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#ifndef QPID_SYS_LATENCYTRACKER_H
#define QPID_SYS_LATENCYTRACKER_H
/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
#include "Time.h"
namespace qpid {
namespace sys {
/**
* Record latency between events in the lifecycle of an object.
* For testing/debugging purposes: use the macros to declare
* and #define QPID_LATENCY_TRACKER to enable in a build.
*/
template <class T> class LatencyTracker
{
public:
static void start(const char* name, const void* p) { instance.doStart(name, p); }
static void stage(const char* name, const void* p) { instance.doStage(name, p); }
static void end(const char* name, const void* p) { instance.doEnd(name, p); }
private:
LatencyTracker() : object(), times(), totals(), count(), names(), index(), maxIndex() { }
~LatencyTracker() { print(); }
void doStart(const char* n, const void* p) { if (!object) { name(n); object=p; times[0] = now(); index = 1; } }
void doStage(const char* n, const void* p) { if (p == object) { name(n); times[index++] = now(); } }
void doEnd(const char* n, const void* p) { if (p == object) { name(n); times[index++] = now(); record(); object = 0; } }
void name(const char* n) {
if (names[index] == 0) names[index] = n;
assert(names[index] == n);
}
void record() {
if (maxIndex == 0) maxIndex = index;
assert(maxIndex == index);
for (int i = 0; i < index-1; ++i)
totals[i] += Duration(times[i], times[i+1]);
++count;
}
void print() {
printf("\nLatency from %s (%lu samples, %d stages) :\n", names[0], count, maxIndex-1);
for (int i = 0; i < maxIndex-1; ++i)
printf("to %s:\t%luus\n", names[i+1], (totals[i]/count)/TIME_USEC);
}
static const int SIZE = 1024;
const void* object;
AbsTime times[SIZE];
unsigned long totals[SIZE];
unsigned long count;
const char* names[SIZE];
int index, maxIndex;
static LatencyTracker instance;
};
template <class T> struct LatencyEndOnExit {
const char* name;
const void* ptr;
LatencyEndOnExit(const char* n, const void* p) : name(n), ptr(p) {}
~LatencyEndOnExit() { LatencyTracker<T>::end(name, ptr); }
};
template <class T> LatencyTracker<T> LatencyTracker<T>::instance;
#if defined(QPID_LATENCY_TRACKER)
#define LATENCY_START(TAG, NAME, PTR) ::qpid::sys::LatencyTracker<TAG>::start(NAME, PTR)
#define LATENCY_STAGE(TAG, NAME, PTR) ::qpid::sys::LatencyTracker<TAG>::stage(NAME, PTR)
#define LATENCY_END(TAG, NAME, PTR) ::qpid::sys::LatencyTracker<TAG>::end(NAME, PTR)
#define LATENCY_END_ON_EXIT(TAG, NAME, PTR) ::qpid::sys::LatencyEndOnExit<TAG>(NAME, PTR)
#else
#define LATENCY_START(TAG, NAME, PTR) void(0)
#define LATENCY_STAGE(TAG, NAME, PTR) void(0)
#define LATENCY_END(TAG, NAME, PTR) void(0)
#define LATENCY_END_ON_EXIT(TAG, NAME, PTR) void(0)
#endif
}} // namespace qpid::sys
#endif /*!QPID_SYS_LATENCYTRACKER_H*/
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