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6614a48418
This eliminates the need to remember to call PERF_TIMER_STOP when a section has
been timed. This allows more useful design with the perf timers and enables
possible return value optimizations. Simplistic example:
class Foo {
public:
Foo(int v) : m_v(v);
private:
int m_v;
}
Foo makeFrobbedFoo(int *errno)
{
*errno = 0;
return Foo();
}
Foo bar(int *errno)
{
PERF_TIMER_GUARD(some_timer);
return makeFrobbedFoo(errno);
}
int main(int argc, char[] argv)
{
Foo f;
int errno;
f = bar(&errno);
if (errno)
return -1;
return 0;
}
After bar() is called, perf_context.some_timer would be incremented as if
Stop(&perf_context.some_timer) was called at the end, and the compiler is still
able to produce optimizations on the return value from makeFrobbedFoo() through
to main().
89 lines
2 KiB
C++
89 lines
2 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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//
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#pragma once
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#include "rocksdb/perf_context.h"
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#include "util/stop_watch.h"
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namespace rocksdb {
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#if defined(NPERF_CONTEXT) || defined(IOS_CROSS_COMPILE)
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#define PERF_TIMER_GUARD(metric)
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#define PERF_TIMER_MEASURE(metric)
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#define PERF_TIMER_STOP(metric)
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#define PERF_TIMER_START(metric)
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#define PERF_COUNTER_ADD(metric, value)
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#else
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extern __thread PerfLevel perf_level;
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class PerfStepTimer {
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public:
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PerfStepTimer(uint64_t* metric)
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: enabled_(perf_level >= PerfLevel::kEnableTime),
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env_(enabled_ ? Env::Default() : nullptr),
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start_(0),
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metric_(metric) {
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}
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~PerfStepTimer() {
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Stop();
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}
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void Start() {
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if (enabled_) {
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start_ = env_->NowNanos();
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}
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}
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void Measure() {
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if (start_) {
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uint64_t now = env_->NowNanos();
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*metric_ += now - start_;
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start_ = now;
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}
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}
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void Stop() {
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if (start_) {
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*metric_ += env_->NowNanos() - start_;
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start_ = 0;
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}
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}
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private:
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const bool enabled_;
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Env* const env_;
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uint64_t start_;
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uint64_t* metric_;
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};
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// Stop the timer and update the metric
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#define PERF_TIMER_STOP(metric) \
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perf_step_timer_ ## metric.Stop();
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#define PERF_TIMER_START(metric) \
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perf_step_timer_ ## metric.Start();
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// Declare and set start time of the timer
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#define PERF_TIMER_GUARD(metric) \
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PerfStepTimer perf_step_timer_ ## metric(&(perf_context.metric)); \
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perf_step_timer_ ## metric.Start();
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// Update metric with time elapsed since last START. start time is reset
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// to current timestamp.
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#define PERF_TIMER_MEASURE(metric) \
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perf_step_timer_ ## metric.Measure();
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// Increase metric value
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#define PERF_COUNTER_ADD(metric, value) \
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perf_context.metric += value;
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#endif
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}
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