* Async Ssh writer. Takes messages(byte arrays) and sends them encrypted to remote server.
* Also handles pending writes by caching requests until pending state is over.
*/
-final class AsyncSshHandlerWriter implements AutoCloseable {
+public final class AsyncSshHandlerWriter implements AutoCloseable {
- private static final Logger logger = LoggerFactory
+ private static final Logger LOG = LoggerFactory
.getLogger(AsyncSshHandlerWriter.class);
// public static final int MAX_PENDING_WRITES = 1000;
// 2. At this level we might be dealing with Chunks of messages(not whole messages) and unexpected behavior might occur
// when we send/queue 1 chunk and fail the other chunks
- private IoOutputStream asyncIn;
+ private volatile IoOutputStream asyncIn;
// Order has to be preserved for queued writes
private final Deque<PendingWriteRequest> pending = new LinkedList<>();
this.asyncIn = asyncIn;
}
- public synchronized void write(final ChannelHandlerContext ctx,
+ public void write(final ChannelHandlerContext ctx,
final Object msg, final ChannelPromise promise) {
- // TODO check for isClosed, isClosing might be performed by mina SSH internally and is not required here
- // If we are closed/closing, set immediate fail
- if (asyncIn == null || asyncIn.isClosed() || asyncIn.isClosing()) {
+ if (asyncIn == null) {
promise.setFailure(new IllegalStateException("Channel closed"));
- } else {
- final ByteBuf byteBufMsg = (ByteBuf) msg;
- if (pending.isEmpty() == false) {
- queueRequest(ctx, byteBufMsg, promise);
- return;
+ return;
+ }
+ // synchronized block due to deadlock that happens on ssh window resize
+ // writes and pending writes would lock the underlyinch channel session
+ // window resize write would try to write the message on an already locked channelSession
+ // while the pending write was in progress from the write callback
+ synchronized (asyncIn) {
+ // TODO check for isClosed, isClosing might be performed by mina SSH internally and is not required here
+ // If we are closed/closing, set immediate fail
+ if (asyncIn.isClosed() || asyncIn.isClosing()) {
+ promise.setFailure(new IllegalStateException("Channel closed"));
+ } else {
+ final ByteBuf byteBufMsg = (ByteBuf) msg;
+ if (pending.isEmpty() == false) {
+ queueRequest(ctx, byteBufMsg, promise);
+ return;
+ }
+
+ writeWithPendingDetection(ctx, promise, byteBufMsg, false);
}
-
- writeWithPendingDetection(ctx, promise, byteBufMsg);
}
}
- private void writeWithPendingDetection(final ChannelHandlerContext ctx, final ChannelPromise promise, final ByteBuf byteBufMsg) {
+ //sending message with pending
+ //if resending message not succesfull, then attribute wasPending is true
+ private void writeWithPendingDetection(final ChannelHandlerContext ctx, final ChannelPromise promise, final ByteBuf byteBufMsg, final boolean wasPending) {
try {
- if (logger.isTraceEnabled()) {
- logger.trace("Writing request on channel: {}, message: {}", ctx.channel(), byteBufToString(byteBufMsg));
+
+ if (LOG.isTraceEnabled()) {
+ LOG.trace("Writing request on channel: {}, message: {}", ctx.channel(), byteBufToString(byteBufMsg));
}
asyncIn.write(toBuffer(byteBufMsg)).addListener(new SshFutureListener<IoWriteFuture>() {
- @Override
- public void operationComplete(final IoWriteFuture future) {
- if (logger.isTraceEnabled()) {
- logger.trace("Ssh write request finished on channel: {} with result: {}: and ex:{}, message: {}",
- ctx.channel(), future.isWritten(), future.getException(), byteBufToString(byteBufMsg));
- }
-
- // Notify success or failure
- if (future.isWritten()) {
- promise.setSuccess();
- } else {
- logger.warn("Ssh write request failed on channel: {} for message: {}", ctx.channel(), byteBufToString(byteBufMsg), future.getException());
- promise.setFailure(future.getException());
- }
-
- // Not needed anymore, release
- byteBufMsg.release();
-
- // Check pending queue and schedule next
- // At this time we are guaranteed that we are not in pending state anymore so the next request should succeed
- writePendingIfAny();
