Signed-off-by: Olasoji <olasoji.denloye@intel.com>

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

- Added explicit end-of-stream signaling for IGZIP inflate via out-param and wired it into the inflate dispatch path
- Corrected windowBits handling to map wrapper type/history properly
- Replaced raw magic-number crc_flag check with IGZIP_DEFLATE constant
- Fixed DEBUG-only issues and cleanup edge cases
- Debugging

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

returned eos isnt erronously set.

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

# Conflicts:
#	zlib_accel.cpp

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* igzip: fix raw deflate over-consumption via read_in_length

ISAL's stateful inflate pre-loads input in 8-byte word chunks into a
64-bit shift register (read_in). After reaching ISAL_BLOCK_FINISH for
raw deflate (window_bits < 0), read_in_length still holds the bit count
of bytes fetched beyond the true stream end. Shifting right by 3 gives
the exact over-consumed byte count for every avail_in scenario:

  avail_in in [1,7]  : previous avail_in<8 heuristic approximated this
  avail_in == 0      : previous heuristic was blind; now handled
  avail_in == 8      : gap in both old heuristics; now handled
  avail_in > 8       : multi-frame continuation; now handled

The corrected consumed count is reported back to the caller via
*input_length so that avail_in / next_in on the zlib stream are
advanced accurately, preventing downstream compressed-size and CRC
mismatches (reproduces as ZipException in Java ZipInputStream).

Boundary guard updated: skip the raw-boundary fallback when
*tofixed==1 because the correction has already accounted for any
remaining bytes, so non-zero remaining is legitimate trailing data
rather than un-corrected over-consumption.

BLOCK_INPUT_DONE path (output-buffer-limited mid-stream) retains the
existing Z_DATA_ERROR->zlib-fallback behaviour unchanged.

Previously attempted stateless-probe approach removed entirely; the
read_in_length field is simpler, exact, and has no multi-frame failure
mode.

Validated: 8/8 IGZIPInflateRegressionTest pass; full make run passes
with only the pre-existing ordering-sensitive case 37961; JAR repro
(250 entries, scan + build-init) passes clean.

* rename trailer_overconsumption_fixed -> read_in_correction_applied; remove stale post-reset pre-set

The old name 'trailer_overconsumption_fixed' was a holdover from the
avail_in < 8 heuristic era. Since EXP-6f the fix is driven entirely by
isal_inflate.read_in_length >> 3; the flag only signals that a correction
was applied *within the current inflate call*.

Rename the field, its parameter aliases, and all local variables to
read_in_correction_applied to match the actual semantics.

Also remove the stale block in inflateReset:
  if (was_igzip_path) {
      inflate_settings->trailer_overconsumption_fixed = 1;
  }
This block predated the read_in_length fix. It pre-armed the flag so
that the old avail_in < 8 boundary guard would not fire on the first
call after a reset. That logic was correct under the old heuristic but
is actively wrong now: ResetUncompressIGZIP already zeros the flag;
re-arming it to 1 would suppress the boundary guard on exactly the call
where it is needed most (first call after reset on a raw stream).

Remove was_igzip_path (now unused after the block removal) and inline
the INPUT_DONE log expression to eliminate an unused-variable warning
when DEBUG_LOG=OFF.

No behaviour change for correct streams; test suite: 8/8 IGZIP inflate
regressions PASS, only pre-existing 37961 flaky failure remains.

* add IGZIP inflate/deflate counters to statistics; enable ENABLE_STATISTICS build flag

Statistics previously tracked QAT and IAA paths but left IGZIP with
commented-out placeholders. Two problems with those placeholders: the
enum values DEFLATE_IGZIP_COUNT, DEFLATE_IGZIP_ERROR_COUNT,
INFLATE_IGZIP_COUNT, INFLATE_IGZIP_ERROR_COUNT did not exist, and the
stat_names array had no entries for them.

Add the four missing Statistic enum values (after the IAA entries,
before ZLIB, matching the QAT/IAA grouping pattern) and their
corresponding stat_names strings.  Uncomment the INCREMENT_STAT calls
in the deflate and inflate IGZIP dispatch blocks.  The error condition
mirrors IAA/QAT: unconditional IGZIP_COUNT on every dispatch, and
IGZIP_ERROR_COUNT when ret != 0 (fallback or hard error).

Enable ENABLE_STATISTICS=ON in cmake.txt so the counters compile in by
default.

Validation (OpenSearch opensearch-core-3.3.1.jar, 250-entry JAR repro,
use_igzip_uncompress=1, log_stats_samples=50):

  Thread (main): inflate_count=750 igzip=749 igzip_errors=0 zlib=0
  — 99.9% of inflate calls served by IGZIP with zero errors or
    zlib fallbacks; one call is the initial probe before path selection.

* add iaa_fallback_igzip: IAA can fall back to IGZIP before software zlib

When IAA inflate or deflate fails (ret != 0), and use_igzip_uncompress /
use_igzip_compress is enabled, the new iaa_fallback_igzip config flag
(default 0) routes the retry to IGZIP before allowing the call to
fall through to software zlib.

Motivation: IAA is stateless and leaves input unconsumed on failure, so
IGZIP can retry from the same position at no extra cost. This keeps
hardware-accelerated decompression in play for inputs that IAA rejects
but IGZIP can handle (e.g. streams that fail IsIAADecompressible or
exceed IAA's single-call constraint).

Implementation:
- New ConfigOption IAA_FALLBACK_IGZIP added between IGNORE_ZLIB_DICTIONARY
  and LOG_LEVEL; default 0 (opt-in), range [0,1].
- inflate(): after IAA dispatch block, if path_selected==IAA && ret!=0 &&
  configs[IAA_FALLBACK_IGZIP] && igzip_available, reset input_len/output_len
  (IAA may have modified them on failure), clear read_in_correction_applied,
  and run IGZIPRunInflateAndSelectPathAction with the same path-action
  handling as the normal IGZIP dispatch. Falls through to zlib if IGZIP
  also fails.
- deflate(): identical pattern; initialises isal_strm via InitCompressIGZIP
  if needed (matching normal IGZIP deflate path).
- Both fallback blocks are wrapped in #ifdef USE_IGZIP and guarded by
  igzip_available so they compile away and are unreachable without IGZIP.
- Existing INFLATE/DEFLATE_IGZIP_COUNT stats capture fallback calls.

Test suite: 44756/44757 PASS (37961 pre-existing flaky only).

* cmake: set ENABLE_STATISTICS=OFF by default

* - Reset statistics to off by default and formatting

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* IGZIP: lift Z_FINISH-only restriction; enable full streaming compress

- SupportedOptionsIGZIPCompress: always returns true (ISA-L natively
  supports NO_FLUSH/SYNC_FLUSH/FULL_FLUSH/FINISH)
- SupportedOptionsIGZIPUncompress: always returns true (remove dead
  zero-input new-stream guard)
- IGZIPShouldFallbackDeflate + IsIGZIPSyncFlush: removed entirely;
  both streaming_flush_with_input and empty_sync_flush_reentry cases
  were artificial constraints inherited from one-shot IAA/QAT model
- CompressIGZIP: add ZSTATE_NEW_HDR guard for empty SYNC_FLUSH calls;
  ISA-L emits sync bytes unconditionally, guard returns 0 progress so
  caller sees Z_BUF_ERROR matching zlib semantics
- deflateSetDictionary: reject mid-stream calls when an accelerator
  path is active; underlying zlib stream is unadvanced so
  orig_deflateSetDictionary would incorrectly return Z_OK
- inflate active-stream no-input block: remove dead
- tests: remove 6 stale path==ZLIB assertions from 3 regression tests
  that assumed IGZIP would fall back on streaming flushes

* fix iaa_fallback_igzip compress: set path_selected=IGZIP after fallback

When IAA compress fails and IGZIP is used as a fallback, path_selected
remained IAA. The return-code block below then used the IAA/QAT one-shot
logic (avail_in==0 -> Z_STREAM_END) instead of IGZIP streaming logic
(IsIGZIPDeflateFinished). ISA-L fills its internal level buffer and
returns after consuming all input but producing only partial output;
avail_in reaches 0 while the stream is not yet at ZSTATE_END. The result
was Z_STREAM_END returned with ~48KB of compressed data still buffered
internally, corrupting every document written during indexing.

