Abseil Common Libraries (C++) (grcp 依赖) https://abseil.io/
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// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef ABSL_CONTAINER_INTERNAL_COUNTING_ALLOCATOR_H_
#define ABSL_CONTAINER_INTERNAL_COUNTING_ALLOCATOR_H_
#include <cassert>
#include <cstdint>
#include <memory>
namespace absl {
namespace container_internal {
// This is a stateful allocator, but the state lives outside of the
// allocator (in whatever test is using the allocator). This is odd
// but helps in tests where the allocator is propagated into nested
// containers - that chain of allocators uses the same state and is
// thus easier to query for aggregate allocation information.
template <typename T>
class CountingAllocator : public std::allocator<T> {
public:
using Alloc = std::allocator<T>;
using pointer = typename Alloc::pointer;
using size_type = typename Alloc::size_type;
CountingAllocator() : bytes_used_(nullptr) {}
explicit CountingAllocator(int64_t* b) : bytes_used_(b) {}
template <typename U>
CountingAllocator(const CountingAllocator<U>& x)
: Alloc(x), bytes_used_(x.bytes_used_) {}
pointer allocate(size_type n,
std::allocator<void>::const_pointer hint = nullptr) {
assert(bytes_used_ != nullptr);
*bytes_used_ += n * sizeof(T);
return Alloc::allocate(n, hint);
}
void deallocate(pointer p, size_type n) {
Alloc::deallocate(p, n);
assert(bytes_used_ != nullptr);
*bytes_used_ -= n * sizeof(T);
}
template<typename U>
class rebind {
public:
using other = CountingAllocator<U>;
};
friend bool operator==(const CountingAllocator& a,
const CountingAllocator& b) {
return a.bytes_used_ == b.bytes_used_;
}
friend bool operator!=(const CountingAllocator& a,
const CountingAllocator& b) {
return !(a == b);
}
int64_t* bytes_used_;
};
} // namespace container_internal
} // namespace absl
#endif // ABSL_CONTAINER_INTERNAL_COUNTING_ALLOCATOR_H_