Merge "Synchronize access to WebViewZygote." am: fd6f631de5

am: c8111e07d0

Change-Id: I8c389a9c06bd0b8d1964756323e6c7e010901f89

core/java/android/webkit/WebViewZygote.java

@@ -24,6 +24,8 @@ import android.os.ZygoteProcess;
 import android.text.TextUtils;
 import android.util.Log;
 
+import com.android.internal.annotations.GuardedBy;
+
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
@@ -38,70 +40,104 @@ public class WebViewZygote {
     private static final String WEBVIEW_ZYGOTE_SERVICE_32 = "webview_zygote32";
     private static final String WEBVIEW_ZYGOTE_SERVICE_64 = "webview_zygote64";
 
+    /**
+     * Lock object that protects all other static members.
+     */
+    private static final Object sLock = new Object();
+
+    /**
+     * Instance that maintains the socket connection to the zygote. This is null if the zygote
+     * is not running or is not connected.
+     */
+    @GuardedBy("sLock")
     private static ZygoteProcess sZygote;
 
+    /**
+     * Information about the selected WebView package. This is set from #onWebViewProviderChanged().
+     */
+    @GuardedBy("sLock")
     private static PackageInfo sPackage;
 
+    /**
+     * Flag for whether multi-process WebView is enabled. If this is false, the zygote
+     * will not be started.
+     */
+    @GuardedBy("sLock")
     private static boolean sMultiprocessEnabled = false;
 
     public static ZygoteProcess getProcess() {
-        connectToZygoteIfNeeded();
-        return sZygote;
+        synchronized (sLock) {
+            connectToZygoteIfNeededLocked();
+            return sZygote;
+        }
     }
 
     public static String getPackageName() {
-        return sPackage.packageName;
+        synchronized (sLock) {
+            return sPackage.packageName;
+        }
     }
 
     public static boolean isMultiprocessEnabled() {
-        return sMultiprocessEnabled && sPackage != null;
+        synchronized (sLock) {
+            return sMultiprocessEnabled && sPackage != null;
+        }
     }
 
     public static void setMultiprocessEnabled(boolean enabled) {
-        sMultiprocessEnabled = enabled;
+        synchronized (sLock) {
+            sMultiprocessEnabled = enabled;
 
-        // When toggling between multi-process being on/off, start or stop the
-        // service. If it is enabled and the zygote is not yet started, bring up the service.
-        // Otherwise, bring down the service. The name may be null if the package
-        // information has not yet been resolved.
-        final String serviceName = getServiceName();
-        if (serviceName == null) return;
+            // When toggling between multi-process being on/off, start or stop the
+            // service. If it is enabled and the zygote is not yet started, bring up the service.
+            // Otherwise, bring down the service. The name may be null if the package
+            // information has not yet been resolved.
+            final String serviceName = getServiceNameLocked();
+            if (serviceName == null) return;
 
-        if (enabled && sZygote == null) {
-            SystemService.start(serviceName);
-        } else {
-            SystemService.stop(serviceName);
-            sZygote = null;
+            if (enabled && sZygote == null) {
+                SystemService.start(serviceName);
+            } else {
+                SystemService.stop(serviceName);
+                sZygote = null;
+            }
         }
     }
 
     public static void onWebViewProviderChanged(PackageInfo packageInfo) {
-        sPackage = packageInfo;
+        String serviceName;
+        synchronized (sLock) {
+            sPackage = packageInfo;
 
-        // If multi-process is not enabled, then do not start the zygote service.
-        if (!sMultiprocessEnabled) {
-            return;
+            // If multi-process is not enabled, then do not start the zygote service.
+            if (!sMultiprocessEnabled) {
+                return;
+            }
+
+            serviceName = getServiceNameLocked();
+            sZygote = null;
+
+            // The service may enter the RUNNING state before it opens the socket,
+            // so connectToZygoteIfNeededLocked() may still fail.
+            if (SystemService.isStopped(serviceName)) {
+                SystemService.start(serviceName);
+            } else {
+                SystemService.restart(serviceName);
+            }
+
+            try {
+                SystemService.waitForState(serviceName, SystemService.State.RUNNING, 5000);
+            } catch (TimeoutException e) {
+                Log.e(LOGTAG, "Timed out waiting for " + serviceName);
+                return;
+            }
+
+            connectToZygoteIfNeededLocked();
         }
-
-        final String serviceName = getServiceName();
-
-        if (SystemService.isStopped(serviceName)) {
-            SystemService.start(serviceName);
-        } else if (sZygote != null) {
-            SystemService.restart(serviceName);
-        }
-
-        try {
-            SystemService.waitForState(serviceName, SystemService.State.RUNNING, 5000);
-        } catch (TimeoutException e) {
-            Log.e(LOGTAG, "Timed out waiting for " + serviceName);
-            return;
-        }
-
-        connectToZygoteIfNeeded();
     }
 
-    private static String getServiceName() {
+    @GuardedBy("sLock")
+    private static String getServiceNameLocked() {
         if (sPackage == null)
             return null;
 
@@ -113,7 +149,8 @@ public class WebViewZygote {
         return WEBVIEW_ZYGOTE_SERVICE_32;
     }
 
-    private static void connectToZygoteIfNeeded() {
+    @GuardedBy("sLock")
+    private static void connectToZygoteIfNeededLocked() {
         if (sZygote != null)
             return;
 
@@ -122,7 +159,7 @@ public class WebViewZygote {
             return;
         }
 
-        final String serviceName = getServiceName();
+        final String serviceName = getServiceNameLocked();
         if (!SystemService.isRunning(serviceName)) {
             Log.e(LOGTAG, serviceName + " is not running");
             return;