Re: [PR] [CASSANDRA-21102] Fix off-by-one bug in exponential backoff for repair retry config [cassandra]
dcapwell closed pull request #4549: [CASSANDRA-21102] Fix off-by-one bug in exponential backoff for repair retry config URL: https://github.com/apache/cassandra/pull/4549 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] - To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
Re: [PR] [CASSANDRA-21102] Fix off-by-one bug in exponential backoff for repair retry config [cassandra]
dcapwell commented on PR #4549: URL: https://github.com/apache/cassandra/pull/4549#issuecomment-3731134081 ``` commit 386183fce11707f176b736d92e50cb75ad0680b8 Author: Nivy Kani Date: Thu Jan 8 14:27:36 2026 -0800 Fix off-by-one bug in exponential backoff for repair retry config patch by Nivy Kani; reviewed by David Capwell, Jyothsna Konisa for CASSANDRA-21102 ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] - To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
Re: [PR] [CASSANDRA-21102] Fix off-by-one bug in exponential backoff for repair retry config [cassandra]
dcapwell commented on PR #4549: URL: https://github.com/apache/cassandra/pull/4549#issuecomment-3726436511 checkstyles fails File NameLine Number Message /workspace/cassandra/test/unit/org/apache/cassandra/service/TimeoutStrategyTest.java 24 Wrong order for 'java.util.concurrent.TimeUnit' import. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] - To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
Re: [PR] [CASSANDRA-21102] Fix off-by-one bug in exponential backoff for repair retry config [cassandra]
dcapwell commented on code in PR #4549:
URL: https://github.com/apache/cassandra/pull/4549#discussion_r2674064326
##
test/unit/org/apache/cassandra/service/TimeoutStrategyTest.java:
##
@@ -0,0 +1,72 @@
+/*
+ * 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.cassandra.service;
+
+import org.assertj.core.api.Assertions;
+import org.junit.Test;
+
+import java.util.concurrent.TimeUnit;
+
+public class TimeoutStrategyTest {
Review Comment:
style: `{` are always on a new line
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Re: [PR] [CASSANDRA-21102] Fix off-by-one bug in exponential backoff for repair retry config [cassandra]
dcapwell commented on code in PR #4549:
URL: https://github.com/apache/cassandra/pull/4549#discussion_r2674061499
##
src/java/org/apache/cassandra/service/TimeoutStrategy.java:
##
@@ -97,7 +97,8 @@ interface LatencyModifierFactory
default LatencyModifier identity() { return (l, a) -> l; }
default LatencyModifier multiply(double constant) { return (l, a) ->
saturatedCast(l * constant); }
default LatencyModifier multiplyByAttempts(double multiply) { return
(l, a) -> saturatedCast(l * multiply * a); }
-default LatencyModifier multiplyByAttemptsExp(double base) { return
(l, a) -> saturatedCast(l * pow(base, a)); }
+// Ensure attempts is non-negative before subtracting 1.
+default LatencyModifier multiplyByAttemptsExp(double base) { return
(l, a) -> saturatedCast(l * pow(base, max(0, (max(a, 0) - 1; }
Review Comment:
this looks safe
```
$ rg '\^attempts' src
src/java/org/apache/cassandra/config/RetrySpec.java
164:return RetryStrategy.parse(spec.baseSleepTime.toMilliseconds() +
"ms * 2^attempts <= " + spec.maxSleepTime.toMilliseconds() + "ms,retries=" +
(spec.maxAttempts.value - 1), LatencySourceFactory.none());
src/java/org/apache/cassandra/service/RetryStrategy.java
72: * {@code 10ms <= p95(rw)*1.8^attempts <= 100ms}
src/java/org/apache/cassandra/service/TimeoutStrategy.java
73: * {@code 10ms <= p95(rw)*1.8^attempts <= 100ms}
```
The only user is repair, so not really a breaking change to paxos. If
anyone was using this in paxos v2, the only impact is that it would have the
first retry respect the min value rather than do `min * 2`, so LGTM
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Re: [PR] [CASSANDRA-21102] Fix off-by-one bug in exponential backoff for repair retry config [cassandra]
nivykani commented on code in PR #4549:
URL: https://github.com/apache/cassandra/pull/4549#discussion_r2670315876
##
test/unit/org/apache/cassandra/service/TimeoutStrategyTest.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.cassandra.service;
+
+import org.assertj.core.api.Assertions;
+import org.junit.Test;
+
+import java.util.concurrent.TimeUnit;
+
+public class TimeoutStrategyTest {
+
+@Test
+public void testParseLatencyModifierExponential() {
Review Comment:
Great catch with the overflows; Integer.MIN_VALUE would break this logic so
I added a max(a, 0). For Integer.MAX_VALUE, the maximum number of retries has
to be specified in the input string. Also added a case for fractional bases.
