JAVA-6055 Implement prose backpressure retryable writes tests by stIncMale · Pull Request #1929 · mongodb/mongo-java-driver

stIncMale · 2026-03-27T00:15:23Z

The relevant spec changes:

https://github.com/mongodb/specifications/blame/ba14b6bdc1dc695aa9cc20ccf9378592da1b2329/source/retryable-writes/tests/README.md#L265-L418
See also https://jira.mongodb.org/browse/DRIVERS-3432 for the required fixes for "Test 3 Case 3"

I recommend reviewing the first two commits one by one to simplify reviewing: the first commit does the refactoring, including the necessary refactoring (the introduction of ConfigureFailPointCommandListener), the second commit adds the new tests.

I used the TODO-BACKPRESSURE Valentin comments as described in #1918.

JAVA-6055

Copilot

Pull request overview

Adds/updates prose tests to cover the retryable writes “backpressure retryable writes” scenarios from the spec updates, including refactoring test infrastructure to configure fail points in reaction to command events.

Changes:

Introduce ConfigureFailPointCommandListener to enable a failpoint once upon matching a CommandEvent, and automatically disable it via try-with-resources.
Refactor existing retryable reads/writes prose tests to use the new helper and updated spec link references.
Add new “error propagation after encountering multiple errors” retryable writes prose test cases (with Case 1 temporarily disabled behind TODO-BACKPRESSURE).

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

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File	Description
driver-sync/src/test/functional/com/mongodb/internal/event/ConfigureFailPointCommandListener.java	New test utility to configure/cleanup failpoints triggered by command events.
driver-sync/src/test/functional/com/mongodb/client/RetryableWritesProseTest.java	Refactor existing prose tests; add new multi-error propagation cases.
driver-sync/src/test/functional/com/mongodb/client/RetryableReadsProseTest.java	Update prose-test references and align helper usage/signatures.
driver-reactive-streams/src/test/functional/com/mongodb/reactivestreams/client/RetryableWritesProseTest.java	Mirror sync prose test updates via sync-adapter delegation; add new cases.
driver-reactive-streams/src/test/functional/com/mongodb/reactivestreams/client/RetryableReadsProseTest.java	Update prose-test references and align helper usage/signatures.

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driver-sync/src/test/functional/com/mongodb/client/RetryableWritesProseTest.java

...-streams/src/test/functional/com/mongodb/reactivestreams/client/RetryableReadsProseTest.java

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Pull request overview

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Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

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...r-sync/src/test/functional/com/mongodb/internal/event/ConfigureFailPointCommandListener.java

driver-sync/src/test/functional/com/mongodb/client/RetryableWritesProseTest.java

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

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driver-sync/src/test/functional/com/mongodb/client/RetryableWritesProseTest.java

JAVA-6055

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

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...-streams/src/test/functional/com/mongodb/reactivestreams/client/RetryableReadsProseTest.java

driver-sync/src/test/functional/com/mongodb/client/RetryableWritesProseTest.java

The relevant spec changes: - https://github.com/mongodb/specifications/blame/ba14b6bdc1dc695aa9cc20ccf9378592da1b2329/source/retryable-writes/tests/README.md#L265-L418 - See also https://jira.mongodb.org/browse/DRIVERS-3432 for the required fixes for "Test 3 Case 3" JAVA-6055

nhachicha

Good idea extracting ConfigureFailPointCommandListener as a reusable utility 👍
some minor comments from me & Claude review

nhachicha · 2026-03-28T16:33:01Z

...r-sync/src/test/functional/com/mongodb/internal/event/ConfigureFailPointCommandListener.java

+                fail("The listener was closed before (in the happens-before order) it attempted to configure the fail point");
+            } else {
+                assertTrue(failPointFuture.isDone());
+                assertNotNull(failPointFuture.get()).close();


[minor]
If failPointFuture is completed exceptionally (via completeExceptionally), then failPointFuture.get() in close() will throw, so the normal FailPoint.close() is skipped and the fail point may remain enabled.

This is, however, low-risk since there may be nothing to clean up if FailPoint.enable() fails ...

nhachicha · 2026-03-28T16:37:05Z

...r-sync/src/test/functional/com/mongodb/internal/event/ConfigureFailPointCommandListener.java

+    @Override
+    public void close() throws InterruptedException, ExecutionException {
+        synchronized (lock) {
+            if (failPointFuture.cancel(true)) {


[TIL]
mayInterruptIfRunning is no-op

mayInterruptIfRunning - this value has no effect in this implementation because interrupts are not used to control processing.

nhachicha · 2026-03-28T16:55:19Z

driver-sync/src/test/functional/com/mongodb/client/RetryableWritesProseTest.java

                + "    data: {\n"
-                + "        failCommands: [\"" + operationName + "\"],\n"
+                + "        failCommands: [\"" + expectedCommandName + "\"],\n"
+                + "        errorCode: 6,\n"


[claude-review]
Trailing comma in generated JSON when write=false.

