[GitHub] [cassandra] maedhroz commented on a change in pull request #1173: CASSANDRA-16883 Weak visibility guarantees of Accumulator can lead to failure to recognize digest mismatches

[GitBox <gi...@apache.org>]

maedhroz commented on a change in pull request #1173:
URL: https://github.com/apache/cassandra/pull/1173#discussion_r697740846



##########
File path: src/java/org/apache/cassandra/service/ReadCallback.java
##########
@@ -158,7 +158,14 @@ public void response(MessageIn<ReadResponse> message)
         int n = waitingFor(message.from)
               ? recievedUpdater.incrementAndGet(this)
               : received;
-        if (n >= blockfor && resolver.isDataPresent())
+
+        /*
+         * Ensure that data is present and the response accumulator has properly published the
+         * responses it has received. This may result in not signaling immediately when we receive
+         * the minimum number of required results, but it guarantees at least the minimum will
+         * be accessible when we do signal. (see rdar://77320313)
+         */
+        if (n >= blockfor && resolver.responses.size() >= blockfor && resolver.isDataPresent())

Review comment:
       For reviewers: remove this line and run the attached test. You should eventually get an assertion error.




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