Revert "Revert "Update ParcelFileDescriptor to use non-blocking I/O."" (6fd9f9af) · Commits · e / os / android_frameworks_base

core/java/android/os/ParcelFileDescriptor.java

+31 −39

Original line number	Diff line number	Diff line
		@@ -19,11 +19,13 @@ package android.os;
		import static android.system.OsConstants.AF_UNIX;
		import static android.system.OsConstants.SEEK_SET;
		import static android.system.OsConstants.SOCK_STREAM;
		import static android.system.OsConstants.SOCK_SEQPACKET;
		import static android.system.OsConstants.S_ISLNK;
		import static android.system.OsConstants.S_ISREG;

		import android.content.BroadcastReceiver;
		import android.content.ContentProvider;
		import android.os.MessageQueue.FileDescriptorCallback;
		import android.system.ErrnoException;
		import android.system.Os;
		import android.system.OsConstants;
		@@ -31,7 +33,6 @@ import android.system.StructStat;
		import android.util.Log;

		import dalvik.system.CloseGuard;

		import libcore.io.IoUtils;
		import libcore.io.Memory;

		@@ -220,8 +221,8 @@ public class ParcelFileDescriptor implements Parcelable, Closeable {
		* be opened with the requested mode.
		* @see #parseMode(String)
		*/
		public static ParcelFileDescriptor open(
		File file, int mode, Handler handler, OnCloseListener listener) throws IOException {
		public static ParcelFileDescriptor open(File file, int mode, Handler handler,
		final OnCloseListener listener) throws IOException {
		if (handler == null) {
		throw new IllegalArgumentException("Handler must not be null");
		}
		@@ -235,10 +236,25 @@ public class ParcelFileDescriptor implements Parcelable, Closeable {
		final FileDescriptor[] comm = createCommSocketPair();
		final ParcelFileDescriptor pfd = new ParcelFileDescriptor(fd, comm[0]);

		// Kick off thread to watch for status updates
		IoUtils.setBlocking(comm[1], true);
		final ListenerBridge bridge = new ListenerBridge(comm[1], handler.getLooper(), listener);
		bridge.start();
		handler.getLooper().getQueue().registerFileDescriptorCallback(comm[1],
		FileDescriptorCallback.EVENT_INPUT, new FileDescriptorCallback() {
		@Override
		public int onFileDescriptorEvents(FileDescriptor fd, int events) {
		Status status = null;
		if ((events & FileDescriptorCallback.EVENT_INPUT) != 0) {
		final byte[] buf = new byte[MAX_STATUS];
		status = readCommStatus(fd, buf);
		} else if ((events & FileDescriptorCallback.EVENT_ERROR) != 0) {
		status = new Status(Status.DEAD);
		}
		if (status != null) {
		IoUtils.closeQuietly(fd);
		listener.onClose(status.asIOException());
		return 0; // unregister the callback
		}
		return EVENT_INPUT;
		}
		});

		return pfd;
		}
		@@ -446,9 +462,12 @@ public class ParcelFileDescriptor implements Parcelable, Closeable {

		private static FileDescriptor[] createCommSocketPair() throws IOException {
		try {
		// Use SOCK_SEQPACKET so that we have a guarantee that the status
		// is written and read atomically as one unit and is not split
		// across multiple IO operations.
		final FileDescriptor comm1 = new FileDescriptor();
		final FileDescriptor comm2 = new FileDescriptor();
		Os.socketpair(AF_UNIX, SOCK_STREAM, 0, comm1, comm2);
		Os.socketpair(AF_UNIX, SOCK_SEQPACKET, 0, comm1, comm2);
		IoUtils.setBlocking(comm1, false);
		IoUtils.setBlocking(comm2, false);
		return new FileDescriptor[] { comm1, comm2 };
		@@ -709,6 +728,7 @@ public class ParcelFileDescriptor implements Parcelable, Closeable {
		writePtr += len;
		}

		// Must write the entire status as a single operation.
		Os.write(mCommFd, buf, 0, writePtr);
		} catch (ErrnoException e) {
		// Reporting status is best-effort
		@@ -726,6 +746,7 @@ public class ParcelFileDescriptor implements Parcelable, Closeable {

		private static Status readCommStatus(FileDescriptor comm, byte[] buf) {
		try {
		// Must read the entire status as a single operation.
		final int n = Os.read(comm, buf, 0, buf.length);
		if (n == 0) {
		// EOF means they're dead
		@@ -1014,39 +1035,10 @@ public class ParcelFileDescriptor implements Parcelable, Closeable {
		return new IOException("Unknown status: " + status);
		}
		}
		}

		/**
		* Bridge to watch for remote status, and deliver to listener. Currently
		* requires that communication socket is <em>blocking</em>.
		*/
		private static final class ListenerBridge extends Thread {
		// TODO: switch to using Looper to avoid burning a thread

		private FileDescriptor mCommFd;
		private final Handler mHandler;

		public ListenerBridge(FileDescriptor comm, Looper looper, final OnCloseListener listener) {
		mCommFd = comm;
		mHandler = new Handler(looper) {
		@Override
		public void handleMessage(Message msg) {
		final Status s = (Status) msg.obj;
		listener.onClose(s != null ? s.asIOException() : null);
		}
		};
		}

		@Override
		public void run() {
		try {
		final byte[] buf = new byte[MAX_STATUS];
		final Status status = readCommStatus(mCommFd, buf);
		mHandler.obtainMessage(0, status).sendToTarget();
		} finally {
		IoUtils.closeQuietly(mCommFd);
		mCommFd = null;
		}
		public String toString() {
		return "{" + status + ": " + msg + "}";
		}
		}
		}