Dns prefetch implementation on Froyo

Change-Id: Ic0223dc2f4ce1443402a69dbb5bd864e92d142b9

4 files changed, 246 insertions, 0 deletions

diff --git a/core/java/android/webkit/BrowserFrame.java b/core/java/android/webkit/BrowserFrame.java
index 219a469..071f87c 100644
--- a/core/java/android/webkit/BrowserFrame.java
+++ b/core/java/android/webkit/BrowserFrame.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2006 The Android Open Source Project
+ * Copyright (c) 2010, Code Aurora Forum. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -229,6 +230,22 @@ class BrowserFrame extends Handler {
         }
     }
 
+    public void startDnsPrefetch() {
+        if (DebugFlags.BROWSER_FRAME) {
+            Log.v(LOGTAG, "Starting DNS prefetch");
+        }
+
+        DnsResolver dnsResolver = DnsResolver.getInstance();
+        if(dnsResolver == null )
+            return;
+
+        HashMap hostsMap = nativeGetEmbeddedHostNames(dnsResolver.getMaxParallelDnsQueryPerPage());
+        if(hostsMap == null)
+            return;
+
+        dnsResolver.resolveDnsForHostMap(hostsMap);
+    }
+
     /**
      * Load a url from the network or the filesystem into the main frame.
      * Following the same behaviour as Safari, javascript: URLs are not passed
@@ -967,6 +984,8 @@ class BrowserFrame extends Handler {
     private native void nativeLoadData(String baseUrl, String data,
             String mimeType, String encoding, String historyUrl);
 
+    private native HashMap nativeGetEmbeddedHostNames(int maxDnsHostCount);
+
     /**
      * Stop loading the current page.
      */
diff --git a/core/java/android/webkit/DnsResolver.java b/core/java/android/webkit/DnsResolver.java
new file mode 100644
index 0000000..80a0808
--- /dev/null
+++ b/core/java/android/webkit/DnsResolver.java
@@ -0,0 +1,206 @@
+/*

+ * Copyright (c) 2010, Code Aurora Forum. All rights reserved.

+ *

+ * Redistribution and use in source and binary forms, with or without

+ * modification, are permitted provided that the following conditions are met:

+ *    * Redistributions of source code must retain the above copyright

+ *      notice, this list of conditions and the following disclaimer.

+ *    * Redistributions in binary form must reproduce the above copyright

+ *      notice, this list of conditions and the following disclaimer in the

+ *      documentation and/or other materials provided with the distribution.

+ *    * Neither the name of Code Aurora nor

+ *      the names of its contributors may be used to endorse or promote

+ *      products derived from this software without specific prior written

+ *      permission.

+ *

+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

+ * IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

+ * NON-INFRINGEMENT ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR

+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;

+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF

+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

+ */

+

+package android.webkit;

+

+import android.os.Handler;

+import android.util.Log;

+import android.os.Message;

+import android.os.Process;

+

+import java.lang.Thread;

+import java.lang.InterruptedException;

+import java.net.UnknownHostException;

+import java.util.concurrent.Executors;

+import java.util.concurrent.ExecutorService;

+import java.util.concurrent.Semaphore;

+import java.util.HashMap;

+import java.util.Iterator;

+import java.util.Map;

+

+final class DnsResolver {

+

+    private static final String LOGTAG = "webcore";

+

+    /* Max Thread pool size is  taken from data published by google

+     * that mentions max hosts per webpage = 8 */

+    private final int MAX_DNS_RESOLVER_THREAD_POOL_SIZE = 8;

+

+    /* This number is derived by considering various factors such as OS DNS cache size,

+     * Browser Cache size and realistic need to spent time on DNS prefetch

+     */

+    private final int MAX_PARALLEL_DNS_QUERIES_PER_PAGE = 64;

+

+    private volatile boolean mDnsResolverThreadPoolRunning = false;

+

+    private volatile boolean mShutDownInProgress = false;

+

+    private static DnsResolver sDnsResolver;

+

+    private HashMap mHostNamesToBeResolved;

+

+    private ExecutorService  mDnsResolverThreadPool;

+

+    private static int mDnsResolverRefCount = 0;

+

+    /* Lock to synchronize the access to threadpool */

+    private static Object mThreadPoolLock = new Object();

+

+    public static synchronized DnsResolver createDnsResolver() {

+        if (sDnsResolver == null) {

+            sDnsResolver = new DnsResolver();

