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// snapshots.cpp
/**
* 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/>.
*
* 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.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kDefault
#include "mongo/platform/basic.h"
#include "mongo/db/stats/snapshots.h"
#include "mongo/db/client.h"
#include "mongo/db/clientcursor.h"
#include "mongo/db/service_context.h"
#include "mongo/util/exit.h"
#include "mongo/util/log.h"
/**
handles snapshotting performance metrics and other such things
*/
namespace mongo {
using std::unique_ptr;
using std::endl;
void SnapshotData::takeSnapshot() {
_created = curTimeMicros64();
Top::get(getGlobalServiceContext()).cloneMap(_usage);
}
SnapshotDelta::SnapshotDelta(const SnapshotData& older, const SnapshotData& newer)
: _older(older), _newer(newer) {
verify(_newer._created > _older._created);
_elapsed = _newer._created - _older._created;
}
Top::UsageMap SnapshotDelta::collectionUsageDiff() {
verify(_newer._created > _older._created);
Top::UsageMap u;
for (Top::UsageMap::const_iterator i = _newer._usage.begin(); i != _newer._usage.end(); ++i) {
Top::UsageMap::const_iterator j = _older._usage.find(i->first);
if (j != _older._usage.end())
u[i->first] = Top::CollectionData(j->second, i->second);
else
u[i->first] = i->second;
}
return u;
}
Snapshots::Snapshots() : _loc(0), _stored(0) {}
const SnapshotData* Snapshots::takeSnapshot() {
stdx::lock_guard<stdx::mutex> lk(_lock);
_loc = (_loc + 1) % kNumSnapshots;
_snapshots[_loc].takeSnapshot();
if (_stored < kNumSnapshots)
_stored++;
return &_snapshots[_loc];
}
StatusWith<SnapshotDiff> Snapshots::computeDelta() {
stdx::lock_guard<stdx::mutex> lk(_lock);
// We need 2 snapshots to calculate a delta
if (_stored < 2) {
return StatusWith<SnapshotDiff>(ErrorCodes::BadValue, "Less than 2 snapshots exist");
}
// The following logic depends on there being exactly 2 stored snapshots
BOOST_STATIC_ASSERT(kNumSnapshots == 2);
// Current and previous napshot alternates between indexes 0 and 1
int currIdx = _loc;
int prevIdx = _loc > 0 ? 0 : 1;
SnapshotDelta delta(_snapshots[prevIdx], _snapshots[currIdx]);
return SnapshotDiff(delta.collectionUsageDiff(), delta.elapsed());
}
void StatsSnapshotThread::run() {
Client::initThread("statsSnapshot");
while (!inShutdown()) {
try {
statsSnapshots.takeSnapshot();
} catch (std::exception& e) {
log() << "ERROR in SnapshotThread: " << e.what() << endl;
}
sleepsecs(4);
}
}
Snapshots statsSnapshots;
StatsSnapshotThread statsSnapshotThread;
}
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