mirror of
https://github.com/nestriness/cdc-file-transfer.git
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42f5ee9b44
Fixes an issue in UnzstdStream where the Read() method always tries to read new input data if no input data is available, instead of first trying to uncompress. Since zstd maintains internal buffers, uncompression might succeed even without reading more input, so this is faster. This bug can lead to pipeline stalls in cdc_rsync.
90 lines
2.6 KiB
C++
90 lines
2.6 KiB
C++
// 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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#include "cdc_rsync_server/unzstd_stream.h"
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#include "cdc_rsync/base/socket.h"
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#include "common/status.h"
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namespace cdc_ft {
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UnzstdStream::UnzstdStream(Socket* socket) : socket_(socket) {
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init_status_ =
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WrapStatus(Initialize(), "Failed to initialize stream decompressor");
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}
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UnzstdStream::~UnzstdStream() {
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if (dctx_) {
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ZSTD_freeDCtx(dctx_);
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dctx_ = nullptr;
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}
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}
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absl::Status UnzstdStream::Read(void* out_buffer, size_t out_size,
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size_t* bytes_read, bool* eof) {
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*bytes_read = 0;
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*eof = false;
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if (!init_status_.ok()) {
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return init_status_;
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}
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ZSTD_outBuffer output = {out_buffer, out_size, 0};
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while (output.pos < output.size && !*eof) {
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// Decompress.
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size_t ret = ZSTD_decompressStream(dctx_, &output, &input_);
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if (ZSTD_isError(ret)) {
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return MakeStatus("Failed to decompress data: %s",
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ZSTD_getErrorName(ret));
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}
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*eof = (ret == 0);
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if (*eof && input_.pos < input_.size) {
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return MakeStatus("EOF with %u bytes input data available",
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input_.size - input_.pos);
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}
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if (input_.pos == input_.size && output.pos < output.size && !*eof) {
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// Read more compressed input data.
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// Allow partial reads since the stream could end any time.
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size_t in_size;
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absl::Status status =
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socket_->Receive(in_buffer_.data(), in_buffer_.size(),
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/*allow_partial_read=*/true, &in_size);
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if (!status.ok()) {
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return WrapStatus(status, "socket_->ReceiveEx() failed");
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}
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input_.pos = 0;
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input_.size = in_size;
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}
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}
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// Output buffer is full or eof.
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*bytes_read = output.pos;
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return absl::OkStatus();
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}
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absl::Status UnzstdStream::Initialize() {
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dctx_ = ZSTD_createDCtx();
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if (!dctx_) {
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return MakeStatus("Decompression context creation failed");
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}
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in_buffer_.resize(ZSTD_DStreamInSize());
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input_ = {in_buffer_.data(), 0, 0};
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return absl::OkStatus();
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}
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} // namespace cdc_ft
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