Simplify and unify the use of Timers.

13 files changed, 102 insertions, 144 deletions

diff --git a/container-search/src/main/java/com/yahoo/search/dispatch/InvokerFactory.java b/container-search/src/main/java/com/yahoo/search/dispatch/InvokerFactory.java
index b0505fc5517..02cf11c9fe7 100644
--- a/container-search/src/main/java/com/yahoo/search/dispatch/InvokerFactory.java
+++ b/container-search/src/main/java/com/yahoo/search/dispatch/InvokerFactory.java
@@ -1,7 +1,6 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.search.dispatch;
 
-import com.yahoo.concurrent.MonotonicTimer;
 import com.yahoo.concurrent.Timer;
 import com.yahoo.prelude.fastsearch.VespaBackEndSearcher;
 import com.yahoo.search.Query;
@@ -24,7 +23,6 @@ import java.util.Set;
 public abstract class InvokerFactory {
 
     protected final SearchCluster searchCluster;
-    private static final Timer timer = new MonotonicTimer();
 
     public InvokerFactory(SearchCluster searchCluster) {
         this.searchCluster = searchCluster;
@@ -92,7 +90,7 @@ public abstract class InvokerFactory {
         if (invokers.size() == 1 && failed == null) {
             return Optional.of(invokers.get(0));
         } else {
-            return Optional.of(new InterleavedSearchInvoker(timer, invokers, searchCluster, group, failed));
+            return Optional.of(new InterleavedSearchInvoker(Timer.monotonic, invokers, searchCluster, group, failed));
         }
     }
 
diff --git a/container-search/src/test/java/com/yahoo/search/dispatch/InterleavedSearchInvokerTest.java b/container-search/src/test/java/com/yahoo/search/dispatch/InterleavedSearchInvokerTest.java
index b935e07cf4d..7fe2d2c2d9d 100644
--- a/container-search/src/test/java/com/yahoo/search/dispatch/InterleavedSearchInvokerTest.java
+++ b/container-search/src/test/java/com/yahoo/search/dispatch/InterleavedSearchInvokerTest.java
@@ -1,7 +1,6 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.search.dispatch;
 
-import com.yahoo.concurrent.MonotonicTimer;
 import com.yahoo.concurrent.Timer;
 import com.yahoo.document.GlobalId;
 import com.yahoo.document.idstring.IdString;
@@ -351,7 +350,7 @@ public class InterleavedSearchInvokerTest {
                         .addAggregationResult(new MinAggregationResult().setMin(new IntegerResultNode(6)).setTag(3))));
         invokers.add(new MockInvoker(0).setHits(List.of(new GroupingListHit(List.of(grouping2)))));
 
-        InterleavedSearchInvoker invoker = new InterleavedSearchInvoker(new MonotonicTimer(), invokers, cluster, new Group(0, List.of()), Collections.emptySet());
+        InterleavedSearchInvoker invoker = new InterleavedSearchInvoker(Timer.monotonic, invokers, cluster, new Group(0, List.of()), Collections.emptySet());
         invoker.responseAvailable(invokers.get(0));
         invoker.responseAvailable(invokers.get(1));
         Result result = invoker.search(query, null);
@@ -364,7 +363,7 @@ public class InterleavedSearchInvokerTest {
         List<SearchInvoker> invokers = new ArrayList<>();
         invokers.add(createInvoker(a, 0));
         invokers.add(createInvoker(b, 1));
-        InterleavedSearchInvoker invoker = new InterleavedSearchInvoker(new MonotonicTimer(), invokers, cluster, group, Collections.emptySet());
+        InterleavedSearchInvoker invoker = new InterleavedSearchInvoker(Timer.monotonic, invokers, cluster, group, Collections.emptySet());
         invoker.responseAvailable(invokers.get(0));
         invoker.responseAvailable(invokers.get(1));
         return invoker;
@@ -410,22 +409,12 @@ public class InterleavedSearchInvokerTest {
         assertTrue(cov.isDegradedByTimeout());
     }
 
-    private static class ClockAsTimer implements Timer {
-        private final Clock clock;
-        ClockAsTimer(Clock clock) { this.clock = clock; }
-
-        @Override
-        public long milliTime() {
-            return clock.millis();
-        }
-    }
-
     private InterleavedSearchInvoker createInterleavedInvoker(SearchCluster searchCluster, Group group, int numInvokers) {
         for (int i = 0; i < numInvokers; i++) {
             invokers.add(new MockInvoker(i));
         }
 
