From b832dce8489ef7b6231384909fd9b68d5a5ff2b7 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Tue, 25 Feb 2020 22:27:31 +0100 Subject: Creation of LTS branch "lts_2020_02_25" - 0033c9ea91a52ade7c6b725aa2ef3cbe15463421 Fix build on FreeBSD/powerpc (#616) by kgotlinux <60880393+kgotlinux@users.noreply.github.com> - 0d5ce2797eb695aee7e019e25323251ef6ffc277 Export of internal Abseil changes by Abseil Team - b69c7d880caddfc25bf348dbcfe9d45fdd8bc6e6 Export of internal Abseil changes by Abseil Team - 2a5633fc077a58528cdbfe78720f3f6bfdc6044d Merge "Export of internal Abseil changes" by Xiaoyi Zhang - f9b3d6e493c1b6ab3dbdab71c5f8fa849db4abaf Add RISCV support to GetProgramCounter() (#621) by Khem Raj - 0232c87f21c26718aa3eb2d86678070f3b498a4e Add missing ABSL_HAVE_VDSO_SUPPORT conditional (#622) by Sinan Kaya <41809318+franksinankaya@users.noreply.github.com> - 3c814105108680997d0821077694f663693b5382 Export of internal Abseil changes by Abseil Team - c44657f55692eddf5504156645d1f4ec7b3acabd Export of internal Abseil changes by Abseil Team - 98eb410c93ad059f9bba1bf43f5bb916fc92a5ea Export of internal Abseil changes by Abseil Team - bf78e977309c4cb946914b456404141ddac1c302 Export of internal Abseil changes by Abseil Team - d95d1567165d449e4c213ea31a15cbb112a9865f Export of internal Abseil changes by Abseil Team - 24713a7036a81498334807fa5c7ad3cb7c643711 Export of internal Abseil changes by Abseil Team - 72382c21fefed981b4b8a2a1b82e2d231c2c2e39 Export of internal Abseil changes by Abseil Team - 08a7e7bf972c8451855a5022f2faf3d3655db015 Export of internal Abseil changes by Abseil Team - 36bcd9599b3f48c99357ba61cf33584889306d6a Fix pointer format specifier in documentation (#614) by Andre Nguyen - 0f86336b6939ea673cc1cbe29189286cae67d63a Export of internal Abseil changes by Abseil Team - c512f118dde6ffd51cb7d8ac8804bbaf4d266c3a Export of internal Abseil changes by Abseil Team - 37dd2562ec830d547a1524bb306be313ac3f2556 Export of internal Abseil changes by Abseil Team - 44427702614d7b86b064ba06a390f5eb2f85dbf6 fix: Add support for more ARM processors detection (#608) by Andre Nguyen - 159bf2bf6d1cc8087e02468d071e94d1177d1bae Export of internal Abseil changes by Abseil Team - a2e6adecc294dc4cd98cc285a9134ce58e0f2ad0 Use https links. (#586) by nlewycky - 564001ae506a17c51fa1223684a78f05f91d3d91 Export of internal Abseil changes by Abseil Team - b3aaac8a37c467a1125c794196caa90d0957bdc3 Export of internal Abseil changes by Abseil Team - 63ee2f8877915a3565c29707dba8fe4d7822596a Export of internal Abseil changes by Abseil Team - a048203a881f11f4b7b8df5fb563aec85522f8db Export of internal Abseil changes by Abseil Team - 1de0166368e2ae67347f92099d6dca3ab3a4a496 Export of internal Abseil changes by Abseil Team - ad904b6cd3906ddf79878003d92b7bc08d7786ae Export of internal Abseil changes by Abseil Team - 29235139149790f5afc430c11cec8f1eb1677607 Export of internal Abseil changes by Abseil Team - bf86cfe165ef7d70dfe68f0b8fc0c018bc79a577 Export of internal Abseil changes by Abseil Team - 12bc53e0318d80569270a5b26ccbc62b52022b89 Export of internal Abseil changes by Abseil Team - 1e39f8626a4dadec1f56920b999dd4c3cfae333e Export of internal Abseil changes by Abseil Team - 77f87009a34c745255bd84d8f2647040d831a2b3 Export of internal Abseil changes by Abseil Team - d659fe54b35ab9b8e35c72e50a4b8814167d5a84 Export of internal Abseil changes by Abseil Team - a4b757b5d42694306a9de853cee0a5fba9c7bbe9 Export of internal Abseil changes by Abseil Team - 0514227d2547793b23e209809276375e41c76617 Export of internal Abseil changes by Abseil Team - 7f4fe64af80fe3c84db8ea938276c3690573c45e Export of internal Abseil changes by Abseil Team - 16d9fd58a51c6083234e2e9f8f50e49ed5ed02e4 Export of internal Abseil changes by Abseil Team - bcaae6009c0833b73c6fa7bdd972921d8081a724 Export of internal Abseil changes by Abseil Team - 8ba96a8244bbe334d09542e92d566673a65c1f78 Export of internal Abseil changes by Abseil Team - 2103fd9acdf58279f739860bff3f8c9f4b845605 Export of