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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stddef.h>
#include "base/memory/ref_counted.h"
#include "net/base/io_buffer.h"
namespace chromecast {
// Buffer pool to allocate ::net::IOBuffers of a constant size. When a buffer
// from this pool is destroyed, it is returned to the pool to be reused (rather
// than constantly reallocating memory). If the buffer is destroyed after the
// pool has been destroyed, the buffer's memory will be freed correctly.
class IOBufferPool : public base::RefCountedThreadSafe<IOBufferPool> {
// |buffer_size| is the usable size of each buffer that will be returned
// by GetBuffer(). |max_buffers| is the maximum number of buffers that this
// pool will allocate. If |threadsafe| is true then the pool and any buffers
// allocated from it may be used safely on any thread; otherwise all access
// to pool and buffers must be made on the creating sequence.
IOBufferPool(size_t buffer_size, size_t max_buffers, bool threadsafe = false);
// If |max_buffers| is not specified, the maximum value of size_t is used.
explicit IOBufferPool(size_t buffer_size);
IOBufferPool(const IOBufferPool&) = delete;
IOBufferPool& operator=(const IOBufferPool&) = delete;
size_t buffer_size() const { return buffer_size_; }
size_t max_buffers() const { return max_buffers_; }
bool threadsafe() const { return threadsafe_; }
// Ensures that at least |num_buffers| are allocated. If |num_buffers| is
// greater than |max_buffers|, makes sure that |max_buffers| buffers have been
// allocated.
void Preallocate(size_t num_buffers);
// Returns an IOBuffer from the pool, or |nullptr| if there are no buffers in
// the pool and |max buffers| has been reached. The pool does not keep any
// references to the buffer. It is safe to use the returned buffer after the
// pool has been destroyed; if the buffer is destroyed after the pool is
// destroyed, the buffer's memory will be freed correctly.
scoped_refptr<net::IOBuffer> GetBuffer();
// Returns the number of buffers that have ever been allocated by the pool.
size_t NumAllocatedForTesting() const;
// Returns the number of buffers that are currently free in the pool.
size_t NumFreeForTesting() const;
class Internal;
friend class base::RefCountedThreadSafe<IOBufferPool>;
const size_t buffer_size_;
const size_t max_buffers_;
const bool threadsafe_;
Internal* internal_; // Manages its own lifetime.
} // namespace chromecast