From 638f406e5459483cf7cc115e6f0ec6de395a2240 Mon Sep 17 00:00:00 2001
From: Jon Marius Venstad <venstad@gmail.com>
Date: Wed, 2 Jun 2021 09:54:11 +0200
Subject: One request per second when circuit broken—immediate resends when it
 mends
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---
 .../ai/vespa/feed/client/HttpRequestStrategy.java  | 59 +++++++++++++++-------
 1 file changed, 42 insertions(+), 17 deletions(-)

(limited to 'vespa-feed-client/src')

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 1dd8736cd2b..a202aa92126 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
@@ -10,10 +10,9 @@ import java.time.Clock;
 import java.time.Instant;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.Executors;
-import java.util.concurrent.ScheduledExecutorService;
-import java.util.concurrent.TimeUnit;
+import java.util.concurrent.LinkedBlockingQueue;
 import java.util.function.BiConsumer;
 import java.util.logging.Logger;
 
@@ -40,14 +39,16 @@ class HttpRequestStrategy implements RequestStrategy, AutoCloseable {
     private final Object monitor = new Object();
     private final Clock clock;
     private final RetryStrategy wrapped;
-    private final ScheduledExecutorService delayer = Executors.newScheduledThreadPool(1);
+    private final Thread delayer = new Thread(this::drainDelayed);
+    private final BlockingQueue<CompletableFuture<Void>> delayed = new LinkedBlockingQueue<>();
     private final long maxInflight;
     private final long minInflight;
     private double targetInflight;
     private long inflight = 0;
     private long consecutiveSuccesses = 0;
-    private boolean failed = false;
     private Instant lastSuccess;
+    private boolean failed = false;
+    private boolean closed = false;
 
     HttpRequestStrategy(FeedClientBuilder builder, Clock clock) {
         this.wrapped = builder.retryStrategy;
@@ -55,7 +56,22 @@ class HttpRequestStrategy implements RequestStrategy, AutoCloseable {
         this.minInflight = builder.maxConnections * (long) min(16, builder.maxStreamsPerConnection);
         this.targetInflight = Math.sqrt(maxInflight) * (Math.sqrt(minInflight));
         this.clock = clock;
-        lastSuccess = clock.instant();
+        this.lastSuccess = clock.instant();
+        this.delayer.start();
+    }
+
+    private void drainDelayed() {
+        try {
+            while (true) {
+                do delayed.take().complete(null);
+                while ( ! hasFailed());
+
+                Thread.sleep(1000);
+            }
+        }
+        catch (InterruptedException e) {
+            delayed.forEach(action -> action.cancel(true));
+        }
     }
 
     private boolean retry(SimpleHttpRequest request, int attempt) {
@@ -184,16 +200,17 @@ class HttpRequestStrategy implements RequestStrategy, AutoCloseable {
                                DocumentId documentId, int attempt) {
         vessel.whenComplete((response, thrown) -> {
             // Retry the operation if it failed with a transient error ...
-            if ( ! failed && (thrown != null ? retry(request, thrown, attempt)
-                                             : retry(request, response, attempt))) {
-                    CompletableFuture<SimpleHttpResponse> retry = new CompletableFuture<>();
-                    if (hasFailed())
-                        delayer.schedule(() -> dispatch.accept(request, retry), 1, TimeUnit.SECONDS);
-                    else
-                        dispatch.accept(request, retry);
-                    handleAttempt(retry, dispatch, blocker, request, result, documentId, attempt + 1);
-                    return;
-                }
+            if (thrown != null ? retry(request, thrown, attempt)
+                               : retry(request, response, attempt)) {
+                CompletableFuture<SimpleHttpResponse> retry = new CompletableFuture<>();
+                boolean hasFailed = hasFailed();
+                if (hasFailed)
+                    delayed.add(new CompletableFuture<>().thenRun(() -> dispatch.accept(request, retry)));
+                else
+                    dispatch.accept(request, retry);
+                handleAttempt(retry, dispatch, blocker, request, result, documentId, attempt + (hasFailed ? 0 : 1));
+                return;
+            }
 
             // ... or accept the outcome and mark the operation as complete.
             CompletableFuture<Void> current;
@@ -214,7 +231,15 @@ class HttpRequestStrategy implements RequestStrategy, AutoCloseable {
 
     @Override
     public void close() {
-        delayer.shutdown();
+        synchronized (monitor) {
+            if (closed)
+                return;
+
+            closed = true;
+        }
+        delayer.interrupt();
+        try { delayer.join(); }
+        catch (InterruptedException e) { Thread.currentThread().interrupt(); }
     }
 
 }
-- 
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