+        }

+        ++mDnsResolverRefCount;

+        return sDnsResolver;

+    }

+

+    public static DnsResolver getInstance() {

+        return sDnsResolver;

+    }

+

+    private DnsResolver() {

+        createDnsResolverThreadPool();

+    }

+

+    private void createDnsResolverThreadPool() {

+        final Runnable startDnsResolver = new Runnable() {

+            public void run() {

+                /* DNS resolver priority should be same as of HTTP thread pool */

+                Process.setThreadPriority( android.os.Process.THREAD_PRIORITY_DEFAULT +

+                                           android.os.Process.THREAD_PRIORITY_LESS_FAVORABLE);

+                mDnsResolverThreadPool = Executors.newFixedThreadPool(MAX_DNS_RESOLVER_THREAD_POOL_SIZE);

+                mHostNamesToBeResolved = new HashMap();

+                boolean bResolvedPriorityHostNames = false;

+                int dnsQueryCounter = 0;

+                int numHosts = 0;

+                while(!mShutDownInProgress) {

+                    synchronized(mHostNamesToBeResolved) {

+                        numHosts = mHostNamesToBeResolved.size();

+                    }

+                    if(numHosts <= 0) {

+                        try {

+                            dnsQueryCounter = 0;

+                            bResolvedPriorityHostNames = false;

+                            mDnsResolverThreadPoolRunning = true;

+                            synchronized(mThreadPoolLock) {

+                                mThreadPoolLock.wait();

+                            }

+                        } catch(java.lang.InterruptedException e) {

+                        }

+                    }

+                    else {

+                        synchronized(mHostNamesToBeResolved) {

+                            Iterator iterator = mHostNamesToBeResolved.entrySet().iterator();

+                            while(iterator.hasNext() && mDnsResolverThreadPoolRunning && (dnsQueryCounter < MAX_PARALLEL_DNS_QUERIES_PER_PAGE)) {

+                                Map.Entry entry = (Map.Entry) iterator.next();

+                                final String hostName = (String)entry.getKey();

+                                final String priority = (String)entry.getValue();

+                                if( (!bResolvedPriorityHostNames && priority.equalsIgnoreCase("1"))  ||

+                                    ( bResolvedPriorityHostNames && priority.equalsIgnoreCase("0"))

+                                  ) {

+                                    ++dnsQueryCounter;

+                                    iterator.remove();

+                                    Runnable task = new Runnable() {

+                                        public void run() {

+                                            try {

+                                                java.net.InetAddress.getByName(hostName);

+                                            } catch(java.net.UnknownHostException e) {

+                                            }

+                                        }

+                                    };

+                                    mDnsResolverThreadPool.execute (task);

+                                }

+                            }

+                            if(!mDnsResolverThreadPoolRunning || (dnsQueryCounter >= MAX_PARALLEL_DNS_QUERIES_PER_PAGE)) {

+                                mHostNamesToBeResolved.clear();

+                            }

+                            bResolvedPriorityHostNames = (bResolvedPriorityHostNames) ? false:true;

+                        }

+                    }

+                }

+                mDnsResolverThreadPool.shutdown();

+                sDnsResolver = null;

+            }

+        };

+        Thread dnsResolver = new Thread(startDnsResolver);

+        dnsResolver.setName("DNS resolver");

+        dnsResolver.start();

+    }

+

+    public synchronized void destroyDnsResolver() {

+        --mDnsResolverRefCount;

+        if(mDnsResolverRefCount == 0) {

+            mShutDownInProgress = true;

+            mDnsResolverThreadPoolRunning = false;

+            synchronized(mThreadPoolLock) {

+                mThreadPoolLock.notifyAll();

+            }

+        }

+    }

+

+    public void resolveDnsForHost(String hostName, String priority) {

+        if(hostName == null) {

+            return;

+        }

+        synchronized(mHostNamesToBeResolved) {

+            if(mHostNamesToBeResolved.size() > 0 ) {

+                return;

+            }

+            mHostNamesToBeResolved.put(hostName,priority);

+        }

+        resumeDnsResolverThreadPool();

+    }

+

+    public void resolveDnsForHostMap(HashMap hostMap) {

+        if(hostMap == null) {

+            return;

+        }

+        synchronized (mHostNamesToBeResolved) {

+            mHostNamesToBeResolved.putAll(hostMap);

+        }

+        resumeDnsResolverThreadPool();

