Propagate last retried result when aborting execution (and fix shutdown)

2 files changed, 137 insertions, 38 deletions

diff --git a/vespa-feed-client/src/main/java/ai/vespa/feed/client/HttpRequestStrategy.java b/vespa-feed-client/src/main/java/ai/vespa/feed/client/HttpRequestStrategy.java
index 71de6ff2065..dc01f01b2e8 100644
--- a/vespa-feed-client/src/main/java/ai/vespa/feed/client/HttpRequestStrategy.java
+++ b/vespa-feed-client/src/main/java/ai/vespa/feed/client/HttpRequestStrategy.java
@@ -16,6 +16,7 @@ import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -26,17 +27,13 @@ import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.logging.Level.FINE;
 import static java.util.logging.Level.FINER;
 import static java.util.logging.Level.FINEST;
-import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 
-// TODO: update doc
 /**
- * Controls request execution and retries:
- * <ul>
- *     <li>Whenever throttled (429, 503), set target inflight to 0.9 * current, and retry over a different connection;</li>
- *     <li>retry other transient errors (500, 502 and IOException) a specified number of times, for specified operation types;</li>
- *     <li>and on every successful response, increase target inflight by 0.1.</li>
- * </ul>
+ * Controls request execution and retries.
+ *
+ * This class has all control flow for throttling and dispatching HTTP requests to an injected
+ * HTTP cluster, including error handling and retries, and a circuit breaker mechanism.
  *
  * @author jonmv
  */
@@ -45,10 +42,10 @@ class HttpRequestStrategy implements RequestStrategy {
     private static final Logger log = Logger.getLogger(HttpRequestStrategy.class.getName());
 
     private final Cluster cluster;
-    private final Map<DocumentId, CompletableFuture<?>> inflightById = new ConcurrentHashMap<>();
+    private final Map<DocumentId, RetriableFuture<HttpResponse>> inflightById = new ConcurrentHashMap<>();
     private final RetryStrategy strategy;
     private final CircuitBreaker breaker;
-    final FeedClient.Throttler throttler;
+    private final FeedClient.Throttler throttler;
     private final Queue<Runnable> queue = new ConcurrentLinkedQueue<>();
     private final AtomicLong inflight = new AtomicLong(0);
     private final AtomicBoolean destroyed = new AtomicBoolean(false);
@@ -89,21 +86,49 @@ class HttpRequestStrategy implements RequestStrategy {
             while (breaker.state() != OPEN && ! destroyed.get()) {
                 while ( ! isInExcess() && poll() && breaker.state() == CLOSED);
                 // Sleep when circuit is half-open, nap when queue is empty, or we are throttled.
-                Thread.sleep(breaker.state() == HALF_OPEN ? 1000 : 10); // TODO: Reduce throughput when turning half-open?
+                Thread.sleep(breaker.state() == HALF_OPEN ? 1000 : 10);
             }
         }
-        catch (InterruptedException e) {
-            Thread.currentThread().interrupt();
-            log.log(WARNING, "Dispatch thread interrupted; shutting down");
+        catch (Throwable t) {
+            log.log(WARNING, "Dispatch thread threw; shutting down", t);
         }
         destroy();
     }
 
     private void offer(HttpRequest request, CompletableFuture<HttpResponse> vessel) {
         delayedCount.incrementAndGet();
-        queue.offer(() -> {
-            cluster.dispatch(request, vessel);
-        });
+        queue.offer(() -> cluster.dispatch(request, vessel));
+    }
+
+
+    /** A completable future which stores a temporary failure result to return upon abortion. */
+    private static class RetriableFuture<T> extends CompletableFuture<T> {
+
+        private final AtomicReference<Runnable> completion = new AtomicReference<>();
+        private final AtomicReference<RetriableFuture<T>> dependency = new AtomicReference<>();
+
+        private RetriableFuture() {
+            completion.set(() -> completeExceptionally(new FeedException("Operation aborted")));
+        }
+
+        /** Complete now with the last result or error. */
+        void complete() {
+            completion.get().run();
+            if (dependency.get() != null) dependency.getAndSet(null).complete();
+        }
+
+        /** Ensures the dependency is completed whenever this is. */
+        void dependOn(RetriableFuture<T> dependency) {
+            this.dependency.set(dependency);
+            if (isDone()) dependency.complete();
+        }
+
+        /** Set the result of the last attempt at completing the computation represented by this. */
+        void set(T result, Throwable thrown) {
+            completion.set(thrown != null ? () -> completeExceptionally(thrown)
+                                          : () -> complete(result));
+        }
+
     }
 
