Java tutorial
/* * 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. */ /** * Hangs onto idle live connections for a little while */ package android.net.http; import org.apache.http.HttpHost; import android.os.SystemClock; /** * {@hide} */ class IdleCache { class Entry { HttpHost mHost; Connection mConnection; long mTimeout; }; private final static int IDLE_CACHE_MAX = 8; /* Allow five consecutive empty queue checks before shutdown */ private final static int EMPTY_CHECK_MAX = 5; /* six second timeout for connections */ private final static int TIMEOUT = 6 * 1000; private final static int CHECK_INTERVAL = 2 * 1000; private Entry[] mEntries = new Entry[IDLE_CACHE_MAX]; private int mCount = 0; private IdleReaper mThread = null; /* stats */ private int mCached = 0; private int mReused = 0; IdleCache() { for (int i = 0; i < IDLE_CACHE_MAX; i++) { mEntries[i] = new Entry(); } } /** * Caches connection, if there is room. * @return true if connection cached */ synchronized boolean cacheConnection(HttpHost host, Connection connection) { boolean ret = false; if (HttpLog.LOGV) { HttpLog.v("IdleCache size " + mCount + " host " + host); } if (mCount < IDLE_CACHE_MAX) { long time = SystemClock.uptimeMillis(); for (int i = 0; i < IDLE_CACHE_MAX; i++) { Entry entry = mEntries[i]; if (entry.mHost == null) { entry.mHost = host; entry.mConnection = connection; entry.mTimeout = time + TIMEOUT; mCount++; if (HttpLog.LOGV) mCached++; ret = true; if (mThread == null) { mThread = new IdleReaper(); mThread.start(); } break; } } } return ret; } synchronized Connection getConnection(HttpHost host) { Connection ret = null; if (mCount > 0) { for (int i = 0; i < IDLE_CACHE_MAX; i++) { Entry entry = mEntries[i]; HttpHost eHost = entry.mHost; if (eHost != null && eHost.equals(host)) { ret = entry.mConnection; entry.mHost = null; entry.mConnection = null; mCount--; if (HttpLog.LOGV) mReused++; break; } } } return ret; } synchronized void clear() { for (int i = 0; mCount > 0 && i < IDLE_CACHE_MAX; i++) { Entry entry = mEntries[i]; if (entry.mHost != null) { entry.mHost = null; entry.mConnection.closeConnection(); entry.mConnection = null; mCount--; } } } private synchronized void clearIdle() { if (mCount > 0) { long time = SystemClock.uptimeMillis(); for (int i = 0; i < IDLE_CACHE_MAX; i++) { Entry entry = mEntries[i]; if (entry.mHost != null && time > entry.mTimeout) { entry.mHost = null; entry.mConnection.closeConnection(); entry.mConnection = null; mCount--; } } } } private class IdleReaper extends Thread { public void run() { int check = 0; setName("IdleReaper"); android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_BACKGROUND); synchronized (IdleCache.this) { while (check < EMPTY_CHECK_MAX) { try { IdleCache.this.wait(CHECK_INTERVAL); } catch (InterruptedException ex) { } if (mCount == 0) { check++; } else { check = 0; clearIdle(); } } mThread = null; } if (HttpLog.LOGV) { HttpLog.v("IdleCache IdleReaper shutdown: cached " + mCached + " reused " + mReused); mCached = 0; mReused = 0; } } } }