Fix: set path_selected = IGZIP immediately after the fallback completes
so that the return-code logic correctly calls IsIGZIPDeflateFinished and
returns Z_OK for partial output, allowing the caller to drain the stream.

* iaa: replace marker-based IsIAADecompressible with 512-byte threshold

When iaa_prepend_empty_block=0 (the default), the old code returned true
for all raw deflate and gzip inputs unconditionally, causing QPL's
overconsumption bug to surface for Java ZipInputStream callers. JAR
loading feeds inflate() with 512-byte chunks where avail_in > actual
compressed size; QPL reports total_in == available_in, causing the
Java-level ZipException that kills OpenSearch at launch.

Fix (ported from exp-8): replace the IAA_PREPEND_EMPTY_BLOCK=0 branch
with a 512-byte threshold guard. ZipInputStream always feeds <=512-byte
chunks; Lucene stored-field reads always provide the exact compressed
size which is typically well above 512 bytes. The few Lucene entries
below the threshold fall back to IGZIP, which is also correct.

Also removes PrependedEmptyBlockPresent() which is no longer called
from the decompression path. The compress-side marker write in
CompressIAA is unaffected (still controlled by iaa_prepend_empty_block).

* README: document USE_IGZIP cmake option and ISA-L dependency

Add USE_IGZIP (ON/OFF) and ISAL_PATH to the cmake options list, and
add a Requirements for IGZIP section with a link to ISA-L.

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* zlib_accel: guard pre_avail_in declaration with USE_IGZIP

pre_avail_in is only referenced inside #ifdef USE_IGZIP blocks.
Without this guard, builds with USE_IGZIP=OFF trigger an
-Wunused-variable error under -Werror, breaking CI.

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* Clang format

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* remove cmake.txt; fix null deref in deflateSetDictionary

cmake.txt contained a local build command with hardcoded absolute paths
(/home/sdp/...). Remove it from the repo and add to .gitignore.

deflateSetDictionary: deflate_stream_settings.Get(strm) can return
nullptr if called without a prior deflateInit. Guard the mid-stream
rejection check to avoid a null dereference in that case, returning
Z_STREAM_ERROR consistent with zlib behaviour.

Addresses review comments on PR #54 (matt-welch, Copilot).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* igzip: remove dead SupportedOptions/IGZIPShouldFallback stubs

SupportedOptionsIGZIPCompress, SupportedOptionsIGZIPUncompress, and
IGZIPShouldFallbackDeflate unconditionally returned fixed values with
all parameters voided. Remove them entirely and inline the fixed values
at all 8 call sites in zlib_accel.cpp.

Addresses review comment on PR #54 (matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* zlib_accel: fix read_in_correction_applied semantics and reset asymmetry

The flag is per-stream-session (set once when the read_in_length
over-consumption correction fires; cleared only on inflateReset), not
per-call as the comment incorrectly stated.

Fix the struct comment to reflect this, and remove the erroneous reset
to 0 on the IAA->IGZIP fallback path which was inconsistent with the
primary IGZIP path and the inflateReset behavior.

Addresses review comment on PR #54 (Copilot, matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* iaa: deprecate iaa_prepend_empty_block config option

The empty stored-block marker approach was abandoned in favour of a
512-byte minimum input length threshold in IsIAADecompressible. The
config option is retained for backward compatibility but has no effect
on decompression and will be removed in a future release.

Rationale for the threshold approach: QPL hardware always consumes all
available_in bytes regardless of where the BFINAL=1 token falls
(overconsumption bug). Java ZipInputStream feeds <=512-byte chunks
when csize is unknown, triggering overconsumption errors. Lucene
stored-field reads always supply the exact compressed size (>512 bytes),
where consuming all input is correct.

Document the deprecation in README and add a comment in iaa.cpp
explaining the history and the replacement mechanism.

Addresses review comment on PR #54 (matt-welch).

Signed-off-by: $(git config user.name) <$(git config user.email)>

* tests: add IAA->IGZIP fallback coverage

Add IAAFallbackIGZIPTest with three tests exercising the fallback
path for both deflate and inflate:

  - DeflateUsesIGZIPWhenIAAFailsAndFallbackEnabled: configures
    USE_IAA_COMPRESS+USE_IGZIP_COMPRESS+IAA_FALLBACK_IGZIP=1 and
    asserts the stream lands on IGZIP (or IAA if hardware present).

  - DeflateDoesNotUseIGZIPWhenFallbackDisabled: same IAA+IGZIP config
    but IAA_FALLBACK_IGZIP=0; asserts IGZIP is never selected.

  - InflateUsesIGZIPWhenIAAFailsAndFallbackEnabled: data compressed
    with IGZIP, decompressed via USE_IAA_UNCOMPRESS+IAA_FALLBACK_IGZIP=1;
    asserts round-trip correctness and IGZIP (or IAA) execution path.

On machines without IAA hardware the QPL init fails (non-zero return),
which naturally exercises the fallback branch without mocking. On
machines that do have IAA hardware and succeed, the assertions accept
either IAA or IGZIP so the tests remain valid in both environments.

Tests are guarded by #ifdef USE_IAA and #ifdef USE_IGZIP (both are
in scope here via the outer USE_IGZIP guard around the regression
block).

Addresses should-fix #6 from PR #54 review (matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* tests: restore IGZIP path assertions for SYNC_FLUSH regression tests

Three IGZIPDeflateRegressionTest tests originally asserted
ASSERT_EQ(path, ZLIB) because IGZIPShouldFallbackDeflate redirected
SYNC_FLUSH calls to the zlib path. Commit f7ee0ec (lift Z_FINISH-only
restriction) removed those assertions when IGZIP gained native
SYNC_FLUSH support, but left no replacement.

Now that IGZIPShouldFallbackDeflate is removed entirely, restore the
path assertions with the new expected behavior: IGZIP must remain on
the IGZIP path through Z_NO_FLUSH, Z_SYNC_FLUSH, and Z_FINISH calls.

Changes:
  - ResetMustNotStallSyncFlushOnSameStream: assert IGZIP after
    Z_NO_FLUSH and Z_SYNC_FLUSH on each cycle.
  - RepeatedEmptySyncFlushMustEventuallyReportNoProgress: assert IGZIP
    after Z_NO_FLUSH and on every Z_SYNC_FLUSH iteration.
  - SyncFlushWithInputMustFallbackToZlibForStreamSafety: renamed to
    SyncFlushWithInputMustStayOnIGZIPPath (the old name described the
    removed fallback behavior); assert IGZIP after Z_SYNC_FLUSH and on
    every Z_FINISH iteration.

Addresses review comment #7 on PR #54 (matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* igzip: document read_in_correction_applied reset and ZSTATE_NEW_HDR coupling

#8 — Explain why read_in_correction_applied is cleared on inflateReset:
isal_inflate_reset clears the internal read_in/read_in_length buffer,
so any over-consumption correction from the previous stream session no
longer applies. The flag must be reset so the new session can fire the
correction fresh if needed. This is intentional; keeping it set across
a reset would incorrectly suppress the correction on data that has not
yet over-consumed.

#9 — Document ISA-L version for ZSTATE_NEW_HDR coupling:
The SYNC_FLUSH no-progress guard directly accesses
isal_strm->internal_state.state == ZSTATE_NEW_HDR. Note that this was
validated against ISA-L v2.32.0 (commit c196241) so future ISA-L
updates can be audited for state machine changes.

