Multiprocess test client: Android child process launcher rework.

base/test/android/java/src/org/chromium/base/MultiprocessTestClientLauncher.java

Index: base/test/android/java/src/org/chromium/base/MultiprocessTestClientLauncher.java
diff --git a/base/test/android/java/src/org/chromium/base/MultiprocessTestClientLauncher.java b/base/test/android/java/src/org/chromium/base/MultiprocessTestClientLauncher.java
new file mode 100644
index 0000000000000000000000000000000000000000..6c1f3981f9afdc0586d5067047cce5374bef9410
--- /dev/null
+++ b/base/test/android/java/src/org/chromium/base/MultiprocessTestClientLauncher.java
@@ -0,0 +1,293 @@
+// Copyright 2016 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.base;
+
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.content.ServiceConnection;
+import android.os.IBinder;
+import android.os.ParcelFileDescriptor;
+import android.os.RemoteException;
+
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+
+import javax.annotation.concurrent.GuardedBy;
+
+/**
+ * Helper class for launching test client processes for multiprocess unit tests.
+ */
+@JNINamespace("base::android")
+public final class MultiprocessTestClientLauncher {
+    private static final String TAG = "cr_MProcTCLauncher";
+
+    private static ConnectionAllocator sConnectionAllocator = new ConnectionAllocator();
+
+    // Not supposed to be instantiated.
+    private MultiprocessTestClientLauncher() {}
+
+    private static class ConnectionAllocator {
+        // Services are identified by a slot number, which is used in the service name to
+        // differentiate them (MultiprocessTestClientService0, MultiprocessTestClientService1, ...).
+        // They are stored in a FIFO queue in order to minimize the risk of the framework reusing a
+        // service without restarting its associated process (which can cause all kind of problems
+        // with static native variables already being initialized).
+        private static final int MAX_SUBPROCESS_COUNT = 5;
+
+        private final Object mLock = new Object();
+
+        @GuardedBy("mLock")
+        private final Queue<Integer> mFreeServiceSlot = new LinkedList<>();
+        @GuardedBy("mLock")
+        private final List<ClientServiceConnection> mConnections = new ArrayList<>();
+
+        public ConnectionAllocator() {
+            synchronized (mLock) {
+                for (int i = 0; i < MAX_SUBPROCESS_COUNT; i++) {
+                    mFreeServiceSlot.add(i);
+                }
+            }
+        }
+
+        public ClientServiceConnection allocateConnection(
+                String[] commandLine, FileDescriptorInfo[] filesToMap) {
+            synchronized (mLock) {
+                while (mFreeServiceSlot.isEmpty()) {
+                    try {
+                        mLock.wait();
+                    } catch (InterruptedException ie) {
+                        Log.e(TAG, "Interrupted while waiting for a free connection.");
+                    }
+                }
+
+                int slot = mFreeServiceSlot.remove();
+                ClientServiceConnection connection =
+                        new ClientServiceConnection(slot, commandLine, filesToMap);
+                mConnections.add(connection);
+                return connection;
+            }
+        }
+
+        public void freeConnection(ClientServiceConnection connection) {
+            synchronized (mLock) {
+                mFreeServiceSlot.add(connection.getSlot());
+                mConnections.remove(connection);
+            }
+        }
+
+        public ClientServiceConnection getConnectionByPid(int pid) {
+            synchronized (mLock) {
+                // List of connections is short, iterating is OK.
+                for (ClientServiceConnection connection : mConnections) {
+                    if (connection.getPid() == pid) {
+                        return connection;
+                    }
+                }
+            }
+            return null;
+        }
+    }
+
+    private static class ClientServiceConnection implements ServiceConnection {
+        private final String[] mCommandLine;
+        private final FileDescriptorInfo[] mFilesToMap;
+        private final Object mConnectedLock = new Object();
+        private final int mSlot;
+        private ITestClient mService = null;
+        @GuardedBy("mConnectedLock")
+        private boolean mConnected;
+        private int mPid;
+
+        ClientServiceConnection(int slot, String[] commandLine, FileDescriptorInfo[] filesToMap) {
+            mSlot = slot;
+            mCommandLine = commandLine;
+            mFilesToMap = filesToMap;
+        }
+
+        public void waitForConnection() {
+            synchronized (mConnectedLock) {
+                while (!mConnected) {
+                    try {
+                        mConnectedLock.wait();
+                    } catch (InterruptedException ie) {
+                        Log.e(TAG, "Interrupted while waiting for connection.");
+                    }
+                }
+            }
+        }
+
+        @Override
+        public void onServiceConnected(ComponentName className, IBinder service) {
+            try {
+                mService = ITestClient.Stub.asInterface(service);
+                mPid = mService.launch(mCommandLine, mFilesToMap);
+                synchronized (mConnectedLock) {
+                    mConnected = true;
+                    mConnectedLock.notifyAll();
+                }
+            } catch (RemoteException e) {
+                Log.e(TAG, "Connect failed");
+            }
+        }
+
+        @Override
+        public void onServiceDisconnected(ComponentName className) {
+            if (mPid == 0) {
+                Log.e(TAG, "Early ClientServiceConnection disconnection.");
+                return;
+            }
+            sConnectionAllocator.freeConnection(this);
+        }
+
+        public ITestClient getService() {
+            return mService;
+        }
+
+        public String getServiceClassName() {
+            // In order to use different processes, we have to declare multiple services in the
+            // AndroidManifest.xml file, each service associated with its own process. The various
+            // services are functionnaly identical but need to each have their own class.
