systrace/perfetto中需要actrace打tag相关方法-车载车机framework系统开发实战

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：

/*
 * 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：

ATRACE_NAME方法

这个方法的本质定义如下

//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

ATRACE_INT

具体源码：

/**
 * 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：
![在这里插入图片描述](https://img-blog.csdnimg.cn/6f4e7a7f62c24145af81e537611ba155.png#pic_center

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

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

 #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：

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：

ATRACE_FORMAT

有时候想要Trace上的显示的标签是动态可以变化的比如打印一个数字，或者是某个变量的值
比如上面这种，你看到很多数字其实都是每次执行都是不一样的，那么这个时候打印trace名字时候，就会要求有动态变化的需求，需要把变量值也打印出来，这个时候就需要使用ATRACE_FORMAT这个宏，当然你可以自己每次把变量组合到一个string变量，然后ATRACE_NAME打印这个string既可以,但是这样比较麻烦
使用方式：
ATRACE_FORMAT和上面的ATRACE_NAME没啥区别
不过include文件夹有区别需要引入TraceUtils
#include <gui/TraceUtils.h>
调用方式和打log没啥差别：

  ATRACE_FORMAT("%s %" PRId64 " vsyncIn %.2fms%s", __func__, vsyncId, vsyncIn,
                  mExpectedPresentTime == expectedVsyncTime ? "" : " (adjusted)");

相关源码如下：
frameworks/native/include/gui/TraceUtils.h

#pragma once

#include <stdarg.h>

#include <cutils/trace.h>
#include <utils/Trace.h>

#define ATRACE_FORMAT(fmt, ...)           \
    TraceUtils::TraceEnder __traceEnder = \
            (TraceUtils::atraceFormatBegin(fmt, ##__VA_ARGS__), TraceUtils::TraceEnder())

#define ATRACE_FORMAT_BEGIN(fmt, ...) TraceUtils::atraceFormatBegin(fmt, ##__VA_ARGS__)

namespace android {

class TraceUtils {
public:
    class TraceEnder {
    public:
        ~TraceEnder() { ATRACE_END(); }
    };

    static void atraceFormatBegin(const char* fmt, ...) {
        if (CC_LIKELY(!ATRACE_ENABLED())) return;

        const int BUFFER_SIZE = 256;
        va_list ap;
        char buf[BUFFER_SIZE];

        va_start(ap, fmt);
        vsnprintf(buf, BUFFER_SIZE, fmt, ap);
        va_end(ap);

        ATRACE_BEGIN(buf);
    }

}; // class TraceUtils

} /* namespace android */

java端的trace打印

app层面时候也有trace打印方式

  Trace.traceBegin(Trace.TRACE_TAG_ALWAYS,"aaaaa");//开始trace 字符为aaaaa
  Trace.traceEnd(Trace.TRACE_TAG_ALWAYS);//结束trace

源码如下：
frameworks/base/core/java/android/os/Trace.java

    /**
     * Writes a trace message to indicate that a given section of code has
     * begun. Must be followed by a call to {@link #traceEnd} using the same
     * tag.
     *
     * @param traceTag The trace tag.
     * @param methodName The method name to appear in the trace.
     *
     * @hide
     */
    @UnsupportedAppUsage
    @SystemApi(client = MODULE_LIBRARIES)
    public static void traceBegin(long traceTag, @NonNull String methodName) {
        if (isTagEnabled(traceTag)) {
            nativeTraceBegin(traceTag, methodName);
        }
    }

    /**
     * Writes a trace message to indicate that the current method has ended.
     * Must be called exactly once for each call to {@link #traceBegin} using the same tag.
     *
     * @param traceTag The trace tag.
     *
     * @hide
     */
    @UnsupportedAppUsage
    @SystemApi(client = MODULE_LIBRARIES)
    public static void traceEnd(long traceTag) {
        if (isTagEnabled(traceTag)) {
            nativeTraceEnd(traceTag);
        }
    }

具体使用方法：

  protected void onStart() {
        Trace.traceBegin(Trace.TRACE_TAG_ALWAYS,"Settings Home onStart()");
        ((SettingsApplication) getApplication()).setHomeActivity(this);
        super.onStart();
        doAidlHalCall();
        Trace.traceEnd(Trace.TRACE_TAG_ALWAYS);
    }

然后再抓对应trace

是不是把我们Settings Home onStart()在trace中给打印出来了

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