rocksdb/monitoring/instrumented_mutex.h
mrambacher 3dff28cf9b Use SystemClock* instead of std::shared_ptr<SystemClock> in lower level routines (#8033)
Summary:
For performance purposes, the lower level routines were changed to use a SystemClock* instead of a std::shared_ptr<SystemClock>.  The shared ptr has some performance degradation on certain hardware classes.

For most of the system, there is no risk of the pointer being deleted/invalid because the shared_ptr will be stored elsewhere.  For example, the ImmutableDBOptions stores the Env which has a std::shared_ptr<SystemClock> in it.  The SystemClock* within the ImmutableDBOptions is essentially a "short cut" to gain access to this constant resource.

There were a few classes (PeriodicWorkScheduler?) where the "short cut" property did not hold.  In those cases, the shared pointer was preserved.

Using db_bench readrandom perf_level=3 on my EC2 box, this change performed as well or better than 6.17:

6.17: readrandom   :      28.046 micros/op 854902 ops/sec;   61.3 MB/s (355999 of 355999 found)
6.18: readrandom   :      32.615 micros/op 735306 ops/sec;   52.7 MB/s (290999 of 290999 found)
PR: readrandom   :      27.500 micros/op 871909 ops/sec;   62.5 MB/s (367999 of 367999 found)

(Note that the times for 6.18 are prior to revert of the SystemClock).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8033

Reviewed By: pdillinger

Differential Revision: D27014563

Pulled By: mrambacher

fbshipit-source-id: ad0459eba03182e454391b5926bf5cdd45657b67
2021-03-15 04:34:11 -07:00

102 lines
2.5 KiB
C++

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#pragma once
#include "monitoring/statistics.h"
#include "port/port.h"
#include "rocksdb/statistics.h"
#include "rocksdb/system_clock.h"
#include "rocksdb/thread_status.h"
#include "util/stop_watch.h"
namespace ROCKSDB_NAMESPACE {
class InstrumentedCondVar;
// A wrapper class for port::Mutex that provides additional layer
// for collecting stats and instrumentation.
class InstrumentedMutex {
public:
explicit InstrumentedMutex(bool adaptive = false)
: mutex_(adaptive), stats_(nullptr), clock_(nullptr), stats_code_(0) {}
explicit InstrumentedMutex(SystemClock* clock, bool adaptive = false)
: mutex_(adaptive), stats_(nullptr), clock_(clock), stats_code_(0) {}
InstrumentedMutex(Statistics* stats, SystemClock* clock, int stats_code,
bool adaptive = false)
: mutex_(adaptive),
stats_(stats),
clock_(clock),
stats_code_(stats_code) {}
void Lock();
void Unlock() {
mutex_.Unlock();
}
void AssertHeld() {
mutex_.AssertHeld();
}
private:
void LockInternal();
friend class InstrumentedCondVar;
port::Mutex mutex_;
Statistics* stats_;
SystemClock* clock_;
int stats_code_;
};
// A wrapper class for port::Mutex that provides additional layer
// for collecting stats and instrumentation.
class InstrumentedMutexLock {
public:
explicit InstrumentedMutexLock(InstrumentedMutex* mutex) : mutex_(mutex) {
mutex_->Lock();
}
~InstrumentedMutexLock() {
mutex_->Unlock();
}
private:
InstrumentedMutex* const mutex_;
InstrumentedMutexLock(const InstrumentedMutexLock&) = delete;
void operator=(const InstrumentedMutexLock&) = delete;
};
class InstrumentedCondVar {
public:
explicit InstrumentedCondVar(InstrumentedMutex* instrumented_mutex)
: cond_(&(instrumented_mutex->mutex_)),
stats_(instrumented_mutex->stats_),
clock_(instrumented_mutex->clock_),
stats_code_(instrumented_mutex->stats_code_) {}
void Wait();
bool TimedWait(uint64_t abs_time_us);
void Signal() {
cond_.Signal();
}
void SignalAll() {
cond_.SignalAll();
}
private:
void WaitInternal();
bool TimedWaitInternal(uint64_t abs_time_us);
port::CondVar cond_;
Statistics* stats_;
SystemClock* clock_;
int stats_code_;
};
} // namespace ROCKSDB_NAMESPACE