/*
* Quasar: lightweight threads and actors for the JVM.
* Copyright (c) 2013-2016, Parallel Universe Software Co. All rights reserved.
*
* This program and the accompanying materials are dual-licensed under
* either the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation
*
* or (per the licensee's choosing)
*
* under the terms of the GNU Lesser General Public License version 3.0
* as published by the Free Software Foundation.
*/
package co.paralleluniverse.strands.channels;
import co.paralleluniverse.common.monitoring.FlightRecorder;
import co.paralleluniverse.common.monitoring.FlightRecorderMessage;
import co.paralleluniverse.common.util.Debug;
import co.paralleluniverse.common.util.DelegatingEquals;
import co.paralleluniverse.common.util.Objects;
import co.paralleluniverse.fibers.SuspendExecution;
import co.paralleluniverse.remote.RemoteChannelProxyFactoryService;
import co.paralleluniverse.strands.Condition;
import co.paralleluniverse.strands.OwnedSynchronizer;
import co.paralleluniverse.strands.SimpleConditionSynchronizer;
import co.paralleluniverse.strands.Strand;
import co.paralleluniverse.strands.Synchronization;
import co.paralleluniverse.strands.Timeout;
import co.paralleluniverse.strands.channels.Channels.OverflowPolicy;
import co.paralleluniverse.strands.queues.BasicQueue;
import co.paralleluniverse.strands.queues.CircularBuffer;
import co.paralleluniverse.strands.queues.QueueCapacityExceededException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
*
* @author pron
*/
public abstract class QueueChannel<Message> implements StandardChannel<Message>, Selectable<Message>, Synchronization, java.io.Serializable {
private static final int MAX_SEND_RETRIES = 10;
final BasicQueue<Message> queue;
private final boolean singleProducer;
private final boolean singleConsumer;
final Condition sync;
final Condition sendersSync;
final OverflowPolicy overflowPolicy;
private Throwable closeException;
private volatile boolean sendClosed;
private boolean receiveClosed;
protected QueueChannel(BasicQueue<Message> queue, OverflowPolicy overflowPolicy, boolean singleConsumer) {
this(queue, overflowPolicy, false, singleConsumer);
}
protected QueueChannel(BasicQueue<Message> queue, OverflowPolicy overflowPolicy, boolean singleProducer, boolean singleConsumer) {
this.queue = queue;
if (!singleConsumer || queue instanceof CircularBuffer)
this.sync = new SimpleConditionSynchronizer(this);
else
this.sync = new OwnedSynchronizer(this);
this.overflowPolicy = overflowPolicy;
this.sendersSync = overflowPolicy == OverflowPolicy.BLOCK ? new SimpleConditionSynchronizer(this) : null;
this.singleProducer = singleProducer;
this.singleConsumer = singleConsumer;
}
@Override
public boolean equals(Object other) {
if (other instanceof DelegatingEquals)
return other.equals(this);
return super.equals(other);
}
@Override
public int capacity() {
return queue.capacity();
}
@Override
public boolean isSingleProducer() {
return singleProducer;
}
@Override
public boolean isSingleConsumer() {
return singleConsumer;
}
public OverflowPolicy getOverflowPolicy() {
return overflowPolicy;
}
protected Condition sync() {
verifySync();
return sync;
}
protected void signalReceivers() {
record("signalReceivers", "");
sync.signalAll();
}
protected void signalAndWait() throws SuspendExecution, InterruptedException {
record("signalAndWait", "");
if (sync instanceof OwnedSynchronizer)
((OwnedSynchronizer) sync).signalAndWait();
else
sync.signalAll();
}
void signalSenders() {
if (overflowPolicy == OverflowPolicy.BLOCK) {
record("signalSenders", "");
sendersSync.signal();
}
}
@Override
public Object register(SelectAction<Message> action) {
if (((SelectActionImpl) action).isData()) {
if (sendersSync != null)
sendersSync.register();
} else
sync.register();
return action;
}
@Override
public Object register() {
// for queues, a simple registration is always a receive
return sync.register();
}
@Override
public boolean tryNow(Object token) {
SelectActionImpl<Message> action = (SelectActionImpl<Message>) token;
if (!action.lease())
return false;
boolean res;
if (action.isData()) {
res = trySend(action.message());
