cleaning ScanAndOrder

2011-08-01 17:51:13 -04:00
parent c7f7ba2098
commit d8d05fdc71
3 changed files with 106 additions and 70 deletions
--- a/db/scanandorder.cpp
+++ b/db/scanandorder.cpp
@@ -0,0 +1,91 @@
+/* scanandorder.cpp
+   Order results (that aren't already indexes and in order.)
+*/
+
+/**
+ *    Copyright (C) 2008 10gen Inc.
+ *
+ *    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 "scanandorder.h"
+
+namespace mongo {
+
+    void ScanAndOrder::_add(BSONObj& k, BSONObj o, DiskLoc* loc) {
+        if (!loc) {
+            _best.insert(make_pair(k.getOwned(),o.getOwned()));
+        }
+        else {
+            BSONObjBuilder b;
+            b.appendElements(o);
+            b.append("$diskLoc", loc->toBSONObj());
+            _best.insert(make_pair(k.getOwned(), b.obj().getOwned()));
+        }
+    }
+
+    void ScanAndOrder::_addIfBetter(BSONObj& k, BSONObj o, BestMap::iterator i, DiskLoc* loc) {
+        /* todo : we don't correct _approxSize here. */
+        const BSONObj& worstBestKey = i->first;
+        int c = worstBestKey.woCompare(k, _order._spec.keyPattern);
+        if ( c > 0 ) {
+            // k is better, 'upgrade'
+            _best.erase(i);
+            _add(k, o, loc);
+        }
+    }
+
+
+    void ScanAndOrder::add(BSONObj o, DiskLoc* loc) {
+        assert( o.isValid() );
+        BSONObj k = _order.getKeyFromObject(o);
+        if ( k.isEmpty() ) {
+            return;   
+        }
+        if ( (int) _best.size() < _limit ) {
+            _approxSize += k.objsize();
+            _approxSize += o.objsize();
+            
+            /* note : adjust when bson return limit adjusts. note this limit should be a bit higher. */
+            uassert( 10128 ,  "too much data for sort() with no index.  add an index or specify a smaller limit", _approxSize < 32 * 1024 * 1024 );
+            
+            _add(k, o, loc);
+            return;
+        }
+        BestMap::iterator i;
+        assert( _best.end() != _best.begin() );
+        i = _best.end();
+        i--;
+        _addIfBetter(k, o, i, loc);
+    }
+
+
+    void ScanAndOrder::fill(BufBuilder& b, Projection *filter, int& nout ) const {
+        int n = 0;
+        int nFilled = 0;
+        for ( BestMap::const_iterator i = _best.begin(); i != _best.end(); i++ ) {
+            n++;
+            if ( n <= _startFrom )
+                continue;
+            const BSONObj& o = i->second;
+            fillQueryResultFromObj(b, filter, o);
+            nFilled++;
+            if ( nFilled >= _limit )
+                break;
+            uassert( 10129 ,  "too much data for sort() with no index", b.len() < 4000000 ); // appserver limit
+        }
+        nout = nFilled;
+    }
+
+} // namespace mongo