背景：
经常在看systrace、perfetto相关trace时候，其实我们主要就是看各种方法的调用tag，如下图所示
正因为有了系统中各个地方埋下的这些tag，才让我们可以根据这些方法tag分析出整个系统的运行情况。但是大家有没有想过，请问这些tag是怎么打上去的？如果我们自己要打印自己方法的tag应该怎么搞？
使用atrace相关类方法介绍
这里还需要看对应的trace源码是最全面的
路径：system/core/libcutils/include/cutils/trace.h
源码：
cpp
/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed 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.
*/
#ifndef _LIBS_CUTILS_TRACE_H
#define _LIBS_CUTILS_TRACE_H
#include <inttypes.h>
#include <stdatomic.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <sys/cdefs.h>
#include <sys/types.h>
#include <unistd.h>
#include <cutils/compiler.h>
__BEGIN_DECLS
/**
* The ATRACE_TAG macro can be defined before including this header to trace
* using one of the tags defined below. It must be defined to one of the
* following ATRACE_TAG_* macros. The trace tag is used to filter tracing in
* userland to avoid some of the runtime cost of tracing when it is not desired.
*
* Defining ATRACE_TAG to be ATRACE_TAG_ALWAYS will result in the tracing always
* being enabled - this should ONLY be done for debug code, as userland tracing
* has a performance cost even when the trace is not being recorded. Defining
* ATRACE_TAG to be ATRACE_TAG_NEVER or leaving ATRACE_TAG undefined will result
* in the tracing always being disabled.
*
* ATRACE_TAG_HAL should be bitwise ORed with the relevant tags for tracing
* within a hardware module. For example a camera hardware module would set:
* #define ATRACE_TAG (ATRACE_TAG_CAMERA | ATRACE_TAG_HAL)
*
* Keep these in sync with frameworks/base/core/java/android/os/Trace.java.
*/
#define ATRACE_TAG_NEVER 0 // This tag is never enabled.
#define ATRACE_TAG_ALWAYS (1<<0) // This tag is always enabled.
#define ATRACE_TAG_GRAPHICS (1<<1)
#define ATRACE_TAG_INPUT (1<<2)
#define ATRACE_TAG_VIEW (1<<3)
#define ATRACE_TAG_WEBVIEW (1<<4)
#define ATRACE_TAG_WINDOW_MANAGER (1<<5)
#define ATRACE_TAG_ACTIVITY_MANAGER (1<<6)
#define ATRACE_TAG_SYNC_MANAGER (1<<7)
#define ATRACE_TAG_AUDIO (1<<8)
#define ATRACE_TAG_VIDEO (1<<9)
#define ATRACE_TAG_CAMERA (1<<10)
#define ATRACE_TAG_HAL (1<<11)
#define ATRACE_TAG_APP (1<<12)
#define ATRACE_TAG_RESOURCES (1<<13)
#define ATRACE_TAG_DALVIK (1<<14)
#define ATRACE_TAG_RS (1<<15)
#define ATRACE_TAG_BIONIC (1<<16)
#define ATRACE_TAG_POWER (1<<17)
#define ATRACE_TAG_PACKAGE_MANAGER (1<<18)
#define ATRACE_TAG_SYSTEM_SERVER (1<<19)
#define ATRACE_TAG_DATABASE (1<<20)
#define ATRACE_TAG_NETWORK (1<<21)
#define ATRACE_TAG_ADB (1<<22)
#define ATRACE_TAG_VIBRATOR (1<<23)
#define ATRACE_TAG_AIDL (1<<24)
#define ATRACE_TAG_NNAPI (1<<25)
#define ATRACE_TAG_RRO (1<<26)
#define ATRACE_TAG_THERMAL (1 << 27)
#define ATRACE_TAG_LAST ATRACE_TAG_THERMAL
// Reserved for initialization.
