WakeLock 在仍持有时完成

发布于 2024-11-05 15:05:12 字数 937 浏览 7 评论 0原文

pm 和 keepScreenOn 变量是全局定义的。

我在 OnCreate 方法中获取 PowerManager.WakeLock：

pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
keepScreenOn = pm.newWakeLock(PowerManager.SCREEN_BRIGHT_LOCK,"tpd");

在 onStart、onResume 和 onRestart 中，我在 onDestroy、onPause 和 onStop 中获取锁

if (keepScreenOn == null) {
    keepScreenOn = pm.newakeLock(PowerManager,SCREEN_BRIGHT_LOCK,"tpd");
}
keepScreenOn.acquire();

，然后释放锁：

if (keepScreenOn != null) {
  keepScreenOn.release();
  keepScreenOn = null
}

在我的应用程序退出后，出现故障屏幕并且 adb 抱怨那

java.lang.Exception：WakeLock 在仍持有时完成：tpd

跟踪显示我在退出之前释放了锁。我错过了什么？

如果不跨越至少一个，就无法退出该应用程序 onPause、onStop 或 onDestroy。我可以看到该应用程序名为 release() 和调用 acquire() 一样频繁，所以即使唤醒锁是引用计数的，它应该仍然有零引用。

原文

The pm and keepScreenOn variables are globally defined.

I grab the PowerManager.WakeLock in my OnCreate method:

pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
keepScreenOn = pm.newWakeLock(PowerManager.SCREEN_BRIGHT_LOCK,"tpd");

in my onStart, onResume, and onRestart I grab the lock with

if (keepScreenOn == null) {
    keepScreenOn = pm.newakeLock(PowerManager,SCREEN_BRIGHT_LOCK,"tpd");
}
keepScreenOn.acquire();

in my onDestroy, onPause, and onStop I release the lock with:

if (keepScreenOn != null) {
  keepScreenOn.release();
  keepScreenOn = null
}

After my app exits I get a failure screen and adb complains that

java.lang.Exception: WakeLock finalized while still held: tpd

Tracing shows that I released the lock before exit.
What have I missed?

There is no way out of the app without crossing at least one of
onPause, onStop, or onDestroy. I can see that the app called
release() as often as it called acquire() so even though the
wakelock is reference counted it should still have zero refs.

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享受孤独 2024-11-12 15:05:12

好吧，我相信我找到了问题。

WakeLock 是引用计数的。这意味着如果第二个 acquire()
发生这种情况只会增加引用计数。每次调用 acquire()
需要通过调用 isHeld() 进行保护，如下所示：

if ((keepScreenOn != null) &&           // we have a WakeLock
    (keepScreenOn.isHeld() == false)) {  // but we don't hold it 
  keepScreenOn.acquire();
}

我假设我持有的锁上的 acquire() 没有执行任何操作，因此
多次 acquire() 调用导致了该问题。自从参考
count 不为零，GC 会抛出错误。

Ok I believe I found the problem.

The WakeLock is reference counted. That means that if a second acquire()
happens it will just bump the reference count. Every call to acquire()
needs to be protected by a call to isHeld() as in:

if ((keepScreenOn != null) &&           // we have a WakeLock
    (keepScreenOn.isHeld() == false)) {  // but we don't hold it 
  keepScreenOn.acquire();
}

I had assumed that acquire() on a lock I held did nothing so
multiple acquire() calls caused the problem. Since the reference
count is not zero the GC throws an error.

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深海蓝天 2024-11-12 15:05:12

我知道这个问题很老了，但请记住，WakeLocks 默认情况下是“引用计数”的。您可以使用 setReferenceCounted(boolean) 关闭引用计数，请参阅 http://developer.android.com/reference/android/os/PowerManager.WakeLock.html#setReferenceCounted(boolean)

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