1 files changed, 131 insertions, 0 deletions
diff --git a/src/mongo/db/exec/keep_mutations.cpp b/src/mongo/db/exec/keep_mutations.cpp
new file mode 100644
index 00000000000..a16d5f7e462
--- /dev/null
+++ b/src/mongo/db/exec/keep_mutations.cpp
@@ -0,0 +1,131 @@
+/**
+ *    Copyright (C) 2014 MongoDB 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/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/db/exec/keep_mutations.h"
+#include "mongo/db/exec/filter.h"
+
+namespace mongo {
+
+    KeepMutationsStage::KeepMutationsStage(const MatchExpression* filter,
+                                           WorkingSet* ws,
+                                           PlanStage* child)
+        : _workingSet(ws),
+          _child(child),
+          _filter(filter),
+          _doneReadingChild(false),
+          _doneReturningFlagged(false) { }
+
+    KeepMutationsStage::~KeepMutationsStage() { }
+
+    bool KeepMutationsStage::isEOF() {
+        return _doneReadingChild && _doneReturningFlagged;
+    }
+
+    PlanStage::StageState KeepMutationsStage::work(WorkingSetID* out) {
+        ++_commonStats.works;
+
+        // If we've returned as many results as we're limited to, isEOF will be true.
+        if (isEOF()) { return PlanStage::IS_EOF; }
+
+        // Stream child results until the child is all done.
+        if (!_doneReadingChild) {
+            StageState status = _child->work(out);
+
+            // Child is still returning results.  Pass them through.
+            if (PlanStage::IS_EOF != status) {
+                if (PlanStage::ADVANCED == status) {
+                    ++_commonStats.advanced;
+                }
+                else if (PlanStage::NEED_TIME == status) {
+                    ++_commonStats.needTime;
+                }
+                else if (PlanStage::NEED_FETCH == status) {
+                    ++_commonStats.needFetch;
+                }
+
+                return status;
+            }
+
+            // Child is EOF.  We want to stream flagged results if there are any.
+            _doneReadingChild = true;
+
+            // Read out all of the flagged results from the working set.  We can't iterate through
+            // the working set's flagged result set directly, since it may be modified later if
+            // further documents are invalidated during a yield.
+            std::copy(_workingSet->getFlagged().begin(), _workingSet->getFlagged().end(),
+                      std::back_inserter(_flagged));
+            _flaggedIterator = _flagged.begin();
+        }
+
+        // We're streaming flagged results.
+        invariant(!_doneReturningFlagged);
+        if (_flaggedIterator == _flagged.end()) {
+            _doneReturningFlagged = true;
+            return PlanStage::IS_EOF;
+        }
+
+        WorkingSetID idToTest = *_flaggedIterator;
+        _flaggedIterator++;
+
+        WorkingSetMember* member = _workingSet->get(idToTest);
+        if (Filter::passes(member, _filter)) {
+            *out = idToTest;
+            ++_commonStats.advanced;
+            return PlanStage::ADVANCED;
+        }
+        else {
+            _workingSet->free(idToTest);
+            ++_commonStats.needTime;
+            return PlanStage::NEED_TIME;
+        }
+    }
+
+    void KeepMutationsStage::prepareToYield() {
+        ++_commonStats.yields;
+        _child->prepareToYield();
+    }
+
+    void KeepMutationsStage::recoverFromYield() {
+        ++_commonStats.unyields;
+        _child->recoverFromYield();
+    }
+
+    void KeepMutationsStage::invalidate(const DiskLoc& dl, InvalidationType type) {
+        ++_commonStats.invalidates;
+        _child->invalidate(dl, type);
+    }
+
+    PlanStageStats* KeepMutationsStage::getStats() {
+        _commonStats.isEOF = isEOF();
+        auto_ptr<PlanStageStats> ret(new PlanStageStats(_commonStats, STAGE_KEEP_MUTATIONS));
+        // Takes ownership of the object returned from _child->getStats().
+        ret->children.push_back(_child->getStats());
+        return ret.release();
+    }
+
+}  // namespace mongo