From b56cbdd23834a65682c0b46f367f8679e83bc894 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Fri, 18 Sep 2020 15:55:15 -0700 Subject: Abseil LTS 20200923 What's New: * `absl::StatusOr` has been released. See our [blog post](https://abseil.io/blog/2020-091021-status) for more information. * Abseil Flags reflection interfaces have been released. * Abseil Flags memory usage has been significantly optimized. * Abseil now supports a "hardened" build mode. This build mode enables runtime checks that guard against programming errors that may lead to security vulnerabilities. Notable Fixes: * Sanitizer dynamic annotations like `AnnotateRWLockCreate` that are also defined by the compiler sanitizer implementation are no longer also defined by Abseil. * Sanitizer macros are now prefixed with `ABSL_` to avoid naming collisions. * Sanitizer usage is now automatically detected and no longer requires macros like `ADDRESS_SANITIZER` to be defined on the command line. Breaking Changes: * Abseil no longer contains a `dynamic_annotations` library. Users using a supported build system (Bazel or CMake) are unaffected by this, but users manually specifying link libraries may get an error about a missing linker input. Baseline: 7680a5f8efe32de4753baadbd63e74e59d95bac1 Cherry picks: None --- absl/strings/cord.cc | 203 +++++++++++++++++++++++---------------------------- 1 file changed, 91 insertions(+), 112 deletions(-) (limited to 'absl/strings/cord.cc') diff --git a/absl/strings/cord.cc b/absl/strings/cord.cc index d9503ae3..763dcc45 100644 --- a/absl/strings/cord.cc +++ b/absl/strings/cord.cc @@ -15,10 +15,12 @@ #include "absl/strings/cord.h" #include +#include #include #include #include #include +#include #include #include #include @@ -28,6 +30,7 @@ #include "absl/base/casts.h" #include "absl/base/internal/raw_logging.h" +#include "absl/base/macros.h" #include "absl/base/port.h" #include "absl/container/fixed_array.h" #include "absl/container/inlined_vector.h" @@ -58,48 +61,6 @@ enum CordRepKind { FLAT = 3, }; -namespace { - -// Type used with std::allocator for allocating and deallocating -// `CordRepExternal`. std::allocator is used because it opaquely handles the -// different new / delete overloads available on a given platform. -struct alignas(absl::cord_internal::ExternalRepAlignment()) ExternalAllocType { - unsigned char value[absl::cord_internal::ExternalRepAlignment()]; -}; - -// Returns the number of objects to pass in to std::allocator -// allocate() and deallocate() to create enough room for `CordRepExternal` with -// `releaser_size` bytes on the end. -constexpr size_t GetExternalAllocNumObjects(size_t releaser_size) { - // Be sure to round up since `releaser_size` could be smaller than - // `sizeof(ExternalAllocType)`. - return (sizeof(CordRepExternal) + releaser_size + sizeof(ExternalAllocType) - - 1) / - sizeof(ExternalAllocType); -} - -// Allocates enough memory for `CordRepExternal` and a releaser with size -// `releaser_size` bytes. -void* AllocateExternal(size_t releaser_size) { - return std::allocator().allocate( - GetExternalAllocNumObjects(releaser_size)); -} - -// Deallocates the memory for a `CordRepExternal` assuming it was allocated with -// a releaser of given size and alignment. -void DeallocateExternal(CordRepExternal* p, size_t releaser_size) { - std::allocator().deallocate( - reinterpret_cast(p), - GetExternalAllocNumObjects(releaser_size)); -} - -// Returns a pointer to the type erased releaser for the given CordRepExternal. -void* GetExternalReleaser(CordRepExternal* rep) { - return rep + 1; -} - -} // namespace - namespace cord_internal { inline CordRepConcat* CordRep::concat() { @@ -136,8 +97,6 @@ inline const CordRepExternal* CordRep::external() const { static const size_t kFlatOverhead = offsetof(CordRep, data); -static_assert(kFlatOverhead == 13, "Unittests assume kFlatOverhead == 13"); - // Largest and smallest