if (res)
action.setItem(null);
} else {
Message m = tryReceive();
action.setItem(m);
if (m == null)
res = isClosed();
else
res = true;
}
if (res)
action.won();
else
action.returnLease();
return res;
}
@Override
public void unregister(Object token) {
if (token == null)
return;
SelectActionImpl<Message> action = (SelectActionImpl<Message>) token;
if (action.isData()) {
if (sendersSync != null)
sendersSync.unregister(null);
} else
sync.unregister(null);
}
@Override
public void send(Message message) throws SuspendExecution, InterruptedException {
send0(message, false, false, 0);
}
@Override
public boolean send(Message message, long timeout, TimeUnit unit) throws SuspendExecution, InterruptedException {
return send0(message, false, true, unit.toNanos(timeout));
}
@Override
public boolean send(Message message, Timeout timeout) throws SuspendExecution, InterruptedException {
return send0(message, false, true, timeout.nanosLeft());
}
@Override
public boolean trySend(Message message) {
if (message == null)
throw new IllegalArgumentException("message is null");
if (isSendClosed())
return true;
if (queue.enq(message)) {
signalReceivers();
return true;
} else
return false;
}
protected void sendSync(Message message) throws SuspendExecution {
try {
send0(message, true, false, 0);
} catch (InterruptedException e) {
Strand.currentStrand().interrupt();
}
}
public boolean send0(Message message, boolean sync, boolean timed, long nanos) throws SuspendExecution, InterruptedException {
if (message == null)
throw new IllegalArgumentException("message is null");
if (isSendClosed())
return true;
if (overflowPolicy == OverflowPolicy.BLOCK)
sendersSync.register();
try {
int i = 0;
final long deadline = timed ? System.nanoTime() + nanos : 0L;
record("send0", "%s enqueing message %s", this, message);
while (!queue.enq(message)) {
if (isSendClosed()) {
record("send0", "%s channel is closed for send. Dropping message %s", this, message);
return true;
}
record("send0", "%s channel queue is full. policy: %s", this, overflowPolicy);
if (!onQueueFull(i++, timed, nanos))
return true;
if (timed) {
nanos = deadline - System.nanoTime();
if (nanos <= 0)
throw new TimeoutException();
}
}
} catch (TimeoutException e) {
return false;
} finally {
if (overflowPolicy == OverflowPolicy.BLOCK)
sendersSync.unregister(null);
}
if (sync)
signalAndWait();
else
signalReceivers();
return true;
}
private boolean onQueueFull(int iter, boolean timed, long nanos) throws SuspendExecution, InterruptedException, TimeoutException {
switch (overflowPolicy) {
case DROP:
return false;
case THROW:
throw new QueueCapacityExceededException();
case BLOCK:
if (timed)
sendersSync.await(iter, nanos, TimeUnit.NANOSECONDS);
else
sendersSync.await(iter);
return true;
case BACKOFF:
if (iter > MAX_SEND_RETRIES)
throw new QueueCapacityExceededException();
if (iter > 5)
Strand.sleep((iter - 5) * 5);
else if (iter > 4)
Strand.yield();
return true;
default:
throw new AssertionError("Unsupportd policy: " + overflowPolicy);
}
}
@Override
public void close() {
if (!sendClosed) {
sendClosed = true;
signalReceivers();
if (sendersSync != null)
sendersSync.signalAll();
}
}
@Override
public void close(Throwable t) {
if (!sendClosed) // possible race here, but it's OK – we just let one of the concurrent exceptions through
closeException = t;
close();
}
public void sendNonSuspendable(Message message) throws QueueCapacityExceededException {
if (isSendClosed()) {
record("sendNonSuspendable", "%s channel is closed for send. Dropping message %s", this, message);
return;
}
record("sendNonSuspendable", "%s enqueing message %s", this, message);
if (!queue.enq(message))
throw new QueueCapacityExceededException();
signalReceivers();
}
/**
* This method must only be called by the channel's owner (the receiver)
*/
@Override
public boolean isClosed() {
if (receiveClosed)
return true;
// racy, but that's OK because we don't guarantee anything if we return false
if (sendClosed && queue.isEmpty()) {
setReceiveClosed();
return true;
}
return false;
}
boolean isSendClosed() {
return sendClosed;
}
void setReceiveClosed() {
this.receiveClosed = true;
}