internal Abseil changes by Abseil Team - 3df7b52a6ada51a72a23796b844549a7b282f1b8 Export of internal Abseil changes by Abseil Team - fa8c75182fbfdeddb2485fc0d53baeda3f40b7a3 Export of internal Abseil changes by Abseil Team - 85092b4b648ca729c6263c4a302a41dfff28705e Fix Conan builds (#400) by Adrian Ostrowski - e96ae2203b80d5ae2e0b7abe0c77b722b224b16d Export of internal Abseil changes by Abseil Team - 20de2db748ca0471cfb61cb53e813dd12938c12b Export of internal Abseil changes by Abseil Team - 846e5dbedac123d12455adcfe6f53c8b5dcbfeef Export of internal Abseil changes by Abseil Team - 8207907f4f7fbaeeaa2b7340c76875e06fd345ba Export of internal Abseil changes by Abseil Team - 078b89b3c046d230ef3ad39494e5852184eb528b Export of internal Abseil changes by Abseil Team - 19b021cb3ff23048dfbe236a4e611925d8930831 Export of internal Abseil changes by Abseil Team - ecc0033b54847f6c9ee37dbb0be8aa17e5b6d37b Always enable proper symbolize implementation on Windows ... by Loo Rong Jie - 2796d500aea5a31d26b8b24a33fab7a1c8fa2f32 Export of internal Abseil changes by Abseil Team - e4c8d0eb8ef4acb5d7a4252b3b87feb391ef7e41 Export of internal Abseil changes by Abseil Team - a15364ce4d88534ae2295127e5d8e32aefb6b446 Export of internal Abseil changes by Abseil Team - ab3552a18964e7063c8324f45b3896a6a20b08a8 Export of internal Abseil changes by Abseil Team - e9f9000c7c80993cb589d011616b7a8016e42f4a Fix ABSL_WAITER_MODE detection for mingw (#342) by Joe Sylve - abea769b551f7a100f540967cb95debdb0080df8 Fix ABSL_HAVE_ALARM check on mingw (#341) by Joe Sylve - 25597bdfc148e91e27678ec30efa52f4fc8c164f Export of internal Abseil changes by Abseil Team - aad33fefaa8f744d71ce747a53717b835bdf8e84 Export of internal Abseil changes by Abseil Team - 8fe7214fe2d7a45ecc4d85f6a524c6b1532426de Export of internal Abseil changes by Abseil Team - debac94cfb5a0fa75d1d97c399682bd1c72e3191 Export of internal Abseil changes by Abseil Team - 882b3501a31eb0e4ae4213afb91a0e43feda7d5f Fix spelling errors (#384) by Sungmann Cho <55860394+chosungmann@users.noreply.github.com> - 502efe6d7841bff82b1aeef5500491fe9a48c635 Export of internal Abseil changes by Abseil Team - ccdd1d57b6386ebc26fb0c7d99b604672437c124 Export of internal Abseil changes by Abseil Team - ddf8e52a2918dd0ccec75d3e2426125fa3926724 Export of internal Abseil changes by Abseil Team - 6ec136281086b71da32b5fb068bd6e46b78a5c79 Export of internal Abseil changes by Abseil Team - ac78ffc3bc0a8b295cab9a03817760fd460df2a1 Export of internal Abseil changes by Abseil Team - 5374c56e5196320681993869e3126b51edac2a43 Export of internal Abseil changes by Abseil Team - 97c1664b4bbab5f78fac2b151ab02656268fb34b Export of internal Abseil changes by Abseil Team - 325fd7b042ff4ec34f7dd32e602cd81ad0e24b22 Export of internal Abseil changes by Abseil Team - 83c1d65c90a92aa49632b9ac5a793214bb0768bc Export of internal Abseil changes by Abseil Team - eb6b7bd23bc0815bfd784e1a74021ce166765280 Export of internal Abseil changes by Abseil Team - 9ddac555b7861dc178d0dbe758a1cfbed718784b Export of internal Abseil changes by Abseil Team - 1948f6f967e34db9793cfa8b4bcbaf370d039fd8 Export of internal Abseil changes by Abseil Team - a0d1e098c2f99694fa399b175a7ccf920762030e Export of internal Abseil changes by Abseil Team - 2d2d7fbc283315b676159716376e739d3d23ed94 Export of internal Abseil changes by Abseil Team - 0302d1e5fa4fcdd1763b7d1bb3212943b1ae911d supppress unused variable warning for gcc (#372) by Martin - 262d74ba81b1fc4d71f459555cde8ecb39786d68 Export of internal Abseil changes by Abseil Team - f0afae0d49af3e15a7169e019634d7719143d94d Export of internal Abseil changes by Abseil Team - 0e7afdcbd24c7e5b7cab4e0217d8886f1525b520 Export of internal Abseil changes by Abseil Team - 9a41ffdd3a0ccbcdd29c4e3886b28e06f2cd9c66 Export of internal Abseil changes by Abseil Team - 36910d3d7e9fccadd6603f232d0c4f54dcd47c7e [bazel] Add fixes for --incompatible_load_cc_rules_from_b... by Yannic - aae8143cf9aa611f70d7ea9b95b8b8b383b2271a Export of internal