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Merged
bainian12345 merged 1 commit into from
May 6, 2020
Merged

Improve synchronization of fields #68

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58 changes: 34 additions & 24 deletions src/main/java/com/microsoft/azure/relay/HybridConnectionListener.java
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,8 @@
import java.util.Map;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionException;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Consumer;
import java.util.function.Function;

Expand All @@ -29,8 +31,8 @@ public class HybridConnectionListener implements RelayTraceSource, AutoCloseable
private final InputQueue<HybridConnectionChannel> connectionInputQueue;
private final ControlConnection controlConnection;
private final Object thisLock = new Object();
private boolean openCalled;
private volatile boolean closeCalled;
private final AtomicBoolean openCalled;
private final AtomicBoolean closeCalled;
private Duration operationTimeout;
private int maxWebSocketBufferSize;
private String cachedString;
Expand Down Expand Up @@ -69,6 +71,8 @@ public HybridConnectionListener(URI address, TokenProvider tokenProvider) {
this.trackingContext = TrackingContext.create(this.address);
this.connectionInputQueue = new InputQueue<HybridConnectionChannel>(EXECUTOR);
this.controlConnection = new ControlConnection(this);
this.openCalled = new AtomicBoolean(false);
this.closeCalled = new AtomicBoolean(false);
}

/**
Expand Down Expand Up @@ -143,6 +147,8 @@ public HybridConnectionListener(String connectionString, String path) throws URI
this.trackingContext = TrackingContext.create(this.address);
this.connectionInputQueue = new InputQueue<HybridConnectionChannel>(EXECUTOR);
this.controlConnection = new ControlConnection(this);
this.openCalled = new AtomicBoolean(false);
this.closeCalled = new AtomicBoolean(false);
}

public boolean isOnline() {
Expand Down Expand Up @@ -293,7 +299,7 @@ public CompletableFuture<Void> openAsync(Duration timeout) {
} catch (RelayException e) {
return CompletableFutureUtil.fromException(e);
}
this.openCalled = true;
this.openCalled.set(true);
}

return this.controlConnection.openAsync(timeout);
Expand All @@ -320,12 +326,12 @@ public CompletableFuture<Void> closeAsync(Duration timeout) {
TimeoutHelper timeoutHelper = new TimeoutHelper(timeout);
CompletableFuture<?>[] closeTasks;
synchronized (this.thisLock) {
if (this.closeCalled) {
if (this.closeCalled.get()) {
return CompletableFuture.completedFuture(null);
}

RelayLogger.logEvent("closing", this);
this.closeCalled = true;
this.closeCalled.set(true);

// If the input queue is empty this completes all pending waiters with null and
// prevents any new items being added to the input queue.
Expand Down Expand Up @@ -364,12 +370,15 @@ public void close() {
* @return A CompletableFuture which completes when a websocket connection from the sender is established.
*/
public CompletableFuture<HybridConnectionChannel> acceptConnectionAsync() {
CompletableFuture<HybridConnectionChannel> connection = null;
synchronized (this.thisLock) {
if (!this.openCalled) {
if (!this.openCalled.get()) {
throw RelayLogger.invalidOperation("cannot accept connection because listener is not open.", this);
}

connection = this.connectionInputQueue.dequeueAsync();
}
return this.connectionInputQueue.dequeueAsync();
return connection;
}

@Override
Expand All @@ -385,16 +394,14 @@ CompletableFuture<Void> sendControlCommandAndStreamAsync(ListenerCommand command
}

void throwIfDisposed() throws RelayException {
if (this.closeCalled) {
if (this.closeCalled.get()) {
throw RelayLogger.invalidOperation("Invalid operation. Cannot call open when it's already closed.", this);
}
}

void throwIfReadOnly() throws RelayException {
synchronized (this.thisLock) {
if (this.openCalled) {
throw RelayLogger.invalidOperation("Invalid operation. Cannot call open when it's already open.", this);
}
if (this.openCalled.get()) {
throw RelayLogger.invalidOperation("Invalid operation. Cannot call open when it's already open.", this);
}
}

