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6e9fbeb27c
Summary: We want to keep Env a think layer for better portability. Less platform dependent codes should be moved out of Env. In this patch, I create a wrapper of file readers and writers, and put rate limiting, write buffering, as well as most perf context instrumentation and random kill out of Env. It will make it easier to maintain multiple Env in the future. Test Plan: Run all existing unit tests. Reviewers: anthony, kradhakrishnan, IslamAbdelRahman, yhchiang, igor Reviewed By: igor Subscribers: leveldb, dhruba Differential Revision: https://reviews.facebook.net/D42321
98 lines
3.8 KiB
C++
98 lines
3.8 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#pragma once
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#ifndef ROCKSDB_LITE
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#include "rocksdb/slice.h"
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#include "db/dbformat.h"
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namespace rocksdb {
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class WritableFile;
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struct ParsedInternalKey;
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// Helper class to write out a key to an output file
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// Actual data format of the key is documented in plain_table_factory.h
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class PlainTableKeyEncoder {
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public:
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explicit PlainTableKeyEncoder(EncodingType encoding_type,
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uint32_t user_key_len,
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const SliceTransform* prefix_extractor,
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size_t index_sparseness)
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: encoding_type_((prefix_extractor != nullptr) ? encoding_type : kPlain),
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fixed_user_key_len_(user_key_len),
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prefix_extractor_(prefix_extractor),
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index_sparseness_((index_sparseness > 1) ? index_sparseness : 1),
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key_count_for_prefix_(0) {}
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// key: the key to write out, in the format of internal key.
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// file: the output file to write out
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// offset: offset in the file. Needs to be updated after appending bytes
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// for the key
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// meta_bytes_buf: buffer for extra meta bytes
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// meta_bytes_buf_size: offset to append extra meta bytes. Will be updated
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// if meta_bytes_buf is updated.
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Status AppendKey(const Slice& key, WritableFileWriter* file, uint64_t* offset,
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char* meta_bytes_buf, size_t* meta_bytes_buf_size);
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// Return actual encoding type to be picked
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EncodingType GetEncodingType() { return encoding_type_; }
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private:
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EncodingType encoding_type_;
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uint32_t fixed_user_key_len_;
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const SliceTransform* prefix_extractor_;
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const size_t index_sparseness_;
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size_t key_count_for_prefix_;
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IterKey pre_prefix_;
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};
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// A helper class to decode keys from input buffer
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// Actual data format of the key is documented in plain_table_factory.h
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class PlainTableKeyDecoder {
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public:
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explicit PlainTableKeyDecoder(EncodingType encoding_type,
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uint32_t user_key_len,
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const SliceTransform* prefix_extractor)
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: encoding_type_(encoding_type),
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prefix_len_(0),
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fixed_user_key_len_(user_key_len),
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prefix_extractor_(prefix_extractor),
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in_prefix_(false) {}
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// Find the next key.
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// start: char array where the key starts.
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// limit: boundary of the char array
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// parsed_key: the output of the result key
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// internal_key: if not null, fill with the output of the result key in
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// un-parsed format
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// bytes_read: how many bytes read from start. Output
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// seekable: whether key can be read from this place. Used when building
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// indexes. Output.
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Status NextKey(const char* start, const char* limit,
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ParsedInternalKey* parsed_key, Slice* internal_key,
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size_t* bytes_read, bool* seekable = nullptr);
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EncodingType encoding_type_;
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uint32_t prefix_len_;
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uint32_t fixed_user_key_len_;
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Slice saved_user_key_;
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IterKey cur_key_;
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const SliceTransform* prefix_extractor_;
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bool in_prefix_;
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private:
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Status NextPlainEncodingKey(const char* start, const char* limit,
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ParsedInternalKey* parsed_key,
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Slice* internal_key, size_t* bytes_read,
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bool* seekable = nullptr);
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Status NextPrefixEncodingKey(const char* start, const char* limit,
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ParsedInternalKey* parsed_key,
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Slice* internal_key, size_t* bytes_read,
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bool* seekable = nullptr);
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};
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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