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/*
* Copyright (C) 2008 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.launcher2;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.os.MessageQueue;
import android.util.Pair;
import java.util.LinkedList;
import java.util.ListIterator;
/**
* Queue of things to run on a looper thread. Items posted with {@link #post} will not
* be actually enqued on the handler until after the last one has run, to keep from
* starving the thread.
*
* This class is fifo.
*/
public class DeferredHandler {
private LinkedList<Pair<Runnable, Integer>> mQueue = new LinkedList<Pair<Runnable, Integer>>();
private MessageQueue mMessageQueue = Looper.myQueue();
private Impl mHandler = new Impl();
private class Impl extends Handler implements MessageQueue.IdleHandler {
public void handleMessage(Message msg) {
Pair<Runnable, Integer> p;
Runnable r;
synchronized (mQueue) {
if (mQueue.size() == 0) {
return;
}
p = mQueue.removeFirst();
r = p.first;
}
r.run();
synchronized (mQueue) {
scheduleNextLocked();
}
}
public boolean queueIdle() {
handleMessage(null);
return false;
}
}
private class IdleRunnable implements Runnable {
Runnable mRunnable;
IdleRunnable(Runnable r) {
mRunnable = r;
}
public void run() {
mRunnable.run();
}
}
public DeferredHandler() {
}
/** Schedule runnable to run after everything that's on the queue right now. */
public void post(Runnable runnable) {
post(runnable, 0);
}
public void post(Runnable runnable, int type) {
synchronized (mQueue) {
mQueue.add(new Pair<Runnable, Integer>(runnable, type));
if (mQueue.size() == 1) {
scheduleNextLocked();
}
}
}
/** Schedule runnable to run when the queue goes idle. */
public void postIdle(final Runnable runnable) {
postIdle(runnable, 0);
}
public void postIdle(final Runnable runnable, int type) {
post(new IdleRunnable(runnable), type);
}
public void cancelRunnable(Runnable runnable) {
synchronized (mQueue) {
while (mQueue.remove(runnable)) { }
}
}
public void cancelAllRunnablesOfType(int type) {
synchronized (mQueue) {
ListIterator<Pair<Runnable, Integer>> iter = mQueue.listIterator();
Pair<Runnable, Integer> p;
while (iter.hasNext()) {
p = iter.next();
if (p.second == type) {
iter.remove();
}
}
}
}
public void cancel() {
synchronized (mQueue) {
mQueue.clear();
}
}
/** Runs all queued Runnables from the calling thread. */
public void flush() {
LinkedList<Pair<Runnable, Integer>> queue = new LinkedList<Pair<Runnable, Integer>>();
synchronized (mQueue) {
queue.addAll(mQueue);
mQueue.clear();
}
for (Pair<Runnable, Integer> p : queue) {
p.first.run();
}
}
void scheduleNextLocked() {
if (mQueue.size() > 0) {
Pair<Runnable, Integer> p = mQueue.getFirst();
Runnable peek = p.first;
if (peek instanceof IdleRunnable) {
mMessageQueue.addIdleHandler(mHandler);
} else {
mHandler.sendEmptyMessage(1);
}
}
}
}