Abseil changes by Abseil Team - d9aa92d7fb324314f9df487ac23d32a25650b742 Export of internal Abseil changes by Abseil Team - 321ab5303023c86cd15d9ddc5740fb4b4fde32e1 Export of internal Abseil changes by Abseil Team - 4ef574064e75b86f115549e9eb4c7e806781b3ab Export of internal Abseil changes by Abseil Team GitOrigin-RevId: 0033c9ea91a52ade7c6b725aa2ef3cbe15463421 Change-Id: I8a2b70063cb3ab40c6943a6db0fe40cae71ed8d7 --- absl/hash/internal/hash.h | 141 ++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 136 insertions(+), 5 deletions(-) (limited to 'absl/hash/internal/hash.h') diff --git a/absl/hash/internal/hash.h b/absl/hash/internal/hash.h index 81f1edf8..ae7a60cd 100644 --- a/absl/hash/internal/hash.h +++ b/absl/hash/internal/hash.h @@ -50,9 +50,15 @@ #include "absl/hash/internal/city.h" namespace absl { -inline namespace lts_2019_08_08 { +ABSL_NAMESPACE_BEGIN namespace hash_internal { +class PiecewiseCombiner; + +// Internal detail: Large buffers are hashed in smaller chunks. This function +// returns the size of these chunks. +constexpr size_t PiecewiseChunkSize() { return 1024; } + // HashStateBase // // A hash state object represents an intermediate state in the computation @@ -69,7 +75,7 @@ namespace hash_internal { // // `static H combine_contiguous(H state, const unsigned char*, size_t)`. // -// `HashStateBase` will provide a complete implementations for a hash state +// `HashStateBase` will provide a complete implementation for a hash state // object in terms of this method. // // Example: @@ -118,6 +124,9 @@ class HashStateBase { // for-loop instead. template static H combine_contiguous(H state, const T* data, size_t size); + + private: + friend class PiecewiseCombiner; }; // is_uniquely_represented @@ -188,6 +197,61 @@ H hash_bytes(H hash_state, const T& value) { return H::combine_contiguous(std::move(hash_state), start, sizeof(value)); } +// PiecewiseCombiner +// +// PiecewiseCombiner is an internal-only helper class for hashing a piecewise +// buffer of `char` or `unsigned char` as though it were contiguous. This class +// provides two methods: +// +// H add_buffer(state, data, size) +// H finalize(state) +// +// `add_buffer` can be called zero or more times, followed by a single call to +// `finalize`. This will produce the same hash expansion as concatenating each +// buffer piece into a single contiguous buffer, and passing this to +// `H::combine_contiguous`. +// +// Example usage: +// PiecewiseCombiner combiner; +// for (const auto& piece : pieces) { +// state = combiner.add_buffer(std::move(state), piece.data, piece.size); +// } +// return combiner.finalize(std::move(state)); +class PiecewiseCombiner { + public: + PiecewiseCombiner() : position_(0) {} + PiecewiseCombiner(const PiecewiseCombiner&) = delete; + PiecewiseCombiner& operator=(const PiecewiseCombiner&) = delete; + + // PiecewiseCombiner::add_buffer() + // + // Appends the given range of bytes to the sequence to be hashed, which may + // modify the provided hash state. + template + H add_buffer(H state, const unsigned char* data, size_t size); + template + H add_buffer(H state, const char* data, size_t size) { + return add_buffer(std::move(state), + reinterpret_cast(data), size); + } + + // PiecewiseCombiner::finalize() + // + // Finishes combining the hash sequence, which may may modify the provided + // hash state. + // + // Once finalize() is called, add_buffer() may no longer be called. The + // resulting hash state will be the same as if the pieces passed to + // add_buffer() were concatenated into a single flat buffer, and then provided + // to H::combine_contiguous(). + template + H finalize(H state); + + private: + unsigned char buf_[PiecewiseChunkSize()]; + size_t position_; +}; + // ----------------------------------------------------------------------------- // AbslHashValue for Basic Types // ----------------------------------------------------------------------------- @@ -364,6 +428,19 @@ H AbslHashValue(H