afa2420c2b
Summary: The current Env API encompasses both storage/file operations, as well as OS related operations. Most of the APIs return a Status, which does not have enough metadata about an error, such as whether its retry-able or not, scope (i.e fault domain) of the error etc., that may be required in order to properly handle a storage error. The file APIs also do not provide enough control over the IO SLA, such as timeout, prioritization, hinting about placement and redundancy etc. This PR separates out the file/storage APIs from Env into a new FileSystem class. The APIs are updated to return an IOStatus with metadata about the error, as well as to take an IOOptions structure as input in order to allow more control over the IO. The user can set both ```options.env``` and ```options.file_system``` to specify that RocksDB should use the former for OS related operations and the latter for storage operations. Internally, a ```CompositeEnvWrapper``` has been introduced that inherits from ```Env``` and redirects individual methods to either an ```Env``` implementation or the ```FileSystem``` as appropriate. When options are sanitized during ```DB::Open```, ```options.env``` is replaced with a newly allocated ```CompositeEnvWrapper``` instance if both env and file_system have been specified. This way, the rest of the RocksDB code can continue to function as before. This PR also ports PosixEnv to the new API by splitting it into two - PosixEnv and PosixFileSystem. PosixEnv is defined as a sub-class of CompositeEnvWrapper, and threading/time functions are overridden with Posix specific implementations in order to avoid an extra level of indirection. The ```CompositeEnvWrapper``` translates ```IOStatus``` return code to ```Status```, and sets the severity to ```kSoftError``` if the io_status is retryable. The error handling code in RocksDB can then recover the DB automatically. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5761 Differential Revision: D18868376 Pulled By: anand1976 fbshipit-source-id: 39efe18a162ea746fabac6360ff529baba48486f
124 lines
3.7 KiB
C++
124 lines
3.7 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#include "utilities/trace/file_trace_reader_writer.h"
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#include "env/composite_env_wrapper.h"
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#include "file/random_access_file_reader.h"
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#include "file/writable_file_writer.h"
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#include "trace_replay/trace_replay.h"
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#include "util/coding.h"
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namespace rocksdb {
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const unsigned int FileTraceReader::kBufferSize = 1024; // 1KB
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FileTraceReader::FileTraceReader(
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std::unique_ptr<RandomAccessFileReader>&& reader)
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: file_reader_(std::move(reader)),
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offset_(0),
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buffer_(new char[kBufferSize]) {}
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FileTraceReader::~FileTraceReader() {
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Close();
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delete[] buffer_;
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}
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Status FileTraceReader::Close() {
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file_reader_.reset();
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return Status::OK();
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}
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Status FileTraceReader::Read(std::string* data) {
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assert(file_reader_ != nullptr);
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Status s = file_reader_->Read(offset_, kTraceMetadataSize, &result_, buffer_);
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if (!s.ok()) {
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return s;
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}
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if (result_.size() == 0) {
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// No more data to read
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// Todo: Come up with a better way to indicate end of data. May be this
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// could be avoided once footer is introduced.
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return Status::Incomplete();
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}
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if (result_.size() < kTraceMetadataSize) {
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return Status::Corruption("Corrupted trace file.");
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}
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*data = result_.ToString();
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offset_ += kTraceMetadataSize;
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uint32_t payload_len =
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DecodeFixed32(&buffer_[kTraceTimestampSize + kTraceTypeSize]);
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// Read Payload
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unsigned int bytes_to_read = payload_len;
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unsigned int to_read =
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bytes_to_read > kBufferSize ? kBufferSize : bytes_to_read;
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while (to_read > 0) {
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s = file_reader_->Read(offset_, to_read, &result_, buffer_);
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if (!s.ok()) {
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return s;
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}
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if (result_.size() < to_read) {
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return Status::Corruption("Corrupted trace file.");
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}
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data->append(result_.data(), result_.size());
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offset_ += to_read;
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bytes_to_read -= to_read;
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to_read = bytes_to_read > kBufferSize ? kBufferSize : bytes_to_read;
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}
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return s;
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}
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FileTraceWriter::~FileTraceWriter() { Close(); }
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Status FileTraceWriter::Close() {
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file_writer_.reset();
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return Status::OK();
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}
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Status FileTraceWriter::Write(const Slice& data) {
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return file_writer_->Append(data);
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}
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uint64_t FileTraceWriter::GetFileSize() { return file_writer_->GetFileSize(); }
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Status NewFileTraceReader(Env* env, const EnvOptions& env_options,
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const std::string& trace_filename,
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std::unique_ptr<TraceReader>* trace_reader) {
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std::unique_ptr<RandomAccessFile> trace_file;
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Status s = env->NewRandomAccessFile(trace_filename, &trace_file, env_options);
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if (!s.ok()) {
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return s;
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}
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std::unique_ptr<RandomAccessFileReader> file_reader;
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file_reader.reset(new RandomAccessFileReader(
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NewLegacyRandomAccessFileWrapper(trace_file), trace_filename));
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trace_reader->reset(new FileTraceReader(std::move(file_reader)));
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return s;
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}
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Status NewFileTraceWriter(Env* env, const EnvOptions& env_options,
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const std::string& trace_filename,
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std::unique_ptr<TraceWriter>* trace_writer) {
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std::unique_ptr<WritableFile> trace_file;
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Status s = env->NewWritableFile(trace_filename, &trace_file, env_options);
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if (!s.ok()) {
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return s;
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}
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std::unique_ptr<WritableFileWriter> file_writer;
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file_writer.reset(new WritableFileWriter(
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NewLegacyWritableFileWrapper(std::move(trace_file)), trace_filename,
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env_options));
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trace_writer->reset(new FileTraceWriter(std::move(file_writer)));
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return s;
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}
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} // namespace rocksdb
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