Export of internal Abseil changes

--
074a799119ac881b8b8ce59ef7a3166d1aa025ac by Tom Manshreck <shreck@google.com>:

nit: Add return info for StrCat

PiperOrigin-RevId: 278647298

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d58a2a39ab6f50266cc695506ba2e86bdb45d795 by Mark Barolak <mbar@google.com>:

Stop suppressing no-nested-anon-types warnings because there aren't actually any warnings to suppress.

PiperOrigin-RevId: 278440548

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445051bd280b9a6f608a8c80b3d7cafcc1377a03 by Abseil Team <absl-team@google.com>:

ResetThreadIdentity does not need to clear identity->waiter_state.

ResetThreadIdentity is only called by NewThreadIdentity. NewThreadIdentity is
only called by CreateThreadIdentity. CreateThreadIdentity calls
PerThreadSem::Init, which initializes identity->waiter_state, immediately after
calling NewThreadIdentity. Therefore ResetThreadIdentity does not need to clear
identity->waiter_state.
PiperOrigin-RevId: 278429844

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c2079b664d92be40d5e365abcca4e9b3505a75a6 by Abseil Team <absl-team@google.com>:

Delete the f->header.magic check in LowLevelAlloc::Free().

The f->header.magic check in LowLevelAlloc::Free() is redundant, because
AddToFreeList() will immediately perform the same check.

Also fix a typo in the comment that documents the lock requirements for
Next(). The comment should say "L >= arena->mu", which is equivalent to
EXCLUSIVE_LOCKS_REQUIRED(arena->mu).

NOTE: LowLevelAlloc::Free() performs the f->header.magic check without
holding the arena lock. This may have caused the TSAN data race warning
reported in bug 143697235.
PiperOrigin-RevId: 278414140

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5534f35ce677165700117d868f51607ed1f0d73b by Greg Falcon <gfalcon@google.com>:

Add an internal (unsupported) PiecewiseCombiner class to allow hashing buffers piecewise.

PiperOrigin-RevId: 278388902
GitOrigin-RevId: 074a799119ac881b8b8ce59ef7a3166d1aa025ac
Change-Id: I61734850cbbb01c7585e8c736a5bb56e416512a8

1 files changed, 13 insertions, 0 deletions

diff --git a/absl/hash/internal/spy_hash_state.h b/absl/hash/internal/spy_hash_state.h
index c4cc8d0..05c7caf 100644
--- a/absl/hash/internal/spy_hash_state.h
+++ b/absl/hash/internal/spy_hash_state.h
@@ -146,6 +146,19 @@ class SpyHashStateImpl : public HashStateBase<SpyHashStateImpl<T>> {
   static SpyHashStateImpl combine_contiguous(SpyHashStateImpl hash_state,
                                              const unsigned char* begin,
                                              size_t size) {
+    const size_t large_chunk_stride = PiecewiseChunkSize();
+    if (size > large_chunk_stride) {
+      // Combining a large contiguous buffer must have the same effect as
+      // doing it piecewise by the stride length, followed by the (possibly
+      // empty) remainder.
+      while (size >= large_chunk_stride) {
+        hash_state = SpyHashStateImpl::combine_contiguous(
+            std::move(hash_state), begin, large_chunk_stride);
+        begin += large_chunk_stride;
+        size -= large_chunk_stride;
+      }
+    }
+
     hash_state.hash_representation_.emplace_back(
         reinterpret_cast<const char*>(begin), size);
     return hash_state;