protected Throwable getCloseException() {
return closeException;
}
private Message closeValue() {
if (closeException != null)
throw new ProducerException(closeException);
return null;
}
@Override
public Message tryReceive() {
if (receiveClosed)
return closeValue();
boolean closed = isSendClosed();
final Message m = queue.poll();
if (m != null)
signalSenders();
else if (closed) {
setReceiveClosed();
return closeValue();
}
return m;
}
@Override
public Message receive() throws SuspendExecution, InterruptedException {
if (receiveClosed)
return closeValue();
Message m;
boolean closed;
final Object token = sync.register();
try {
for (int i = 0;; i++) {
closed = isSendClosed(); // must be read BEFORE queue.poll()
if ((m = queue.poll()) != null)
break;
// i can be > 0 if task state is LEASED
if (closed) {
setReceiveClosed();
return closeValue();
}
sync.await(i);
}
} finally {
sync.unregister(token);
}
assert m != null;
signalSenders();
return m;
}
@Override
public Message receive(long timeout, TimeUnit unit) throws SuspendExecution, InterruptedException {
if (receiveClosed)
return closeValue();
if (unit == null)
return receive();
if (timeout <= 0)
return tryReceive();
long left = unit.toNanos(timeout);
final long deadline = System.nanoTime() + left;
Message m;
boolean closed;
final Object token = sync.register();
try {
for (int i = 0;; i++) {
closed = isSendClosed(); // must be read BEFORE queue.poll()
if ((m = queue.poll()) != null)
break;
if (closed) {
setReceiveClosed();
return closeValue();
}
sync.await(i, left, TimeUnit.NANOSECONDS);
left = deadline - System.nanoTime();
if (left <= 0)
return null;
}
} finally {
sync.unregister(token);
}
if (m != null)
signalSenders();
return m;
}
@Override
public Message receive(Timeout timeout) throws SuspendExecution, InterruptedException {
return receive(timeout.nanosLeft(), TimeUnit.NANOSECONDS);
}
public Message receiveFromThread() throws InterruptedException {
try {
return receive();
} catch (SuspendExecution ex) {
throw new AssertionError(ex);
}
}
public Message receiveFromThread(long timeout, TimeUnit unit) throws InterruptedException {
try {
return receive(timeout, unit);
} catch (SuspendExecution ex) {
throw new AssertionError(ex);
}
}
private void verifySync() {
if (sync == null)
throw new IllegalStateException("Owning strand has not been set");
}
public int getQueueLength() {
return queue.size();
}
@Override
public String toString() {
return "Channel{" + "sync: " + sync + ", queue: " + Objects.systemToString(queue) + ", capacity: " + capacity() + '}';
}
protected Object writeReplace() throws java.io.ObjectStreamException {
return RemoteChannelProxyFactoryService.create(this, null);
}
////////////////////////////
public static final FlightRecorder RECORDER = Debug.isDebug() ? Debug.getGlobalFlightRecorder() : null;
boolean isRecording() {
return RECORDER != null;
}
static void record(String method, String format) {
if (RECORDER != null)
RECORDER.record(1, new FlightRecorderMessage("QueueChannel", method, format, null));
}
static void record(String method, String format, Object arg1) {
if (RECORDER != null)
RECORDER.record(1, new FlightRecorderMessage("QueueChannel", method, format, new Object[]{arg1}));
}
static void record(String method, String format, Object arg1, Object arg2) {
if (RECORDER != null)
RECORDER.record(1, new FlightRecorderMessage("QueueChannel", method, format, new Object[]{arg1, arg2}));
}
static void record(String method, String format, Object arg1, Object arg2, Object arg3) {
if (RECORDER != null)
RECORDER.record(1, new FlightRecorderMessage("QueueChannel", method, format, new Object[]{arg1, arg2, arg3}));
}
static void record(String method, String format, Object arg1, Object arg2, Object arg3, Object arg4) {
if (RECORDER != null)
RECORDER.record(1, new FlightRecorderMessage("QueueChannel", method, format, new Object[]{arg1, arg2, arg3, arg4}));
}
static void record(String method, String format, Object arg1, Object arg2, Object arg3, Object arg4, Object arg5) {
if (RECORDER != null)
RECORDER.record(1, new FlightRecorderMessage("QueueChannel", method, format, new Object[]{arg1, arg2, arg3, arg4, arg5}));
}
}