maurice/snix
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Export of internal Abseil changes

Browse source 
--
2e894f3c2fadc789abf9011222526d5da1e0433e by Gennadiy Rozental <rogeeff@google.com>:

Internal change

PiperOrigin-RevId: 267557172

--
535be36d401a556156223ecc1aabd73a271f0f05 by Abseil Team <absl-team@google.com>:

Internal change.

PiperOrigin-RevId: 267456795
GitOrigin-RevId: 2e894f3c2fadc789abf9011222526d5da1e0433e
Change-Id: I95d29cbde5cd8342ae71b77728baa61b7cf6d440
This commit is contained in:
Abseil Team 2019-09-06 02:25:12 -07:00 • committed by Gennadiy Rozental
parent 83c1d65c90
commit 325fd7b042
4 changed files with 23 additions and 30 deletions
Download patch file Download diff file Expand all files Collapse all files

20
absl/flags/internal/flag.h
View file

@ -16,12 +16,16 @@
#ifndef ABSL_FLAGS_INTERNAL_FLAG_H_
#define ABSL_FLAGS_INTERNAL_FLAG_H_
#include <cstring>
#include "absl/flags/internal/commandlineflag.h"
#include "absl/flags/internal/registry.h"
namespace absl {
namespace flags_internal {
constexpr int64_t AtomicInit() { return 0xababababababababll; }
// Signature for the mutation callback used by watched Flags
// The callback is noexcept.
// TODO(rogeeff): add noexcept after C++17 support is added.
@ -44,6 +48,7 @@ class Flag final : public flags_internal::CommandLineFlag {
initial_value_gen,
/*def=*/nullptr,
/*cur=*/nullptr),
atomic_(flags_internal::AtomicInit()),
callback_(nullptr) {}
T Get() const {
@ -76,8 +81,8 @@ class Flag final : public flags_internal::CommandLineFlag {
bool AtomicGet(T* v) const {
const int64_t r = atomic_.load(std::memory_order_acquire);
if (r != flags_internal::CommandLineFlag::kAtomicInit) {
memcpy(v, &r, sizeof(T));
if (r != flags_internal::AtomicInit()) {
std::memcpy(v, &r, sizeof(T));
return true;
}
@ -108,7 +113,18 @@ class Flag final : public flags_internal::CommandLineFlag {
delete locks_;
}
void StoreAtomic() override {
if (sizeof(T) <= sizeof(int64_t)) {
int64_t t = 0;
std::memcpy(&t, cur_, (std::min)(sizeof(T), sizeof(int64_t)));
atomic_.store(t, std::memory_order_release);
}
}
// Flag's data
// For some types, a copy of the current value is kept in an atomically
// accessible field.
std::atomic<int64_t> atomic_;
FlagCallback callback_; // Mutation callback
};