CustomTabs: Base version for prerender switch

chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.customtabs;
 
 import android.app.ActivityManager;
 import android.app.Application;
 import android.app.PendingIntent;
 import android.content.Context;
@@ skipping 76 matching lines @@
     @VisibleForTesting
     static final int NO_PRERENDERING = 1;
     @VisibleForTesting
     static final int PREFETCH_ONLY = 2;
 
     private static AtomicReference<CustomTabsConnection> sInstance = new AtomicReference<>();
 
     /** Holds the parameters for the current speculation. */
     @VisibleForTesting
     static final class SpeculationParams {
+        @VisibleForTesting
+        static final int NO_SPECULATION = 0;
+        @VisibleForTesting
+        static final int PREFETCH = 1;
+        @VisibleForTesting
+        static final int PRERENDER = 2;
+
         public final CustomTabsSessionToken session;
         public final String url;
+        public final int speculationMode;
 
         // Only for prerender.
         public final WebContents webContents;
         public final String referrer;
         public final Bundle extras;
 
-        public final boolean prefetchOnly;
+        static SpeculationParams forPrefetch(CustomTabsSessionToken session, String url) {
+            return new SpeculationParams(session, url, PREFETCH, null, null, null);
+        }
 
         static SpeculationParams forPrerender(CustomTabsSessionToken session, String url,
                 WebContents webcontents, String referrer, Bundle extras) {
-            return new SpeculationParams(session, url, webcontents, referrer, extras, false);
+            return new SpeculationParams(session, url, PRERENDER, webcontents, referrer, extras);
         }
 
-        static SpeculationParams forPrefetch(CustomTabsSessionToken session, String url) {
-            return new SpeculationParams(session, url, null, null, null, true);
-        }
-
-        private SpeculationParams(CustomTabsSessionToken session, String url,
-                WebContents webContents, String referrer, Bundle extras, boolean prefetchOnly) {
+        private SpeculationParams(CustomTabsSessionToken session, String url, int speculationMode,
+                WebContents webContents, String referrer, Bundle extras) {
             this.session = session;
             this.url = url;
+            this.speculationMode = speculationMode;
             this.webContents = webContents;
             this.referrer = referrer;
             this.extras = extras;
-            this.prefetchOnly = prefetchOnly;
         }
     }
 
     @VisibleForTesting
     SpeculationParams mSpeculation;
     protected final Application mApplication;
     protected final ClientManager mClientManager;
     private final boolean mLogRequests;
     private final AtomicBoolean mWarmupHasBeenCalled = new AtomicBoolean();
     private final AtomicBoolean mWarmupHasBeenFinished = new AtomicBoolean();
@@ skipping 48 matching lines @@
         if (mForcePrerenderForTesting) mClientManager.setPrerenderCellularForSession(session, true);
         logCall("newSession()", success);
         return success;
     }
 
     private boolean newSessionInternal(CustomTabsSessionToken session) {
         if (session == null) return false;
         ClientManager.DisconnectCallback onDisconnect = new ClientManager.DisconnectCallback() {
             @Override
             public void run(CustomTabsSessionToken session) {
-                cancelPrerender(session);
+                cancelSpeculation(session);
             }
         };
         PostMessageHandler handler = new PostMessageHandler(session);
         return mClientManager.newSession(session, Binder.getCallingUid(), onDisconnect, handler);
     }
 
     /** Warmup activities that should only happen once. */
     @SuppressFBWarnings("DM_EXIT")
     private static void initializeBrowser(final Application app) {
         ThreadUtils.assertOnUiThread();
@@ skipping 105 matching lines @@
     /**
      * High confidence mayLaunchUrl() call, that is:
      * - Tries to prerender if possible.
      * - An empty URL cancels the current prerender if any.
      * - If prerendering is not possible, makes sure that there is a spare renderer.
      */
     private void highConfidenceMayLaunchUrl(CustomTabsSessionToken session,
             int uid, String url, Bundle extras, List<Bundle> otherLikelyBundles) {
         ThreadUtils.assertOnUiThread();
         if (TextUtils.isEmpty(url)) {
-            cancelPrerender(session);
+            cancelSpeculation(session);
             return;
         }
 
