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https://issues.apache.org/jira/browse/HTTPCORE-172?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12629982#action_12629982
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Oleg Kalnichevski commented on HTTPCORE-172:
--------------------------------------------
Hi Jason
I see the problem but I am not sure the proposed fix is the right thing to do,
as the endOfStream flag should retain its original semantics, that is,
indicating that the buffer should close in orderly fashion by flushing buffered
content first. I think the right thing to do is to call #shutdown() on the
SharedOutputBuffer, not #close(), in case the underlying connection is no
longer writable / open.
Does this make sense to you?
Oleg
> SharedInputBuffer stops returing data to reading thread once shutdown is
> called
> -------------------------------------------------------------------------------
>
> Key: HTTPCORE-172
> URL: https://issues.apache.org/jira/browse/HTTPCORE-172
> Project: HttpComponents HttpCore
> Issue Type: Bug
> Components: HttpCore NIO
> Affects Versions: 4.0-beta2
> Environment: Synapse 1.2
> Reporter: Jason Walton
> Fix For: 4.0-beta3
>
> Attachments: sharedbuf.patch
>
>
> This problem won't happen in Synapse 1.2 without the fix I proposed for
> https://issues.apache.org/jira/browse/SYNAPSE-415 in ClientHandler.java.
> To briefly recap: If a ClientWorker attempts to read from a
> SharedInputBuffer, but no data is availabled, SharedInputBuffer.read() will
> call into waitForData(). If the next event to the ClientHandler is a
> "closed()" event, then the ClientHandler will remove its references to the
> SharedInputBuffer. At this point in time, the ClientWorker is left waiting
> for data forever. The fix I proposed for SYNAPSE-415 was to call into
> SharedInputBuffer.shutdown() from ClientHandler.closed(), as this will send a
> notify to the SharedInputBuffer and wake up the ClientWorker.
> This seemed like a good fix at the time, but now I'm running into this from
> the "other side", so to speak. Suppose the ClientWorker is a bit late in
> reading the stream.
> 1) I/O Dispatcher thread receives data from the socket, and calls
> ClientHandler.inputReady(), which in turn calls
> SharedInputBuffer.consumeContent(). This puts some data into the
> SharedInputBuffer's buffer.
> 2) I/O Dispathcer thread sees the socket close, and so calls
> ClientHandler.closed(). This calls into SharedInputBuffer.shutdown().
> 3) The ClientWorker thread calls into SharedInputBuffer.read(), which starts
> out with:
> if (this.shutdown) {
> return -1;
> }
> The result is that the ClientWorker will erroneously think we never got a
> reply.
> A similar issue exists in SharedOutputBuffer, except here you would have to
> call "shutdown()" followed by "produceContent()". Since both of these
> methods are called from the I/O dispatcher side, this wouldn't make a lot of
> sense (how can we produce content for a socket which is closed?). I suppose
> someone might call "shutdown()" instead of "writeCompleted()" in some sort of
> error scenario on the worker side? Probably not really worth worrying about.
> Here's my proposed fix (comments welcome, since I don't know this code as
> well as I could):
> Index:
> module-nio/src/main/java/org/apache/http/nio/util/SharedInputBuffer.java
> ===================================================================
> --- module-nio/src/main/java/org/apache/http/nio/util/SharedInputBuffer.java
> (revision 689999)
> +++ module-nio/src/main/java/org/apache/http/nio/util/SharedInputBuffer.java
> (working copy)
> @@ -125,11 +125,11 @@
> }
> protected boolean isEndOfStream() {
> - return this.shutdown || (!hasData() && this.endOfStream);
> + return !hasData() && (this.shutdown || this.endOfStream);
> }
> public int read() throws IOException {
> - if (this.shutdown) {
> + if (this.isEndOfStream()) {
> return -1;
> }
> synchronized (this.mutex) {
> @@ -144,7 +144,7 @@
> }
> public int read(final byte[] b, int off, int len) throws IOException {
> - if (this.shutdown) {
> + if (this.isEndOfStream()) {
> return -1;
> }
> if (b == null) {
> @@ -168,7 +168,7 @@
> }
> public int read(final byte[] b) throws IOException {
> - if (this.shutdown) {
> + if (this.isEndOfStream()) {
> return -1;
> }
> if (b == null) {
--
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