HTTPClient: include details about where in the request the client was at point of timeout

This tracks the state of the client request.  If the request is canceled (likely through the watchdog / timeout, but possibly externally by the user as well), then state at point of being canceled will be reported in the message of the CancellationException.

Author: jentfoo

client/src/main/java/org/threadly/litesockets/client/http/HTTPClient.java

@@ -331,8 +331,12 @@ private void processQueue() {
   }
 
   private void process(HTTPRequestWrapper hrw) {
+    if (hrw.slf.isDone()) {
+      // don't process, request either timed out while queued or otherwise completed in error
+      return;
+    }
     try {
-      hrw.updateReadTime();
+      hrw.requestStarting();
       hrw.client = getTCPClient(hrw.chr.getHTTPAddress());
       inProcess.put(hrw.client, hrw);
       SimpleMergedByteBuffers writeBuffer;
@@ -504,21 +508,29 @@ public void onClose(Client client) {
     public void onRead(Client client) {
       HTTPRequestWrapper hrw = inProcess.get(client);
       if(hrw != null) {
-        hrw.hrp.processData(client.getRead());
+        hrw.processIncomingData(client.getRead());
       } else {
         client.close();
       }
     }
   }
 
+  /**
+   * State the request is currently in, state should transition in order of enum.
+   */
+  private enum RequestState { Queued, SendingRequest, 
+                              ReadingResponseHeader, ReadingResponseBody, 
+                              Finished }
+  
   /**
    * Wrapper for the request that will handle the incoming response data (as well as notifying 
    * back to the client once the response is complete).
    */
   private class HTTPRequestWrapper implements HTTPResponseCallback {
-    private final SettableListenableFuture<HTTPResponseData> slf = new SettableListenableFuture<>(false);
+    private final SettableListenableFuture<HTTPResponseData> slf = new TimeoutTrackingSettableListenableFuture<>();
     private final HTTPResponseProcessor hrp;
     private final ClientHTTPRequest chr;
+    private RequestState currentState = RequestState.Queued;
     private HTTPResponse response;
     private ReuseableMergedByteBuffers responseMBB = new ReuseableMergedByteBuffers();
     private TCPClient client;
@@ -534,8 +546,17 @@ private HTTPRequestWrapper(ClientHTTPRequest chr) {
       sei.watchFuture(slf, chr.getTimeoutMS());
     }
 
-    public void updateReadTime() {
+    public void requestStarting() {
+      currentState = RequestState.SendingRequest;
+      lastRead = Clock.lastKnownForwardProgressingMillis();
+    }
+
+    public void processIncomingData(ReuseableMergedByteBuffers read) {
+      if (currentState == RequestState.SendingRequest) {
+        currentState = RequestState.ReadingResponseHeader;
+      }
       lastRead = Clock.lastKnownForwardProgressingMillis();
+      hrp.processData(read);
     }
 
     public long timeTillExpired() {
@@ -544,6 +565,7 @@ public long timeTillExpired() {
 
     @Override
     public void headersFinished(HTTPResponse hr) {
+      currentState = RequestState.ReadingResponseBody;
       response = hr;
     }
 
@@ -558,6 +580,7 @@ public void bodyData(ByteBuffer bb) {
 
     @Override
     public void finished() {
+      currentState = RequestState.Finished;
       slf.setResult(new HTTPResponseData(HTTPClient.this, chr.getHTTPRequest(), response, 
                                          responseMBB.duplicateAndClean()));
       hrp.removeHTTPResponseCallback(this);
@@ -579,6 +602,31 @@ public void websocketData(WSFrame wsf, ByteBuffer bb) {
       slf.setFailure(new Exception("HTTPClient does not currently support websockets!"));
       client.close();
     }
+    
+    /**
+     * Implementation of {@link SettableListenableFuture} which records the RequestState at the time 
+     * of cancel / timeout so that it can later be reported for debugging.
+     *
+     * @param <T> The type of result returned by the future
+     */
+    protected class TimeoutTrackingSettableListenableFuture<T> extends SettableListenableFuture<T> {
+      private RequestState stateBeforeCancel = null;
+      
+      protected TimeoutTrackingSettableListenableFuture() {
+        super(false);
+      }
+      
+      @Override
+      protected void setCanceled() {
+        stateBeforeCancel = currentState;
+        super.setCanceled();
+      }
+
+      @Override
+      protected String getCancellationExceptionMessage() {
+        return "Request timed out at point: " + stateBeforeCancel.name();
+      }
+    }
   }
 
   /**

gradle.properties

@@ -1,6 +1,6 @@
 group = org.threadly
 version = 0.21-SNAPSHOT
-threadlyVersion = 5.30
+threadlyVersion = 5.31
 litesocketsVersion = 4.9
 org.gradle.parallel=false
 junitVersion = 4.12