1 files changed, 114 insertions, 0 deletions
diff --git a/src/mongo/db/stats/snapshots.h b/src/mongo/db/stats/snapshots.h
new file mode 100644
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+++ b/src/mongo/db/stats/snapshots.h
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+// snapshots.h
+
+/**
+*    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/>.
+*/
+
+#pragma once
+#include "../../pch.h"
+#include "../jsobj.h"
+#include "top.h"
+#include "../../util/background.h"
+
+/**
+   handles snapshotting performance metrics and other such things
+ */
+namespace mongo {
+
+    class SnapshotThread;
+
+    /**
+     * stores a point in time snapshot
+     * i.e. all counters at a given time
+     */
+    class SnapshotData {
+        void takeSnapshot();
+
+        unsigned long long _created;
+        Top::CollectionData _globalUsage;
+        unsigned long long _totalWriteLockedTime; // micros of total time locked
+        Top::UsageMap _usage;
+
+        friend class SnapshotThread;
+        friend class SnapshotDelta;
+        friend class Snapshots;
+    };
+
+    /**
+     * contains performance information for a time period
+     */
+    class SnapshotDelta {
+    public:
+        SnapshotDelta( const SnapshotData& older , const SnapshotData& newer );
+
+        unsigned long long start() const {
+            return _older._created;
+        }
+
+        unsigned long long elapsed() const {
+            return _elapsed;
+        }
+
+        unsigned long long timeInWriteLock() const {
+            return _newer._totalWriteLockedTime - _older._totalWriteLockedTime;
+        }
+        double percentWriteLocked() const {
+            double e = (double) elapsed();
+            double w = (double) timeInWriteLock();
+            return w/e;
+        }
+
+        Top::CollectionData globalUsageDiff();
+        Top::UsageMap collectionUsageDiff();
+
+    private:
+        const SnapshotData& _older;
+        const SnapshotData& _newer;
+
+        unsigned long long _elapsed;
+    };
+
+    class Snapshots {
+    public:
+        Snapshots(int n=100);
+
+        const SnapshotData* takeSnapshot();
+
+        int numDeltas() const { return _stored-1; }
+
+        const SnapshotData& getPrev( int numBack = 0 );
+        auto_ptr<SnapshotDelta> computeDelta( int numBack = 0 );
+
+
+        void outputLockInfoHTML( stringstream& ss );
+    private:
+        mongo::mutex _lock;
+        int _n;
+        boost::scoped_array<SnapshotData> _snapshots;
+        int _loc;
+        int _stored;
+    };
+
+    class SnapshotThread : public BackgroundJob {
+    public:
+        virtual string name() const { return "snapshot"; }
+        void run();
+    };
+
+    extern Snapshots statsSnapshots;
+    extern SnapshotThread snapshotThread;
+
+
+}