-        WarmupManager warmupManager = WarmupManager.getInstance();
-        Profile profile = Profile.getLastUsedProfile();
-
         url = DataReductionProxySettings.getInstance().maybeRewriteWebliteUrl(url);
         int debugOverrideValue = NO_OVERRIDE;
         if (extras != null) debugOverrideValue = extras.getInt(DEBUG_OVERRIDE_KEY, NO_OVERRIDE);
 
-        boolean didStartPrerender = false, didStartPrefetch = false;
-        boolean mayPrerender = mayPrerender(session);
-        if (mayPrerender) {
-            if (debugOverrideValue == PREFETCH_ONLY) {
-                didStartPrefetch = new ResourcePrefetchPredictor(profile).startPrefetching(url);
-                if (didStartPrefetch) mSpeculation = SpeculationParams.forPrefetch(session, url);
-            } else if (debugOverrideValue != NO_PRERENDERING) {
-                didStartPrerender = prerenderUrl(session, url, extras, uid);
-            }
-        }
+        int speculationMode = getSpeculationMode(session, debugOverrideValue);
+        if (maySpeculate(session)) startSpeculation(session, url, speculationMode, extras, uid);
         preconnectUrls(otherLikelyBundles);
-        if (!didStartPrefetch) warmupManager.maybePreconnectUrlAndSubResources(profile, url);
-        if (!didStartPrerender) warmupManager.createSpareWebContents();
     }
 
     /**
      * Low confidence mayLaunchUrl() call, that is:
      * - Preconnects to the ordered list of URLs.
      * - Makes sure that there is a spare renderer.
      */
     @VisibleForTesting
     boolean lowConfidenceMayLaunchUrl(List<Bundle> likelyBundles) {
         ThreadUtils.assertOnUiThread();
@@ skipping 228 matching lines @@
      * @param url The URL the WebContents is for.
      * @param referrer The referrer to use for |url|.
      * @return The prerendered WebContents, or null.
      */
     WebContents takePrerenderedUrl(CustomTabsSessionToken session, String url, String referrer) {
         ThreadUtils.assertOnUiThread();
         if (mSpeculation == null || session == null || !session.equals(mSpeculation.session)) {
             return null;
         }
 
-        if (mSpeculation.prefetchOnly) {
-            Profile profile = Profile.getLastUsedProfile();
-            new ResourcePrefetchPredictor(profile).stopPrefetching(mSpeculation.url);
-            mSpeculation = null;
+        if (mSpeculation.speculationMode == SpeculationParams.PREFETCH) {
+            cancelSpeculation(session);
             return null;
         }
 
         WebContents webContents = mSpeculation.webContents;
         String prerenderedUrl = mSpeculation.url;
         String prerenderReferrer = mSpeculation.referrer;
         if (referrer == null) referrer = "";
         boolean ignoreFragments = mClientManager.getIgnoreFragmentsForSession(session);
         boolean urlsMatch = TextUtils.equals(prerenderedUrl, url)
                 || (ignoreFragments
                         && UrlUtilities.urlsMatchIgnoringFragments(prerenderedUrl, url));
         WebContents result = null;
         if (urlsMatch && TextUtils.equals(prerenderReferrer, referrer)) {
             result = webContents;
             mSpeculation = null;
         } else {
-            cancelPrerender(session);
+            cancelSpeculation(session);
         }
         if (!mClientManager.usesDefaultSessionParameters(session) && webContents != null) {
             RecordHistogram.recordBooleanHistogram(
                     "CustomTabs.NonDefaultSessionPrerenderMatched", result != null);
         }
 
         return result;
     }
 
     /** Returns the URL prerendered for a session, or null. */
@@ skipping 44 matching lines @@
         mClientManager.setPrerenderCellularForSession(session, value);
     }
 
     /**
      * See {@link ClientManager#setSendNavigationInfoForSession(CustomTabsSessionToken, boolean)}.
      */
     void setSendNavigationInfoForSession(CustomTabsSessionToken session, boolean send) {
         mClientManager.setSendNavigationInfoForSession(session, send);
     }
 
+    void setSpeculationModeForSession(CustomTabsSessionToken session, int speculationMode) {
+        mClientManager.setSpeculationModeForSession(session, speculationMode);
+    }
+
+    int getSpeculationModeForSession(CustomTabsSessionToken session) {
+        return mClientManager.getSpeculationModeForSession(session);
+    }
+
     /**
      * Extracts the creator package name from the intent.
      * @param intent The intent to get the package name from.
      * @return the package name which can be null.
      */
     String extractCreatorPackage(Intent intent) {
         return null;
     }
 