Addresses review comments #8 and #9 on PR #54 (matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* address round-2 Copilot review: README doc, igzip.h comment, IGZIP stats tests, inflate fallback=0 test

- README.md: document iaa_fallback_igzip config option
- igzip.h: fix read_in_correction_applied comment to reflect per-stream-session
  semantics (not per-call)
- tests/zlib_accel_test.cpp: add DEFLATE_IGZIP_COUNT/INFLATE_IGZIP_COUNT
  branches to CompressDecompress stats verification
- tests/zlib_accel_test.cpp: add InflateDoesNotUseIGZIPWhenFallbackDisabled
  as companion to the existing inflate=1 test

* fix: restore gzip_flag after deflateReset on IGZIP stream (Cassandra corruption)

isal_deflate_reset preserves gzip_flag. After the first chunk, ISA-L
internally changes gzip_flag from IGZIP_ZLIB (3) to IGZIP_ZLIB_NO_HDR (4)
to suppress the header on continuation calls. Without a reset, the reused
stream produced headerless chunks, causing Java's Inflater (nowrap=false)
to report 'incorrect header check' / 'unknown compression method' on every
subsequent SSTable chunk — resulting in CorruptSSTableException at read time.

Fix: add ResetCompressIGZIP() which wraps isal_deflate_reset + calls
ConfigureDeflateWindow to restore gzip_flag and hist_bits from window_bits.
Replace the inline isal_deflate_reset call in deflateReset() with this.

Regression test: ResetMustRestoreZlibHeaderForSubsequentChunks compresses
5 independent chunks via a reused IGZIP z_stream (deflateReset between each)
and decompresses each with a fresh zlib inflater — would have failed before
this fix on chunk 2 onward.

Reproduced via: Cassandra 5 mix workload (80% reads, 20% updates) with
IGZIP compress enabled, writing to a zlib-format SSTable.

---------

Signed-off-by: Olasoji <olasoji.denloye@intel.com>
Signed-off-by: $(git config user.name) <$(git config user.email)>

…ault=1 (#57)

* igzip: fix raw deflate over-consumption via read_in_length

ISAL's stateful inflate pre-loads input in 8-byte word chunks into a
64-bit shift register (read_in). After reaching ISAL_BLOCK_FINISH for
raw deflate (window_bits < 0), read_in_length still holds the bit count
of bytes fetched beyond the true stream end. Shifting right by 3 gives
the exact over-consumed byte count for every avail_in scenario:

  avail_in in [1,7]  : previous avail_in<8 heuristic approximated this
  avail_in == 0      : previous heuristic was blind; now handled
  avail_in == 8      : gap in both old heuristics; now handled
  avail_in > 8       : multi-frame continuation; now handled

The corrected consumed count is reported back to the caller via
*input_length so that avail_in / next_in on the zlib stream are
advanced accurately, preventing downstream compressed-size and CRC
mismatches (reproduces as ZipException in Java ZipInputStream).

Boundary guard updated: skip the raw-boundary fallback when
*tofixed==1 because the correction has already accounted for any
remaining bytes, so non-zero remaining is legitimate trailing data
rather than un-corrected over-consumption.

BLOCK_INPUT_DONE path (output-buffer-limited mid-stream) retains the
existing Z_DATA_ERROR->zlib-fallback behaviour unchanged.

Previously attempted stateless-probe approach removed entirely; the
read_in_length field is simpler, exact, and has no multi-frame failure
mode.

Validated: 8/8 IGZIPInflateRegressionTest pass; full make run passes
with only the pre-existing ordering-sensitive case 37961; JAR repro
(250 entries, scan + build-init) passes clean.

* rename trailer_overconsumption_fixed -> read_in_correction_applied; remove stale post-reset pre-set

The old name 'trailer_overconsumption_fixed' was a holdover from the
avail_in < 8 heuristic era. Since EXP-6f the fix is driven entirely by
isal_inflate.read_in_length >> 3; the flag only signals that a correction
was applied *within the current inflate call*.

Rename the field, its parameter aliases, and all local variables to
read_in_correction_applied to match the actual semantics.

Also remove the stale block in inflateReset:
  if (was_igzip_path) {
      inflate_settings->trailer_overconsumption_fixed = 1;
  }
This block predated the read_in_length fix. It pre-armed the flag so
that the old avail_in < 8 boundary guard would not fire on the first
call after a reset. That logic was correct under the old heuristic but
is actively wrong now: ResetUncompressIGZIP already zeros the flag;
re-arming it to 1 would suppress the boundary guard on exactly the call
where it is needed most (first call after reset on a raw stream).

Remove was_igzip_path (now unused after the block removal) and inline
the INPUT_DONE log expression to eliminate an unused-variable warning
when DEBUG_LOG=OFF.

No behaviour change for correct streams; test suite: 8/8 IGZIP inflate
regressions PASS, only pre-existing 37961 flaky failure remains.

* add IGZIP inflate/deflate counters to statistics; enable ENABLE_STATISTICS build flag

Statistics previously tracked QAT and IAA paths but left IGZIP with
commented-out placeholders. Two problems with those placeholders: the
enum values DEFLATE_IGZIP_COUNT, DEFLATE_IGZIP_ERROR_COUNT,
INFLATE_IGZIP_COUNT, INFLATE_IGZIP_ERROR_COUNT did not exist, and the
stat_names array had no entries for them.

Add the four missing Statistic enum values (after the IAA entries,
before ZLIB, matching the QAT/IAA grouping pattern) and their
corresponding stat_names strings.  Uncomment the INCREMENT_STAT calls
in the deflate and inflate IGZIP dispatch blocks.  The error condition
mirrors IAA/QAT: unconditional IGZIP_COUNT on every dispatch, and
IGZIP_ERROR_COUNT when ret != 0 (fallback or hard error).

Enable ENABLE_STATISTICS=ON in cmake.txt so the counters compile in by
default.

Validation (OpenSearch opensearch-core-3.3.1.jar, 250-entry JAR repro,
use_igzip_uncompress=1, log_stats_samples=50):

  Thread (main): inflate_count=750 igzip=749 igzip_errors=0 zlib=0
  — 99.9% of inflate calls served by IGZIP with zero errors or
    zlib fallbacks; one call is the initial probe before path selection.

* add iaa_fallback_igzip: IAA can fall back to IGZIP before software zlib

When IAA inflate or deflate fails (ret != 0), and use_igzip_uncompress /
use_igzip_compress is enabled, the new iaa_fallback_igzip config flag
(default 0) routes the retry to IGZIP before allowing the call to
fall through to software zlib.

Motivation: IAA is stateless and leaves input unconsumed on failure, so
IGZIP can retry from the same position at no extra cost. This keeps
hardware-accelerated decompression in play for inputs that IAA rejects
but IGZIP can handle (e.g. streams that fail IsIAADecompressible or
exceed IAA's single-call constraint).

Implementation:
- New ConfigOption IAA_FALLBACK_IGZIP added between IGNORE_ZLIB_DICTIONARY
  and LOG_LEVEL; default 0 (opt-in), range [0,1].
- inflate(): after IAA dispatch block, if path_selected==IAA && ret!=0 &&
  configs[IAA_FALLBACK_IGZIP] && igzip_available, reset input_len/output_len
  (IAA may have modified them on failure), clear read_in_correction_applied,
  and run IGZIPRunInflateAndSelectPathAction with the same path-action
  handling as the normal IGZIP dispatch. Falls through to zlib if IGZIP
  also fails.
- deflate(): identical pattern; initialises isal_strm via InitCompressIGZIP
  if needed (matching normal IGZIP deflate path).
- Both fallback blocks are wrapped in #ifdef USE_IGZIP and guarded by
  igzip_available so they compile away and are unreachable without IGZIP.
- Existing INFLATE/DEFLATE_IGZIP_COUNT stats capture fallback calls.

Test suite: 44756/44757 PASS (37961 pre-existing flaky only).

