129 lines
4.1 KiB
Java
129 lines
4.1 KiB
Java
/*
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* Copyright (C) 2023 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.internal.midi;
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/**
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* Uses multiple MidiEventSchedulers for waiting for events.
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*
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*/
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public class MidiEventMultiScheduler {
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private MultiLockMidiEventScheduler[] mMidiEventSchedulers;
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private int mNumEventSchedulers;
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private int mNumClosedSchedulers = 0;
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private final Object mMultiLock = new Object();
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private class MultiLockMidiEventScheduler extends MidiEventScheduler {
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@Override
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public void close() {
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synchronized (mMultiLock) {
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mNumClosedSchedulers++;
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}
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super.close();
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}
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@Override
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protected Object getLock() {
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return mMultiLock;
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}
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public boolean isEventBufferEmptyLocked() {
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return mEventBuffer.isEmpty();
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}
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public long getLowestTimeLocked() {
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return mEventBuffer.firstKey();
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}
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}
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/**
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* MidiEventMultiScheduler constructor
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*
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* @param numSchedulers the number of schedulers to create
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*/
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public MidiEventMultiScheduler(int numSchedulers) {
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mNumEventSchedulers = numSchedulers;
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mMidiEventSchedulers = new MultiLockMidiEventScheduler[numSchedulers];
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for (int i = 0; i < numSchedulers; i++) {
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mMidiEventSchedulers[i] = new MultiLockMidiEventScheduler();
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}
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}
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/**
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* Waits for the next MIDI event. This will return true when it receives it.
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* If all MidiEventSchedulers have been closed, this will return false.
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*
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* @return true if a MIDI event is received and false if all schedulers are closed.
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*/
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public boolean waitNextEvent() throws InterruptedException {
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synchronized (mMultiLock) {
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while (true) {
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if (mNumClosedSchedulers >= mNumEventSchedulers) {
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return false;
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}
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long lowestTime = Long.MAX_VALUE;
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long now = System.nanoTime();
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for (MultiLockMidiEventScheduler eventScheduler : mMidiEventSchedulers) {
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if (!eventScheduler.isEventBufferEmptyLocked()) {
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lowestTime = Math.min(lowestTime,
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eventScheduler.getLowestTimeLocked());
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}
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}
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if (lowestTime <= now) {
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return true;
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}
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long nanosToWait = lowestTime - now;
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// Add 1 millisecond so we don't wake up before it is
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// ready.
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long millisToWait = 1 + (nanosToWait / EventScheduler.NANOS_PER_MILLI);
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// Clip 64-bit value to 32-bit max.
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if (millisToWait > Integer.MAX_VALUE) {
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millisToWait = Integer.MAX_VALUE;
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}
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mMultiLock.wait(millisToWait);
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}
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}
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}
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/**
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* Gets the number of MidiEventSchedulers.
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*
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* @return the number of MidiEventSchedulers.
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*/
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public int getNumEventSchedulers() {
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return mNumEventSchedulers;
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}
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/**
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* Gets a specific MidiEventScheduler based on the index.
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*
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* @param index the zero indexed index of a MIDI event scheduler
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* @return a MidiEventScheduler
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*/
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public MidiEventScheduler getEventScheduler(int index) {
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return mMidiEventSchedulers[index];
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}
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/**
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* Closes all event schedulers.
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*/
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public void close() {
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for (MidiEventScheduler eventScheduler : mMidiEventSchedulers) {
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eventScheduler.close();
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}
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}
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}
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