+            // We differentiate them by their class name having a trailing number.
+            return MultiprocessTestClientService.class.getName() + mSlot;
+        }
+
+        public boolean isConnected() {
+            synchronized (mConnectedLock) {
+                return mConnected;
+            }
+        }
+
+        public int getSlot() {
+            return mSlot;
+        }
+
+        public int getPid() {
+            return mPid;
+        }
+    }
+
+    /**
+     * Spawns and connects to a child process.
+     * May not be called from the main thread.
+     *
+     * @param context context used to obtain the application context.
+     * @param commandLine the child process command line argv.
+     * @return the PID of the started process or 0 if the process could not be started.
+     */
+    @CalledByNative
+    private static int launchClient(final Context context, final String[] commandLine,
+            final FileDescriptorInfo[] filesToMap) {
+        if (ThreadUtils.runningOnUiThread()) {
+            // This can't be called on the main thread as the native side will block until
+            // onServiceConnected above is called, which cannot happen if the main thread is
+            // blocked.
+            throw new RuntimeException("launchClient cannot be called on the main thread");
+        }
+
+        ClientServiceConnection connection =
+                sConnectionAllocator.allocateConnection(commandLine, filesToMap);
+        Intent intent = new Intent();
+        String className = connection.getServiceClassName();
+        intent.setComponent(new ComponentName(context.getPackageName(), className));
+        if (!context.bindService(
+                    intent, connection, Context.BIND_AUTO_CREATE | Context.BIND_IMPORTANT)) {
+            Log.e(TAG, "Failed to bind service: " + context.getPackageName() + "." + className);
+            sConnectionAllocator.freeConnection(connection);
+            return 0;
+        }
+
+        connection.waitForConnection();
+
+        return connection.getPid();
+    }
+
+    /**
+     * Blocks until the main method invoked by a previous call to launchClient terminates or until
+     * the specified time-out expires.
+     * Returns immediately if main has already returned.
+     * @param context context used to obtain the application context.
+     * @param pid the process ID that was returned by the call to launchClient
+     * @param timeoutMs the timeout in milliseconds after which the method returns even if main has
+     *        not returned.
+     * @return the return code returned by the main method or whether it timed-out.
+     */
+    @CalledByNative
+    private static MainReturnCodeResult waitForMainToReturn(
+            Context context, int pid, int timeoutMs) {
+        ClientServiceConnection connection = sConnectionAllocator.getConnectionByPid(pid);
+        if (connection == null) {
+            Log.e(TAG, "waitForMainToReturn called on unknown connection for pid " + pid);
+            return null;
+        }
+        try {
+            return connection.getService().waitForMainToReturn(timeoutMs);
+        } catch (RemoteException e) {
+            Log.e(TAG, "Remote call to waitForMainToReturn failed.");
+            return null;
+        } finally {
+            freeConnection(context, connection);
+        }
+    }
+
+    @CalledByNative
+    private static boolean terminate(Context context, int pid, int exitCode, boolean wait) {
+        ClientServiceConnection connection = sConnectionAllocator.getConnectionByPid(pid);
+        if (connection == null) {
+            Log.e(TAG, "terminate called on unknown connection for pid " + pid);
+            return false;
+        }
+        try {
+            if (wait) {
+                connection.getService().forceStopSynchronous(exitCode);
+            } else {
+                connection.getService().forceStop(exitCode);
+            }
+        } catch (RemoteException e) {
+            // We expect this failure, since the forceStop's service implementation calls
+            // System.exit().
+        } finally {
+            freeConnection(context, connection);
+        }
+        return true;
+    }
+
+    private static void freeConnection(Context context, ClientServiceConnection connection) {
+        context.unbindService(connection);
+        sConnectionAllocator.freeConnection(connection);
+    }
+
+    /** Does not take ownership of of fds. */
+    @CalledByNative
+    private static FileDescriptorInfo[] makeFdInfoArray(int[] keys, int[] fds) {
+        FileDescriptorInfo[] fdInfos = new FileDescriptorInfo[keys.length];
+        for (int i = 0; i < keys.length; i++) {
+            FileDescriptorInfo fdInfo = makeFdInfo(keys[i], fds[i]);
+            if (fdInfo == null) {
+                Log.e(TAG, "Failed to make file descriptor (" + keys[i] + ", " + fds[i] + ").");
+                return null;
+            }
+            fdInfos[i] = fdInfo;
+        }
+        return fdInfos;
+    }
+
+    private static FileDescriptorInfo makeFdInfo(int id, int fd) {
+        ParcelFileDescriptor parcelableFd = null;
+        try {
+            parcelableFd = ParcelFileDescriptor.fromFd(fd);
+        } catch (IOException e) {
+            Log.e(TAG, "Invalid FD provided for process connection, aborting connection.", e);
+            return null;
+        }
+        return new FileDescriptorInfo(id, parcelableFd);
+    }
+}