* cmake: set ENABLE_STATISTICS=OFF by default

* - Reset statistics to off by default and formatting

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* IGZIP: lift Z_FINISH-only restriction; enable full streaming compress

- SupportedOptionsIGZIPCompress: always returns true (ISA-L natively
  supports NO_FLUSH/SYNC_FLUSH/FULL_FLUSH/FINISH)
- SupportedOptionsIGZIPUncompress: always returns true (remove dead
  zero-input new-stream guard)
- IGZIPShouldFallbackDeflate + IsIGZIPSyncFlush: removed entirely;
  both streaming_flush_with_input and empty_sync_flush_reentry cases
  were artificial constraints inherited from one-shot IAA/QAT model
- CompressIGZIP: add ZSTATE_NEW_HDR guard for empty SYNC_FLUSH calls;
  ISA-L emits sync bytes unconditionally, guard returns 0 progress so
  caller sees Z_BUF_ERROR matching zlib semantics
- deflateSetDictionary: reject mid-stream calls when an accelerator
  path is active; underlying zlib stream is unadvanced so
  orig_deflateSetDictionary would incorrectly return Z_OK
- inflate active-stream no-input block: remove dead
- tests: remove 6 stale path==ZLIB assertions from 3 regression tests
  that assumed IGZIP would fall back on streaming flushes

* fix iaa_fallback_igzip compress: set path_selected=IGZIP after fallback

When IAA compress fails and IGZIP is used as a fallback, path_selected
remained IAA. The return-code block below then used the IAA/QAT one-shot
logic (avail_in==0 -> Z_STREAM_END) instead of IGZIP streaming logic
(IsIGZIPDeflateFinished). ISA-L fills its internal level buffer and
returns after consuming all input but producing only partial output;
avail_in reaches 0 while the stream is not yet at ZSTATE_END. The result
was Z_STREAM_END returned with ~48KB of compressed data still buffered
internally, corrupting every document written during indexing.

Fix: set path_selected = IGZIP immediately after the fallback completes
so that the return-code logic correctly calls IsIGZIPDeflateFinished and
returns Z_OK for partial output, allowing the caller to drain the stream.

* iaa: replace marker-based IsIAADecompressible with 512-byte threshold

When iaa_prepend_empty_block=0 (the default), the old code returned true
for all raw deflate and gzip inputs unconditionally, causing QPL's
overconsumption bug to surface for Java ZipInputStream callers. JAR
loading feeds inflate() with 512-byte chunks where avail_in > actual
compressed size; QPL reports total_in == available_in, causing the
Java-level ZipException that kills OpenSearch at launch.

Fix (ported from exp-8): replace the IAA_PREPEND_EMPTY_BLOCK=0 branch
with a 512-byte threshold guard. ZipInputStream always feeds <=512-byte
chunks; Lucene stored-field reads always provide the exact compressed
size which is typically well above 512 bytes. The few Lucene entries
below the threshold fall back to IGZIP, which is also correct.

Also removes PrependedEmptyBlockPresent() which is no longer called
from the decompression path. The compress-side marker write in
CompressIAA is unaffected (still controlled by iaa_prepend_empty_block).

* README: document USE_IGZIP cmake option and ISA-L dependency

Add USE_IGZIP (ON/OFF) and ISAL_PATH to the cmake options list, and
add a Requirements for IGZIP section with a link to ISA-L.

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* zlib_accel: guard pre_avail_in declaration with USE_IGZIP

pre_avail_in is only referenced inside #ifdef USE_IGZIP blocks.
Without this guard, builds with USE_IGZIP=OFF trigger an
-Wunused-variable error under -Werror, breaking CI.

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* Clang format

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* remove cmake.txt; fix null deref in deflateSetDictionary

cmake.txt contained a local build command with hardcoded absolute paths
(/home/sdp/...). Remove it from the repo and add to .gitignore.

deflateSetDictionary: deflate_stream_settings.Get(strm) can return
nullptr if called without a prior deflateInit. Guard the mid-stream
rejection check to avoid a null dereference in that case, returning
Z_STREAM_ERROR consistent with zlib behaviour.

Addresses review comments on PR #54 (matt-welch, Copilot).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* igzip: remove dead SupportedOptions/IGZIPShouldFallback stubs

SupportedOptionsIGZIPCompress, SupportedOptionsIGZIPUncompress, and
IGZIPShouldFallbackDeflate unconditionally returned fixed values with
all parameters voided. Remove them entirely and inline the fixed values
at all 8 call sites in zlib_accel.cpp.

Addresses review comment on PR #54 (matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* zlib_accel: fix read_in_correction_applied semantics and reset asymmetry

The flag is per-stream-session (set once when the read_in_length
over-consumption correction fires; cleared only on inflateReset), not
per-call as the comment incorrectly stated.

Fix the struct comment to reflect this, and remove the erroneous reset
to 0 on the IAA->IGZIP fallback path which was inconsistent with the
primary IGZIP path and the inflateReset behavior.

Addresses review comment on PR #54 (Copilot, matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* iaa: deprecate iaa_prepend_empty_block config option

The empty stored-block marker approach was abandoned in favour of a
512-byte minimum input length threshold in IsIAADecompressible. The
config option is retained for backward compatibility but has no effect
on decompression and will be removed in a future release.

Rationale for the threshold approach: QPL hardware always consumes all
available_in bytes regardless of where the BFINAL=1 token falls
(overconsumption bug). Java ZipInputStream feeds <=512-byte chunks
when csize is unknown, triggering overconsumption errors. Lucene
stored-field reads always supply the exact compressed size (>512 bytes),
where consuming all input is correct.

Document the deprecation in README and add a comment in iaa.cpp
explaining the history and the replacement mechanism.

Addresses review comment on PR #54 (matt-welch).

Signed-off-by: $(git config user.name) <$(git config user.email)>

* tests: add IAA->IGZIP fallback coverage

Add IAAFallbackIGZIPTest with three tests exercising the fallback
path for both deflate and inflate:

  - DeflateUsesIGZIPWhenIAAFailsAndFallbackEnabled: configures
    USE_IAA_COMPRESS+USE_IGZIP_COMPRESS+IAA_FALLBACK_IGZIP=1 and
    asserts the stream lands on IGZIP (or IAA if hardware present).

  - DeflateDoesNotUseIGZIPWhenFallbackDisabled: same IAA+IGZIP config
    but IAA_FALLBACK_IGZIP=0; asserts IGZIP is never selected.

  - InflateUsesIGZIPWhenIAAFailsAndFallbackEnabled: data compressed
    with IGZIP, decompressed via USE_IAA_UNCOMPRESS+IAA_FALLBACK_IGZIP=1;
    asserts round-trip correctness and IGZIP (or IAA) execution path.

On machines without IAA hardware the QPL init fails (non-zero return),
which naturally exercises the fallback branch without mocking. On
machines that do have IAA hardware and succeed, the assertions accept
either IAA or IGZIP so the tests remain valid in both environments.

Tests are guarded by #ifdef USE_IAA and #ifdef USE_IGZIP (both are
in scope here via the outer USE_IGZIP guard around the regression
block).

Addresses should-fix #6 from PR #54 review (matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* tests: restore IGZIP path assertions for SYNC_FLUSH regression tests

Three IGZIPDeflateRegressionTest tests originally asserted
ASSERT_EQ(path, ZLIB) because IGZIPShouldFallbackDeflate redirected
SYNC_FLUSH calls to the zlib path. Commit f7ee0ec (lift Z_FINISH-only
restriction) removed those assertions when IGZIP gained native
SYNC_FLUSH support, but left no replacement.

Now that IGZIPShouldFallbackDeflate is removed entirely, restore the
path assertions with the new expected behavior: IGZIP must remain on
the IGZIP path through Z_NO_FLUSH, Z_SYNC_FLUSH, and Z_FINISH calls.

Changes:
  - ResetMustNotStallSyncFlushOnSameStream: assert IGZIP after
    Z_NO_FLUSH and Z_SYNC_FLUSH on each cycle.
  - RepeatedEmptySyncFlushMustEventuallyReportNoProgress: assert IGZIP
    after Z_NO_FLUSH and on every Z_SYNC_FLUSH iteration.
  - SyncFlushWithInputMustFallbackToZlibForStreamSafety: renamed to
    SyncFlushWithInputMustStayOnIGZIPPath (the old name described the
    removed fallback behavior); assert IGZIP after Z_SYNC_FLUSH and on
    every Z_FINISH iteration.

Addresses review comment #7 on PR #54 (matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* igzip: document read_in_correction_applied reset and ZSTATE_NEW_HDR coupling

#8 — Explain why read_in_correction_applied is cleared on inflateReset:
isal_inflate_reset clears the internal read_in/read_in_length buffer,
so any over-consumption correction from the previous stream session no
longer applies. The flag must be reset so the new session can fire the
correction fresh if needed. This is intentional; keeping it set across
a reset would incorrectly suppress the correction on data that has not
yet over-consumed.

