Trace.h revision 081c80c2e0f97fb50595b138271d14892aea1b4a
1/* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#ifndef ANDROID_TRACE_H 18#define ANDROID_TRACE_H 19 20#include <fcntl.h> 21#include <stdint.h> 22#include <stdio.h> 23#include <string.h> 24#include <sys/stat.h> 25#include <sys/types.h> 26#include <unistd.h> 27 28#include <cutils/compiler.h> 29#include <utils/threads.h> 30 31// The ATRACE_TAG macro can be defined before including this header to trace 32// using one of the tags defined below. It must be defined to one of the 33// following ATRACE_TAG_* macros. The trace tag is used to filter tracing in 34// userland to avoid some of the runtime cost of tracing when it is not desired. 35// 36// Defining ATRACE_TAG to be ATRACE_TAG_ALWAYS will result in the tracing always 37// being enabled - this should ONLY be done for debug code, as userland tracing 38// has a performance cost even when the trace is not being recorded. Defining 39// ATRACE_TAG to be ATRACE_TAG_NEVER or leaving ATRACE_TAG undefined will result 40// in the tracing always being disabled. 41// 42// These tags must be kept in sync with frameworks/base/core/java/android/os/Trace.java. 43#define ATRACE_TAG_NEVER 0 // The "never" tag is never enabled. 44#define ATRACE_TAG_ALWAYS (1<<0) // The "always" tag is always enabled. 45#define ATRACE_TAG_GRAPHICS (1<<1) 46#define ATRACE_TAG_INPUT (1<<2) 47#define ATRACE_TAG_VIEW (1<<3) 48#define ATRACE_TAG_WEBVIEW (1<<4) 49#define ATRACE_TAG_WINDOW_MANAGER (1<<5) 50#define ATRACE_TAG_ACTIVITY_MANAGER (1<<6) 51#define ATRACE_TAG_SYNC_MANAGER (1<<7) 52#define ATRACE_TAG_LAST ATRACE_TAG_SYNC_MANAGER 53 54#define ATRACE_TAG_VALID_MASK ((ATRACE_TAG_LAST - 1) | ATRACE_TAG_LAST) 55 56#ifndef ATRACE_TAG 57#define ATRACE_TAG ATRACE_TAG_NEVER 58#elif ATRACE_TAG > ATRACE_TAG_LAST 59#error ATRACE_TAG must be defined to be one of the tags defined in utils/Trace.h 60#endif 61 62// ATRACE_CALL traces the beginning and end of the current function. To trace 63// the correct start and end times this macro should be the first line of the 64// function body. 65#define ATRACE_CALL() android::ScopedTrace ___tracer(ATRACE_TAG, __FUNCTION__) 66 67// ATRACE_INT traces a named integer value. This can be used to track how the 68// value changes over time in a trace. 69#define ATRACE_INT(name, value) android::Tracer::traceCounter(ATRACE_TAG, name, value) 70 71// ATRACE_ENABLED returns true if the trace tag is enabled. It can be used as a 72// guard condition around more expensive trace calculations. 73#define ATRACE_ENABLED() android::Tracer::isTagEnabled(ATRACE_TAG) 74 75namespace android { 76 77class Tracer { 78 79public: 80 81 static uint64_t getEnabledTags() { 82 initIfNeeded(); 83 return sEnabledTags; 84 } 85 86 static inline bool isTagEnabled(uint64_t tag) { 87 initIfNeeded(); 88 return sEnabledTags & tag; 89 } 90 91 static inline void traceCounter(uint64_t tag, const char* name, 92 int32_t value) { 93 if (CC_UNLIKELY(isTagEnabled(tag))) { 94 char buf[1024]; 95 snprintf(buf, 1024, "C|%d|%s|%d", getpid(), name, value); 96 write(sTraceFD, buf, strlen(buf)); 97 } 98 } 99 100 static inline void traceBegin(uint64_t tag, const char* name) { 101 if (CC_UNLIKELY(isTagEnabled(tag))) { 102 char buf[1024]; 103 size_t len = snprintf(buf, 1024, "B|%d|%s", getpid(), name); 104 write(sTraceFD, buf, len); 105 } 106 } 107 108 static inline void traceEnd(uint64_t tag) { 109 if (CC_UNLIKELY(isTagEnabled(tag))) { 110 char buf = 'E'; 111 write(sTraceFD, &buf, 1); 112 } 113 } 114 115private: 116 117 static inline void initIfNeeded() { 118 if (!android_atomic_acquire_load(&sIsReady)) { 119 init(); 120 } 121 } 122 123 // init opens the trace marker file for writing and reads the 124 // atrace.tags.enableflags system property. It does this only the first 125 // time it is run, using sMutex for synchronization. 126 static void init(); 127 128 // sIsReady is a boolean value indicating whether a call to init() has 129 // completed in this process. It is initialized to 0 and set to 1 when the 130 // first init() call completes. It is set to 1 even if a failure occurred 131 // in init (e.g. the trace marker file couldn't be opened). 132 // 133 // This should be checked by all tracing functions using an atomic acquire 134 // load operation before calling init(). This check avoids the need to lock 135 // a mutex each time a trace function gets called. 136 static volatile int32_t sIsReady; 137 138 // sTraceFD is the file descriptor used to write to the kernel's trace 139 // buffer. It is initialized to -1 and set to an open file descriptor in 140 // init() while a lock on sMutex is held. 141 // 142 // This should only be used by a trace function after init() has 143 // successfully completed. 144 static int sTraceFD; 145 146 // sEnabledTags is the set of tag bits for which tracing is currently 147 // enabled. It is initialized to 0 and set based on the 148 // atrace.tags.enableflags system property in init() while a lock on sMutex 149 // is held. 150 // 151 // This should only be used by a trace function after init() has 152 // successfully completed. 153 // 154 // This value is only ever non-zero when tracing is initialized and sTraceFD is not -1. 155 static uint64_t sEnabledTags; 156 157 // sMutex is used to protect the execution of init(). 158 static Mutex sMutex; 159}; 160 161class ScopedTrace { 162 163public: 164 inline ScopedTrace(uint64_t tag, const char* name) : 165 mTag(tag) { 166 Tracer::traceBegin(mTag, name); 167 } 168 169 inline ~ScopedTrace() { 170 Tracer::traceEnd(mTag); 171 } 172 173private: 174 175 uint64_t mTag; 176}; 177 178}; // namespace android 179 180#endif // ANDROID_TRACE_H 181