The old code avoided this by placing errorCode last

The same pattern appears in retriesOnSameMongosWhenAnotherNotAvailable

nhachicha · 2026-03-28T17:25:14Z

driver-sync/src/test/functional/com/mongodb/client/RetryableWritesProseTest.java

+        Predicate<CommandEvent> configureFailPointEventMatcher = event -> {
+            if (event instanceof CommandFailedEvent) {
+                CommandFailedEvent commandFailedEvent = (CommandFailedEvent) event;
+                MongoException cause = assertInstanceOf(MongoException.class, commandFailedEvent.getThrowable());


[claude-review]
The predicates use assertInstanceOf(MongoException.class, ...) which throws AssertionFailedError if the type doesn't match. A Predicate.test() should return false, not throw. The exception is caught by onEvent() and routed to completeExceptionally, so it works, but the semantics are surprising. Consider using a plain instanceof check instead.

nhachicha · 2026-03-28T17:25:36Z

driver-sync/src/test/functional/com/mongodb/client/RetryableWritesProseTest.java

+        Predicate<CommandEvent> configureFailPointEventMatcher = event -> {
+            if (event instanceof CommandFailedEvent) {
+                CommandFailedEvent commandFailedEvent = (CommandFailedEvent) event;
+                MongoException cause = assertInstanceOf(MongoException.class, commandFailedEvent.getThrowable());


Ditto https://github.com/mongodb/mongo-java-driver/pull/1929/changes#diff-8fe5319aef55e451d009c31e961108720a7d361d60dd5c5d2c0a99e088d0545dR378

nhachicha · 2026-03-28T17:49:56Z

...r-sync/src/test/functional/com/mongodb/internal/event/ConfigureFailPointCommandListener.java

+import static com.mongodb.assertions.Assertions.assertTrue;
+import static com.mongodb.assertions.Assertions.fail;
+
+public final class ConfigureFailPointCommandListener implements CommandListener, AutoCloseable {


Worth annotating with @ThreadSafe ?

nhachicha · 2026-03-28T18:26:16Z

driver-sync/src/test/functional/com/mongodb/client/RetryableWritesProseTest.java

+                + "        failCommands: ['" + commandName + "'],\n"
+                + "        errorCode: 91,\n"
+                + "        blockConnection: true,\n"
+                + "        blockTimeMS: 1000,\n"


Trailing comma issue when write == false. I wonder if we should keep the append approach of building the BsonDocument

similar to https://github.com/mongodb/mongo-java-driver/pull/1929/changes#r3005045523

nhachicha · 2026-03-28T20:43:11Z

driver-sync/src/test/functional/com/mongodb/client/RetryableWritesProseTest.java

                + "    data: {\n"
-                + "        failCommands: [\"" + operationName + "\"],\n"
+                + "        failCommands: [\"" + expectedCommandName + "\"],\n"
+                + "        errorCode: 6,\n"


Ditto https://github.com/mongodb/mongo-java-driver/pull/1929/changes#r3005045523

nhachicha · 2026-03-30T06:48:28Z

driver-sync/src/test/functional/com/mongodb/client/RetryableWritesProseTest.java

+                + "', '" + NO_WRITES_PERFORMED_ERROR_LABEL + "']\n"
+                + "    }\n"
+                + "}\n");
+        Predicate<CommandEvent> configureFailPointEventMatcher = event -> event instanceof CommandFailedEvent;


[minor]
Both the initial and the listener fail points use error code 91, for consistency and defensiveness, checking code == 91 wouldn't hurt — if something unexpected fails first (e.g., a different command), the test would configure the second fail point at the wrong time and produce a confusing failure.

stIncMale requested a review from nhachicha March 27, 2026 00:15

stIncMale self-assigned this Mar 27, 2026

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stIncMale force-pushed the backpressure_JAVA-6055_proseTests branch 3 times, most recently from 53e526f to 44c8119 Compare March 27, 2026 18:31

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stIncMale force-pushed the backpressure_JAVA-6055_proseTests branch from 44c8119 to 973ee55 Compare March 27, 2026 18:45

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stIncMale force-pushed the backpressure_JAVA-6055_proseTests branch from 973ee55 to 758b89e Compare March 27, 2026 21:02

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Refactor prose retryable writes/reads tests

e79eee1

JAVA-6055

stIncMale force-pushed the backpressure_JAVA-6055_proseTests branch from 758b89e to d270460 Compare March 27, 2026 21:36

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stIncMale force-pushed the backpressure_JAVA-6055_proseTests branch from d270460 to 72d70e4 Compare March 27, 2026 22:14

stIncMale marked this pull request as ready for review March 27, 2026 22:15

stIncMale requested a review from a team as a code owner March 27, 2026 22:15

stIncMale changed the title ~~Implement prose backpressure retryable writes tests~~ JAVA-6055 Implement prose backpressure retryable writes tests Mar 28, 2026

stIncMale changed the title ~~JAVA-6055 Implement prose backpressure retryable writes tests~~ JAVA-6055: Implement prose backpressure retryable writes tests Mar 28, 2026

stIncMale changed the title ~~JAVA-6055: Implement prose backpressure retryable writes tests~~ JAVA-6055 Implement prose backpressure retryable writes tests Mar 28, 2026

nhachicha reviewed Mar 30, 2026

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stIncMale commented Mar 27, 2026 •

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