     /**
@@ skipping 195 matching lines @@
     @VisibleForTesting
     void cleanUpSession(final CustomTabsSessionToken session) {
         ThreadUtils.runOnUiThread(new Runnable() {
             @Override
             public void run() {
                 mClientManager.cleanupSession(session);
             }
         });
     }
 
-    private boolean mayPrerender(CustomTabsSessionToken session) {
+    private boolean maySpeculate(CustomTabsSessionToken session) {
         if (!DeviceClassManager.enablePrerendering()) return false;
         // TODO(yusufo): The check for prerender in PrivacyManager now checks for the network
         // connection type as well, we should either change that or add another check for custom
         // tabs. Then PrivacyManager should be used to make the below check.
         if (!PrefServiceBridge.getInstance().getNetworkPredictionEnabled()) return false;
         if (DataReductionProxySettings.getInstance().isDataReductionProxyEnabled()) return false;
         ConnectivityManager cm =
                 (ConnectivityManager) mApplication.getApplicationContext().getSystemService(
                         Context.CONNECTIVITY_SERVICE);
         return !cm.isActiveNetworkMetered() || shouldPrerenderOnCellularForSession(session);
     }
 
-    /** Cancels a prerender for a given session, or any session if null. */
-    void cancelPrerender(CustomTabsSessionToken session) {
+    /** Cancels the speculation for a given session, or any session if null. */
+    void cancelSpeculation(CustomTabsSessionToken session) {
         ThreadUtils.assertOnUiThread();
-        if (mSpeculation != null && (session == null || session.equals(mSpeculation.session))
-                && mSpeculation.webContents != null) {
-            mExternalPrerenderHandler.cancelCurrentPrerender();
-            mSpeculation.webContents.destroy();
+        if (mSpeculation == null) return;
+        if (session == null || session.equals(mSpeculation.session)) {
+            switch (mSpeculation.speculationMode) {
+                case SpeculationParams.PRERENDER:
+                    if (mSpeculation.webContents == null) return;
+                    mExternalPrerenderHandler.cancelCurrentPrerender();
+                    mSpeculation.webContents.destroy();
+                    break;
+                case SpeculationParams.PREFETCH:
+                    Profile profile = Profile.getLastUsedProfile();
+                    new ResourcePrefetchPredictor(profile).stopPrefetching(mSpeculation.url);
+                    break;
+                default:
+                    return;
+            }
             mSpeculation = null;
         }
     }
 
+    /*
+     * This function will do as much as it can to have a subsequent navigation
+     * to the specified url sped up.
+     */
+    private void startSpeculation(CustomTabsSessionToken session, String url, int speculationMode,

[mattcary, 2017/03/28 09:50:23]

This is much more comprehensible, thanks.

+            Bundle extras, int uid) {
+        WarmupManager warmupManager = WarmupManager.getInstance();

[Benoit L, 2017/03/28 09:45:15]

I think it would be slightly clearer this way:

boolean preconnect = true, createSpareWebContents = true;

and in the switch:

case PREFETCH:
  preconnect = !didPrefetch;
case PRERENDER:
  createSpareWebContents = !didPrerender;

And after the switch:

if (preconnect)_warmupManager.preconnect();
if (createSpareWebContents) warmupManager.createSpareWebContents();

[ahemery1, 2017/03/28 11:37:14]

Done.

+        Profile profile = Profile.getLastUsedProfile();
+        switch (speculationMode) {
+            case SpeculationParams.PREFETCH:

[ahemery1, 2017/03/28 09:30:15]

Just reordered to match constants ordering.

