Export of internal Abseil changes
-- a3e58c1870a9626039f4d178d2d599319bd9f8a8 by Matt Kulukundis <kfm@google.com>: Allow MakeCordFromExternal to take a zero arg releaser. PiperOrigin-RevId: 298650274 -- 01897c4a9bb99f3dc329a794019498ad345ddebd by Samuel Benzaquen <sbenza@google.com>: Reduce library bloat for absl::Flag by moving the definition of base virtual functions to a .cc file. This removes the duplicate symbols in user translation units and has the side effect of moving the vtable definition too (re key function) PiperOrigin-RevId: 298617920 -- 190f0d3782c63aed01046886d7fbc1be5bca2de9 by Derek Mauro <dmauro@google.com>: Import GitHub #596: Unbreak stacktrace code for UWP apps PiperOrigin-RevId: 298600834 -- cd5cf6f8c87b35b85a9584e94da2a99057345b73 by Gennadiy Rozental <rogeeff@google.com>: Use union of heap allocated pointer, one word atomic and two word atomic to represent flags value. Any type T, which is trivially copy-able and with with sizeof(T) <= 8, will be stored in atomic int64_t. Any type T, which is trivially copy-able and with with 8 < sizeof(T) <= 16, will be stored in atomic AlignedTwoWords. We also introducing value storage type to distinguish these cases. PiperOrigin-RevId: 298497200 -- f8fe7bd53bfed601f002f521e34ab4bc083fc28b by Matthew Brown <matthewbr@google.com>: Ensure a deep copy and proper equality on absl::Status::ErasePayload PiperOrigin-RevId: 298482742 -- a5c9ccddf4b04f444e3f7e27dbc14faf1fcb5373 by Gennadiy Rozental <rogeeff@google.com>: Change ChunkIterator implementation to use fixed capacity collection of CordRep*. We can now assume that depth never exceeds 91. That makes comparison operator exception safe. I've tested that with this CL we do not observe an overhead of chunk_end. Compiler optimized this iterator completely. PiperOrigin-RevId: 298458472 -- 327ea5e8910bc388b03389c730763f9823abfce5 by Abseil Team <absl-team@google.com>: Minor cleanups in b-tree code: - Rename some variables: fix issues of different param names between definition/declaration, move away from `x` as a default meaningless variable name. - Make init_leaf/init_internal be non-static methods (they already take the node as the first parameter). - In internal_emplace/try_shrink, update root/rightmost the same way as in insert_unique/insert_multi. - Replace a TODO with a comment. PiperOrigin-RevId: 298432836 -- 8020ce9ec8558ee712d9733ae3d660ac1d3ffe1a by Abseil Team <absl-team@google.com>: Guard against unnecessary copy in case the buffer is empty. This is important in cases were the user is explicitly tuning their chunks to match PiecewiseChunkSize(). PiperOrigin-RevId: 298366044 -- 89324441d1c0c697c90ba7d8fc63639805fcaa9d by Abseil Team <absl-team@google.com>: Internal change PiperOrigin-RevId: 298219363 GitOrigin-RevId: a3e58c1870a9626039f4d178d2d599319bd9f8a8 Change-Id: I28dffc684b6fd0292b94807b88ec6664d5d0e183
This commit is contained in:
Abseil Team
Andy Soffer
parent
06f0e767d1
commit
b19ba96766
24 changed files with 842 additions and 501 deletions
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@ -41,13 +41,13 @@
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#include <iostream>
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#include <iterator>
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#include <string>
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#include <type_traits>
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#include "absl/base/internal/endian.h"
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#include "absl/base/internal/invoke.h"
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#include "absl/base/internal/per_thread_tls.h"
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#include "absl/base/macros.h"
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#include "absl/base/port.h"
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#include "absl/container/inlined_vector.h"
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#include "absl/functional/function_ref.h"
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#include "absl/meta/type_traits.h"
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#include "absl/strings/internal/cord_internal.h"
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@ -66,6 +66,73 @@ template <typename H>
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H HashFragmentedCord(H, const Cord&);
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}
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namespace cord_internal {
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// It's expensive to keep a tree perfectly balanced, so instead we keep trees
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// approximately balanced. A tree node N of depth D(N) that contains a string
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// of L(N) characters is considered balanced if L >= Fibonacci(D + 2).
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// The "+ 2" is used to ensure that every leaf node contains at least one
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// character. Here we presume that
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// Fibonacci(0) = 0
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// Fibonacci(1) = 1
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// Fibonacci(2) = 1
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// Fibonacci(3) = 2
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// ...