-        return new InterleavedSearchInvoker(new ClockAsTimer(clock), invokers, searchCluster, group,null) {
+        return new InterleavedSearchInvoker(Timer.wrap(clock), invokers, searchCluster, group,null) {
 
             @Override
             protected LinkedBlockingQueue<SearchInvoker> newQueue() {
diff --git a/documentapi/src/test/java/com/yahoo/documentapi/messagebus/ScheduledEventQueueTestCase.java b/documentapi/src/test/java/com/yahoo/documentapi/messagebus/ScheduledEventQueueTestCase.java
index 4f937aa26ba..ad73aa92d7c 100755
--- a/documentapi/src/test/java/com/yahoo/documentapi/messagebus/ScheduledEventQueueTestCase.java
+++ b/documentapi/src/test/java/com/yahoo/documentapi/messagebus/ScheduledEventQueueTestCase.java
@@ -1,7 +1,7 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.documentapi.messagebus;
 
-import com.yahoo.concurrent.Timer;
+import com.yahoo.concurrent.ManualTimer;
 import org.junit.Test;
 
 import java.util.concurrent.RejectedExecutionException;
@@ -13,7 +13,7 @@ import static org.junit.Assert.fail;
 
 public class ScheduledEventQueueTestCase {
 
-    class TestTask implements Runnable {
+    static class TestTask implements Runnable {
         public long timestamp = 0;
 
         public void run() {
@@ -46,42 +46,34 @@ public class ScheduledEventQueueTestCase {
         assertNull(queue.popTask());
     }
 
-    class TestTimer implements Timer {
-        public long milliTime = 0;
-
-        public long milliTime() {
-            return milliTime;
-        }
-    }
-
     @Test
     public void testPushTaskWithTime() {
-        TestTimer timer = new TestTimer();
+        ManualTimer timer = new ManualTimer();
         ScheduledEventQueue queue = new ScheduledEventQueue(timer);
         TestTask task = new TestTask();
         queue.pushTask(task, 1000);
         assertNull(queue.popTask());
-        timer.milliTime = 1000;
+        timer.set(1000);
         assertEquals(task, queue.popTask());
     }
 
     @Test
     public void testTwoTasksWithSameTime() {
-        TestTimer timer = new TestTimer();
+        ManualTimer timer = new ManualTimer();
         ScheduledEventQueue queue = new ScheduledEventQueue(timer);
         TestTask task1 = new TestTask();
         queue.pushTask(task1, 1000);
         TestTask task2 = new TestTask();
         queue.pushTask(task2, 1000);
         assertNull(queue.popTask());
-        timer.milliTime = 1000;
+        timer.set(1000);
         assertEquals(task1, queue.popTask());
         assertEquals(task2, queue.popTask());
     }
 
     @Test
     public void testThreeTasksWithDifferentTime() {
-        TestTimer timer = new TestTimer();
+        ManualTimer timer = new ManualTimer();
         ScheduledEventQueue queue = new ScheduledEventQueue(timer);
         TestTask task1 = new TestTask();
         queue.pushTask(task1, 1000);
@@ -91,17 +83,17 @@ public class ScheduledEventQueueTestCase {
         queue.pushTask(task3);
         assertEquals(task3, queue.popTask());
         assertNull(queue.popTask());
-        timer.milliTime = 1000;
+        timer.set(1000);
         assertEquals(task2, queue.popTask());
         assertEquals(task1, queue.popTask());
     }
 
-    class ClockSetterThread implements Runnable {
+    static class ClockSetterThread implements Runnable {
         ScheduledEventQueue queue;
-        TestTimer timer;
+        ManualTimer timer;
         long newTime;
 
-        public ClockSetterThread(ScheduledEventQueue queue, TestTimer timer, long newTime) {
+        public ClockSetterThread(ScheduledEventQueue queue, ManualTimer timer, long newTime) {
             this.queue = queue;
             this.timer = timer;
             this.newTime = newTime;
@@ -114,14 +106,14 @@ public class ScheduledEventQueueTestCase {
                 }
             } catch (InterruptedException e) {
             }
-            timer.milliTime = newTime;
+            timer.set(newTime);
             queue.wakeTasks();
         }
     }
 
