| /* |
| * Copyright (C) 2010 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. |
| */ |
| |
| package com.android.email; |
| |
| import com.android.emailcommon.Logging; |
| |
| import android.os.Handler; |
| import android.util.Log; |
| |
| import java.util.Timer; |
| import java.util.TimerTask; |
| |
| /** |
| * This class used to "throttle" a flow of events. |
| * |
| * When {@link #onEvent()} is called, it calls the callback in a certain timeout later. |
| * Initially {@link #mMinTimeout} is used as the timeout, but if it gets multiple {@link #onEvent} |
| * calls in a certain amount of time, it extends the timeout, until it reaches {@link #mMaxTimeout}. |
| * |
| * This class is primarily used to throttle content changed events. |
| */ |
| public class Throttle { |
| public static final boolean DEBUG = false; // Don't submit with true |
| |
| public static final int DEFAULT_MIN_TIMEOUT = 150; |
| public static final int DEFAULT_MAX_TIMEOUT = 2500; |
| /* package */ static final int TIMEOUT_EXTEND_INTERVAL = 500; |
| |
| private static Timer TIMER = new Timer(); |
| |
| private final Clock mClock; |
| private final Timer mTimer; |
| |
| /** Name of the instance. Only for logging. */ |
| private final String mName; |
| |
| /** Handler for UI thread. */ |
| private final Handler mHandler; |
| |
| /** Callback to be called */ |
| private final Runnable mCallback; |
| |
| /** Minimum (default) timeout, in milliseconds. */ |
| private final int mMinTimeout; |
| |
| /** Max timeout, in milliseconds. */ |
| private final int mMaxTimeout; |
| |
| /** Current timeout, in milliseconds. */ |
| private int mTimeout; |
| |
| /** When {@link #onEvent()} was last called. */ |
| private long mLastEventTime; |
| |
| private MyTimerTask mRunningTimerTask; |
| |
| /** Constructor with default timeout */ |
| public Throttle(String name, Runnable callback, Handler handler) { |
| this(name, callback, handler, DEFAULT_MIN_TIMEOUT, DEFAULT_MAX_TIMEOUT); |
| } |
| |
| /** Constructor that takes custom timeout */ |
| public Throttle(String name, Runnable callback, Handler handler,int minTimeout, |
| int maxTimeout) { |
| this(name, callback, handler, minTimeout, maxTimeout, Clock.INSTANCE, TIMER); |
| } |
| |
| /** Constructor for tests */ |
| /* package */ Throttle(String name, Runnable callback, Handler handler,int minTimeout, |
| int maxTimeout, Clock clock, Timer timer) { |
| if (maxTimeout < minTimeout) { |
| throw new IllegalArgumentException(); |
| } |
| mName = name; |
| mCallback = callback; |
| mClock = clock; |
| mTimer = timer; |
| mHandler = handler; |
| mMinTimeout = minTimeout; |
| mMaxTimeout = maxTimeout; |
| mTimeout = mMinTimeout; |
| } |
| |
| private void debugLog(String message) { |
| Log.d(Logging.LOG_TAG, "Throttle: [" + mName + "] " + message); |
| } |
| |
| private boolean isCallbackScheduled() { |
| return mRunningTimerTask != null; |
| } |
| |
| public void cancelScheduledCallback() { |
| if (mRunningTimerTask != null) { |
| if (DEBUG) debugLog("Canceling scheduled callback"); |
| mRunningTimerTask.cancel(); |
| mRunningTimerTask = null; |
| } |
| } |
| |
| /* package */ void updateTimeout() { |
| final long now = mClock.getTime(); |
| if ((now - mLastEventTime) <= TIMEOUT_EXTEND_INTERVAL) { |
| mTimeout *= 2; |
| if (mTimeout >= mMaxTimeout) { |
| mTimeout = mMaxTimeout; |
| } |
| if (DEBUG) debugLog("Timeout extended " + mTimeout); |
| } else { |
| mTimeout = mMinTimeout; |
| if (DEBUG) debugLog("Timeout reset to " + mTimeout); |
| } |
| |
| mLastEventTime = now; |
| } |
| |
| public void onEvent() { |
| if (DEBUG) debugLog("onEvent"); |
| |
| updateTimeout(); |
| |
| if (isCallbackScheduled()) { |
| if (DEBUG) debugLog(" callback already scheduled"); |
| } else { |
| if (DEBUG) debugLog(" scheduling callback"); |
| mRunningTimerTask = new MyTimerTask(); |
| mTimer.schedule(mRunningTimerTask, mTimeout); |
| } |
| } |
| |
| /** |
| * Timer task called on timeout, |
| */ |
| private class MyTimerTask extends TimerTask { |
| private boolean mCanceled; |
| |
| @Override |
| public void run() { |
| mHandler.post(new HandlerRunnable()); |
| } |
| |
| @Override |
| public boolean cancel() { |
| mCanceled = true; |
| return super.cancel(); |
| } |
| |
| private class HandlerRunnable implements Runnable { |
| @Override |
| public void run() { |
| mRunningTimerTask = null; |
| if (!mCanceled) { // This check has to be done on the UI thread. |
| if (DEBUG) debugLog("Kicking callback"); |
| mCallback.run(); |
| } |
| } |
| } |
| } |
| |
| /* package */ int getTimeoutForTest() { |
| return mTimeout; |
| } |
| |
| /* package */ long getLastEventTimeForTest() { |
| return mLastEventTime; |
| } |
| } |