( idx.inKeyPattern( key ) ) {
+                        cursor = NamespaceDetailsTransient::bestGuessCursor( ns.c_str() ,
+                                                                            BSONObj() ,
+                                                                            idx.keyPattern() );
+                        if( cursor.get() ) break;
+                    }
+
+                }
+
+                if ( ! cursor.get() )
+                    cursor = NamespaceDetailsTransient::getCursor(ns.c_str() , query , BSONObj() );
+
+            }
+
+            
+            verify( cursor );
+            string cursorName = cursor->toString();
+            
+            auto_ptr<ClientCursor> cc (new ClientCursor(QueryOption_NoCursorTimeout, cursor, ns));
+
+            while ( cursor->ok() ) {
+                nscanned++;
+                bool loadedRecord = false;
+
+                if ( cursor->currentMatches( &md ) && !cursor->getsetdup( cursor->currLoc() ) ) {
+                    n++;
+
+                    BSONObj holder;
+                    BSONElementSet temp;
+                    loadedRecord = ! cc->getFieldsDotted( key , temp, holder );
+
+                    for ( BSONElementSet::iterator i=temp.begin(); i!=temp.end(); ++i ) {
+                        BSONElement e = *i;
+                        if ( values.count( e ) )
+                            continue;
+
+                        int now = bb.len();
+
+                        uassert(10044,  "distinct too big, 16mb cap", ( now + e.size() + 1024 ) < bufSize );
+
+                        arr.append( e );
+                        BSONElement x( start + now );
+
+                        values.insert( x );
+                    }
+                }
+
+                if ( loadedRecord || md.hasLoadedRecord() )
+                    nscannedObjects++;
+
+                cursor->advance();
+
+                if (!cc->yieldSometimes( ClientCursor::MaybeCovered )) {
+                    cc.release();
+                    break;
+                }
+
+                RARELY killCurrentOp.checkForInterrupt();
+            }
+
+            verify( start == bb.buf() );
+
+            result.appendArray( "values" , arr.done() );
+
+            {
+                BSONObjBuilder b;
+                b.appendNumber( "n" , n );
+                b.appendNumber( "nscanned" , nscanned );
+                b.appendNumber( "nscannedObjects" , nscannedObjects );
+                b.appendNumber( "timems" , t.millis() );
+                b.append( "cursor" , cursorName );
+                result.append( "stats" , b.obj() );
+            }
+
+            return true;
+        }
+
+    } distinctCmd;
+
+}