     private boolean poll() {
@@ -208,11 +233,11 @@ class HttpRequestStrategy implements RequestStrategy {
 
     @Override
     public CompletableFuture<HttpResponse> enqueue(DocumentId documentId, HttpRequest request) {
-        CompletableFuture<HttpResponse> result = new CompletableFuture<>(); // Carries the aggregate result of the operation, including retries.
+        RetriableFuture<HttpResponse> result = new RetriableFuture<>(); // Carries the aggregate result of the operation, including retries.
         CompletableFuture<HttpResponse> vessel = new CompletableFuture<>(); // Holds the computation of a single dispatch to the HTTP client.
-        CompletableFuture<?> previous = inflightById.put(documentId, result);
+        RetriableFuture<HttpResponse> previous = inflightById.put(documentId, result);
         if (destroyed.get()) {
-            result.cancel(true);
+            result.complete();
             return result;
         }
 
@@ -221,13 +246,15 @@ class HttpRequestStrategy implements RequestStrategy {
             offer(request, vessel);
             throttler.sent(inflight.get(), result);
         }
-        else
+        else {
+            result.dependOn(previous); // In case result is aborted, also abort the previous if still inflight.
             previous.whenComplete((__, ___) -> offer(request, vessel));
+        }
 
         handleAttempt(vessel, request, result, 1);
 
         return result.handle((response, error) -> {
-            if (inflightById.compute(documentId, (____, current) -> current == result ? null : current) == null)
+            if (inflightById.compute(documentId, (__, current) -> current == result ? null : current) == null)
                 releaseSlot();
 
             if (error != null) {
@@ -239,29 +266,26 @@ class HttpRequestStrategy implements RequestStrategy {
     }
 
     /** Handles the result of one attempt at the given operation, retrying if necessary. */
-    private void handleAttempt(CompletableFuture<HttpResponse> vessel, HttpRequest request, CompletableFuture<HttpResponse> result, int attempt) {
+    private void handleAttempt(CompletableFuture<HttpResponse> vessel, HttpRequest request, RetriableFuture<HttpResponse> result, int attempt) {
         vessel.whenCompleteAsync((response, thrown) -> {
+                                     result.set(response, thrown);
                                      // Retry the operation if it failed with a transient error ...
                                      if (thrown != null ? retry(request, thrown, attempt)
                                                         : retry(request, response, attempt)) {
-                                         CircuitBreaker.State state = breaker.state();
                                          CompletableFuture<HttpResponse> retry = new CompletableFuture<>();
                                          offer(request, retry);
-                                         handleAttempt(retry, request, result, attempt + (state == HALF_OPEN ? 0 : 1));
+                                         handleAttempt(retry, request, result, attempt + (breaker.state() == HALF_OPEN ? 0 : 1));
                                      }
                                      // ... or accept the outcome and mark the operation as complete.
-                                     else {
-                                         if (thrown == null) result.complete(response);
-                                         else result.completeExceptionally(thrown);
-                                     }
+                                     else result.complete();
                                  },
                                  resultExecutor);
     }
 
