From 33caf1097ecce4fe892567462fa8821d477854b4 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Tue, 26 May 2020 10:57:33 -0700 Subject: Export of internal Abseil changes -- 7d0468a6610ed85586d5c87fd65de8dac5118923 by Derek Mauro : Import of CCTZ from GitHub. PiperOrigin-RevId: 313226473 -- 1131ef6d116f5ce7d46537a82f300ea06dcaaa53 by Gennadiy Rozental : Migrate internal interface to use mutable references. PiperOrigin-RevId: 312931131 -- 96225212a9f5fbd0b38c71fe65539164992c7c3b by Laramie Leavitt : Remove random/internal/distributions.h This file was something of an historical artifact. All of the related code has either been removed or migraged, and so the only remaining type belongs with uniform_helper.h, as it is used to infer the return type of the absl::Uniform method in a few cases. PiperOrigin-RevId: 312878173 -- 6dcbd5be58ad425e08740ff64088373ee7fe4a72 by Mark Barolak : Release the StrFormat test case for Cords to open source. PiperOrigin-RevId: 312707974 -- 34484d18dfb63a0a7ad6e2aaeb570e33592968be by Abseil Team : Let Cord::Cord(string&&), Cord::operator=(string&&), Cord::Append(string&&), and Cord::Prepend(string&&) steal string data and embed it into the Cord as a single external chunk, instead of copying it into flat chunks (at most 4083-byte each). Stealing string data is faster, but it creates a long chunk, which leads to a higher more memory usage if its subcords are created and outlive the whole Cord. These functions revert to copying the data if any of the following conditions holds: - string size is at most kMaxBytesToCopy (511), to avoid the overhead of an external chunk for short strings; - less than half of string capacity is used, to avoid pinning to much unused memory. PiperOrigin-RevId: 312683785 GitOrigin-RevId: 7d0468a6610ed85586d5c87fd65de8dac5118923 Change-Id: If79b5a1dfe6d53a8ddddbc7da84338f11fc4cfa3 --- absl/strings/cord.cc | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) (limited to 'absl/strings/cord.cc') diff --git a/absl/strings/cord.cc b/absl/strings/cord.cc index 1ddd6aec..68f53987 100644 --- a/absl/strings/cord.cc +++ b/absl/strings/cord.cc @@ -705,6 +705,37 @@ 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; + CordRepExternal* rep = + static_cast(absl::cord_internal::NewExternalRep( + original_data, StringReleaser{std::move(src)})); + // Moving src may have invalidated its data pointer, so adjust it. + rep->base = + static_cast(GetExternalReleaser(rep))->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() { @@ -742,6 +773,18 @@ 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::move(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) { @@ -853,6 +896,17 @@ 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::move(src))); + } +} + +template void Cord::Append(std::string&& src); + void Cord::Prepend(const Cord& src) { CordRep* src_tree = src.contents_.tree(); if (src_tree != nullptr) { @@ -882,6 +936,17 @@ 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::move(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); -- cgit v1.2.3