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//
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// Fibonacci numbers are convenient because it means when two balanced trees of
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// the same depth are made the children of a new node, the resulting tree is
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// guaranteed to also be balanced:
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//
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//
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// L(left) >= Fibonacci(D(left) + 2)
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// L(right) >= Fibonacci(D(right) + 2)
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//
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// L(left) + L(right) >= Fibonacci(D(left) + 2) + Fibonacci(D(right) + 2)
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// L(left) + L(right) == L(new_tree)
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//
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// L(new_tree) >= 2 * Fibonacci(D(child) + 2)
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// D(child) == D(new_tree) - 1
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//
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// L(new_tree) >= 2 * Fibonacci(D(new_tree) + 1)
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// 2 * Fibonacci(N) >= Fibonacci(N + 1)
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//
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// L(new_tree) >= Fibonacci(D(new_tree) + 2)
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//
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//
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// The 93rd Fibonacci number is the largest Fibonacci number that can be
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// represented in 64 bits, so the size of a balanced Cord of depth 92 is too big
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// for an unsigned 64 bit integer to hold. Therefore we can safely assume that
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// the maximum depth of a Cord is 91.
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constexpr size_t MaxCordDepth() { return 91; }
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// This class models fixed max size stack of CordRep pointers.
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// The elements are being pushed back and popped from the back.
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template <typename CordRepPtr, size_t N>
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class CordTreePath {
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public:
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CordTreePath() {}
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explicit CordTreePath(CordRepPtr root) { push_back(root); }
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bool empty() const { return size_ == 0; }
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size_t size() const { return size_; }
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void clear() { size_ = 0; }
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CordRepPtr back() { return data_[size_ - 1]; }
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void pop_back() {
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--size_;
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assert(size_ < N);
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}
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void push_back(CordRepPtr elem) { data_[size_++] = elem; }
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private:
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CordRepPtr data_[N];
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size_t size_ = 0;
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};
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using CordTreeMutablePath = CordTreePath<CordRep*, MaxCordDepth()>;
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} // namespace cord_internal
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// A Cord is a sequence of characters.
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class Cord {
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private:
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@ -114,7 +181,8 @@ class Cord {
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// finished with `data`. The data must remain live and unchanging until the
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// releaser is called. The requirements for the releaser are that it:
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// * is move constructible,
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// * supports `void operator()(absl::string_view) const`,
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// * supports `void operator()(absl::string_view) const` or
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// `void operator()() const`,
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// * does not have alignment requirement greater than what is guaranteed by
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// ::operator new. This is dictated by alignof(std::max_align_t) before
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// C++17 and __STDCPP_DEFAULT_NEW_ALIGNMENT__ if compiling with C++17 or
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@ -127,8 +195,8 @@ class Cord {
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// FillBlock(block);
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// return absl::MakeCordFromExternal(
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// block->ToStringView(),
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// [pool, block](absl::string_view /*ignored*/) {
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// pool->FreeBlock(block);
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// [pool, block](absl::string_view v) {
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// pool->FreeBlock(block, v);
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// });
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// }
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//
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@ -282,8 +350,7 @@ class Cord {
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absl::cord_internal::CordRep* current_leaf_ = nullptr;
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// The number of bytes left in the `Cord` over which we are iterating.
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size_t bytes_remaining_ = 0;
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absl::InlinedVector<absl::cord_internal::CordRep*, 4>
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stack_of_right_children_;
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absl::cord_internal::CordTreeMutablePath stack_of_right_children_;
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};
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// Returns an iterator to the first chunk of the `Cord`.
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@ -667,6 +734,21 @@ ExternalRepReleaserPair NewExternalWithUninitializedReleaser(
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absl::string_view data, ExternalReleaserInvoker invoker,
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size_t releaser_size);
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struct Rank1 {};
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struct Rank0 : Rank1 {};
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template <typename Releaser, typename = ::absl::base_internal::InvokeT<
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Releaser, absl::string_view>>
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void InvokeReleaser(Rank0, Releaser&& releaser, absl::string_view data) {
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::absl::base_internal::Invoke(std::forward<Releaser>(releaser), data);
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}
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template <typename Releaser,
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typename = ::absl::base_internal::InvokeT<Releaser>>
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void InvokeReleaser(Rank1, Releaser&& releaser, absl::string_view) {
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::absl::base_internal::Invoke(std::forward<Releaser>(releaser));
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}
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// Creates a new `CordRep` that owns `data` and `releaser` and returns a pointer
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// to it, or `nullptr` if `data` was empty.
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template <typename Releaser>
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@ -684,14 +766,14 @@ CordRep* NewExternalRep(absl::string_view data, Releaser&& releaser) {
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using ReleaserType = absl::decay_t<Releaser>;
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if (data.empty()) {
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// Never create empty external nodes.
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::absl::base_internal::Invoke(
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ReleaserType(std::forward<Releaser>(releaser)), data);
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InvokeReleaser(Rank0{}, ReleaserType(std::forward<Releaser>(releaser)),
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data);
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return nullptr;
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}
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auto releaser_invoker = [](void* type_erased_releaser, absl::string_view d) {
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auto* my_releaser = static_cast<ReleaserType*>(type_erased_releaser);
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::absl::base_internal::Invoke(std::move(*my_releaser), d);
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InvokeReleaser(Rank0{}, std::move(*my_releaser), d);
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my_releaser->~ReleaserType();
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return sizeof(Releaser);
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};
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