This is an automated email from the ASF dual-hosted git repository.
sewen pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/flink-statefun.git
commit 85f3be9dc0848d4f0b9e5337583d40f4fed2df85
Author: Igal Shilman <igalshil...@gmail.com>
AuthorDate: Thu Feb 13 14:16:09 2020 +0100
[FLINK-15956] Add an exponential backoff
This commit adds an exponential backoff mechanism with
a total upper limit for the execution time.
---
.../backpressure/BoundedExponentialBackoff.java | 66 ++++++++++++++++++++++
.../flink/core/backpressure/SystemNanoTimer.java | 50 ++++++++++++++++
.../statefun/flink/core/backpressure/Timer.java | 26 +++++++++
.../BoundedExponentialBackoffTest.java | 65 +++++++++++++++++++++
4 files changed, 207 insertions(+)
diff --git
a/statefun-flink/statefun-flink-core/src/main/java/org/apache/flink/statefun/flink/core/backpressure/BoundedExponentialBackoff.java
b/statefun-flink/statefun-flink-core/src/main/java/org/apache/flink/statefun/flink/core/backpressure/BoundedExponentialBackoff.java
new file mode 100644
index 0000000..52622eb
--- /dev/null
+++
b/statefun-flink/statefun-flink-core/src/main/java/org/apache/flink/statefun/flink/core/backpressure/BoundedExponentialBackoff.java
@@ -0,0 +1,66 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.statefun.flink.core.backpressure;
+
+import java.time.Duration;
+import java.util.Objects;
+import org.apache.flink.annotation.VisibleForTesting;
+
+public final class BoundedExponentialBackoff {
+ private final Timer timer;
+ private final long requestStartTimeInNanos;
+ private final long maxRequestDurationInNanos;
+
+ private long nextSleepTimeNanos;
+
+ public BoundedExponentialBackoff(Duration initialBackoffDuration, Duration
maxRequestDuration) {
+ this(SystemNanoTimer.instance(), initialBackoffDuration,
maxRequestDuration);
+ }
+
+ @VisibleForTesting
+ BoundedExponentialBackoff(
+ Timer timer, Duration initialBackoffDuration, Duration
maxRequestDuration) {
+ this.timer = Objects.requireNonNull(timer);
+ this.requestStartTimeInNanos = timer.now();
+ this.maxRequestDurationInNanos = maxRequestDuration.toNanos();
+ this.nextSleepTimeNanos = initialBackoffDuration.toNanos();
+ }
+
+ public boolean applyNow() {
+ final long remainingNanos = remainingNanosUntilDeadLine();
+ final long nextAmountOfNanosToSleep = nextAmountOfNanosToSleep();
+ final long actualSleep = Math.min(remainingNanos,
nextAmountOfNanosToSleep);
+ if (actualSleep <= 0) {
+ return false;
+ }
+ timer.sleep(actualSleep);
+ return true;
+ }
+
+ private long remainingNanosUntilDeadLine() {
+ final long totalElapsedTime = timer.now() - requestStartTimeInNanos;
+ return maxRequestDurationInNanos - totalElapsedTime;
+ }
+
+ private long nextAmountOfNanosToSleep() {
+ final long current = nextSleepTimeNanos;
+ nextSleepTimeNanos *= 2;
+ return current;
+ }
+}
diff --git
a/statefun-flink/statefun-flink-core/src/main/java/org/apache/flink/statefun/flink/core/backpressure/SystemNanoTimer.java
b/statefun-flink/statefun-flink-core/src/main/java/org/apache/flink/statefun/flink/core/backpressure/SystemNanoTimer.java
new file mode 100644
index 0000000..3eaefe3
--- /dev/null
+++
b/statefun-flink/statefun-flink-core/src/main/java/org/apache/flink/statefun/flink/core/backpressure/SystemNanoTimer.java
@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.statefun.flink.core.backpressure;
+
+import static java.util.concurrent.TimeUnit.NANOSECONDS;
+
+/** A {@code Timer} backed by {@link System#nanoTime()}. */
+final class SystemNanoTimer implements Timer {
+ private static final SystemNanoTimer INSTANCE = new SystemNanoTimer();
+
+ public static SystemNanoTimer instance() {
+ return INSTANCE;
+ }
+
+ private SystemNanoTimer() {}
+
+ @Override
+ public long now() {
+ return System.nanoTime();
+ }
+
+ @Override
+ public void sleep(long sleepTimeNanos) {
+ try {
+ final long sleepTimeMs = NANOSECONDS.toMillis(sleepTimeNanos);
+ Thread.sleep(sleepTimeMs);
+ } catch (InterruptedException ex) {
+ if (Thread.interrupted()) {
+ Thread.currentThread().interrupt();
+ throw new RuntimeException("interrupted while sleeping", ex);
+ }
+ }
+ }
+}
diff --git
a/statefun-flink/statefun-flink-core/src/main/java/org/apache/flink/statefun/flink/core/backpressure/Timer.java
b/statefun-flink/statefun-flink-core/src/main/java/org/apache/flink/statefun/flink/core/backpressure/Timer.java
new file mode 100644
index 0000000..2651a52
--- /dev/null
+++
b/statefun-flink/statefun-flink-core/src/main/java/org/apache/flink/statefun/flink/core/backpressure/Timer.java
@@ -0,0 +1,26 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.statefun.flink.core.backpressure;
+
+interface Timer {
+
+ long now();
+
+ void sleep(long durationNanos);
+}
diff --git
a/statefun-flink/statefun-flink-core/src/test/java/org/apache/flink/statefun/flink/core/backpressure/BoundedExponentialBackoffTest.java
b/statefun-flink/statefun-flink-core/src/test/java/org/apache/flink/statefun/flink/core/backpressure/BoundedExponentialBackoffTest.java
new file mode 100644
index 0000000..6b0eed5
--- /dev/null
+++
b/statefun-flink/statefun-flink-core/src/test/java/org/apache/flink/statefun/flink/core/backpressure/BoundedExponentialBackoffTest.java
@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.flink.statefun.flink.core.backpressure;
+
+import static org.hamcrest.Matchers.greaterThan;
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+import java.time.Duration;
+import org.junit.Test;
+
+public class BoundedExponentialBackoffTest {
+ private final FakeNanoClock fakeTime = new FakeNanoClock();
+ private final BoundedExponentialBackoff backoffUnderTest =
+ new BoundedExponentialBackoff(fakeTime, Duration.ofSeconds(1),
Duration.ofMinutes(1));
+
+ @Test
+ public void simpleUsage() {
+ assertThat(backoffUnderTest.applyNow(), is(true));
+ assertThat(fakeTime.now(), greaterThan(0L));
+ }
+
+ @Test
+ public void timeoutExpired() {
+ fakeTime.now = Duration.ofMinutes(1).toNanos();
+ assertThat(backoffUnderTest.applyNow(), is(false));
+ }
+
+ @Test
+ @SuppressWarnings("StatementWithEmptyBody")
+ public void totalNumberOfBackoffsIsEqualToTimeout() {
+ while (backoffUnderTest.applyNow()) {}
+
+ assertThat(fakeTime.now(), is(Duration.ofMinutes(1).toNanos()));
+ }
+
+ private static final class FakeNanoClock implements Timer {
+ long now;
+
+ @Override
+ public long now() {
+ return now;
+ }
+
+ @Override
+ public void sleep(long durationNano) {
+ now += durationNano;
+ }
+ }
+}