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Re: [PR] [CASSANDRA-21102] Fix off-by-one bug in exponential backoff for repair retry config [cassandra]
jyothsnakonisa commented on code in PR #4549:
URL: https://github.com/apache/cassandra/pull/4549#discussion_r2670026516
##
test/unit/org/apache/cassandra/service/TimeoutStrategyTest.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.cassandra.service;
+
+import org.assertj.core.api.Assertions;
+import org.junit.Test;
+
+import java.util.concurrent.TimeUnit;
+
+public class TimeoutStrategyTest {
+
+@Test
+public void testParseLatencyModifierExponential() {
+long expectedBaseLatencyMicros = TimeUnit.MILLISECONDS.toMicros(30);
+String spec = "30ms * 2^attempts";
+TimeoutStrategy.Wait w =
org.apache.cassandra.service.TimeoutStrategy.parseWait(spec,
TimeoutStrategy.LatencySourceFactory.none());
+
+// Attempt 1: baseLatency * 2^(1-1) = baseLatency * 1
+Assertions.assertThat(w.getMicros(1))
+.isEqualTo(expectedBaseLatencyMicros);
+
+// Attempt 2: baseLatency * 2^(2-1) = baseLatency * 2
+Assertions.assertThat(w.getMicros(2))
+.isEqualTo(expectedBaseLatencyMicros * 2);
+
+// Attempt 3: baseLatency * 2^(3-1) = baseLatency * 4
+Assertions.assertThat(w.getMicros(3))
+.isEqualTo(expectedBaseLatencyMicros * 4);
+
+// Edge case to check for 0 attempts: max(0, -1) = 0
+Assertions.assertThat(w.getMicros(0))
+.isEqualTo(expectedBaseLatencyMicros);
+}
+}
Review Comment:
Please add new line
##
src/java/org/apache/cassandra/service/TimeoutStrategy.java:
##
@@ -97,7 +97,7 @@ interface LatencyModifierFactory
default LatencyModifier identity() { return (l, a) -> l; }
default LatencyModifier multiply(double constant) { return (l, a) ->
saturatedCast(l * constant); }
default LatencyModifier multiplyByAttempts(double multiply) { return
(l, a) -> saturatedCast(l * multiply * a); }
-default LatencyModifier multiplyByAttemptsExp(double base) { return
(l, a) -> saturatedCast(l * pow(base, a)); }
+default LatencyModifier multiplyByAttemptsExp(double base) { return
(l, a) -> saturatedCast(l * pow(base, max(0, a-1))); }
Review Comment:
```suggestion
default LatencyModifier multiplyByAttemptsExp(double base) { return
(l, a) -> saturatedCast(l * pow(base, max(0, a - 1))); }
```
Please fix formatting
##
test/unit/org/apache/cassandra/service/TimeoutStrategyTest.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.cassandra.service;
+
+import org.assertj.core.api.Assertions;
+import org.junit.Test;
+
+import java.util.concurrent.TimeUnit;
+
+public class TimeoutStrategyTest {
+
+@Test
+public void testParseLatencyModifierExponential() {
Review Comment:
How about checking for Integer.MAX_VALUE & Integer.MIN_VALUE number of
attempts for checking overflows?
Also, can you add another case for fractional base like `0.5`
##
test/unit/org/apache/cassandra/service/TimeoutStrategyTest.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
+ * "Lice