     @Test
     public void testPushAndWaitForTask() {
-        TestTimer timer = new TestTimer();
+        ManualTimer timer = new ManualTimer();
         ScheduledEventQueue queue = new ScheduledEventQueue(timer);
         TestTask task = new TestTask();
         queue.pushTask(task, 50);
@@ -131,7 +123,7 @@ public class ScheduledEventQueueTestCase {
         assertEquals(50, timer.milliTime());
     }
 
-    class TaskPusherThread implements Runnable {
+    static class TaskPusherThread implements Runnable {
         ScheduledEventQueue queue;
         TestTask task;
 
@@ -162,7 +154,7 @@ public class ScheduledEventQueueTestCase {
 
     @Test
     public void testPushAndWaitMultiple() {
-        TestTimer timer = new TestTimer();
+        ManualTimer timer = new ManualTimer();
         ScheduledEventQueue queue = new ScheduledEventQueue(timer);
         TestTask lastTask = new TestTask();
         queue.pushTask(lastTask, 250);
@@ -188,11 +180,11 @@ public class ScheduledEventQueueTestCase {
         }
     }
 
-    class ShutdownThread implements Runnable {
+    static class ShutdownThread implements Runnable {
         ScheduledEventQueue queue;
-        TestTimer timer;
+        ManualTimer timer;
 
-        public ShutdownThread(ScheduledEventQueue queue, TestTimer timer) {
+        public ShutdownThread(ScheduledEventQueue queue, ManualTimer timer) {
             this.queue = queue;
             this.timer = timer;
         }
@@ -205,14 +197,14 @@ public class ScheduledEventQueueTestCase {
             } catch (InterruptedException e) {
             }
             queue.shutdown();
-            timer.milliTime = 100;
+            timer.set(100);
             queue.wakeTasks();
         }
     }
 
     @Test
     public void testShutdownInGetNext() {
-        TestTimer timer = new TestTimer();
+        ManualTimer timer = new ManualTimer();
         ScheduledEventQueue queue = new ScheduledEventQueue(timer);
         TestTask task = new TestTask();
         queue.pushTask(task, 100);
diff --git a/messagebus/src/test/java/com/yahoo/messagebus/CustomTimer.java b/messagebus/src/test/java/com/yahoo/messagebus/CustomTimer.java
deleted file mode 100644
index 539897d6485..00000000000
--- a/messagebus/src/test/java/com/yahoo/messagebus/CustomTimer.java
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-package com.yahoo.messagebus;
-
-import com.yahoo.concurrent.Timer;
-
-/**
- * @author <a href="mailto:thomasg@yahoo-inc.com">Thomas Gundersen</a>
- */
-class CustomTimer implements Timer {
-
-    long millis = 0;
-
-    @Override
-    public long milliTime() {
-        return millis;
-    }
-}
diff --git a/messagebus/src/test/java/com/yahoo/messagebus/DynamicThrottlePolicyTest.java b/messagebus/src/test/java/com/yahoo/messagebus/DynamicThrottlePolicyTest.java
index 8f9ed2323d7..8414f6588ea 100644
--- a/messagebus/src/test/java/com/yahoo/messagebus/DynamicThrottlePolicyTest.java
+++ b/messagebus/src/test/java/com/yahoo/messagebus/DynamicThrottlePolicyTest.java
@@ -1,6 +1,7 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.messagebus;
 
+import com.yahoo.concurrent.ManualTimer;
 import com.yahoo.messagebus.test.SimpleMessage;
 import com.yahoo.messagebus.test.SimpleReply;
 import org.junit.jupiter.api.Test;
@@ -46,7 +47,7 @@ public class DynamicThrottlePolicyTest {
         { // This setup is lucky with the artificial local maxima for latency, and gives good results. See below for counter-examples.
             int workPerSuccess = 8;
 
-            CustomTimer timer = new CustomTimer();
+            ManualTimer timer = new ManualTimer();
             DynamicThrottlePolicy policy = new DynamicThrottlePolicy(timer).setMinWindowSize(1)
                     .setWindowSizeIncrement(0.1)
                     .setResizeRate(100);
@@ -64,7 +65,7 @@ public class DynamicThrottlePolicyTest {
         { // This setup is not so lucky, and the artificial behaviour pushes it into overload.
             int workPerSuccess = 5;
 
