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444416 Interative Callback pattern in AsyncProxyServlet

This commit is contained in:
Greg Wilkins 2014-09-18 16:20:08 +10:00
parent 3b066ca2ae
commit ca07a9947e
1 changed files with 69 additions and 11 deletions
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80
jetty-proxy/src/main/java/org/eclipse/jetty/proxy/AsyncProxyServlet.java
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@ -22,6 +22,8 @@ import java.io.IOException;
import java.net.URI;
import java.nio.ByteBuffer;
import java.nio.channels.WritePendingException;
import java.util.concurrent.atomic.AtomicReference;
import javax.servlet.ReadListener;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
@ -112,12 +114,25 @@ public class AsyncProxyServlet extends ProxyServlet
}
}
/**
* State machine for reader
* null PENDING SUCCESS FAILURE
* ---------------------------------------
* onRequestContent call null null null null
* onRequestContent called PENDING - (iterate) -
* succeeded SUCCESS SUCCESS->ODA - -
* failed FAILED FAILED - -
*
*/
private enum ReadState { OFFER, PENDING, SUCCESS, FAILURE };
protected class StreamReader implements ReadListener, Callback
{
private final byte[] buffer = new byte[getHttpClient().getRequestBufferSize()];
private final Request proxyRequest;
private final HttpServletRequest request;
private final DeferredContentProvider provider;
private final AtomicReference<ReadState> state = new AtomicReference<>(null);
protected StreamReader(Request proxyRequest, HttpServletRequest request, DeferredContentProvider provider)
{
@ -129,10 +144,13 @@ public class AsyncProxyServlet extends ProxyServlet
@Override
public void onDataAvailable() throws IOException
{
int requestId = getRequestId(request);
int requestId=0;
ServletInputStream input = request.getInputStream();
if (_log.isDebugEnabled())
{
requestId= getRequestId(request);
_log.debug("{} asynchronous read start on {}", requestId, input);
}
// First check for isReady() because it has
// side effects, and then for isFinished().
@ -145,9 +163,10 @@ public class AsyncProxyServlet extends ProxyServlet
{
if (_log.isDebugEnabled())
_log.debug("{} proxying content to upstream: {} bytes", requestId, read);
state.set(ReadState.OFFER);
onRequestContent(proxyRequest, request, provider, buffer, 0, read, this);
// Do not call isReady() so that we can apply backpressure.
break;
if (state.compareAndSet(ReadState.OFFER,ReadState.PENDING) || state.get()!=ReadState.SUCCESS)
break;
}
}
if (!input.isFinished())
@ -179,21 +198,60 @@ public class AsyncProxyServlet extends ProxyServlet
@Override
public void succeeded()
{
try
loop: while (true)
{
if (request.getInputStream().isReady())
onDataAvailable();
}
catch (Throwable x)
{
failed(x);
switch(state.get())
{
case OFFER:
if (!state.compareAndSet(ReadState.OFFER,ReadState.SUCCESS))
continue;
// Nothing to do as onDataAvailable() will iterate
break loop;
case PENDING:
if (!state.compareAndSet(ReadState.PENDING,ReadState.SUCCESS))
continue;
try
{
onDataAvailable();
}
catch (Throwable x)
{
failed(x);
}
break loop;
default:
throw new IllegalStateException("state="+state.get());
}
}
}
@Override
public void failed(Throwable x)
{
onClientRequestFailure(proxyRequest, request, x);
while (true)
{
switch(state.get())
{
case OFFER:
if (!state.compareAndSet(ReadState.OFFER,ReadState.SUCCESS))
continue;
onClientRequestFailure(proxyRequest, request, x);
break;
case PENDING:
if (!state.compareAndSet(ReadState.PENDING,ReadState.SUCCESS))
continue;
onClientRequestFailure(proxyRequest, request, x);
break;
default:
throw new IllegalStateException(x);
}
}
}
}