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  1. Infinispan
  2. ISPN-15894

SoftIndexFileStore clear during a write can cause index to point to a non existent data location

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    Description

      During the log appender step of SIFS it will guarantee ordering during the write operation. However, there is an extra step before this to facilitate clear pausing the appender. Unfortunately, due to this extra hand off there is a small window where if a clear comes in and the index update is not done before the clear submits to the index you can get into a case where the clear removes the data file but the index update is queued for later.

      write thread -> writes to log appender
      write thread -> about to update index
      clear thread -> pauses log appender
      clear thread -> removes data files
      clear thread -> submits index sync requests
      write thread -> submits to index (which is pending the index clear)
      clear thread -> finishes
      writes thread -> now updates the index which points to a file that no longer exists.

      Code to reproduce

         public void testClearDuringWrite() throws ExecutionException, InterruptedException, TimeoutException {
            WaitDelegatingNonBlockingStore store = TestingUtil.getFirstStoreWait(cache(0, cacheName));
            LogAppender logAppender = TestingUtil.extractField(store.delegate(), "logAppender");
      
            CheckPoint checkPoint = new CheckPoint();
            checkPoint.triggerForever(Mocks.AFTER_RELEASE);
            TemporaryTable original = Mocks.blockingFieldMock(checkPoint, TemporaryTable.class, logAppender, LogAppender.class, "temporaryTable",
                  (stubber, temporaryTable) -> stubber.when(temporaryTable).set(anyInt(), any(), anyInt(), anyInt()));
      
            // Use fork as the index update in the table is blocked
            Future<Object> future = fork(() -> cache(0, cacheName).put("some-value", "1"));
      
            checkPoint.awaitStrict(Mocks.BEFORE_INVOCATION, 10, TimeUnit.SECONDS);
      
            Exceptions.expectException(TimeoutException.class, () -> future.get(10, TimeUnit.MILLISECONDS));
      
            // Put the original table back so our clear request can work
            TestingUtil.replaceField(original, "temporaryTable", logAppender, LogAppender.class);
      
            store.clear().toCompletableFuture().get(10, TimeUnit.SECONDS);
      
            checkPoint.triggerForever(Mocks.BEFORE_RELEASE);
      
            future.get(10, TimeUnit.SECONDS);
      
      // This line will fail with  Error reading header from 0:0 | 0
            assertEquals(0, cache(0, cacheName).size());
         }
      

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            wburns@redhat.com Will Burns
            wburns@redhat.com Will Burns
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              Created:
              Updated:
              Resolved: