// Now the tricky case - if we fail a few times on one read, then succeed,
// then fail some more on another read, it shouldn't fail.
doAnswer(new FailNTimesAnswer(preSpyNN, maxBlockAcquires))
.when(spyNN).getBlockLocations(anyString(), anyLong(), anyLong());
DFSInputStream is = client.open(file.toString());
byte buf[] = new byte[10];
IOUtils.readFully(is, buf, 0, buf.length);
DFSClient.LOG.info("First read successful after some failures.");
// Further reads at this point will succeed since it has the good block locations.
// So, force the block locations on this stream to be refreshed from bad info.
// When reading again, it should start from a fresh failure count, since
// we're starting a new operation on the user level.
doAnswer(new FailNTimesAnswer(preSpyNN, maxBlockAcquires))
.when(spyNN).getBlockLocations(anyString(), anyLong(), anyLong());
is.openInfo();
// Seek to beginning forces a reopen of the BlockReader - otherwise it'll
// just keep reading on the existing stream and the fact that we've poisoned
// the block info won't do anything.
is.seek(0);
IOUtils.readFully(is, buf, 0, buf.length);
} finally {
cluster.shutdown();
}