#9 — Document ISA-L version for ZSTATE_NEW_HDR coupling:
The SYNC_FLUSH no-progress guard directly accesses
isal_strm->internal_state.state == ZSTATE_NEW_HDR. Note that this was
validated against ISA-L v2.32.0 (commit c196241) so future ISA-L
updates can be audited for state machine changes.

Addresses review comments #8 and #9 on PR #54 (matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* address round-2 Copilot review: README doc, igzip.h comment, IGZIP stats tests, inflate fallback=0 test

- README.md: document iaa_fallback_igzip config option
- igzip.h: fix read_in_correction_applied comment to reflect per-stream-session
  semantics (not per-call)
- tests/zlib_accel_test.cpp: add DEFLATE_IGZIP_COUNT/INFLATE_IGZIP_COUNT
  branches to CompressDecompress stats verification
- tests/zlib_accel_test.cpp: add InflateDoesNotUseIGZIPWhenFallbackDisabled
  as companion to the existing inflate=1 test

* fix: restore gzip_flag after deflateReset on IGZIP stream (Cassandra corruption)

isal_deflate_reset preserves gzip_flag. After the first chunk, ISA-L
internally changes gzip_flag from IGZIP_ZLIB (3) to IGZIP_ZLIB_NO_HDR (4)
to suppress the header on continuation calls. Without a reset, the reused
stream produced headerless chunks, causing Java's Inflater (nowrap=false)
to report 'incorrect header check' / 'unknown compression method' on every
subsequent SSTable chunk — resulting in CorruptSSTableException at read time.

Fix: add ResetCompressIGZIP() which wraps isal_deflate_reset + calls
ConfigureDeflateWindow to restore gzip_flag and hist_bits from window_bits.
Replace the inline isal_deflate_reset call in deflateReset() with this.

Regression test: ResetMustRestoreZlibHeaderForSubsequentChunks compresses
5 independent chunks via a reused IGZIP z_stream (deflateReset between each)
and decompresses each with a fresh zlib inflater — would have failed before
this fix on chunk 2 onward.

Reproduced via: Cassandra 5 mix workload (80% reads, 20% updates) with
IGZIP compress enabled, writing to a zlib-format SSTable.

* Rename iaa_fallback_igzip to igzip_fallback, extend to QAT, default=1

- Rename IAA_FALLBACK_IGZIP -> IGZIP_FALLBACK (single generic key)
- Extend fallback condition in deflate() and inflate() to cover QAT:
  (path_selected == IAA || path_selected == QAT)
- Move failed_accelerator declaration before IGZIP retry call in both blocks
- Log messages updated to identify the failing accelerator (IAA or QAT)
- Flip default from 0 -> 1 (fallback is now on by default when IGZIP enabled)
- Update README: key name, description, default
- Add QATFallbackIGZIPTest suite (4 tests mirroring IAAFallbackIGZIPTest)

Full make run: 51006 tests, 44766 passed, remainder expected skips.

* fix: build error when USE_IGZIP + USE_IAA/USE_QAT all enabled

SetDeflatePath/SetInflatePath take const char*, but commit 8120b29
passed std::string temporaries (string concatenation) which is a
hard compile error. The reason parameter is (void)'d in both
functions, so replace the broken concatenations with plain string
literals and remove the now-unused failed_accelerator variables.

The error was masked because the affected code is inside
#ifdef USE_IGZIP blocks that are only reached when both an
accelerator (IAA or QAT) and IGZIP are compiled in together.
Builds with fewer accelerators enabled did not trigger it.

* tests: assert return codes and guard QAT->IGZIP tests with USE_IGZIP

- Add ASSERT_EQ(ret, Z_STREAM_END) for deflate/inflate calls in
  QATFallbackIGZIPTest::DeflateDoesNotUseIGZIPWhenFallbackDisabled and
  InflateDoesNotUseIGZIPWhenFallbackDisabled so unchecked return codes
  are caught as test failures.
- Guard QATFallbackIGZIPTest block with #if defined(USE_QAT) && defined(USE_IGZIP)
  since these tests exercise the QAT->IGZIP fallback path which requires
  both backends to be compiled in; USE_QAT alone is insufficient.

* fixup: use const char* ternaries to identify accelerator in fallback reasons

Address third-round Copilot review comments on PR #57:

- SetDeflatePath: use path_selected ternary to say "IAA failed" vs "QAT failed"
  instead of the generic "accelerator failed" literal.
- SetInflatePath (accelerator->IGZIP fallback block): declare failed_accelerator
  const char* from path_selected, then use ternaries in all four path-action
  branches so log and reason strings name the failing accelerator (IAA/QAT).
- IAAFallbackIGZIPTest.DeflateDoesNotUseIGZIPWhenFallbackDisabled: capture and
  assert Z_STREAM_END from deflate() so compression failures are caught.

All 44766 tests pass.

---------

Signed-off-by: Olasoji <olasoji.denloye@intel.com>
Signed-off-by: $(git config user.name) <$(git config user.email)>

* igzip: fix raw deflate over-consumption via read_in_length

ISAL's stateful inflate pre-loads input in 8-byte word chunks into a
64-bit shift register (read_in). After reaching ISAL_BLOCK_FINISH for
raw deflate (window_bits < 0), read_in_length still holds the bit count
of bytes fetched beyond the true stream end. Shifting right by 3 gives
the exact over-consumed byte count for every avail_in scenario:

  avail_in in [1,7]  : previous avail_in<8 heuristic approximated this
  avail_in == 0      : previous heuristic was blind; now handled
  avail_in == 8      : gap in both old heuristics; now handled
  avail_in > 8       : multi-frame continuation; now handled

The corrected consumed count is reported back to the caller via
*input_length so that avail_in / next_in on the zlib stream are
advanced accurately, preventing downstream compressed-size and CRC
mismatches (reproduces as ZipException in Java ZipInputStream).

Boundary guard updated: skip the raw-boundary fallback when
*tofixed==1 because the correction has already accounted for any
remaining bytes, so non-zero remaining is legitimate trailing data
rather than un-corrected over-consumption.

BLOCK_INPUT_DONE path (output-buffer-limited mid-stream) retains the
existing Z_DATA_ERROR->zlib-fallback behaviour unchanged.

Previously attempted stateless-probe approach removed entirely; the
read_in_length field is simpler, exact, and has no multi-frame failure
mode.

Validated: 8/8 IGZIPInflateRegressionTest pass; full make run passes
with only the pre-existing ordering-sensitive case 37961; JAR repro
(250 entries, scan + build-init) passes clean.

* rename trailer_overconsumption_fixed -> read_in_correction_applied; remove stale post-reset pre-set

The old name 'trailer_overconsumption_fixed' was a holdover from the
avail_in < 8 heuristic era. Since EXP-6f the fix is driven entirely by
isal_inflate.read_in_length >> 3; the flag only signals that a correction
was applied *within the current inflate call*.

Rename the field, its parameter aliases, and all local variables to
read_in_correction_applied to match the actual semantics.

Also remove the stale block in inflateReset:
  if (was_igzip_path) {
      inflate_settings->trailer_overconsumption_fixed = 1;
  }
This block predated the read_in_length fix. It pre-armed the flag so
that the old avail_in < 8 boundary guard would not fire on the first
call after a reset. That logic was correct under the old heuristic but
is actively wrong now: ResetUncompressIGZIP already zeros the flag;
re-arming it to 1 would suppress the boundary guard on exactly the call
where it is needed most (first call after reset on a raw stream).

Remove was_igzip_path (now unused after the block removal) and inline
the INPUT_DONE log expression to eliminate an unused-variable warning
when DEBUG_LOG=OFF.

No behaviour change for correct streams; test suite: 8/8 IGZIP inflate
regressions PASS, only pre-existing 37961 flaky failure remains.