-            CustomTimer timer = new CustomTimer();
+            ManualTimer timer = new ManualTimer();
             DynamicThrottlePolicy policy = new DynamicThrottlePolicy(timer).setMinWindowSize(1)
                     .setWindowSizeIncrement(0.1)
                     .setResizeRate(100);
@@ -80,7 +81,7 @@ public class DynamicThrottlePolicyTest {
         { // This setup is not so lucky either, and the artificial behaviour keeps it far below a good throughput.
             int workPerSuccess = 4;
 
-            CustomTimer timer = new CustomTimer();
+            ManualTimer timer = new ManualTimer();
             DynamicThrottlePolicy policy = new DynamicThrottlePolicy(timer).setMinWindowSize(1)
                     .setWindowSizeIncrement(0.1)
                     .setResizeRate(100);
@@ -98,7 +99,7 @@ public class DynamicThrottlePolicyTest {
     @Test
     void singlePolicySingleWorkerWithIncreasingParallelism() {
         for (int exponent = 0; exponent < 4; exponent++) {
-            CustomTimer timer = new CustomTimer();
+            ManualTimer timer = new ManualTimer();
             DynamicThrottlePolicy policy = new DynamicThrottlePolicy(timer);
             int scaleFactor = (int) Math.pow(10, exponent);
             long operations = 3_000L * scaleFactor;
@@ -121,7 +122,7 @@ public class DynamicThrottlePolicyTest {
     @Test
     void singlePolicyIncreasingWorkersWithNoParallelism() {
         for (int exponent = 0; exponent < 4; exponent++) {
-            CustomTimer timer = new CustomTimer();
+            ManualTimer timer = new ManualTimer();
             DynamicThrottlePolicy policy = new DynamicThrottlePolicy(timer);
             int scaleFactor = (int) Math.pow(10, exponent);
             long operations = 2_000L * scaleFactor;
@@ -156,7 +157,7 @@ public class DynamicThrottlePolicyTest {
             int numberOfWorkers = 1 + (int) (10 * Math.random());
             int maximumTasksPerWorker = 100_000;
             int workerParallelism = 32;
-            CustomTimer timer = new CustomTimer();
+            ManualTimer timer = new ManualTimer();
             DynamicThrottlePolicy policy1 = new DynamicThrottlePolicy(timer);
             DynamicThrottlePolicy policy2 = new DynamicThrottlePolicy(timer).setWeight(0.5);
             Summary summary = run(operations, workPerSuccess, numberOfWorkers, maximumTasksPerWorker, workerParallelism, timer, policy1, policy2);
@@ -180,7 +181,7 @@ public class DynamicThrottlePolicyTest {
             int numberOfWorkers = 6;
             int maximumTasksPerWorker = 180 + (int) (120 * Math.random());
             int workerParallelism = 60 + (int) (40 * Math.random());
-            CustomTimer timer = new CustomTimer();
+            ManualTimer timer = new ManualTimer();
             int p = 10;
             DynamicThrottlePolicy[] policies = IntStream.range(0, p)
                     .mapToObj(j -> new DynamicThrottlePolicy(timer)
@@ -213,7 +214,7 @@ public class DynamicThrottlePolicyTest {
     }
 
     private Summary run(long operations, int workPerSuccess, int numberOfWorkers, int maximumTasksPerWorker,
-                        int workerParallelism, CustomTimer timer, DynamicThrottlePolicy... policies) {
+                        int workerParallelism, ManualTimer timer, DynamicThrottlePolicy... policies) {
         System.err.printf("\n### Running %d operations of %d ticks each against %d workers with parallelism %d and queue size %d\n",
                           operations, workPerSuccess, numberOfWorkers, workerParallelism, maximumTasksPerWorker);
 
@@ -250,7 +251,7 @@ public class DynamicThrottlePolicyTest {
             ++ticks;
             totalPending += resource.pending();
             resource.tick();
-            ++timer.millis;
+            timer.advance(1);
         }
 
         for (int i = 0; i < windows.length; i++)
diff --git a/messagebus/src/test/java/com/yahoo/messagebus/RateThrottlingTestCase.java b/messagebus/src/test/java/com/yahoo/messagebus/RateThrottlingTestCase.java
index 5e579f5d622..b4ca923c4ff 100644
--- a/messagebus/src/test/java/com/yahoo/messagebus/RateThrottlingTestCase.java
+++ b/messagebus/src/test/java/com/yahoo/messagebus/RateThrottlingTestCase.java
@@ -1,6 +1,7 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.messagebus;
 