#define ATRACE_TAG_NOT_READY (1ULL<<63)
#define ATRACE_TAG_VALID_MASK ((ATRACE_TAG_LAST - 1) | ATRACE_TAG_LAST)
#ifndef ATRACE_TAG
#define ATRACE_TAG ATRACE_TAG_NEVER
#elif ATRACE_TAG > ATRACE_TAG_VALID_MASK
#error ATRACE_TAG must be defined to be one of the tags defined in cutils/trace.h
#endif
/**
* Opens the trace file for writing and reads the property for initial tags.
* The atrace.tags.enableflags property sets the tags to trace.
* This function should not be explicitly called, the first call to any normal
* trace function will cause it to be run safely.
*/
void atrace_setup();
/**
* If tracing is ready, set atrace_enabled_tags to the system property
* debug.atrace.tags.enableflags. Can be used as a sysprop change callback.
*/
void atrace_update_tags();
/**
* Set whether tracing is enabled for the current process. This is used to
* prevent tracing within the Zygote process.
*/
void atrace_set_tracing_enabled(bool enabled);
/**
* This is always set to false. This forces code that uses an old version
* of this header to always call into atrace_setup, in which we call
* atrace_init unconditionally.
*/
extern atomic_bool atrace_is_ready;
/**
* Set of ATRACE_TAG flags to trace for, initialized to ATRACE_TAG_NOT_READY.
* A value of zero indicates setup has failed.
* Any other nonzero value indicates setup has succeeded, and tracing is on.
*/
extern uint64_t atrace_enabled_tags;
/**
* Handle to the kernel's trace buffer, initialized to -1.
* Any other value indicates setup has succeeded, and is a valid fd for tracing.
*/
extern int atrace_marker_fd;
/**
* atrace_init readies the process for tracing by opening the trace_marker file.
* Calling any trace function causes this to be run, so calling it is optional.
* This can be explicitly run to avoid setup delay on first trace function.
*/
#define ATRACE_INIT() atrace_init()
#define ATRACE_GET_ENABLED_TAGS() atrace_get_enabled_tags()
void atrace_init();
uint64_t atrace_get_enabled_tags();
/**
* Test if a given tag is currently enabled.
* Returns nonzero if the tag is enabled, otherwise zero.
* It can be used as a guard condition around more expensive trace calculations.
*/
#define ATRACE_ENABLED() atrace_is_tag_enabled(ATRACE_TAG)
static inline uint64_t atrace_is_tag_enabled(uint64_t tag)
{
return atrace_get_enabled_tags() & tag;
}
/**
* Trace the beginning of a context. name is used to identify the context.
* This is often used to time function execution.
*/
#define ATRACE_BEGIN(name) atrace_begin(ATRACE_TAG, name)
static inline void atrace_begin(uint64_t tag, const char* name)
{
if (CC_UNLIKELY(atrace_is_tag_enabled(tag))) {
void atrace_begin_body(const char*);
atrace_begin_body(name);
}
}
/**
* Trace the end of a context.
* This should match up (and occur after) a corresponding ATRACE_BEGIN.
*/
#define ATRACE_END() atrace_end(ATRACE_TAG)
static inline void atrace_end(uint64_t tag)
{
if (CC_UNLIKELY(atrace_is_tag_enabled(tag))) {
void atrace_end_body();
atrace_end_body();
}
}
/**
* Trace the beginning of an asynchronous event. Unlike ATRACE_BEGIN/ATRACE_END
* contexts, asynchronous events do not need to be nested. The name describes
* the event, and the cookie provides a unique identifier for distinguishing
* simultaneous events. The name and cookie used to begin an event must be
* used to end it.
*/
#define ATRACE_ASYNC_BEGIN(name, cookie) \
atrace_async_begin(ATRACE_TAG, name, cookie)
static inline void atrace_async_begin(uint64_t tag, const char* name,
int32_t cookie)
{
if (CC_UNLIKELY(atrace_is_tag_enabled(tag))) {
void atrace_async_begin_body(const char*, int32_t);
atrace_async_begin_body(name, cookie);
}
}
/**
* Trace the end of an asynchronous event.
* This should have a corresponding ATRACE_ASYNC_BEGIN.