* add IGZIP inflate/deflate counters to statistics; enable ENABLE_STATISTICS build flag

Statistics previously tracked QAT and IAA paths but left IGZIP with
commented-out placeholders. Two problems with those placeholders: the
enum values DEFLATE_IGZIP_COUNT, DEFLATE_IGZIP_ERROR_COUNT,
INFLATE_IGZIP_COUNT, INFLATE_IGZIP_ERROR_COUNT did not exist, and the
stat_names array had no entries for them.

Add the four missing Statistic enum values (after the IAA entries,
before ZLIB, matching the QAT/IAA grouping pattern) and their
corresponding stat_names strings.  Uncomment the INCREMENT_STAT calls
in the deflate and inflate IGZIP dispatch blocks.  The error condition
mirrors IAA/QAT: unconditional IGZIP_COUNT on every dispatch, and
IGZIP_ERROR_COUNT when ret != 0 (fallback or hard error).

Enable ENABLE_STATISTICS=ON in cmake.txt so the counters compile in by
default.

Validation (OpenSearch opensearch-core-3.3.1.jar, 250-entry JAR repro,
use_igzip_uncompress=1, log_stats_samples=50):

  Thread (main): inflate_count=750 igzip=749 igzip_errors=0 zlib=0
  — 99.9% of inflate calls served by IGZIP with zero errors or
    zlib fallbacks; one call is the initial probe before path selection.

* add iaa_fallback_igzip: IAA can fall back to IGZIP before software zlib

When IAA inflate or deflate fails (ret != 0), and use_igzip_uncompress /
use_igzip_compress is enabled, the new iaa_fallback_igzip config flag
(default 0) routes the retry to IGZIP before allowing the call to
fall through to software zlib.

Motivation: IAA is stateless and leaves input unconsumed on failure, so
IGZIP can retry from the same position at no extra cost. This keeps
hardware-accelerated decompression in play for inputs that IAA rejects
but IGZIP can handle (e.g. streams that fail IsIAADecompressible or
exceed IAA's single-call constraint).

Implementation:
- New ConfigOption IAA_FALLBACK_IGZIP added between IGNORE_ZLIB_DICTIONARY
  and LOG_LEVEL; default 0 (opt-in), range [0,1].
- inflate(): after IAA dispatch block, if path_selected==IAA && ret!=0 &&
  configs[IAA_FALLBACK_IGZIP] && igzip_available, reset input_len/output_len
  (IAA may have modified them on failure), clear read_in_correction_applied,
  and run IGZIPRunInflateAndSelectPathAction with the same path-action
  handling as the normal IGZIP dispatch. Falls through to zlib if IGZIP
  also fails.
- deflate(): identical pattern; initialises isal_strm via InitCompressIGZIP
  if needed (matching normal IGZIP deflate path).
- Both fallback blocks are wrapped in #ifdef USE_IGZIP and guarded by
  igzip_available so they compile away and are unreachable without IGZIP.
- Existing INFLATE/DEFLATE_IGZIP_COUNT stats capture fallback calls.

Test suite: 44756/44757 PASS (37961 pre-existing flaky only).

* cmake: set ENABLE_STATISTICS=OFF by default

* - Reset statistics to off by default and formatting

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* IGZIP: lift Z_FINISH-only restriction; enable full streaming compress

- SupportedOptionsIGZIPCompress: always returns true (ISA-L natively
  supports NO_FLUSH/SYNC_FLUSH/FULL_FLUSH/FINISH)
- SupportedOptionsIGZIPUncompress: always returns true (remove dead
  zero-input new-stream guard)
- IGZIPShouldFallbackDeflate + IsIGZIPSyncFlush: removed entirely;
  both streaming_flush_with_input and empty_sync_flush_reentry cases
  were artificial constraints inherited from one-shot IAA/QAT model
- CompressIGZIP: add ZSTATE_NEW_HDR guard for empty SYNC_FLUSH calls;
  ISA-L emits sync bytes unconditionally, guard returns 0 progress so
  caller sees Z_BUF_ERROR matching zlib semantics
- deflateSetDictionary: reject mid-stream calls when an accelerator
  path is active; underlying zlib stream is unadvanced so
  orig_deflateSetDictionary would incorrectly return Z_OK
- inflate active-stream no-input block: remove dead
- tests: remove 6 stale path==ZLIB assertions from 3 regression tests
  that assumed IGZIP would fall back on streaming flushes

* fix iaa_fallback_igzip compress: set path_selected=IGZIP after fallback

When IAA compress fails and IGZIP is used as a fallback, path_selected
remained IAA. The return-code block below then used the IAA/QAT one-shot
logic (avail_in==0 -> Z_STREAM_END) instead of IGZIP streaming logic
(IsIGZIPDeflateFinished). ISA-L fills its internal level buffer and
returns after consuming all input but producing only partial output;
avail_in reaches 0 while the stream is not yet at ZSTATE_END. The result
was Z_STREAM_END returned with ~48KB of compressed data still buffered
internally, corrupting every document written during indexing.

Fix: set path_selected = IGZIP immediately after the fallback completes
so that the return-code logic correctly calls IsIGZIPDeflateFinished and
returns Z_OK for partial output, allowing the caller to drain the stream.

* iaa: replace marker-based IsIAADecompressible with 512-byte threshold

When iaa_prepend_empty_block=0 (the default), the old code returned true
for all raw deflate and gzip inputs unconditionally, causing QPL's
overconsumption bug to surface for Java ZipInputStream callers. JAR
loading feeds inflate() with 512-byte chunks where avail_in > actual
compressed size; QPL reports total_in == available_in, causing the
Java-level ZipException that kills OpenSearch at launch.

Fix (ported from exp-8): replace the IAA_PREPEND_EMPTY_BLOCK=0 branch
with a 512-byte threshold guard. ZipInputStream always feeds <=512-byte
chunks; Lucene stored-field reads always provide the exact compressed
size which is typically well above 512 bytes. The few Lucene entries
below the threshold fall back to IGZIP, which is also correct.

Also removes PrependedEmptyBlockPresent() which is no longer called
from the decompression path. The compress-side marker write in
CompressIAA is unaffected (still controlled by iaa_prepend_empty_block).

* README: document USE_IGZIP cmake option and ISA-L dependency

Add USE_IGZIP (ON/OFF) and ISAL_PATH to the cmake options list, and
add a Requirements for IGZIP section with a link to ISA-L.

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* zlib_accel: guard pre_avail_in declaration with USE_IGZIP

pre_avail_in is only referenced inside #ifdef USE_IGZIP blocks.
Without this guard, builds with USE_IGZIP=OFF trigger an
-Wunused-variable error under -Werror, breaking CI.

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* Clang format

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* remove cmake.txt; fix null deref in deflateSetDictionary

cmake.txt contained a local build command with hardcoded absolute paths
(/home/sdp/...). Remove it from the repo and add to .gitignore.

deflateSetDictionary: deflate_stream_settings.Get(strm) can return
nullptr if called without a prior deflateInit. Guard the mid-stream
rejection check to avoid a null dereference in that case, returning
Z_STREAM_ERROR consistent with zlib behaviour.

Addresses review comments on PR #54 (matt-welch, Copilot).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* igzip: remove dead SupportedOptions/IGZIPShouldFallback stubs

SupportedOptionsIGZIPCompress, SupportedOptionsIGZIPUncompress, and
IGZIPShouldFallbackDeflate unconditionally returned fixed values with
all parameters voided. Remove them entirely and inline the fixed values
at all 8 call sites in zlib_accel.cpp.

Addresses review comment on PR #54 (matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* zlib_accel: fix read_in_correction_applied semantics and reset asymmetry

The flag is per-stream-session (set once when the read_in_length
over-consumption correction fires; cleared only on inflateReset), not
per-call as the comment incorrectly stated.

Fix the struct comment to reflect this, and remove the erroneous reset
to 0 on the IAA->IGZIP fallback path which was inconsistent with the
primary IGZIP path and the inflateReset behavior.

Addresses review comment on PR #54 (Copilot, matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* iaa: deprecate iaa_prepend_empty_block config option

The empty stored-block marker approach was abandoned in favour of a
512-byte minimum input length threshold in IsIAADecompressible. The
config option is retained for backward compatibility but has no effect
on decompression and will be removed in a future release.

