| // Copyright (c) 2015 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef QUICHE_QUIC_CORE_QUIC_STREAM_SEQUENCER_BUFFER_H_ |
| #define QUICHE_QUIC_CORE_QUIC_STREAM_SEQUENCER_BUFFER_H_ |
| |
| // QuicStreamSequencerBuffer is a circular stream buffer with random write and |
| // in-sequence read. It consists of a vector of pointers pointing |
| // to memory blocks created as needed and an interval set recording received |
| // data. |
| // - Data are written in with offset indicating where it should be in the |
| // stream, and the buffer grown as needed (up to the maximum buffer capacity), |
| // without expensive copying (extra blocks are allocated). |
| // - Data can be read from the buffer if there is no gap before it, |
| // and the buffer shrinks as the data are consumed. |
| // - An upper limit on the number of blocks in the buffer provides an upper |
| // bound on memory use. |
| // |
| // This class is thread-unsafe. |
| // |
| // QuicStreamSequencerBuffer maintains a concept of the readable region, which |
| // contains all written data that has not been read. |
| // It promises stability of the underlying memory addresses in the readable |
| // region, so pointers into it can be maintained, and the offset of a pointer |
| // from the start of the read region can be calculated. |
| // |
| // Expected Use: |
| // QuicStreamSequencerBuffer buffer(2.5 * 8 * 1024); |
| // std::string source(1024, 'a'); |
| // absl::string_view string_piece(source.data(), source.size()); |
| // size_t written = 0; |
| // buffer.OnStreamData(800, string_piece, GetEpollClockNow(), &written); |
| // source = std::string{800, 'b'}; |
| // absl::string_view string_piece1(source.data(), 800); |
| // // Try to write to [1, 801), but should fail due to overlapping, |
| // // res should be QUIC_INVALID_STREAM_DATA |
| // auto res = buffer.OnStreamData(1, string_piece1, &written)); |
| // // write to [0, 800), res should be QUIC_NO_ERROR |
| // auto res = buffer.OnStreamData(0, string_piece1, GetEpollClockNow(), |
| // &written); |
| // |
| // // Read into a iovec array with total capacity of 120 bytes. |
| // char dest[120]; |
| // iovec iovecs[3]{iovec{dest, 40}, iovec{dest + 40, 40}, |
| // iovec{dest + 80, 40}}; |
| // size_t read = buffer.Readv(iovecs, 3); |
| // |
| // // Get single readable region. |
| // iovec iov; |
| // buffer.GetReadableRegion(iov); |
| // |
| // // Get readable regions from [256, 1024) and consume some of it. |
| // iovec iovs[2]; |
| // int iov_count = buffer.GetReadableRegions(iovs, 2); |
| // // Consume some bytes in iovs, returning number of bytes having been |
| // consumed. |
| // size_t consumed = consume_iovs(iovs, iov_count); |
| // buffer.MarkConsumed(consumed); |
| |
| #include <cstddef> |
| #include <functional> |
| #include <list> |
| #include <memory> |
| #include <string> |
| |
| #include "absl/strings/string_view.h" |
| #include "quic/core/quic_interval_set.h" |
| #include "quic/core/quic_packets.h" |
| #include "quic/core/quic_types.h" |
| #include "quic/platform/api/quic_export.h" |
| #include "quic/platform/api/quic_iovec.h" |
| |
| namespace quic { |
| |
| namespace test { |
| class QuicStreamSequencerBufferPeer; |
| } // namespace test |
| |
| class QUIC_EXPORT_PRIVATE QuicStreamSequencerBuffer { |
| public: |
| // Size of blocks used by this buffer. |
| // Choose 8K to make block large enough to hold multiple frames, each of |
| // which could be up to 1.5 KB. |
| static const size_t kBlockSizeBytes = 8 * 1024; // 8KB |
| |
| // The basic storage block used by this buffer. |
| struct QUIC_EXPORT_PRIVATE BufferBlock { |
| char buffer[kBlockSizeBytes]; |
| }; |
| |
| explicit QuicStreamSequencerBuffer(size_t max_capacity_bytes); |
| QuicStreamSequencerBuffer(const QuicStreamSequencerBuffer&) = delete; |
| QuicStreamSequencerBuffer(QuicStreamSequencerBuffer&&) = default; |
| QuicStreamSequencerBuffer& operator=(const QuicStreamSequencerBuffer&) = |
| delete; |
| QuicStreamSequencerBuffer& operator=(QuicStreamSequencerBuffer&&) = default; |
| ~QuicStreamSequencerBuffer(); |
| |
| // Free the space used to buffer data. |
| void Clear(); |
| |
| // Returns true if there is nothing to read in this buffer. |
| bool Empty() const; |
| |
| // Called to buffer new data received for this stream. If the data was |
| // successfully buffered, returns QUIC_NO_ERROR and stores the number of |
| // bytes buffered in |bytes_buffered|. Returns an error otherwise. |
| QuicErrorCode OnStreamData(QuicStreamOffset offset, |
| absl::string_view data, |
| size_t* bytes_buffered, |
| std::string* error_details); |
| |
| // Reads from this buffer into given iovec array, up to number of iov_len |
| // iovec objects and returns the number of bytes read. |
| QuicErrorCode Readv(const struct iovec* dest_iov, |
| size_t dest_count, |
| size_t* bytes_read, |
| std::string* error_details); |
| |
| // Returns the readable region of valid data in iovec format. The readable |
| // region is the buffer region where there is valid data not yet read by |
| // client. |