+import com.yahoo.concurrent.ManualTimer;
 import com.yahoo.messagebus.test.SimpleMessage;
 import org.junit.jupiter.api.Test;
 
@@ -11,7 +12,7 @@ public class RateThrottlingTestCase {
 
     @Test
     void testPending() {
-        CustomTimer timer = new CustomTimer();
+        ManualTimer timer = new ManualTimer();
         RateThrottlingPolicy policy = new RateThrottlingPolicy(5.0, timer);
         policy.setMaxPendingCount(200);
 
@@ -20,7 +21,7 @@ public class RateThrottlingTestCase {
     }
 
     public int getActualRate(double desiredRate) {
-        CustomTimer timer = new CustomTimer();
+        ManualTimer timer = new ManualTimer();
         RateThrottlingPolicy policy = new RateThrottlingPolicy(desiredRate, timer);
 
         int ok = 0;
@@ -28,7 +29,7 @@ public class RateThrottlingTestCase {
             if (policy.canSend(new SimpleMessage("test"), 0)) {
                 ok++;
             }
-            timer.millis += 10;
+            timer.advance(10);
         }
 
         return ok;
diff --git a/messagebus/src/test/java/com/yahoo/messagebus/ThrottlerTestCase.java b/messagebus/src/test/java/com/yahoo/messagebus/ThrottlerTestCase.java
index 045dc1177db..2e50d561778 100644
--- a/messagebus/src/test/java/com/yahoo/messagebus/ThrottlerTestCase.java
+++ b/messagebus/src/test/java/com/yahoo/messagebus/ThrottlerTestCase.java
@@ -1,6 +1,7 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.messagebus;
 
+import com.yahoo.concurrent.ManualTimer;
 import com.yahoo.jrt.ListenFailedException;
 import com.yahoo.jrt.slobrok.server.Slobrok;
 import com.yahoo.messagebus.network.rpc.test.TestServer;
@@ -14,7 +15,7 @@ import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import java.util.Arrays;
+import java.util.List;
 
 import static org.junit.jupiter.api.Assertions.*;
 
@@ -29,8 +30,8 @@ public class ThrottlerTestCase {
     @BeforeEach
     public void setUp() throws ListenFailedException {
         RoutingTableSpec table = new RoutingTableSpec(SimpleProtocol.NAME);
-        table.addHop("dst", "test/dst/session", Arrays.asList("test/dst/session"));
-        table.addRoute("test", Arrays.asList("dst"));
+        table.addHop("dst", "test/dst/session", List.of("test/dst/session"));
+        table.addRoute("test", List.of("dst"));
         slobrok = new Slobrok();
         src = new TestServer("test/src", table, slobrok, null);
         dst = new TestServer("test/dst", table, slobrok, null);
@@ -127,7 +128,7 @@ public class ThrottlerTestCase {
 
     @Test
     void testDynamicWindowSize() {
-        CustomTimer timer = new CustomTimer();
+        ManualTimer timer = new ManualTimer();
         DynamicThrottlePolicy policy = new DynamicThrottlePolicy(timer);
 
         policy.setWindowSizeIncrement(5)
@@ -151,7 +152,7 @@ public class ThrottlerTestCase {
 
     @Test
     void testIdleTimePeriod() {
-        CustomTimer timer = new CustomTimer();
+        ManualTimer timer = new ManualTimer();
         DynamicThrottlePolicy policy = new DynamicThrottlePolicy(timer);
 
         policy.setWindowSizeIncrement(5)
@@ -162,15 +163,15 @@ public class ThrottlerTestCase {
         assertTrue(windowSize >= 90 && windowSize <= 110);
 
         Message msg = new SimpleMessage("foo");
-        timer.millis += 30 * 1000;
+        timer.advance(30 * 1000);
         assertTrue(policy.canSend(msg, 0));
         assertTrue(windowSize >= 90 && windowSize <= 110);
 
-        timer.millis += 60 * 1000 + 1;
+        timer.advance(60 * 1000 + 1);
         assertTrue(policy.canSend(msg, 50));
         assertEquals(55, policy.getMaxPendingCount());
 
-        timer.millis += 60 * 1000 + 1;
+        timer.advance(60 * 1000 + 1);
         assertTrue(policy.canSend(msg, 0));
         assertEquals(5, policy.getMaxPendingCount());
 