Rationale for the threshold approach: QPL hardware always consumes all
available_in bytes regardless of where the BFINAL=1 token falls
(overconsumption bug). Java ZipInputStream feeds <=512-byte chunks
when csize is unknown, triggering overconsumption errors. Lucene
stored-field reads always supply the exact compressed size (>512 bytes),
where consuming all input is correct.

Document the deprecation in README and add a comment in iaa.cpp
explaining the history and the replacement mechanism.

Addresses review comment on PR #54 (matt-welch).

Signed-off-by: $(git config user.name) <$(git config user.email)>

* tests: add IAA->IGZIP fallback coverage

Add IAAFallbackIGZIPTest with three tests exercising the fallback
path for both deflate and inflate:

  - DeflateUsesIGZIPWhenIAAFailsAndFallbackEnabled: configures
    USE_IAA_COMPRESS+USE_IGZIP_COMPRESS+IAA_FALLBACK_IGZIP=1 and
    asserts the stream lands on IGZIP (or IAA if hardware present).

  - DeflateDoesNotUseIGZIPWhenFallbackDisabled: same IAA+IGZIP config
    but IAA_FALLBACK_IGZIP=0; asserts IGZIP is never selected.

  - InflateUsesIGZIPWhenIAAFailsAndFallbackEnabled: data compressed
    with IGZIP, decompressed via USE_IAA_UNCOMPRESS+IAA_FALLBACK_IGZIP=1;
    asserts round-trip correctness and IGZIP (or IAA) execution path.

On machines without IAA hardware the QPL init fails (non-zero return),
which naturally exercises the fallback branch without mocking. On
machines that do have IAA hardware and succeed, the assertions accept
either IAA or IGZIP so the tests remain valid in both environments.

Tests are guarded by #ifdef USE_IAA and #ifdef USE_IGZIP (both are
in scope here via the outer USE_IGZIP guard around the regression
block).

Addresses should-fix #6 from PR #54 review (matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* tests: restore IGZIP path assertions for SYNC_FLUSH regression tests

Three IGZIPDeflateRegressionTest tests originally asserted
ASSERT_EQ(path, ZLIB) because IGZIPShouldFallbackDeflate redirected
SYNC_FLUSH calls to the zlib path. Commit f7ee0ec (lift Z_FINISH-only
restriction) removed those assertions when IGZIP gained native
SYNC_FLUSH support, but left no replacement.

Now that IGZIPShouldFallbackDeflate is removed entirely, restore the
path assertions with the new expected behavior: IGZIP must remain on
the IGZIP path through Z_NO_FLUSH, Z_SYNC_FLUSH, and Z_FINISH calls.

Changes:
  - ResetMustNotStallSyncFlushOnSameStream: assert IGZIP after
    Z_NO_FLUSH and Z_SYNC_FLUSH on each cycle.
  - RepeatedEmptySyncFlushMustEventuallyReportNoProgress: assert IGZIP
    after Z_NO_FLUSH and on every Z_SYNC_FLUSH iteration.
  - SyncFlushWithInputMustFallbackToZlibForStreamSafety: renamed to
    SyncFlushWithInputMustStayOnIGZIPPath (the old name described the
    removed fallback behavior); assert IGZIP after Z_SYNC_FLUSH and on
    every Z_FINISH iteration.

Addresses review comment #7 on PR #54 (matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* igzip: document read_in_correction_applied reset and ZSTATE_NEW_HDR coupling

#8 — Explain why read_in_correction_applied is cleared on inflateReset:
isal_inflate_reset clears the internal read_in/read_in_length buffer,
so any over-consumption correction from the previous stream session no
longer applies. The flag must be reset so the new session can fire the
correction fresh if needed. This is intentional; keeping it set across
a reset would incorrectly suppress the correction on data that has not
yet over-consumed.

#9 — Document ISA-L version for ZSTATE_NEW_HDR coupling:
The SYNC_FLUSH no-progress guard directly accesses
isal_strm->internal_state.state == ZSTATE_NEW_HDR. Note that this was
validated against ISA-L v2.32.0 (commit c196241) so future ISA-L
updates can be audited for state machine changes.

Addresses review comments #8 and #9 on PR #54 (matt-welch).

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

* address round-2 Copilot review: README doc, igzip.h comment, IGZIP stats tests, inflate fallback=0 test

- README.md: document iaa_fallback_igzip config option
- igzip.h: fix read_in_correction_applied comment to reflect per-stream-session
  semantics (not per-call)
- tests/zlib_accel_test.cpp: add DEFLATE_IGZIP_COUNT/INFLATE_IGZIP_COUNT
  branches to CompressDecompress stats verification
- tests/zlib_accel_test.cpp: add InflateDoesNotUseIGZIPWhenFallbackDisabled
  as companion to the existing inflate=1 test

* fix: restore gzip_flag after deflateReset on IGZIP stream (Cassandra corruption)

isal_deflate_reset preserves gzip_flag. After the first chunk, ISA-L
internally changes gzip_flag from IGZIP_ZLIB (3) to IGZIP_ZLIB_NO_HDR (4)
to suppress the header on continuation calls. Without a reset, the reused
stream produced headerless chunks, causing Java's Inflater (nowrap=false)
to report 'incorrect header check' / 'unknown compression method' on every
subsequent SSTable chunk — resulting in CorruptSSTableException at read time.

Fix: add ResetCompressIGZIP() which wraps isal_deflate_reset + calls
ConfigureDeflateWindow to restore gzip_flag and hist_bits from window_bits.
Replace the inline isal_deflate_reset call in deflateReset() with this.

Regression test: ResetMustRestoreZlibHeaderForSubsequentChunks compresses
5 independent chunks via a reused IGZIP z_stream (deflateReset between each)
and decompresses each with a fresh zlib inflater — would have failed before
this fix on chunk 2 onward.

Reproduced via: Cassandra 5 mix workload (80% reads, 20% updates) with
IGZIP compress enabled, writing to a zlib-format SSTable.

* Rename iaa_fallback_igzip to igzip_fallback, extend to QAT, default=1

- Rename IAA_FALLBACK_IGZIP -> IGZIP_FALLBACK (single generic key)
- Extend fallback condition in deflate() and inflate() to cover QAT:
  (path_selected == IAA || path_selected == QAT)
- Move failed_accelerator declaration before IGZIP retry call in both blocks
- Log messages updated to identify the failing accelerator (IAA or QAT)
- Flip default from 0 -> 1 (fallback is now on by default when IGZIP enabled)
- Update README: key name, description, default
- Add QATFallbackIGZIPTest suite (4 tests mirroring IAAFallbackIGZIPTest)

Full make run: 51006 tests, 44766 passed, remainder expected skips.

* fix: build error when USE_IGZIP + USE_IAA/USE_QAT all enabled

SetDeflatePath/SetInflatePath take const char*, but commit 8120b29
passed std::string temporaries (string concatenation) which is a
hard compile error. The reason parameter is (void)'d in both
functions, so replace the broken concatenations with plain string
literals and remove the now-unused failed_accelerator variables.

The error was masked because the affected code is inside
#ifdef USE_IGZIP blocks that are only reached when both an
accelerator (IAA or QAT) and IGZIP are compiled in together.
Builds with fewer accelerators enabled did not trigger it.

* tests: assert return codes and guard QAT->IGZIP tests with USE_IGZIP

- Add ASSERT_EQ(ret, Z_STREAM_END) for deflate/inflate calls in
  QATFallbackIGZIPTest::DeflateDoesNotUseIGZIPWhenFallbackDisabled and
  InflateDoesNotUseIGZIPWhenFallbackDisabled so unchecked return codes
  are caught as test failures.
- Guard QATFallbackIGZIPTest block with #if defined(USE_QAT) && defined(USE_IGZIP)
  since these tests exercise the QAT->IGZIP fallback path which requires
  both backends to be compiled in; USE_QAT alone is insufficient.

