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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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.
*/
#pragma once
#include "mongo/db/concurrency/lock_manager_defs.h"
#include "mongo/platform/atomic_word.h"
namespace mongo {
class BSONObjBuilder;
/**
* Operations for manipulating the lock statistics abstracting whether they are atomic or not.
*/
struct CounterOps {
static int64_t get(const int64_t& counter) {
return counter;
}
static int64_t get(const AtomicWord<long long>& counter) {
return counter.load();
}
static void set(int64_t& counter, int64_t value) {
counter = value;
}
static void set(AtomicWord<long long>& counter, int64_t value) {
counter.store(value);
}
static void add(int64_t& counter, int64_t value) {
counter += value;
}
static void add(int64_t& counter, const AtomicWord<long long>& value) {
counter += value.load();
}
static void add(AtomicWord<long long>& counter, int64_t value) {
counter.addAndFetch(value);
}
};
/**
* Bundle of locking statistics values.
*/
template <typename CounterType>
struct LockStatCounters {
template <typename OtherType>
void append(const LockStatCounters<OtherType>& other) {
CounterOps::add(numAcquisitions, other.numAcquisitions);
CounterOps::add(numWaits, other.numWaits);
CounterOps::add(combinedWaitTimeMicros, other.combinedWaitTimeMicros);
}
template <typename OtherType>
void subtract(const LockStatCounters<OtherType>& other) {
CounterOps::add(numAcquisitions, -other.numAcquisitions);
CounterOps::add(numWaits, -other.numWaits);
CounterOps::add(combinedWaitTimeMicros, -other.combinedWaitTimeMicros);
}
void reset() {
CounterOps::set(numAcquisitions, 0);
CounterOps::set(numWaits, 0);
CounterOps::set(combinedWaitTimeMicros, 0);
}
CounterType numAcquisitions;
CounterType numWaits;
CounterType combinedWaitTimeMicros;
};
/**
* Templatized lock statistics management class, which can be specialized with atomic integers
* for the global stats and with regular integers for the per-locker stats.
*/
template <typename CounterType>
class LockStats {
public:
// Declare the type for the lock counters bundle
typedef LockStatCounters<CounterType> LockStatCountersType;
/**
* Initializes the locking statistics with zeroes (calls reset).
*/
LockStats();
void recordAcquisition(ResourceId resId, LockMode mode) {
CounterOps::add(get(resId, mode).numAcquisitions, 1);
}
void recordWait(ResourceId resId, LockMode mode) {
CounterOps::add(get(resId, mode).numWaits, 1);
}
void recordWaitTime(ResourceId resId, LockMode mode, int64_t waitMicros) {
CounterOps::add(get(resId, mode).combinedWaitTimeMicros, waitMicros);
}
LockStatCountersType& get(ResourceId resId, LockMode mode) {
if (resId == resourceIdOplog) {
return _oplogStats.modeStats[mode];
}
return _stats[resId.getType()].modeStats[mode];
}
template <typename OtherType>
void append(const LockStats<OtherType>& other) {
typedef LockStatCounters<OtherType> OtherLockStatCountersType;
// Append all lock stats
for (int i = 0; i < ResourceTypesCount; i++) {
for (int mode = 0; mode < LockModesCount; mode++) {
const OtherLockStatCountersType& otherStats = other._stats[i].modeStats[mode];
LockStatCountersType& thisStats = _stats[i].modeStats[mode];
thisStats.append(otherStats);
}
}
// Append the oplog stats
for (int mode = 0; mode < LockModesCount; mode++) {
const OtherLockStatCountersType& otherStats = other._oplogStats.modeStats[mode];
LockStatCountersType& thisStats = _oplogStats.modeStats[mode];
thisStats.append(otherStats);
}
}
template <typename OtherType>
void subtract(const LockStats<OtherType>& other) {
typedef LockStatCounters<OtherType> OtherLockStatCountersType;
for (int i = 0; i < ResourceTypesCount; i++) {
for (int mode = 0; mode < LockModesCount; mode++) {
const OtherLockStatCountersType& otherStats = other._stats[i].modeStats[mode];
LockStatCountersType& thisStats = _stats[i].modeStats[mode];
thisStats.subtract(otherStats);
}
}
for (int mode = 0; mode < LockModesCount; mode++) {
const OtherLockStatCountersType& otherStats = other._oplogStats.modeStats[mode];
LockStatCountersType& thisStats = _oplogStats.modeStats[mode];
thisStats.subtract(otherStats);
}
}
void report(BSONObjBuilder* builder) const;
void reset();
private:
// Necessary for the append call, which accepts argument of type different than our
// template parameter.
template <typename T>
friend class LockStats;
// Keep the per-mode lock stats next to each other in case we want to do fancy operations
// such as atomic operations on 128-bit values.
struct PerModeLockStatCounters {
LockStatCountersType modeStats[LockModesCount];
};
void _report(BSONObjBuilder* builder,
const char* sectionName,
const PerModeLockStatCounters& stat) const;
// Split the lock stats per resource type and special-case the oplog so we can collect
// more detailed stats for it.
PerModeLockStatCounters _stats[ResourceTypesCount];
PerModeLockStatCounters _oplogStats;
};
typedef LockStats<int64_t> SingleThreadedLockStats;
typedef LockStats<AtomicWord<long long>> AtomicLockStats;
/**
* Reports instance-wide locking statistics, which can then be converted to BSON or logged.
*/
void reportGlobalLockingStats(SingleThreadedLockStats* outStats);
/**
* Currently used for testing only.
*/
void resetGlobalLockStats();
} // namespace mongo
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