android/media/midi/MidiDevice.java

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.media.midi;

import android.os.Binder;
import android.os.IBinder;
import android.os.Process;
import android.os.RemoteException;
import android.util.Log;

import dalvik.system.CloseGuard;

import libcore.io.IoUtils;

import java.io.Closeable;
import java.io.FileDescriptor;
import java.io.IOException;

import java.util.HashSet;

/**
 * This class is used for sending and receiving data to and from a MIDI device
 * Instances of this class are created by {@link MidiManager#openDevice}.
 */
public final class MidiDevice implements Closeable {
    private static final String TAG = "MidiDevice";

    private final MidiDeviceInfo mDeviceInfo;    // accessed from native code
    private final IMidiDeviceServer mDeviceServer;
    private final IBinder mDeviceServerBinder;    // accessed from native code
    private final IMidiManager mMidiManager;
    private final IBinder mClientToken;
    private final IBinder mDeviceToken;
    private boolean mIsDeviceClosed;    // accessed from native code

    private long mNativeHandle;    // accessed from native code

    private final CloseGuard mGuard = CloseGuard.get();

    /**
     * This class represents a connection between the output port of one device
     * and the input port of another. Created by {@link #connectPorts}.
     * Close this object to terminate the connection.
     */
    public class MidiConnection implements Closeable {
        private final IMidiDeviceServer mInputPortDeviceServer;
        private final IBinder mInputPortToken;
        private final IBinder mOutputPortToken;
        private final CloseGuard mGuard = CloseGuard.get();
        private boolean mIsClosed;

        MidiConnection(IBinder outputPortToken, MidiInputPort inputPort) {
            mInputPortDeviceServer = inputPort.getDeviceServer();
            mInputPortToken = inputPort.getToken();
            mOutputPortToken = outputPortToken;
            mGuard.open("close");
        }

        @Override
        public void close() throws IOException {
            synchronized (mGuard) {
                if (mIsClosed) return;
                mGuard.close();
                try {
                    // close input port
                    mInputPortDeviceServer.closePort(mInputPortToken);
                    // close output port
                    mDeviceServer.closePort(mOutputPortToken);
                } catch (RemoteException e) {
                    Log.e(TAG, "RemoteException in MidiConnection.close");
                }
                mIsClosed = true;
            }
        }

        @Override
        protected void finalize() throws Throwable {
            try {
                if (mGuard != null) {
                    mGuard.warnIfOpen();
                }

                close();
            } finally {
                super.finalize();
            }
        }
    }

    /* package */ MidiDevice(MidiDeviceInfo deviceInfo, IMidiDeviceServer server,
            IMidiManager midiManager, IBinder clientToken, IBinder deviceToken) {
        mDeviceInfo = deviceInfo;
        mDeviceServer = server;
        mDeviceServerBinder = mDeviceServer.asBinder();
        mMidiManager = midiManager;
        mClientToken = clientToken;
        mDeviceToken = deviceToken;
        mGuard.open("close");
    }

    /**
     * Returns a {@link MidiDeviceInfo} object, which describes this device.
     *
     * @return the {@link MidiDeviceInfo} object
     */
    public MidiDeviceInfo getInfo() {
        return mDeviceInfo;
    }

    /**
     * Called to open a {@link MidiInputPort} for the specified port number.
     *
     * An input port can only be used by one sender at a time.
     * Opening an input port will fail if another application has already opened it for use.
     * A {@link MidiDeviceStatus} can be used to determine if an input port is already open.
     *
     * @param portNumber the number of the input port to open
     * @return the {@link MidiInputPort} if the open is successful,
     *         or null in case of failure.
     */
    public MidiInputPort openInputPort(int portNumber) {
        if (mIsDeviceClosed) {
            return null;
        }
        try {
            IBinder token = new Binder();
            FileDescriptor fd = mDeviceServer.openInputPort(token, portNumber);
            if (fd == null) {
                return null;
            }
            return new MidiInputPort(mDeviceServer, token, fd, portNumber);
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in openInputPort");
            return null;
        }
    }

    /**
     * Called to open a {@link MidiOutputPort} for the specified port number.
     *
     * An output port may be opened by multiple applications.
     *
     * @param portNumber the number of the output port to open
     * @return the {@link MidiOutputPort} if the open is successful,
     *         or null in case of failure.
     */
    public MidiOutputPort openOutputPort(int portNumber) {
        if (mIsDeviceClosed) {
            return null;
        }
        try {
            IBinder token = new Binder();
            FileDescriptor fd = mDeviceServer.openOutputPort(token, portNumber);
            if (fd == null) {
                return null;
            }
            return new MidiOutputPort(mDeviceServer, token, fd, portNumber);
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in openOutputPort");
            return null;
        }
    }

    /**
     * Connects the supplied {@link MidiInputPort} to the output port of this device
     * with the specified port number. Once the connection is made, the MidiInput port instance
     * can no longer receive data via its {@link MidiReceiver#onSend} method.
     * This method returns a {@link MidiDevice.MidiConnection} object, which can be used
     * to close the connection.
     *
     * @param inputPort the inputPort to connect
     * @param outputPortNumber the port number of the output port to connect inputPort to.
     * @return {@link MidiDevice.MidiConnection} object if the connection is successful,
     *         or null in case of failure.
     */
    public MidiConnection connectPorts(MidiInputPort inputPort, int outputPortNumber) {
        if (outputPortNumber < 0 || outputPortNumber >= mDeviceInfo.getOutputPortCount()) {
            throw new IllegalArgumentException("outputPortNumber out of range");
        }
        if (mIsDeviceClosed) {
            return null;
        }

        FileDescriptor fd = inputPort.claimFileDescriptor();
        if (fd == null) {
            return null;
        }
        try {
            IBinder token = new Binder();
            int calleePid = mDeviceServer.connectPorts(token, fd, outputPortNumber);
            // If the service is a different Process then it will duplicate the fd
            // and we can safely close this one.
            // But if the service is in the same Process then closing the fd will
            // kill the connection. So don't do that.
            if (calleePid != Process.myPid()) {
                // close our copy of the file descriptor
                IoUtils.closeQuietly(fd);
            }

            return new MidiConnection(token, inputPort);
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in connectPorts");
            return null;
        }
    }

    @Override
    public void close() throws IOException {
        synchronized (mGuard) {
            // What if there is a native reference to this?
            if (mNativeHandle != 0) {
                Log.w(TAG, "MidiDevice#close() called while there is an outstanding native client 0x"
                           + Long.toHexString(mNativeHandle));
            }
            if (!mIsDeviceClosed && mNativeHandle == 0) {
                mGuard.close();
                mIsDeviceClosed = true;
                try {
                    mMidiManager.closeDevice(mClientToken, mDeviceToken);
                } catch (RemoteException e) {
                    Log.e(TAG, "RemoteException in closeDevice");
                }
            }
        }
    }

    @Override
    protected void finalize() throws Throwable {
        try {
            if (mGuard != null) {
                mGuard.warnIfOpen();
            }

            close();
        } finally {
            super.finalize();
        }
    }

    @Override
    public String toString() {
        return ("MidiDevice: " + mDeviceInfo.toString());
    }
}