     @Override
     public void destroy() {
-        if ( ! destroyed.getAndSet(true)) {
-            inflightById.values().forEach(result -> result.cancel(true)); // TODO: More informative exception.
+        if (destroyed.compareAndSet(false, true)) {
+            inflightById.values().forEach(RetriableFuture::complete);
             cluster.close();
             resultExecutor.shutdown();
         }
diff --git a/vespa-feed-client/src/test/java/ai/vespa/feed/client/HttpRequestStrategyTest.java b/vespa-feed-client/src/test/java/ai/vespa/feed/client/HttpRequestStrategyTest.java
index 6b2087b1828..02175150fed 100644
--- a/vespa-feed-client/src/test/java/ai/vespa/feed/client/HttpRequestStrategyTest.java
+++ b/vespa-feed-client/src/test/java/ai/vespa/feed/client/HttpRequestStrategyTest.java
@@ -15,6 +15,7 @@ import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.concurrent.Phaser;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -27,6 +28,7 @@ import static ai.vespa.feed.client.FeedClient.CircuitBreaker.State.HALF_OPEN;
 import static ai.vespa.feed.client.FeedClient.CircuitBreaker.State.OPEN;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -47,11 +49,8 @@ class HttpRequestStrategyTest {
         CountDownLatch latch = new CountDownLatch(1);
         new Thread(() -> {
             try {
-                while ( ! latch.await(1, TimeUnit.SECONDS)) {
+                while ( ! latch.await(1, TimeUnit.SECONDS))
                     System.err.println(cluster.stats().inflight());
-                    System.err.println(strategy.throttler.targetInflight());
-                    System.err.println();
-                }
             }
             catch (InterruptedException ignored) { }
         }).start();
@@ -78,7 +77,7 @@ class HttpRequestStrategyTest {
     }
 
     @Test
-    void testLogic() throws ExecutionException, InterruptedException {
+    void testRetries() throws ExecutionException, InterruptedException {
         int minStreams = 16; // Hard limit for minimum number of streams per connection.
         MockCluster cluster = new MockCluster();
         AtomicLong now = new AtomicLong(0);
@@ -98,10 +97,11 @@ class HttpRequestStrategyTest {
         HttpRequest request = new HttpRequest("POST", "/", null, null);
 
         // Runtime exception is not retried.
-        cluster.expect((__, vessel) -> vessel.completeExceptionally(new FeedException("boom")));
+        cluster.expect((__, vessel) -> vessel.completeExceptionally(new RuntimeException("boom")));
         ExecutionException expected = assertThrows(ExecutionException.class,
                                                    () -> strategy.enqueue(id1, request).get());
-        assertEquals("boom", expected.getCause().getMessage());
+        assertTrue(expected.getCause() instanceof FeedException);
+        assertEquals("java.lang.RuntimeException: boom", expected.getCause().getMessage());
         assertEquals(1, strategy.stats().requests());
 
         // IOException is retried.
@@ -178,6 +178,81 @@ class HttpRequestStrategyTest {
         assertEquals(3, strategy.stats().exceptions());
     }
 
