From c90866eff408818f0735dad286e8eb4b14990d41 Mon Sep 17 00:00:00 2001
From: Henning Baldersheim <balder@yahoo-inc.com>
Date: Mon, 9 Jan 2017 13:46:52 +0100
Subject: Simplify since there is no longer any race.

---
 .../main/java/com/yahoo/feedapi/SharedSender.java  | 52 +++++++++-------------
 1 file changed, 21 insertions(+), 31 deletions(-)

(limited to 'vespaclient-core/src/main/java/com/yahoo/feedapi/SharedSender.java')

diff --git a/vespaclient-core/src/main/java/com/yahoo/feedapi/SharedSender.java b/vespaclient-core/src/main/java/com/yahoo/feedapi/SharedSender.java
index 2a7fe3e61ad..85e4d700fce 100755
--- a/vespaclient-core/src/main/java/com/yahoo/feedapi/SharedSender.java
+++ b/vespaclient-core/src/main/java/com/yahoo/feedapi/SharedSender.java
@@ -7,6 +7,7 @@ import com.yahoo.log.LogLevel;
 import com.yahoo.messagebus.*;
 import com.yahoo.clientmetrics.RouteMetricSet;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.locks.AbstractQueuedSynchronizer;
 import java.util.logging.Logger;
 
@@ -143,15 +144,15 @@ public class SharedSender implements ReplyHandler {
         if (state == null) {
             OwnerState newState = new OwnerState();
             state = activeOwners.putIfAbsent(owner, newState);
-            if (state == null) {
-                state = newState;
-            }
+
         }
-        if (maxPendingPerOwner != -1 && blockingQueue) {
-            state.waitMaxPendingbelow(maxPendingPerOwner);
+        if (state != null) {
+            if (maxPendingPerOwner != -1 && blockingQueue) {
+                state.waitMaxPendingbelow(maxPendingPerOwner);
+            }
+            state.addPending(1);
         }
 
-        state.addPending(1);
         msg.setContext(owner);
 
         try {
@@ -202,8 +203,8 @@ public class SharedSender implements ReplyHandler {
     }
 
     private static final class Sync extends AbstractQueuedSynchronizer {
-        Sync() {
-            setState(0);
+        Sync(int count) {
+            setState(1);
         }
 
         int getCount() {
@@ -217,24 +218,23 @@ public class SharedSender implements ReplyHandler {
 
         @Override
         protected boolean tryReleaseShared(int releases) {
-            // Decrement count; signal when transition to zero
-            for (;;) {
+            // Increment/Decrement count; signal when transition downwards to zero.
+            while ( true ) {
                 int c = getState();
-                if (c == 0)
-                    return false;
+                if ((c == 0) && (releases >= 0)) { return false; }
                 int nextc = (c > releases) ? c - releases : 0;
-                if (compareAndSetState(c, nextc))
+                if (compareAndSetState(c, nextc)) {
                     return nextc == 0;
+                }
             }
         }
     }
 
-    public static class OwnerState {
-        private static final long MS2NS = 1000000;
-        private static final long REACT_LATENCY_ON_RACE = 5 *MS2NS;
-        private static final long REACT_LATENCY_ON_WATERMARK = 5 *MS2NS;
+    private static final class OwnerState {
 
-        private final Sync sync = new Sync();
+        private static final long REACT_LATENCY_ON_WATERMARK_MS = 5;
+
+        private final Sync sync = new Sync(1);
 
         void addPending(int count) {
             sync.releaseShared(-count);
@@ -247,7 +247,7 @@ public class SharedSender implements ReplyHandler {
         void waitMaxPendingbelow(int limit) {
             try {
                 while (getNumPending() > limit) {
-                    sync.tryAcquireSharedNanos(1, REACT_LATENCY_ON_WATERMARK);
+                    sync.tryAcquireSharedNanos(1, TimeUnit.MILLISECONDS.toNanos(REACT_LATENCY_ON_WATERMARK_MS));
                 }
             } catch (InterruptedException e) {
             }
@@ -262,21 +262,11 @@ public class SharedSender implements ReplyHandler {
         }
 
         boolean waitPending(long timeoutMS) throws InterruptedException {
-            long timeStart = SystemTimer.INSTANCE.milliTime();
-            long timeLeft = timeoutMS;
-
-            while ((getNumPending() > 0) && (timeLeft > 0)) {
-                sync.tryAcquireSharedNanos(1, REACT_LATENCY_ON_RACE);
-                timeLeft = timeoutMS - (SystemTimer.INSTANCE.milliTime() - timeStart);
-            }
-
-            return getNumPending() == 0;
+            return sync.tryAcquireSharedNanos(1, TimeUnit.MILLISECONDS.toNanos(timeoutMS));
         }
 
         void waitPending() throws InterruptedException {
-            while (getNumPending() > 0) {
-                sync.tryAcquireSharedNanos(1, REACT_LATENCY_ON_RACE);
-            }
+            sync.tryAcquireShared(1);
         }
     }
 
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