+ @Override
+ public void operationComplete(final IoWriteFuture future) {
+ // synchronized block due to deadlock that happens on ssh window resize
+ // writes and pending writes would lock the underlyinch channel session
+ // window resize write would try to write the message on an already locked channelSession,
+ // while the pending write was in progress from the write callback
+ synchronized (asyncIn) {
+ if (LOG.isTraceEnabled()) {
+ LOG.trace("Ssh write request finished on channel: {} with result: {}: and ex:{}, message: {}",
+ ctx.channel(), future.isWritten(), future.getException(), byteBufToString(byteBufMsg));
}
- });
+
+ // Notify success or failure
+ if (future.isWritten()) {
+ promise.setSuccess();
+ } else {
+ LOG.warn("Ssh write request failed on channel: {} for message: {}", ctx.channel(), byteBufToString(byteBufMsg), future.getException());
+ promise.setFailure(future.getException());
+ }
+
+ // Not needed anymore, release
+ byteBufMsg.release();
+
+ //rescheduling message from queue after successfully sent
+ if (wasPending) {
+ byteBufMsg.resetReaderIndex();
+ pending.remove();
+ }
+ }
+
+ // Check pending queue and schedule next
+ // At this time we are guaranteed that we are not in pending state anymore so the next request should succeed
+ writePendingIfAny();
+ }
+ });
+
} catch (final WritePendingException e) {
- queueRequest(ctx, byteBufMsg, promise);
+
+ if(wasPending == false){
+ queueRequest(ctx, byteBufMsg, promise);
+ }
}
}
- private synchronized void writePendingIfAny() {
- if (pending.peek() == null) {
- return;
- }
+ private void writePendingIfAny() {
+ synchronized (asyncIn) {
+ if (pending.peek() == null) {
+ return;
+ }
- // In case of pending, reschedule next message from queue
- final PendingWriteRequest pendingWrite = pending.poll();
- final ByteBuf msg = pendingWrite.msg;
- if (logger.isTraceEnabled()) {
- logger.trace("Writing pending request on channel: {}, message: {}", pendingWrite.ctx.channel(), byteBufToString(msg));
- }
+ final PendingWriteRequest pendingWrite = pending.peek();
+ final ByteBuf msg = pendingWrite.msg;
+ if (LOG.isTraceEnabled()) {
+ LOG.trace("Writing pending request on channel: {}, message: {}", pendingWrite.ctx.channel(), byteBufToString(msg));
+ }
- writeWithPendingDetection(pendingWrite.ctx, pendingWrite.promise, msg);
+ writeWithPendingDetection(pendingWrite.ctx, pendingWrite.promise, msg, true);
+ }
}
- private static String byteBufToString(final ByteBuf msg) {
- msg.resetReaderIndex();
+ public static String byteBufToString(final ByteBuf msg) {
final String s = msg.toString(Charsets.UTF_8);
msg.resetReaderIndex();
return s;
private void queueRequest(final ChannelHandlerContext ctx, final ByteBuf msg, final ChannelPromise promise) {
// try {
- logger.debug("Write pending on channel: {}, queueing, current queue size: {}", ctx.channel(), pending.size());
- if (logger.isTraceEnabled()) {
- logger.trace("Queueing request due to pending: {}", byteBufToString(msg));
+ LOG.debug("Write pending on channel: {}, queueing, current queue size: {}", ctx.channel(), pending.size());
+ if (LOG.isTraceEnabled()) {
+ LOG.trace("Queueing request due to pending: {}", byteBufToString(msg));
}
new PendingWriteRequest(ctx, msg, promise).pend(pending);
// } catch (final Exception ex) {
-// logger.warn("Unable to queue write request on channel: {}. Setting fail for the request: {}", ctx.channel(), ex, byteBufToString(msg));
+// LOG.warn("Unable to queue write request on channel: {}. Setting fail for the request: {}", ctx.channel(), ex, byteBufToString(msg));
// msg.release();
// promise.setFailure(ex);
// }
}
@Override
- public synchronized void close() {
+ public void close() {
asyncIn = null;
}
private Buffer toBuffer(final ByteBuf msg) {
// TODO Buffer vs ByteBuf translate, Can we handle that better ?
+ msg.resetReaderIndex();
final byte[] temp = new byte[msg.readableBytes()];
msg.readBytes(temp, 0, msg.readableBytes());
return new Buffer(temp);
Code Review / controller.git / blobdiff