+    @Test
+    void testShutdown() {
+        MockCluster cluster = new MockCluster();
+        AtomicLong now = new AtomicLong(0);
+        CircuitBreaker breaker = new GracePeriodCircuitBreaker(now::get, Duration.ofSeconds(1), Duration.ofMinutes(10));
+        HttpRequestStrategy strategy = new HttpRequestStrategy(FeedClientBuilder.create(URI.create("https://dummy.com:123"))
+                                                                                .setRetryStrategy(new FeedClient.RetryStrategy() {
+                                                                                    @Override public int retries() { return 1; }
+                                                                                })
+                                                                                .setCircuitBreaker(breaker)
+                                                                                .setConnectionsPerEndpoint(1),
+                                                               new BenchmarkingCluster(cluster));
+
+        DocumentId id1 = DocumentId.of("ns", "type", "1");
+        DocumentId id2 = DocumentId.of("ns", "type", "2");
+        DocumentId id3 = DocumentId.of("ns", "type", "3");
+        DocumentId id4 = DocumentId.of("ns", "type", "4");
+        HttpRequest failing = new HttpRequest("POST", "/", null, null);
+        HttpRequest request = new HttpRequest("POST", "/", null, null);
+        HttpRequest blocking = new HttpRequest("POST", "/", null, null);
+
+        // Enqueue some operations to the same id, which are serialised, and then shut down while operations are in flight.
+        Phaser phaser = new Phaser(2);
+        Phaser blocker = new Phaser(2);
+        AtomicReference<CompletableFuture<HttpResponse>> completion = new AtomicReference<>();
+        cluster.expect((req, vessel) -> {
+            if (req == blocking) {
+                phaser.arriveAndAwaitAdvance();  // Synchronise with tst main thread, and then ...
+                blocker.arriveAndAwaitAdvance(); // ... block dispatch thread, so we get something in the queue.
+                throw new RuntimeException("armageddon"); // Dispatch thread should die, tearing down everything.
+            }
+            else if (req == failing) {
+                phaser.arriveAndAwaitAdvance();  // Let test thread enqueue more ops before failing (and retrying) this.
+                vessel.completeExceptionally(new IOException("failed"));
+            }
+            else phaser.arriveAndAwaitAdvance(); // Don't complete from mock cluster, but require destruction to do this.
+        });
+        CompletableFuture<HttpResponse> inflight = strategy.enqueue(id1, request);
+        CompletableFuture<HttpResponse> serialised1 = strategy.enqueue(id1, request);
+        CompletableFuture<HttpResponse> serialised2 = strategy.enqueue(id1, request);
+        CompletableFuture<HttpResponse> failed = strategy.enqueue(id2, failing);
+        CompletableFuture<HttpResponse> blocked = strategy.enqueue(id3, blocking);
+        CompletableFuture<HttpResponse> delayed = strategy.enqueue(id4, request);
+        phaser.arriveAndAwaitAdvance(); // inflight completes dispatch, but causes no response.
+        phaser.arriveAndAwaitAdvance(); // failed completes dispatch, and a retry is enqueued.
+        phaser.arriveAndAwaitAdvance(); // blocked starts dispatch, and hangs, blocking dispatch thread.
+
+        // Current state: inflight is "inflight to cluster", serialised1/2 are waiting completion of it;
+        //                blocked is blocking dispatch, delayed is enqueued, waiting for dispatch;
+        //                failed has a partial result, and has a retry in the dispatch queue.
+        assertFalse(inflight.isDone());
+        assertFalse(serialised1.isDone());
+        assertFalse(serialised2.isDone());
+        assertFalse(failed.isDone());
+        assertFalse(blocked.isDone());
+        assertFalse(delayed.isDone());
+
+        // Kill dispatch thread, and see that all enqueued operations, and new ones, complete.
+        blocker.arriveAndAwaitAdvance();
+        assertEquals("ai.vespa.feed.client.FeedException: Operation aborted",
+                     assertThrows(ExecutionException.class, inflight::get).getMessage());
+        assertEquals("ai.vespa.feed.client.FeedException: Operation aborted",
+                     assertThrows(ExecutionException.class, serialised1::get).getMessage());
+        assertEquals("ai.vespa.feed.client.FeedException: Operation aborted",
+                     assertThrows(ExecutionException.class, serialised2::get).getMessage());
+        assertEquals("ai.vespa.feed.client.FeedException: Operation aborted",
+                     assertThrows(ExecutionException.class, blocked::get).getMessage());
+        assertEquals("ai.vespa.feed.client.FeedException: Operation aborted",
+                     assertThrows(ExecutionException.class, delayed::get).getMessage());
+        assertEquals("ai.vespa.feed.client.FeedException: java.io.IOException: failed",
+                     assertThrows(ExecutionException.class, failed::get).getMessage());
+        assertEquals("ai.vespa.feed.client.FeedException: Operation aborted",
+                     assertThrows(ExecutionException.class, strategy.enqueue(id1, request)::get).getMessage());
+    }
+
     static class MockCluster implements Cluster {
 
         final AtomicReference<BiConsumer<HttpRequest, CompletableFuture<HttpResponse>>> dispatch = new AtomicReference<>();