blockcanary源码

最新推荐文章于 2021-05-29 12:53:31 发布

原创最新推荐文章于 2021-05-29 12:53:31 发布 · 266 阅读

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#blockcanary #handler #源码分析 #卡顿

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blockcanary项目名称AndroidPerformanceMonitor,内含4个模块
1 blockcanary-android-no-op
2 blockcanary-analyzer
3 blockcanary-android
4 blockcanary-sample
本篇文章主要分析blockcanary-analyzer和blockcanary-android

BlockCanary类位于blockcanary-android模块，是整个库的入口

private BlockCanary() {
        BlockCanaryInternals.setContext(BlockCanaryContext.get());
        mBlockCanaryCore = BlockCanaryInternals.getInstance();
        mBlockCanaryCore.addBlockInterceptor(BlockCanaryContext.get());
        if (!BlockCanaryContext.get().displayNotification()) {
            return;
        }
        mBlockCanaryCore.addBlockInterceptor(new DisplayService());

    }

在构造函数中初始化了BlockCanaryInternals，这是卡顿检测的核心管理类,在BlockCanary中另外两个重要函数就是start和stop，在这里面实际是向主线程Looper中设置自定义printer，根据前后两次调用时间确定是否发生卡顿

    public void start() {
        if (!mMonitorStarted) {
            mMonitorStarted = true;

			// 设置自定义printer
            Looper.getMainLooper().setMessageLogging(mBlockCanaryCore.monitor);
        }
    }

    public void stop() {
        if (mMonitorStarted) {
            mMonitorStarted = false;
            Looper.getMainLooper().setMessageLogging(null);
            mBlockCanaryCore.stackSampler.stop();
            mBlockCanaryCore.cpuSampler.stop();
        }
    }

接下来看BlockCanaryInternals类，位于blockcanary-analyzer中，内部有三个变量，负责不同职能

	// 自定义printer
	LooperMonitor monitor;

	// 堆栈信息采集
    StackSampler stackSampler;

	// cpu信息采集
    CpuSampler cpuSampler;

LooperMonitor是自定义的printer类，在BlockCanary的start函数中被设置进主进程looper，当Looper调用hander处理任务时会产生回调

if (logging != null) {
	logging.println(">>>>> Dispatching to " + msg.target + " " +msg.callback + ": " + msg.what);
}

msg.target.dispatchMessage(msg);

if (logging != null) {
	logging.println("<<<<< Finished to " + msg.target + " " + msg.callback);
}

LooperMonitor会在println回调中区分是调用方法开始还是结束，之后调用堆栈的CPU信息的采集

public void println(String x) {
        if (mStopWhenDebugging && Debug.isDebuggerConnected()) {
            return;
        }
        if (!mPrintingStarted) {
            mStartTimestamp = System.currentTimeMillis();
            mStartThreadTimestamp = SystemClock.currentThreadTimeMillis();
            mPrintingStarted = true;
            startDump();
        } else {
            final long endTime = System.currentTimeMillis();
            mPrintingStarted = false;
            if (isBlock(endTime)) {
                notifyBlockEvent(endTime);
            }
            stopDump();
        }
    }

startDump和stopDump实际内部都是调用的StackSampler和CpuSampler，这两个类继承自AbstractSampler，在AbstractSampler中由HandlerThreadFactory提供在子线程中进行信息收集工作的HandlerThread,默认情况每个300ms进行一次信息采集

    public void start() {
        if (mShouldSample.get()) {
            return;
        }
        mShouldSample.set(true);

        HandlerThreadFactory.getTimerThreadHandler().removeCallbacks(mRunnable);
        HandlerThreadFactory.getTimerThreadHandler().postDelayed(mRunnable,
                BlockCanaryInternals.getInstance().getSampleDelay());
    }

StackSampler内部包含一个100条容量的LinkedHashMap，存放最近100条堆栈信息

private static final int DEFAULT_MAX_ENTRY_COUNT = 100;
private static final LinkedHashMap<Long, String> sStackMap = new LinkedHashMap<>();

CpuSampler则存着10条容量的LinkedHashMap