超时机制

    static final int OP_PENDING = 0;
    static final int OP_ACKNOWLEDGED = 1;
    static final int OP_TIMEOUT = -1;

 

 final Object mCurrentOpLock = new Object();

 

 

 

//代码调用就开始等待 在while中等待，直到 超时或者代码执行已经返回。

 boolean waitUntilOperationComplete(int token) {
        int finalState = OP_PENDING;
        synchronized (mCurrentOpLock) {
            try {
                while ((finalState = mCurrentOperations.get(token, OP_TIMEOUT)) == OP_PENDING) {
                    try {
                        mCurrentOpLock.wait();
                    } catch (InterruptedException e) {}
                }
            } catch (IndexOutOfBoundsException e) {
                // the operation has been mysteriously cleared from our
                // bookkeeping -- consider this a success and ignore it.
            }
        }
        mBackupHandler.removeMessages(MSG_TIMEOUT);
        if (DEBUG) Slog.v(TAG, "operation " + Integer.toHexString(token)
                + " complete: finalState=" + finalState);
        return finalState == OP_ACKNOWLEDGED;
    }

 

 

 

public void opComplete(int token) {
        synchronized (mCurrentOpLock) {
            if (DEBUG) Slog.v(TAG, "opComplete: " + Integer.toHexString(token));
            mCurrentOperations.put(token, OP_ACKNOWLEDGED);
            mCurrentOpLock.notifyAll();
        }
    }

 

 

private class BackupHandler extends Handler {
        public BackupHandler(Looper looper) {
            super(looper);
        }

 

      case MSG_TIMEOUT:
            {
                synchronized (mCurrentOpLock) {
                    final int token = msg.arg1;
                    int state = mCurrentOperations.get(token, OP_TIMEOUT);
                    if (state == OP_PENDING) {
                        if (DEBUG) Slog.v(TAG, "TIMEOUT: token=" + token);
                        mCurrentOperations.put(token, OP_TIMEOUT);
                    }
                    mCurrentOpLock.notifyAll();
                }
                break;
            }
}