Export of internal Abseil changes

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

nit: Add return info for StrCat

PiperOrigin-RevId: 278647298

--
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

--
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, 30 insertions, 0 deletions

diff --git a/absl/hash/internal/hash.cc b/absl/hash/internal/hash.cc
index 4ab7a9f8bfd9..c17f3be1719a 100644
--- a/absl/hash/internal/hash.cc
+++ b/absl/hash/internal/hash.cc
@@ -17,6 +17,36 @@
 namespace absl {
 namespace hash_internal {
 
+uint64_t CityHashState::CombineLargeContiguousImpl32(uint64_t state,
+                                                     const unsigned char* first,
+                                                     size_t len) {
+  while (len >= PiecewiseChunkSize()) {
+    state =
+        Mix(state, absl::hash_internal::CityHash32(reinterpret_cast<const char*>(first),
+                                         PiecewiseChunkSize()));
+    len -= PiecewiseChunkSize();
+    first += PiecewiseChunkSize();
+  }
+  // Handle the remainder.
+  return CombineContiguousImpl(state, first, len,
+                               std::integral_constant<int, 4>{});
+}
+
+uint64_t CityHashState::CombineLargeContiguousImpl64(uint64_t state,
+                                                     const unsigned char* first,
+                                                     size_t len) {
+  while (len >= PiecewiseChunkSize()) {
+    state =
+        Mix(state, absl::hash_internal::CityHash64(reinterpret_cast<const char*>(first),
+                                         PiecewiseChunkSize()));
+    len -= PiecewiseChunkSize();
+    first += PiecewiseChunkSize();
+  }
+  // Handle the remainder.
+  return CombineContiguousImpl(state, first, len,
+                               std::integral_constant<int, 8>{});
+}
+
 ABSL_CONST_INIT const void* const CityHashState::kSeed = &kSeed;
 
 }  // namespace hash_internal