@@ -178,7 +179,7 @@ public class ThrottlerTestCase {
 
     @Test
     void testMinWindowSize() {
-        CustomTimer timer = new CustomTimer();
+        ManualTimer timer = new ManualTimer();
         DynamicThrottlePolicy policy = new DynamicThrottlePolicy(timer);
 
         policy.setWindowSizeIncrement(5)
@@ -191,7 +192,7 @@ public class ThrottlerTestCase {
 
     @Test
     void testMaxWindowSize() {
-        CustomTimer timer = new CustomTimer();
+        ManualTimer timer = new ManualTimer();
         DynamicThrottlePolicy policy = new DynamicThrottlePolicy(timer);
 
         policy.setWindowSizeIncrement(5);
@@ -202,7 +203,7 @@ public class ThrottlerTestCase {
         assertTrue(windowSize >= 40 && windowSize <= 50);
     }
 
-    private int getWindowSize(DynamicThrottlePolicy policy, CustomTimer timer, int maxPending) {
+    private int getWindowSize(DynamicThrottlePolicy policy, ManualTimer timer, int maxPending) {
         Message msg = new SimpleMessage("foo");
         Reply reply = new SimpleReply("bar");
         reply.setContext(1);
@@ -213,8 +214,8 @@ public class ThrottlerTestCase {
                 ++numPending;
             }
 
-            long tripTime = (numPending < maxPending) ? 1000 : 1000 + (numPending - maxPending) * 1000;
-            timer.millis += tripTime;
+            long tripTime = (numPending < maxPending) ? 1000L : 1000 + (numPending - maxPending) * 1000L;
+            timer.advance(tripTime);
 
             while (--numPending >= 0) {
                 policy.processReply(reply);
diff --git a/messagebus/src/test/java/com/yahoo/messagebus/network/rpc/TargetPoolTestCase.java b/messagebus/src/test/java/com/yahoo/messagebus/network/rpc/TargetPoolTestCase.java
index afeaa1304a1..9fb817ad12f 100755
--- a/messagebus/src/test/java/com/yahoo/messagebus/network/rpc/TargetPoolTestCase.java
+++ b/messagebus/src/test/java/com/yahoo/messagebus/network/rpc/TargetPoolTestCase.java
@@ -6,6 +6,7 @@ import com.yahoo.jrt.Supervisor;
 import com.yahoo.jrt.Transport;
 import com.yahoo.jrt.slobrok.server.Slobrok;
 import com.yahoo.concurrent.Timer;
+import com.yahoo.concurrent.ManualTimer;
 import com.yahoo.messagebus.network.rpc.test.TestServer;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
@@ -46,7 +47,7 @@ public class TargetPoolTestCase {
         // Necessary setup to be able to resolve targets.
         RPCServiceAddress adr1 = registerServer();
 
-        PoolTimer timer = new PoolTimer();
+        Timer timer = new ManualTimer();
         RPCTargetPool pool1 = new RPCTargetPool(timer, 0.666, 1);
 
         RPCTarget target1 = pool1.getTarget(orb, adr1);
@@ -80,7 +81,7 @@ public class TargetPoolTestCase {
         RPCServiceAddress adr2 = registerServer();
         RPCServiceAddress adr3 = registerServer();
 
-        PoolTimer timer = new PoolTimer();
+        ManualTimer timer = new ManualTimer();
         RPCTargetPool pool = new RPCTargetPool(timer, 0.666, 1);
 
         // Assert that all connections expire.
@@ -96,7 +97,7 @@ public class TargetPoolTestCase {
             pool.flushTargets(false);
             assertEquals(3, pool.size());
         }
-        timer.millis += 999;
+        timer.advance(999);
         pool.flushTargets(false);
         assertEquals(0, pool.size());
 
@@ -108,7 +109,7 @@ public class TargetPoolTestCase {
         assertNotNull(target = pool.getTarget(orb, adr3));
         target.subRef();
         assertEquals(3, pool.size());
-        timer.millis += 444;
+        timer.advance(444);
         pool.flushTargets(false);
         assertEquals(3, pool.size());
         assertNotNull(target = pool.getTarget(orb, adr2));
@@ -116,15 +117,15 @@ public class TargetPoolTestCase {
         assertNotNull(target = pool.getTarget(orb, adr3));
         target.subRef();
         assertEquals(3, pool.size());
-        timer.millis += 444;
+        timer.advance(444);
         pool.flushTargets(false);
         assertEquals(2, pool.size());
         assertNotNull(target = pool.getTarget(orb, adr3));
         target.subRef();
-        timer.millis += 444;
+        timer.advance(444);
         pool.flushTargets(false);
         assertEquals(1, pool.size());
-        timer.millis += 444;
+        timer.advance(444);
         pool.flushTargets(false);
         assertEquals(0, pool.size());
 