*/
#define ATRACE_ASYNC_END(name, cookie) atrace_async_end(ATRACE_TAG, name, cookie)
static inline void atrace_async_end(uint64_t tag, const char* name, int32_t cookie)
{
if (CC_UNLIKELY(atrace_is_tag_enabled(tag))) {
void atrace_async_end_body(const char*, int32_t);
atrace_async_end_body(name, cookie);
}
}
/**
* Trace the beginning of an asynchronous event. In addition to the name and a
* cookie as in ATRACE_ASYNC_BEGIN/ATRACE_ASYNC_END, a track name argument is
* provided, which is the name of the row where this async event should be
* recorded. The track name, name, and cookie used to begin an event must be
* used to end it.
*/
#define ATRACE_ASYNC_FOR_TRACK_BEGIN(track_name, name, cookie) \
atrace_async_for_track_begin(ATRACE_TAG, track_name, name, cookie)
static inline void atrace_async_for_track_begin(uint64_t tag, const char* track_name,
const char* name, int32_t cookie) {
if (CC_UNLIKELY(atrace_is_tag_enabled(tag))) {
void atrace_async_for_track_begin_body(const char*, const char*, int32_t);
atrace_async_for_track_begin_body(track_name, name, cookie);
}
}
/**
* Trace the end of an asynchronous event.
* This should correspond to a previous ATRACE_ASYNC_FOR_TRACK_BEGIN.
*/
#define ATRACE_ASYNC_FOR_TRACK_END(track_name, name, cookie) \
atrace_async_for_track_end(ATRACE_TAG, track_name, name, cookie)
static inline void atrace_async_for_track_end(uint64_t tag, const char* track_name,
const char* name, int32_t cookie) {
if (CC_UNLIKELY(atrace_is_tag_enabled(tag))) {
void atrace_async_for_track_end_body(const char*, const char*, int32_t);
atrace_async_for_track_end_body(track_name, name, cookie);
}
}
/**
* Trace an instantaneous context. name is used to identify the context.
*
* An "instant" is an event with no defined duration. Visually is displayed like a single marker
* in the timeline (rather than a span, in the case of begin/end events).
*
* By default, instant events are added into a dedicated track that has the same name of the event.
* Use atrace_instant_for_track to put different instant events into the same timeline track/row.
*/
#define ATRACE_INSTANT(name) atrace_instant(ATRACE_TAG, name)
static inline void atrace_instant(uint64_t tag, const char* name) {
if (CC_UNLIKELY(atrace_is_tag_enabled(tag))) {
void atrace_instant_body(const char*);
atrace_instant_body(name);
}
}
/**
* Trace an instantaneous context. name is used to identify the context.
* track_name is the name of the row where the event should be recorded.
*
* An "instant" is an event with no defined duration. Visually is displayed like a single marker
* in the timeline (rather than a span, in the case of begin/end events).
*/
#define ATRACE_INSTANT_FOR_TRACK(trackName, name) \
atrace_instant_for_track(ATRACE_TAG, trackName, name)
static inline void atrace_instant_for_track(uint64_t tag, const char* track_name,
const char* name) {
if (CC_UNLIKELY(atrace_is_tag_enabled(tag))) {
void atrace_instant_for_track_body(const char*, const char*);
atrace_instant_for_track_body(track_name, name);
}
}
/**
* Traces an integer counter value. name is used to identify the counter.
* This can be used to track how a value changes over time.
*/
#define ATRACE_INT(name, value) atrace_int(ATRACE_TAG, name, value)
static inline void atrace_int(uint64_t tag, const char* name, int32_t value)
{
if (CC_UNLIKELY(atrace_is_tag_enabled(tag))) {
void atrace_int_body(const char*, int32_t);
atrace_int_body(name, value);
}
}
/**
* Traces a 64-bit integer counter value. name is used to identify the
* counter. This can be used to track how a value changes over time.