flat node lengths we are willing to allocate // Flat allocation size is stored in tag, which currently can encode sizes up // to 4K, encoded as multiple of either 8 or 32 bytes. @@ -195,52 +154,18 @@ static_assert(Fibonacci(63) == 6557470319842, // The root node depth is allowed to become twice as large to reduce rebalancing // for larger strings (see IsRootBalanced). static constexpr uint64_t min_length[] = { - Fibonacci(2), - Fibonacci(3), - Fibonacci(4), - Fibonacci(5), - Fibonacci(6), - Fibonacci(7), - Fibonacci(8), - Fibonacci(9), - Fibonacci(10), - Fibonacci(11), - Fibonacci(12), - Fibonacci(13), - Fibonacci(14), - Fibonacci(15), - Fibonacci(16), - Fibonacci(17), - Fibonacci(18), - Fibonacci(19), - Fibonacci(20), - Fibonacci(21), - Fibonacci(22), - Fibonacci(23), - Fibonacci(24), - Fibonacci(25), - Fibonacci(26), - Fibonacci(27), - Fibonacci(28), - Fibonacci(29), - Fibonacci(30), - Fibonacci(31), - Fibonacci(32), - Fibonacci(33), - Fibonacci(34), - Fibonacci(35), - Fibonacci(36), - Fibonacci(37), - Fibonacci(38), - Fibonacci(39), - Fibonacci(40), - Fibonacci(41), - Fibonacci(42), - Fibonacci(43), - Fibonacci(44), - Fibonacci(45), - Fibonacci(46), - Fibonacci(47), + Fibonacci(2), Fibonacci(3), Fibonacci(4), Fibonacci(5), + Fibonacci(6), Fibonacci(7), Fibonacci(8), Fibonacci(9), + Fibonacci(10), Fibonacci(11), Fibonacci(12), Fibonacci(13), + Fibonacci(14), Fibonacci(15), Fibonacci(16), Fibonacci(17), + Fibonacci(18), Fibonacci(19), Fibonacci(20), Fibonacci(21), + Fibonacci(22), Fibonacci(23), Fibonacci(24), Fibonacci(25), + Fibonacci(26), Fibonacci(27), Fibonacci(28), Fibonacci(29), + Fibonacci(30), Fibonacci(31), Fibonacci(32), Fibonacci(33), + Fibonacci(34), Fibonacci(35), Fibonacci(36), Fibonacci(37), + Fibonacci(38), Fibonacci(39), Fibonacci(40), Fibonacci(41), + Fibonacci(42), Fibonacci(43), Fibonacci(44), Fibonacci(45), + Fibonacci(46), Fibonacci(47), 0xffffffffffffffffull, // Avoid overflow }; @@ -337,11 +262,7 @@ static void UnrefInternal(CordRep* rep) { } } else if (rep->tag == EXTERNAL) { CordRepExternal* rep_external = rep->external(); - absl::string_view data(rep_external->base, rep->length); - void* releaser = GetExternalReleaser(rep_external); - size_t releaser_size = rep_external->releaser_invoker(releaser, data); - rep_external->~CordRepExternal(); - DeallocateExternal(rep_external, releaser_size); + rep_external->releaser_invoker(rep_external); rep = nullptr; } else if (rep->tag == SUBSTRING) { CordRepSubstring* rep_substring = rep->substring(); @@ -491,18 +412,12 @@ static CordRep* NewTree(const char* data, namespace cord_internal { -ExternalRepReleaserPair NewExternalWithUninitializedReleaser( - absl::string_view data, ExternalReleaserInvoker invoker, - size_t releaser_size) { +void InitializeCordRepExternal(absl::string_view data, CordRepExternal* rep) { assert(!data.empty()); - - void* raw_rep = AllocateExternal(releaser_size); - auto* rep = new (raw_rep) CordRepExternal(); rep->length = data.size(); rep->tag = EXTERNAL; rep->base = data.data(); - rep->releaser_invoker = invoker; - return {VerifyTree(rep), GetExternalReleaser(rep)}; + VerifyTree(rep); } } // namespace cord_internal @@ -526,10 +441,7 @@ static CordRep* NewSubstring(CordRep* child, size_t offset, size_t length) { // -------------------------------------------------------------------- // Cord::InlineRep functions -// This will trigger LNK2005 in MSVC. -#ifndef COMPILER_MSVC -const unsigned char Cord::InlineRep::kMaxInline; -#endif // COMPILER_MSVC +constexpr unsigned char Cord::InlineRep::kMaxInline; inline void Cord::InlineRep::set_data(const char* data, size_t n, bool nullify_tail) { @@ -585,7 +497,7 @@ void Cord::InlineRep::AppendTree(CordRep* tree) { } void Cord::InlineRep::PrependTree(CordRep* tree) { - if (tree == nullptr) return; + assert(tree != nullptr); size_t len = data_[kMaxInline]; if (len == 0) { set_tree(tree); @@ -738,6 +650,37 @@ Cord::Cord(absl::string_view src) { } } +template > +Cord::Cord(T&& src) { + if ( + // String is short: copy data to avoid external block overhead. + src.size() <= kMaxBytesToCopy || + // String is wasteful: copy data to avoid pinning too much unused memory. + src.size() < src.capacity() / 2 + ) { + if (src.size() <= InlineRep::kMaxInline) { + contents_.set_data(src.data(), src.size(), false); + } else { + contents_.set_tree(NewTree(src.data(), src.size(), 0)); + } + } else { + struct StringReleaser { + void operator()(absl::string_view /* data */) {} + std::string data; + }; + const absl::string_view original_data = src; + auto* rep = static_cast< + ::absl::cord_internal::CordRepExternalImpl*>( + absl::cord_internal::NewExternalRep( + original_data, StringReleaser{std::forward(src)})); + // Moving src may have invalidated its data pointer, so adjust it. + rep->base = rep->template get<0>().data.data(); + contents_.set_tree(rep); + } +} + +template Cord::Cord(std::string&& src); + // The destruction code is separate so that the compiler can determine // that it does not need to call the destructor on a moved-from Cord. void Cord::DestroyCordSlow() { @@ -775,6 +718,18 @@ Cord& Cord::operator=(absl::string_view src) { return *this; } +template > +Cord& Cord::operator=(T&& src) { + if (src.size() <= kMaxBytesToCopy) { + *this = absl::string_view(src); + } else { + *this = Cord(std::forward(src)); + } + return *this; +} + +template Cord& Cord::operator=(std::string&& src); + // TODO(sanjay): Move to Cord::InlineRep section of file. For now, // we keep it here to make diffs easier. void Cord::InlineRep::AppendArray(const char* src_data, size_t src_size) { @@ -886,6 +841,17 @@ void Cord::Append(const Cord& src) { AppendImpl(src); } void Cord::Append(Cord&& src) { AppendImpl(std::move(src)); } +template > +void Cord::Append(T&& src) { + if (src.size() <= kMaxBytesToCopy) { + Append(absl::string_view(src)); + } else { + Append(Cord(std::forward(src))); + } +} + +template void Cord::Append(std::string&& src); + void Cord::Prepend(const Cord& src) { CordRep* src_tree = src.contents_.tree(); if (src_tree != nullptr) { @@ -915,6 +881,17 @@ void Cord::Prepend(absl::string_view src) { } } +template > +inline void Cord::Prepend(T&& src) { + if (src.size() <= kMaxBytesToCopy) { + Prepend(absl::string_view(src)); + } else { + Prepend(Cord(std::forward(src))); + } +} + +template void Cord::Prepend(std::string&& src); + static CordRep* RemovePrefixFrom(CordRep* node, size_t n) { if (n >= node->length) return nullptr; if (n == 0) return Ref(node); @@ -1175,7 +1152,7 @@ class CordForest { void AddNode(CordRep* node) { CordRep* sum = nullptr; - // Collect together everything with which we will merge node + // Collect together everything with which we will merge with node int i = 0; for (; node->length > min_length[i + 1]; ++i) { auto& tree_at_i = trees_[i]; @@ -1506,7 +1483,8 @@ void Cord::CopyToArraySlowPath(char* dst) const { } Cord::ChunkIterator& Cord::ChunkIterator::operator++() { - assert(bytes_remaining_ > 0 && "Attempted to iterate past `end()`"); + ABSL_HARDENING_ASSERT(bytes_remaining_ > 0 && + "Attempted to iterate past `end()`"); assert(bytes_remaining_ >= current_chunk_.size()); bytes_remaining_ -= current_chunk_.size(); @@ -1545,7 +1523,8 @@ Cord::ChunkIterator& Cord::ChunkIterator::operator++() { } Cord Cord::ChunkIterator::AdvanceAndReadBytes(size_t n) { - assert(bytes_remaining_ >= n && "Attempted to iterate past `end()`"); + ABSL_HARDENING_ASSERT(bytes_remaining_ >= n && + "Attempted to iterate past `end()`"); Cord subcord; if (n <= InlineRep::kMaxInline) { @@ -1716,7 +1695,7 @@ void Cord::ChunkIterator::AdvanceBytesSlowPath(size_t n) { } char Cord::operator[](size_t i) const { - assert(i < size()); + ABSL_HARDENING_ASSERT(i < size()); size_t offset = i; const CordRep* rep = contents_.tree(); if (rep == nullptr) { -- cgit v1.2.3