@@ -132,12 +133,12 @@ public class TargetPoolTestCase {
         assertNotNull(target = pool.getTarget(orb, adr1));
         assertEquals(1, pool.size());
         for (int i = 0; i < 10; ++i) {
-            timer.millis += 999;
+            timer.advance(999);
             pool.flushTargets(false);
             assertEquals(1, pool.size());
         }
         target.subRef();
-        timer.millis += 999;
+        timer.advance(999);
         pool.flushTargets(false);
         assertEquals(0, pool.size());
     }
@@ -147,13 +148,4 @@ public class TargetPoolTestCase {
         return new RPCServiceAddress("foo/bar", servers.get(servers.size() - 1).mb.getConnectionSpec());
     }
 
-    private static class PoolTimer implements Timer {
-        long millis = 0;
-
-        @Override
-        public long milliTime() {
-            return millis;
-        }
-    }
-
 }
diff --git a/vespaclient-java/src/test/java/com/yahoo/vespafeeder/BenchmarkProgressPrinterTest.java b/vespaclient-java/src/test/java/com/yahoo/vespafeeder/BenchmarkProgressPrinterTest.java
index 7268e892c7d..6eba29fe9cb 100644
--- a/vespaclient-java/src/test/java/com/yahoo/vespafeeder/BenchmarkProgressPrinterTest.java
+++ b/vespaclient-java/src/test/java/com/yahoo/vespafeeder/BenchmarkProgressPrinterTest.java
@@ -2,7 +2,7 @@
 package com.yahoo.vespafeeder;
 
 import com.yahoo.clientmetrics.RouteMetricSet;
-import com.yahoo.concurrent.Timer;
+import com.yahoo.concurrent.ManualTimer;
 import com.yahoo.documentapi.messagebus.protocol.PutDocumentMessage;
 import com.yahoo.documentapi.messagebus.protocol.UpdateDocumentMessage;
 import com.yahoo.messagebus.EmptyReply;
@@ -15,17 +15,10 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 public class BenchmarkProgressPrinterTest {
 
-    class DummyTimer implements Timer {
-        long ms;
-
-        public long milliTime() { return ms; }
-    }
-
     @Test
     void testSimple() {
         ByteArrayOutputStream output = new ByteArrayOutputStream();
-        DummyTimer timer = new DummyTimer();
-        timer.ms = 0;
+        ManualTimer timer = new ManualTimer();
         BenchmarkProgressPrinter printer = new BenchmarkProgressPrinter(timer, new PrintStream(output));
         RouteMetricSet metrics = new RouteMetricSet("foobar", printer);
 
@@ -35,7 +28,7 @@ public class BenchmarkProgressPrinterTest {
             metrics.addReply(reply);
         }
 
-        timer.ms = 1200;
+        timer.set(1200);
 
         {
             EmptyReply reply = new EmptyReply();
@@ -49,7 +42,7 @@ public class BenchmarkProgressPrinterTest {
             metrics.addReply(reply);
         }
 
-        timer.ms = 2400;
+        timer.set(2400);
 
         {
             EmptyReply reply = new EmptyReply();
@@ -58,7 +51,7 @@ public class BenchmarkProgressPrinterTest {
             metrics.addReply(reply);
         }
 
-        timer.ms = 62000;
+        timer.set(62000);
 
         {
             EmptyReply reply = new EmptyReply();
diff --git a/vespaclient-java/src/test/java/com/yahoo/vespafeeder/ProgressPrinterTest.java b/vespaclient-java/src/test/java/com/yahoo/vespafeeder/ProgressPrinterTest.java
index 495367ff4c3..2307e27b161 100644
--- a/vespaclient-java/src/test/java/com/yahoo/vespafeeder/ProgressPrinterTest.java
+++ b/vespaclient-java/src/test/java/com/yahoo/vespafeeder/ProgressPrinterTest.java
@@ -2,7 +2,7 @@
 package com.yahoo.vespafeeder;
 
 import com.yahoo.clientmetrics.RouteMetricSet;
-import com.yahoo.concurrent.Timer;
+import com.yahoo.concurrent.ManualTimer;
 import com.yahoo.documentapi.messagebus.protocol.DocumentIgnoredReply;
 import com.yahoo.documentapi.messagebus.protocol.PutDocumentMessage;
 import com.yahoo.documentapi.messagebus.protocol.UpdateDocumentMessage;
@@ -16,17 +16,10 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class ProgressPrinterTest {
 