* fixup: use const char* ternaries to identify accelerator in fallback reasons

Address third-round Copilot review comments on PR #57:

- SetDeflatePath: use path_selected ternary to say "IAA failed" vs "QAT failed"
  instead of the generic "accelerator failed" literal.
- SetInflatePath (accelerator->IGZIP fallback block): declare failed_accelerator
  const char* from path_selected, then use ternaries in all four path-action
  branches so log and reason strings name the failing accelerator (IAA/QAT).
- IAAFallbackIGZIPTest.DeflateDoesNotUseIGZIPWhenFallbackDisabled: capture and
  assert Z_STREAM_END from deflate() so compression failures are caught.

All 44766 tests pass.

* igzip: remove workarounds for ISA-L bugs 1–3, 5 (fixed in public v2.32.1)

ISA-L v2.32.1 (released 2026-07-01, tag v2.32.1 on intel/isa-l) contains
official fixes for four bugs that had local workarounds in zlib-accel:

Bug 1 — avail_in over-consumption at ISAL_BLOCK_FINISH (commit 848daed)
  ISA-L now rewinds next_in/avail_in by read_in_length/8 bytes after a
  block finishes. The read_in_correction_applied workaround and the
  sub-byte fallback to software zlib are both removed.

Bug 2 — ISAL_BLOCK_INPUT_DONE guard for concatenated streams (commit 848daed)
  A consequence of the Bug 1 fix: BLOCK_FINISH now restores avail_in
  correctly, so the pre-emptive fallback at BLOCK_INPUT_DONE is no longer
  needed. The guard block is removed.

Bug 3 — gzip_flag mutation after write_stream_header_stateless (commit d8da2d0)
  ISA-L no longer mutates gzip_flag from IGZIP_ZLIB→IGZIP_ZLIB_NO_HDR
  (or IGZIP_GZIP→IGZIP_GZIP_NO_HDR) after writing the first header.
  isal_deflate_reset now preserves a valid gzip_flag, so the explicit
  ConfigureDeflateWindow call in ResetCompressIGZIP is removed.

Bug 5 — dict_id little-endian (commit 95b7c35)
  ISA-L now stores DICTID in big-endian order matching RFC 1950. The
  __builtin_bswap32 workaround in the NEED_DICT handling path is removed.

Validated: 44,766/44,766 tests pass against ISA-L v2.32.1.

* cmake: require ISA-L >= 2.32.1 when USE_IGZIP=ON

ISA-L v2.32.1 (released 2026-07-01) contains critical bugfixes for
igzip stream reuse (gzip_flag mutation, avail_in over-consumption,
dict_id endianness). Earlier versions produce incorrect output with
zlib-accel's streaming deflate/inflate paths.

Adds a CMake configure-time check that parses MAJOR/MINOR/PATCH from
${ISAL_PATH}/include/isal_api.h and fails with a clear message if the
version is older than 2.32.1.

* format: apply clang-format

* address Copilot review comments on PR #60

zlib_accel.cpp: return Z_STREAM_END when end_of_stream is set but no
I/O progress was made (input_len==0 && output_len==0). The previous
code fell through to Z_BUF_ERROR, which could cause callers to miss
the end-of-stream signal on a final trailer-flush step.

common.cmake: harden ISA-L version macro parsing. Add an explicit
FATAL_ERROR when any ISAL_MAJOR/MINOR/PATCH_VERSION macro is missing
from isal_api.h (previously produced a silent '..'-version string).
Use list(GET ... 0) to normalize before regex-replace, guarding
against multiple matches in a malformed header.

* cmake,igzip: address round-3 Copilot review comments on PR #60

- common.cmake: make ISAL_PATH optional — fall back to find_path() for
  system-installed ISA-L, consistent with the existing QPL_PATH / USE_IAA
  pattern. ISAL_PATH still takes priority when set.
- common.cmake: use whitespace-tolerant regexes ([ \t]+) in both
  file(STRINGS) and string(REGEX REPLACE) calls so tabs or multiple
  spaces in isal_api.h do not silently produce a malformed version string.
- common.cmake: add per-component numeric validation before composing
  _isal_version_found, giving a clear error if parsing fails.
- igzip.cpp: replace /tmp/ ephemeral-file citation in Bug 2 comment with
  a reference to the configure-time version guard in common.cmake.

* igzip: address round-4 vkarpenk review comments on PR #60

- CompressIGZIP, UncompressIGZIP: add const to input, total_in,
  total_out parameters; all three are only read, never written back.
  Use const_cast<uint8_t*> when assigning to ISA-L's non-const
  next_in field (C API limitation).
- CompressIGZIP: remove stale (void)total_in/(void)total_out
  suppression casts; both parameters are actively read.
- Remove IGZIP_INFLATE_PATH_FALLBACK_RAW_BOUNDARY from enum;
  the corresponding code path was already removed from igzip.cpp.

* Formatted code

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

---------

Signed-off-by: Olasoji <olasoji.denloye@intel.com>
Signed-off-by: $(git config user.name) <$(git config user.email)>

…56) (#62)

* Adds test to validate log_stats_samples config



* Reduces excessive error logging in QAT mode



* Bugfix for the log stream



* Treats QPL_STS_MORE_OUTPUT_NEEDED as a non error condition for IAA



* Fixed formatting



* - Modifies iaa behavior so that when QPL_STS_MORE_OUTPUT_NEEDED is
returned eos isnt erronously set.



* -Adds proper formatting



* logging: add LOG_DEBUG level; qat: map log level to QATzip log level

Introduce LOG_DEBUG (value=1) as the most verbose log level, shifting
LOG_INFO to 2 and LOG_ERROR to 3. This follows the conventional ordering
used by syslog, Log4j, Python logging, and QATzip itself (where higher
values mean more verbose).

The default log level remains LOG_ERROR (now value=3), so existing
deployments see no behavioral change unless they explicitly set a lower
value in /etc/zlib-accel.conf.

The config parser max for log_level is updated from 2 to 3 accordingly.

In qat.cpp, replace the hardcoded qzSetLogLevel(LOG_NONE) with a dynamic
mapping from the configured log_level:
  LOG_DEBUG -> LOG_DEBUG3  (maximum QATzip verbosity)
  LOG_INFO  -> LOG_INFO
  LOG_ERROR -> LOG_ERROR
  default   -> LOG_NONE

This corrects an inversion present in PR #55 of intel/zlib-accel, where
LOG_ERROR was incorrectly mapped to LOG_DEBUG3.

New tests: LogDebugLevel, LogDebugFilteredByInfo; LogLevelFiltering
extended to cover DEBUG filtering.

Builds on: #55


* Update README.md



* qat: gate qzSetLogLevel mapping behind DEBUG_LOG; apply formatting

Without the DEBUG_LOG guard, a release build (DEBUG_LOG=OFF) with a
non-zero log_level in the config would cause QATzip to emit verbose
output, contradicting the documented behaviour that log_level only
applies when built with DEBUG_LOG=ON.

Gate the dynamic mapping behind #ifdef DEBUG_LOG and unconditionally
set LOG_NONE in the else branch, matching the original behaviour for
non-debug builds.

Addresses Copilot review comment on PR #56.



* address review comments: enum ordering, call_once, explicit LOG_NONE case

- logging.h: reorder LogLevel enum to match QATzip's QzLogLevel_T convention
  {LOG_NONE=0, LOG_ERROR=1, LOG_INFO=2, LOG_DEBUG=3}; flip filter direction
  from 'level < config' to 'level > config' so higher values = more verbose.
  Apply same fix to PrintDeflateBlockHeader.
- qat.cpp: call qzSetLogLevel once per process via std::call_once instead of
  per session; add explicit case LogLevel::LOG_NONE; move default to end with
  comment; restructure #ifdef to be inside the once lambda.
- config/config.cpp, config/default_config: update default log_level from 3
  to 1 (LOG_ERROR = errors only, matching previous error-only default).
- README.md: update log_level documentation to describe new ordering.
- tests/zlib_accel_test.cpp: update expected log_level default to 1.

---------

Signed-off-by: Olasoji <olasoji.denloye@intel.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Signed-off-by: Olasoji <olasoji.denloye@intel.com>

Remove unused strm/reason params from SetDeflatePath/SetInflatePath and
update all call sites. Replace magic windowBits literals 15 and 31 with
kWindowBitsZlib and kWindowBitsGzip.