+                boolean didPrefetch = prefetchUrl(session, url);
+                if (!didPrefetch) warmupManager.maybePreconnectUrlAndSubResources(profile, url);
+                warmupManager.createSpareWebContents();
+                break;
+            case SpeculationParams.PRERENDER:
+                boolean didPrerender = prerenderUrl(session, url, extras, uid);
+                if (!didPrerender) warmupManager.createSpareWebContents();
+                warmupManager.maybePreconnectUrlAndSubResources(profile, url);
+                break;
+            default:
+                warmupManager.createSpareWebContents();
+                warmupManager.maybePreconnectUrlAndSubResources(profile, url);
+        }
+    }
+
     /**
      * Tries to request a prerender for a given URL.
      *
      * @param session Session the request comes from.
      * @param url URL to prerender.
      * @param extras extra parameters.
      * @param uid UID of the caller.
      * @return true if a prerender has been initiated.
      */
     private boolean prerenderUrl(
             CustomTabsSessionToken session, String url, Bundle extras, int uid) {
         ThreadUtils.assertOnUiThread();
-        // Ignores mayPrerender() for an empty URL, since it cancels an existing prerender.
-        if (!mayPrerender(session) && !TextUtils.isEmpty(url)) return false;
         if (!mWarmupHasBeenCalled.get()) return false;
-        // Last one wins and cancels the previous prerender.
-        cancelPrerender(null);
-        if (TextUtils.isEmpty(url)) return false;
+
         boolean throttle = !shouldPrerenderOnCellularForSession(session);
         if (throttle && !mClientManager.isPrerenderingAllowed(uid)) return false;
 
         // A prerender will be requested. Time to destroy the spare WebContents.
         WarmupManager.getInstance().destroySpareWebContents();
 
         Intent extrasIntent = new Intent();
         if (extras != null) extrasIntent.putExtras(extras);
         if (IntentHandler.getExtraHeadersFromIntent(extrasIntent) != null) return false;
         if (mExternalPrerenderHandler == null) {
             mExternalPrerenderHandler = new ExternalPrerenderHandler();
         }
         Rect contentBounds = ExternalPrerenderHandler.estimateContentSize(mApplication, true);
         String referrer = IntentHandler.getReferrerUrlIncludingExtraHeaders(extrasIntent);
         if (referrer == null && getReferrerForSession(session) != null) {
             referrer = getReferrerForSession(session).getUrl();
         }
         if (referrer == null) referrer = "";
-        Pair<WebContents, WebContents> webContentsPair = mExternalPrerenderHandler.addPrerender(
-                Profile.getLastUsedProfile(), url, referrer,
-                contentBounds,
-                shouldPrerenderOnCellularForSession(session));
+        Pair<WebContents, WebContents> webContentsPair =
+                mExternalPrerenderHandler.addPrerender(Profile.getLastUsedProfile(), url, referrer,
+                        contentBounds, shouldPrerenderOnCellularForSession(session));
         if (webContentsPair == null) return false;
         WebContents dummyWebContents = webContentsPair.first;
         if (webContentsPair.second != null) {
             mClientManager.resetPostMessageHandlerForSession(session, webContentsPair.second);
         }
         if (throttle) mClientManager.registerPrerenderRequest(uid, url);
-        mSpeculation = SpeculationParams.forPrerender(
-                session, url, dummyWebContents, referrer, extras);
+        mSpeculation =
+                SpeculationParams.forPrerender(session, url, dummyWebContents, referrer, extras);
 
         RecordHistogram.recordBooleanHistogram("CustomTabs.PrerenderSessionUsesDefaultParameters",
                 mClientManager.usesDefaultSessionParameters(session));
 
         return true;
     }
 
+    private boolean prefetchUrl(CustomTabsSessionToken session, String url) {

[Benoit L, 2017/03/28 09:45:15]

nit:
Actually, if we remove the profile construction, this methods is two lines.
Inline above?

[ahemery1, 2017/03/28 11:37:14]

Done.

+        Profile profile = Profile.getLastUsedProfile();
+        boolean didStartPrefetching = new ResourcePrefetchPredictor(profile).startPrefetching(url);
+        if (didStartPrefetching) mSpeculation = SpeculationParams.forPrefetch(session, url);
+        return didStartPrefetching;
+    }
+
     @VisibleForTesting
     void resetThrottling(Context context, int uid) {
         mClientManager.resetThrottling(uid);
     }
 
     @VisibleForTesting
     void ban(Context context, int uid) {
         mClientManager.ban(uid);
     }
 
     @VisibleForTesting
     void setForcePrerender(boolean force) {
         mForcePrerenderForTesting = force;
     }
+
+    private int getSpeculationMode(CustomTabsSessionToken session, int debugOverrideValue) {
+        switch (debugOverrideValue) {
+            case PREFETCH_ONLY:
+                return SpeculationParams.PREFETCH;
+            case NO_PRERENDERING:
+                return SpeculationParams.NO_SPECULATION;
+            default:
+                return getSpeculationModeForSession(session);
+        }
+    }
 }