-    class DummyTimer implements Timer {
-        long ms;
-
-        public long milliTime() { return ms; }
-    }
-
     @Test
     void testSimple() {
         ByteArrayOutputStream output = new ByteArrayOutputStream();
-        DummyTimer timer = new DummyTimer();
-        timer.ms = 0;
+        ManualTimer timer = new ManualTimer();
         ProgressPrinter printer = new ProgressPrinter(timer, new PrintStream(output));
         RouteMetricSet metrics = new RouteMetricSet("foobar", printer);
 
@@ -36,7 +29,7 @@ public class ProgressPrinterTest {
             metrics.addReply(reply);
         }
 
-        timer.ms = 1200;
+        timer.set(1200);
 
         {
             EmptyReply reply = new EmptyReply();
@@ -50,7 +43,7 @@ public class ProgressPrinterTest {
             metrics.addReply(reply);
         }
 
-        timer.ms = 2400;
+        timer.set(2400);
 
         {
             DocumentIgnoredReply reply = new DocumentIgnoredReply();
@@ -65,7 +58,7 @@ public class ProgressPrinterTest {
             metrics.addReply(reply);
         }
 
-        timer.ms = 62000;
+        timer.set(62000);
 
         {
             EmptyReply reply = new EmptyReply();
diff --git a/vespajlib/src/main/java/com/yahoo/concurrent/ManualTimer.java b/vespajlib/src/main/java/com/yahoo/concurrent/ManualTimer.java
new file mode 100644
index 00000000000..ffa6acd446a
--- /dev/null
+++ b/vespajlib/src/main/java/com/yahoo/concurrent/ManualTimer.java
@@ -0,0 +1,18 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.concurrent;
+
+/**
+ * Simple manual Timer for use in tests
+ * @author baldersheim
+ */
+public class ManualTimer implements Timer {
+
+    private long millis = 0;
+    public void set(long ms) { millis = ms; }
+    public void advance(long ms) { millis += ms; }
+
+    @Override
+    public long milliTime() {
+        return millis;
+    }
+}
diff --git a/vespajlib/src/main/java/com/yahoo/concurrent/MonotonicTimer.java b/vespajlib/src/main/java/com/yahoo/concurrent/MonotonicTimer.java
deleted file mode 100644
index 03cad7b37a6..00000000000
--- a/vespajlib/src/main/java/com/yahoo/concurrent/MonotonicTimer.java
+++ /dev/null
@@ -1,15 +0,0 @@
-package com.yahoo.concurrent;
-
-import java.util.concurrent.TimeUnit;
-
-/**
- * Implements the Timer interface by using System.nanoTime.
- *
- * @author baldersheim
- */
-public class MonotonicTimer implements Timer {
-    @Override
-    public long milliTime() {
-        return TimeUnit.NANOSECONDS.toMillis(System.nanoTime());
-    }
-}
diff --git a/vespajlib/src/main/java/com/yahoo/concurrent/Timer.java b/vespajlib/src/main/java/com/yahoo/concurrent/Timer.java
index 1793e860af8..282524c0d54 100644
--- a/vespajlib/src/main/java/com/yahoo/concurrent/Timer.java
+++ b/vespajlib/src/main/java/com/yahoo/concurrent/Timer.java
@@ -1,6 +1,9 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.concurrent;
 
+import java.time.Clock;
+import java.util.concurrent.TimeUnit;
+
 /**
  * This interface wraps access to some timer that can be used to measure elapsed time, in milliseconds. This
  * abstraction allows for unit testing the behavior of time-based constructs.
@@ -16,5 +19,14 @@ public interface Timer {
      * @return The current value of the timer, in milliseconds.
      */
     long milliTime();
+    Timer monotonic = () -> TimeUnit.NANOSECONDS.toMillis(System.nanoTime());
+    static Timer wrap(Clock original) {
+        return new Timer() {
+            private final Clock clock = original;
 
+            @Override
+            public long milliTime() {
+                return clock.millis();
+            }
+        }; }
 }