The problem occurs in this scenario:
1. We find a synchronization point.
2. We attmept to create the job.
3. We fail because the job table is full: `mtctx->nextJobID > mtctx->doneJobID + mtctx->jobIDMask`.
4. We call `ZSTDMT_compressStream_generic` again.
5. We forget that we're at a sync point already, and we continue looking
for the next sync point.
This fix is to detect if we're currently paused at a sync point, and if
we are then don't load any more input.
Caught by zstreamtest. I modified it to make the bug occur more often
(~1/100K -> ~1/200) and verified that it is fixed after. I then ran a
few hundred thousand unmodified zstreamtest iterations to verify.
When zstdmt cannot get a buffer and `ZSTD_e_end` is passed an empty
compression job can be created. Additionally, `mtctx->frameEnded` can be
set to 1, which could potentially cause problems like unterminated blocks.
The fix is to adjust to `ZSTD_e_flush` even when we can't get a buffer.
* Run compression twice and check the compressed data is byte-identical.
The compression loop had to be rewritten to ensure deteriminism. It is
guaranteed by always making maximal forward progress.
* When nbWorkers > 0, change the number of workers 1/8 of the time.
* Run in single-pass mode 1/4 of the time.
I've run a few hundred thousand iterations of zstreamtest and have seen
no deteriminism issues so far. Before the zstdmt fix that skips the
single-pass shortcut non-determinism showed up in a few hundred
iterations.
This commit leaves only the functions used by zstd_compress.c. All other
functions have been removed from the API. The ZSTDMT unit tests in
fuzzer.c and zstreamtest.c have been rewritten to use the ZSTD API. And
the --mt zstreamtest tests have been ripped out.
Simplifies the code and removes blocking from zstdmt.
At this point we could completely delete
`ZSTDMT_compress_advanced_internal()`. However I'm leaving it in because
I think we want to do that in the zstd-1.5.0 release, in case anyone is
still using the ZSTDMT API, even though it is not installed by default.
Fixes#2327.
Rename ADDRESS_SANITIZER -> ZSTD_ADDRESS_SANITIZER and same for
MEMORY_SANITIZER. Also set it to 0/1 instead of checking for defined.
This allows the user to override ASAN/MSAN detection for platforms that
don't support it.
This clarifies operator precedence, and quiets cppcheck in
the Kernel Test Robot. I think this is a slight bonus to
readability, so I am accepting the suggestion.
Nick Terrell