Expand Down Expand Up @@ -472,7 +479,7 @@ private CompletableFuture<Void> completeAcceptAsync(RelayedHttpListenerContext l
synchronized (this.thisLock) {
WebSocketChannel rendezvousConnection = new WebSocketChannel(listenerContext.getTrackingContext(), EXECUTOR);

if (this.closeCalled) {
if (this.closeCalled.get()) {
RelayLogger.logEvent("rendezvousClose", this, rendezvousUri.toString());
completeAcceptTask = CompletableFuture.completedFuture(null);
} else {
Expand Down Expand Up @@ -531,7 +538,7 @@ void injectFault(Throwable throwable) {
* Connects, maintains, and transparently reconnects this listener's control
* connection with the cloud service.
*/
static final class ControlConnection implements AutoCloseable {
final class ControlConnection implements AutoCloseable {
private final HybridConnectionListener listener;
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@dlstucki dlstucki Mar 24, 2020 •
edited by bainian12345
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private final HybridConnectionListener listener; [](start = 2, length = 48)

It's a minor point and might introduce unnecessary churn but once this class is no longer static you no longer need to explicitly pass in the "listener" reference, right? #WontFix

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@bainian12345 bainian12345 May 6, 2020

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In that case the "listener" reference would have to be referred to as "HybridConnectionListener.this", I personally feel like it's more readable as it is currently.

In reply to: 397338730 [](ancestors = 397338730)

private final URI address;
@SuppressWarnings("unused")
Expand All @@ -540,16 +547,19 @@ static final class ControlConnection implements AutoCloseable {
private final AsyncLock sendAsyncLock;
private final Object thisLock = new Object();
private CompletableFuture<ClientWebSocket> connectAsyncTask;
private int connectDelayIndex;
private AtomicInteger connectDelayIndex;
private AtomicBoolean closeCalled;
private Throwable lastError;
private boolean closeCalled;


ControlConnection(HybridConnectionListener listener) {
this.listener = listener;
this.address = listener.address;
String rawPath = this.address.getPath();
this.path = (rawPath.startsWith("/")) ? rawPath.substring(1) : rawPath;
this.sendAsyncLock = new AsyncLock(EXECUTOR);
this.connectDelayIndex = new AtomicInteger(0);
this.closeCalled = new AtomicBoolean(false);
this.tokenRenewer = new TokenRenewer(
this.listener, this.address.toString(), TokenProvider.DEFAULT_TOKEN_TIMEOUT);
}
Expand Down Expand Up @@ -600,10 +610,10 @@ private CompletableFuture<Void> closeAsync(Duration duration) {

CompletableFuture<ClientWebSocket> connectTask;
synchronized (this.thisLock) {
if (this.closeCalled) {
if (this.closeCalled.get()) {
return CompletableFuture.completedFuture(null);
}
this.closeCalled = true;
this.closeCalled.set(true);
connectTask = this.connectAsyncTask;
this.connectAsyncTask = null;
}
Expand Down Expand Up @@ -696,7 +706,7 @@ private CompletableFuture<ClientWebSocket> connectAsync(Duration timeout) {
try {
this.listener.throwIfDisposed();

CompletableFuture<Void> delayTask = CompletableFutureUtil.delayAsync(RelayConstants.CONNECTION_DELAY_INTERVALS[this.connectDelayIndex], EXECUTOR);
CompletableFuture<Void> delayTask = CompletableFutureUtil.delayAsync(RelayConstants.CONNECTION_DELAY_INTERVALS[this.connectDelayIndex.get()], EXECUTOR);
CompletableFuture<SecurityToken> token = this.tokenRenewer.getTokenAsync();

// Set the authentication in request header
Expand Down Expand Up @@ -806,7 +816,7 @@ private CompletableFuture<Boolean> receivePumpCoreAsync() {
try {
if (!webSocket.isOpen()) {
this.closeOrAbortWebSocketAsync(connectTask, webSocket.getCloseReason());
if (this.closeCalled) {
if (this.closeCalled.get()) {
keepGoing = false;
}
else {
Expand Down Expand Up @@ -835,7 +845,7 @@ private void onOnline() {
}

this.lastError = null;
this.connectDelayIndex = -1;
this.connectDelayIndex.set(-1);
}
RelayLogger.logEvent("connected", this.listener);

Expand Down Expand Up @@ -863,9 +873,9 @@ private boolean onDisconnect(Throwable lastError) {
synchronized (this.thisLock) {
this.lastError = lastError;

if (this.connectDelayIndex < RelayConstants.CONNECTION_DELAY_INTERVALS.length - 1) {
this.connectDelayIndex++;
}
this.connectDelayIndex.updateAndGet((index) -> {
return index < RelayConstants.CONNECTION_DELAY_INTERVALS.length - 1 ? ++index : index;
});
}

// Inspect the close status/description to see if this is a terminal case
Expand Down