| // Returns the number of iovec entries in |iov| which were populated. |
| // If the region is empty, one iovec entry with 0 length |
| // is returned, and the function returns 0. If there are more readable |
| // regions than |iov_size|, the function only processes the first |
| // |iov_size| of them. |
| int GetReadableRegions(struct iovec* iov, int iov_len) const; |
| |
| // Fills in one iovec with data from the next readable region. |
| // Returns false if there is no readable region available. |
| bool GetReadableRegion(iovec* iov) const; |
| |
| // Returns true and sets |*iov| to point to a region starting at |offset|. |
| // Returns false if no data can be read at |offset|, which can be because data |
| // has not been received yet or it is already consumed. |
| // Does not consume data. |
| bool PeekRegion(QuicStreamOffset offset, iovec* iov) const; |
| |
| // Called after GetReadableRegions() to free up |bytes_consumed| space if |
| // these bytes are processed. |
| // Pre-requisite: bytes_consumed <= available bytes to read. |
| bool MarkConsumed(size_t bytes_consumed); |
| |
| // Deletes and records as consumed any buffered data and clear the buffer. |
| // (To be called only after sequencer's StopReading has been called.) |
| size_t FlushBufferedFrames(); |
| |
| // Free the memory of buffered data. |
| void ReleaseWholeBuffer(); |
| |
| // Whether there are bytes can be read out. |
| bool HasBytesToRead() const; |
| |
| // Count how many bytes have been consumed (read out of buffer). |
| QuicStreamOffset BytesConsumed() const; |
| |
| // Count how many bytes are in buffer at this moment. |
| size_t BytesBuffered() const; |
| |
| // Returns number of bytes available to be read out. |
| size_t ReadableBytes() const; |
| |
| private: |
| friend class test::QuicStreamSequencerBufferPeer; |
| |
| // Copies |data| to blocks_, sets |bytes_copy|. Returns true if the copy is |
| // successful. Otherwise, sets |error_details| and returns false. |
| bool CopyStreamData(QuicStreamOffset offset, |
| absl::string_view data, |
| size_t* bytes_copy, |
| std::string* error_details); |
| |
| // Dispose the given buffer block. |
| // After calling this method, blocks_[index] is set to nullptr |
| // in order to indicate that no memory set is allocated for that block. |
| // Returns true on success, false otherwise. |
| bool RetireBlock(size_t index); |
| |
| // Should only be called after the indexed block is read till the end of the |
| // block or missing data has been reached. |
| // If the block at |block_index| contains no buffered data, the block |
| // should be retired. |
| // Returns true on success, or false otherwise. |
| bool RetireBlockIfEmpty(size_t block_index); |
| |
| // Calculate the capacity of block at specified index. |
| // Return value should be either kBlockSizeBytes for non-trailing blocks and |
| // max_buffer_capacity % kBlockSizeBytes for trailing block. |
| size_t GetBlockCapacity(size_t index) const; |
| |
| // Does not check if offset is within reasonable range. |
| size_t GetBlockIndex(QuicStreamOffset offset) const; |
| |
| // Given an offset in the stream, return the offset from the beginning of the |
| // block which contains this data. |
| size_t GetInBlockOffset(QuicStreamOffset offset) const; |
| |
| // Get offset relative to index 0 in logical 1st block to start next read. |
| size_t ReadOffset() const; |
| |
| // Get the index of the logical 1st block to start next read. |
| size_t NextBlockToRead() const; |
| |
| // Returns offset of first missing byte. |
| QuicStreamOffset FirstMissingByte() const; |
| |
| // Returns offset of highest received byte + 1. |
| QuicStreamOffset NextExpectedByte() const; |
| |
| // Return all received frames as a string. |
| std::string ReceivedFramesDebugString() const; |
| |
| // Resize blocks_ if more blocks are needed to accomodate bytes before |
| // next_expected_byte. |
| void MaybeAddMoreBlocks(QuicStreamOffset next_expected_byte); |
| |
| // The maximum total capacity of this buffer in byte, as constructed. |
| size_t max_buffer_capacity_bytes_; |
| |
| // Number of blocks this buffer would have when it reaches full capacity, |
| // i.e., maximal number of blocks in blocks_. |
| size_t max_blocks_count_; |
| |
| // Number of blocks this buffer currently has. |
| size_t current_blocks_count_; |
| |
| // Number of bytes read out of buffer. |
| QuicStreamOffset total_bytes_read_; |
| |
| // An ordered, variable-length list of blocks, with the length limited |
| // such that the number of blocks never exceeds max_blocks_count_. |
| // Each list entry can hold up to kBlockSizeBytes bytes. |
| std::unique_ptr<BufferBlock*[]> blocks_; |
| |
| // Number of bytes in buffer. |
| size_t num_bytes_buffered_; |
| |
| // Currently received data. |
| QuicIntervalSet<QuicStreamOffset> bytes_received_; |
| |
| bool delay_allocation_until_new_data_ = GetQuicReloadableFlag( |
| quic_delay_sequencer_buffer_allocation_until_new_data); |
| }; |
| |
| } // namespace quic |
| |
| #endif // QUICHE_QUIC_CORE_QUIC_STREAM_SEQUENCER_BUFFER_H_ |