hash_state, absl::string_view str) { str.size()); } +// Support std::wstring, std::u16string and std::u32string. +template ::value || + std::is_same::value || + std::is_same::value>> +H AbslHashValue( + H hash_state, + const std::basic_string, Alloc>& str) { + return H::combine( + H::combine_contiguous(std::move(hash_state), str.data(), str.size()), + str.size()); +} + // ----------------------------------------------------------------------------- // AbslHashValue for Sequence Containers // ----------------------------------------------------------------------------- @@ -631,7 +708,8 @@ struct is_hashable : std::integral_constant::value> {}; // CityHashState -class CityHashState : public HashStateBase { +class ABSL_DLL CityHashState + : public HashStateBase { // absl::uint128 is not an alias or a thin wrapper around the intrinsic. // We use the intrinsic when available to improve performance. #ifdef ABSL_HAVE_INTRINSIC_INT128 @@ -710,6 +788,16 @@ class CityHashState : public HashStateBase { std::integral_constant /* sizeof_size_t*/); + // Slow dispatch path for calls to CombineContiguousImpl with a size argument + // larger than PiecewiseChunkSize(). Has the same effect as calling + // CombineContiguousImpl() repeatedly with the chunk stride size. + static uint64_t CombineLargeContiguousImpl32(uint64_t state, + const unsigned char* first, + size_t len); + static uint64_t CombineLargeContiguousImpl64(uint64_t state, + const unsigned char* first, + size_t len); + // Reads 9 to 16 bytes from p. // The first 8 bytes are in .first, the rest (zero padded) bytes are in // .second. @@ -777,6 +865,9 @@ inline uint64_t CityHashState::CombineContiguousImpl( // multiplicative hash. uint64_t v; if (len > 8) { + if (ABSL_PREDICT_FALSE(len > PiecewiseChunkSize())) { + return CombineLargeContiguousImpl32(state, first, len); + } v = absl::hash_internal::CityHash32(reinterpret_cast(first), len); } else if (len >= 4) { v = Read4To8(first, len); @@ -797,6 +888,9 @@ inline uint64_t CityHashState::CombineContiguousImpl( // multiplicative hash. uint64_t v; if (len > 16) { + if (ABSL_PREDICT_FALSE(len > PiecewiseChunkSize())) { + return CombineLargeContiguousImpl64(state, first, len); + } v = absl::hash_internal::CityHash64(reinterpret_cast(first), len); } else if (len > 8) { auto p = Read9To16(first, len); @@ -813,7 +907,6 @@ inline uint64_t CityHashState::CombineContiguousImpl( return Mix(state, v); } - struct AggregateBarrier {}; // HashImpl @@ -850,8 +943,46 @@ template H HashStateBase::combine_contiguous(H state, const T* data, size_t size) { return hash_internal::hash_range_or_bytes(std::move(state), data, size); } + +// HashStateBase::PiecewiseCombiner::add_buffer() +template +H PiecewiseCombiner::add_buffer(H state, const unsigned char* data, + size_t size) { + if (position_ + size < PiecewiseChunkSize()) { + // This partial chunk does not fill our existing buffer + memcpy(buf_ + position_, data, size); + position_ += size; + return state; + } + + // Complete the buffer and hash it + const size_t bytes_needed = PiecewiseChunkSize() - position_; + memcpy(buf_ + position_, data, bytes_needed); + state = H::combine_contiguous(std::move(state), buf_, PiecewiseChunkSize()); + data += bytes_needed; + size -= bytes_needed; + + // Hash whatever chunks we can without copying + while (size >= PiecewiseChunkSize()) { + state = H::combine_contiguous(std::move(state), data, PiecewiseChunkSize()); + data += PiecewiseChunkSize(); + size -= PiecewiseChunkSize(); + } + // Fill the buffer with the remainder + memcpy(buf_, data, size); + position_ = size; + return state; +} + +// HashStateBase::PiecewiseCombiner::finalize() +template +H PiecewiseCombiner::finalize(H state) { + // Hash the remainder left in the buffer, which may be empty + return H::combine_contiguous(std::move(state), buf_, position_); +} + } // namespace hash_internal -} // inline namespace lts_2019_08_08 +ABSL_NAMESPACE_END } // namespace absl #endif // ABSL_HASH_INTERNAL_HASH_H_ -- cgit v1.2.3