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https://github.com/nestriness/cdc-file-transfer.git
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4326e972ac
The tools allow efficient and fast synchronization of large directory trees from a Windows workstation to a Linux target machine. cdc_rsync* support efficient copy of files by using content-defined chunking (CDC) to identify chunks within files that can be reused. asset_stream_manager + cdc_fuse_fs support efficient streaming of a local directory to a remote virtual file system based on FUSE. It also employs CDC to identify and reuse unchanged data chunks.
88 lines
2.7 KiB
C++
88 lines
2.7 KiB
C++
/*
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* Copyright 2022 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef COMMON_BUFFER_H_
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#define COMMON_BUFFER_H_
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#include <cstdlib>
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#include <initializer_list>
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namespace cdc_ft {
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// Buffer for generic data blobs. It is a managed and dynamically sized memory
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// buffer with an interface similar to that of std::vector. It can be used as an
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// in-place replacement in some use cases like reading files.
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// The class solves a performance problem on Linux where resize() can be
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// relatively expensive since a vector default-constructs elements. This can
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// be a big performance bottleneck in some cases.
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class Buffer {
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public:
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Buffer();
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explicit Buffer(size_t size);
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Buffer(std::initializer_list<char> list);
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~Buffer();
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// Non-copyable, non-assignable for safety.
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Buffer(const Buffer& other) = delete;
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Buffer& operator=(const Buffer& other) = delete;
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Buffer(Buffer&& other) noexcept;
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Buffer& operator=(Buffer&& other) noexcept;
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bool operator==(const Buffer& other) const;
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bool operator!=(const Buffer& other) const;
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// Resizes the buffer. Only reallocates if the size increases. In that case,
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// allocates 1.5x more than required. If size shrinks, keeps the buffer.
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// Does not initialize the buffer.
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void resize(size_t new_size);
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// Makes sure the buffer capacity is at least the given number of bytes.
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void reserve(size_t capacity);
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// Returns the current size of the buffer.
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size_t size() const { return size_; }
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// Returns true if the size is zero.
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bool empty() const { return size_ == 0; }
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// Returns the currently allocated buffer size.
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size_t capacity() const { return capacity_; }
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// Resizes the buffer to 0.
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void clear() { size_ = 0; }
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// Returns the data pointer.
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char* data() { return data_; }
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// Returns the data pointer.
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const char* data() const { return data_; }
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// Appends |data| of size |data_size| to the end of the buffer. The behavior
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// is undefined if the provided memory range overlaps with the buffer's data.
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void append(const void* data, size_t data_size);
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private:
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char* data_ = nullptr;
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size_t size_ = 0;
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size_t capacity_ = 0;
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};
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} // namespace cdc_ft
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#endif // COMMON_BUFFER_H_
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