+    }

+

+    /* pause will flush all pending DNS queries at the DNS resolver */

+    public void pauseDnsResolverThreadPool()  {

+        mDnsResolverThreadPoolRunning = false;

+    }

+

+    /* resume will start DNS resolver executing DNS queries  */

+    public void resumeDnsResolverThreadPool()  {

+        mDnsResolverThreadPoolRunning = true;

+        synchronized(mThreadPoolLock) {

+            mThreadPoolLock.notifyAll();

+        }

+    }

+

+    /* returns the max number of DNS queries that can be made in background for a page */

+    public int getMaxParallelDnsQueryPerPage() {

+        return MAX_PARALLEL_DNS_QUERIES_PER_PAGE;

+    }

+}

diff --git a/core/java/android/webkit/WebView.java b/core/java/android/webkit/WebView.java
index 766a80c..f3ddbb6 100644
--- a/core/java/android/webkit/WebView.java
+++ b/core/java/android/webkit/WebView.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2006 The Android Open Source Project
+ * Copyright (c) 2010, Code Aurora Forum. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -1298,6 +1299,13 @@ public class WebView extends AbsoluteLayout
     }
 
     /**
+     * @hide pending API council approval.
+     */
+    public void startDnsPrefetch() {
+        mWebViewCore.sendMessage(EventHub.START_DNS_PREFETCH);
+    }
+
+    /**
      * Inform WebView of the network state. This is used to set
      * the javascript property window.navigator.isOnline and
      * generates the online/offline event as specified in HTML5, sec. 5.7.7
diff --git a/core/java/android/webkit/WebViewCore.java b/core/java/android/webkit/WebViewCore.java
index 4118119..7a1f7b5 100644
--- a/core/java/android/webkit/WebViewCore.java
+++ b/core/java/android/webkit/WebViewCore.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2007 The Android Open Source Project
+ * Copyright (c) 2010, Code Aurora Forum. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -197,6 +198,8 @@ final class WebViewCore {
         // WebCore thread handler.
         mEventHub.transferMessages();
 
+        DnsResolver.createDnsResolver();
+
         // Send a message back to WebView to tell it that we have set up the
         // WebCore thread.
         if (mWebView != null) {
@@ -771,6 +774,7 @@ final class WebViewCore {
             "ON_RESUME",    // = 144
             "FREE_MEMORY",  // = 145
             "VALID_NODE_BOUNDS", // = 146
+            "START_DNS_PREFETCH",  // = 151
         };
 
     class EventHub {
@@ -839,6 +843,7 @@ final class WebViewCore {
 
         // Network-based messaging
         static final int CLEAR_SSL_PREF_TABLE = 150;
+        static final int START_DNS_PREFETCH = 151;
 
         // Test harness messages
         static final int REQUEST_EXT_REPRESENTATION = 160;
@@ -944,6 +949,7 @@ final class WebViewCore {
                             break;
 
                         case LOAD_URL: {
+                            DnsResolver.getInstance().pauseDnsResolverThreadPool();
                             GetUrlData param = (GetUrlData) msg.obj;
                             loadUrl(param.mUrl, param.mExtraHeaders);
                             break;
@@ -1000,6 +1006,7 @@ final class WebViewCore {
                             break;
 
                         case RELOAD:
+                            DnsResolver.getInstance().pauseDnsResolverThreadPool();
                             mBrowserFrame.reload(false);
                             break;
 
@@ -1043,6 +1050,7 @@ final class WebViewCore {
                             if (!mBrowserFrame.committed() && msg.arg1 == -1 &&
                                     (mBrowserFrame.loadType() ==
                                     BrowserFrame.FRAME_LOADTYPE_STANDARD)) {
+                                DnsResolver.getInstance().pauseDnsResolverThreadPool();
                                 mBrowserFrame.reload(true);
                             } else {
                                 mBrowserFrame.goBackOrForward(msg.arg1);
@@ -1357,6 +1365,10 @@ final class WebViewCore {
                             BrowserFrame.sJavaBridge.removePackageName(
                                     (String) msg.obj);
                             break;
+
+                        case START_DNS_PREFETCH:
+                            mBrowserFrame.startDnsPrefetch();
+                            break;
                     }
                 }
             };
@@ -1544,6 +1556,7 @@ final class WebViewCore {
             }
             mEventHub.blockMessages();
         }
+        DnsResolver.getInstance().destroyDnsResolver();
     }
 
     //-------------------------------------------------------------------------