*/
#define ATRACE_INT64(name, value) atrace_int64(ATRACE_TAG, name, value)
static inline void atrace_int64(uint64_t tag, const char* name, int64_t value)
{
if (CC_UNLIKELY(atrace_is_tag_enabled(tag))) {
void atrace_int64_body(const char*, int64_t);
atrace_int64_body(name, value);
}
}
__END_DECLS
#endif // _LIBS_CUTILS_TRACE_H日常使用trace打TAG其实本质上都是基于这个类的，在这个的基础上会加一些额外包装
比如常见的几个方法：
1、ATRACE_CALL();
这个方法，代表对一个function的开头和结尾进行tag，它的源码如下
#define ATRACE_CALL() ATRACE_NAME(FUNCTION )
即本质调用的是ATRACE_NAME
调用如下：
2、ATRACE_NAME方法
这个方法的本质定义如下
cpp
//这里的ATRACE_NAME其实本质是个临时对象构造和析构进行调用的atrace_begin和atrace_end，这两个其实就是trace.h原始方法
#define ATRACE_NAME(name) ::android::ScopedTrace PASTE(___tracer, __LINE__)(ATRACE_TAG, name)
namespace android {
//临时对象，调用该时候该对象刚好构造，一般方法域结束就代表作用无效了，因为会进行对象的析构
class ScopedTrace {
public:
inline ScopedTrace(uint64_t tag, const char* name) : mTag(tag) {
atrace_begin(mTag, name);//构造时候进行begin
}
inline ~ScopedTrace() {
atrace_end(mTag);//析构时候代表trace结束end
}
private:
uint64_t mTag;
};调用如下：
效果如下：
其他常见还有
3、ATRACE_INT
具体源码：
cpp
/**
* Traces an integer counter value. name is used to identify the counter.
* This can be used to track how a value changes over time.
*/
#define ATRACE_INT(name, value) atrace_int(ATRACE_TAG, name, value)
static inline void atrace_int(uint64_t tag, const char* name, int32_t value)
{
if (CC_UNLIKELY(atrace_is_tag_enabled(tag))) {
void atrace_int_body(const char*, int32_t);
atrace_int_body(name, value);
}
}代码调用：
效果如下：
trace相关实战使用：
1、引入相关的头文件及相关库
#include <utils/Trace.h>
编译时候还得考率相关utils的lib是否引入
如这里以截图代码为例就有引入libutils
frameworks/base/cmds/screencap/Android.bp
cpp
cc_binary {
name: "screencap",
srcs: ["screencap.cpp"],
shared_libs: [
"libcutils",
"libutils",
"libbinder",
"libjnigraphics",
"libui",
"libgui",
],
cflags: [
"-Wall",
"-Werror",
"-Wunused",
"-Wunreachable-code",
],
}2、定义好相关的TAG
cpp
#undef ATRACE_TAG
#define ATRACE_TAG ATRACE_TAG_GRAPHICS这里就选了一个ATRACE_TAG_GRAPHICS即graphics这个组
3、调用相关actrace方法
ATRACE_CALL
ATRACE_NAME
一般针对整个方法或者单独作用域，ATRACE_CALL和ATRACE_NAME本质没有区别，只是把名字变成了function的name
具体效果如下：
优点：只需要一个调用既可以实现tag打印，自动跟随作用域进行tag的结束
缺点：需要自己熟练掌握好作用域，没有可以手动控制的tag结束的点
4、相关灵活控制开始与结束的trace方法
直接使用atrace_begin和atrace_end方法，使用如下：
c
GraphicBuffer::GraphicBuffer()
: BASE(), mOwner(ownData), mBufferMapper(GraphicBufferMapper::get()),
mInitCheck(NO_ERROR), mId(getUniqueId()), mGenerationNumber(0)
{
ATRACE_NAME("GraphicBuffer::GraphicBuffer()1");
atrace_begin(ATRACE_TAG, "GraphicBuffer 1");
width =
height =
stride =
format =
usage_deprecated = 0;
atrace_end(ATRACE_TAG);
usage = 0;
layerCount = 0;
handle = nullptr;
}具体效果如下：
同时也可以使用对应宏定义：
ATRACE_BEGIN(name);
ATRACE_END();
来控制
执行后效果如下：
更多framework干货手把手教学视频及答疑可以看这里，可以加我v（androidframework007）获取：
https://blog.csdn.net/learnframework/article/details/132739059