Refactoring ChildProcessConnection.

content/public/android/java/src/org/chromium/content/browser/ChildProcessLauncherHelper.java

 // Copyright 2017 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.content.browser;
 
 import android.content.Context;
 import android.os.ParcelFileDescriptor;
 
 import org.chromium.base.ContextUtils;
 import org.chromium.base.Log;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
 import org.chromium.base.process_launcher.ChildProcessCreationParams;
 import org.chromium.base.process_launcher.FileDescriptorInfo;
 
 import java.io.IOException;
 
 /**
  * This is the java counterpart to ChildProcessLauncherHelper. It is owned by native side and
  * has an explicit destroy method.
  * Each public or jni methods should have explicit documentation on what threads they are called.
  */
 @JNINamespace("content::internal")
 class ChildProcessLauncherHelper {
     private static final String TAG = "ChildProcLH";
 
+    // Represents an invalid process handle; same as base/process/process.h kNullProcessHandle.
+    private static final int NULL_PROCESS_HANDLE = 0;
+
     // Note native pointer is only guaranteed live until nativeOnChildProcessStarted.
     private long mNativeChildProcessLauncherHelper;
-    private int mPid;
+    private BaseChildProcessConnection mChildProcessConnection;
 
     @CalledByNative
     private static FileDescriptorInfo makeFdInfo(
             int id, int fd, boolean autoClose, long offset, long size) {
         assert LauncherThread.runningOnLauncherThread();
         ParcelFileDescriptor pFd;
         if (autoClose) {
             // Adopt the FD, it will be closed when we close the ParcelFileDescriptor.
             pFd = ParcelFileDescriptor.adoptFd(fd);
         } else {
@@ skipping 17 matching lines @@
     }
 
     private ChildProcessLauncherHelper(long nativePointer, Context context, int paramId,
             final String[] commandLine, int childProcessId, FileDescriptorInfo[] filesToBeMapped) {
         assert LauncherThread.runningOnLauncherThread();
         mNativeChildProcessLauncherHelper = nativePointer;
 
         ChildProcessLauncher.start(context, paramId, commandLine, childProcessId, filesToBeMapped,
                 new ChildProcessLauncher.LaunchCallback() {
                     @Override
-                    public void onChildProcessStarted(int pid) {
-                        mPid = pid;
+                    public void onChildProcessStarted(BaseChildProcessConnection connection) {
+                        mChildProcessConnection = connection;
                         if (mNativeChildProcessLauncherHelper != 0) {
-                            nativeOnChildProcessStarted(mNativeChildProcessLauncherHelper, pid);
+                            nativeOnChildProcessStarted(
+                                    mNativeChildProcessLauncherHelper, getPid());
                         }
                         mNativeChildProcessLauncherHelper = 0;
                     }
                 });
     }
 
+    private int getPid() {
+        return mChildProcessConnection == null ? NULL_PROCESS_HANDLE
+                                               : mChildProcessConnection.getPid();
+    }
     // Called on client (UI or IO) thread.
     @CalledByNative
     private boolean isOomProtected() {
-        return ChildProcessLauncher.getBindingManager().isOomProtected(mPid);
+        if (mChildProcessConnection == null) {

[boliu, 2017/04/20 22:33:34]

hmm, this is "kind of" thread safe, only because mChildProcessConnection is set
at most once, and can only go from null to non-null.

either add a lock, or document this?

[Jay Civelli, 2017/04/25 06:02:46]

As you mentioned before, reference assignation are atomic, so the lock would not
give us much (since once it is non null it stays that way).
Added comment.

+            return false;
+        }
+
+        if (mChildProcessConnection instanceof ImportantChildProcessConnection) {
+            // The connection was bound as BIND_IMPORTANT. This should prevent it from being killed
+            // when the app is on the foreground (that's our best guess, but there is no absolute
+            // guarantee).
+            return ChildProcessLauncher.isApplicationInForeground();
+        }
+
+        return ((ManagedChildProcessConnection) mChildProcessConnection)
+                .isOomProtectedOrWasWhenDied();
     }
 
     @CalledByNative
     private void setInForeground(int pid, boolean inForeground) {
         assert LauncherThread.runningOnLauncherThread();
-        assert mPid == pid;
-        ChildProcessLauncher.getBindingManager().setInForeground(mPid, inForeground);
+        assert getPid() == pid;
+        ChildProcessLauncher.getBindingManager().setInForeground(pid, inForeground);
     }
 
     @CalledByNative
     private static void stop(int pid) {
         assert LauncherThread.runningOnLauncherThread();
         ChildProcessLauncher.stop(pid);
     }
 
     // Called on UI thread.
     @CalledByNative
     private static int getNumberOfRendererSlots() {
         final ChildProcessCreationParams params = ChildProcessCreationParams.getDefault();
         final Context context = ContextUtils.getApplicationContext();
         final boolean inSandbox = true;
         final String packageName =
                 params == null ? context.getPackageName() : params.getPackageName();
         try {
             return ChildConnectionAllocator.getNumberOfServices(context, inSandbox, packageName);
         } catch (RuntimeException e) {
             // Unittest packages do not declare services. Some tests require a realistic number
             // to test child process policies, so pick a high-ish number here.
             return 65535;
         }
     }
 
     // Can be called on a number of threads, including launcher, and binder.
     private static native void nativeOnChildProcessStarted(
             long nativeChildProcessLauncherHelper, int pid);
 }