Squashed 'src/rocksdb/' content from commit 224932d

git-subtree-dir: src/rocksdb
git-subtree-split: 224932d4d0b561712107d747c662df181c39644d

table/plain_table_reader.h

@@ -0,0 +1,215 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#pragma once
+
+#ifndef ROCKSDB_LITE
+#include <unordered_map>
+#include <memory>
+#include <vector>
+#include <string>
+#include <stdint.h>
+
+#include "db/dbformat.h"
+#include "rocksdb/env.h"
+#include "rocksdb/iterator.h"
+#include "rocksdb/slice_transform.h"
+#include "rocksdb/table.h"
+#include "rocksdb/table_properties.h"
+#include "table/table_reader.h"
+#include "table/plain_table_factory.h"
+#include "table/plain_table_index.h"
+#include "util/arena.h"
+#include "util/dynamic_bloom.h"
+
+namespace rocksdb {
+
+class Block;
+struct BlockContents;
+class BlockHandle;
+class Footer;
+struct Options;
+class RandomAccessFile;
+struct ReadOptions;
+class TableCache;
+class TableReader;
+class InternalKeyComparator;
+class PlainTableKeyDecoder;
+
+using std::unique_ptr;
+using std::unordered_map;
+using std::vector;
+extern const uint32_t kPlainTableVariableLength;
+
+// Based on following output file format shown in plain_table_factory.h
+// When opening the output file, IndexedTableReader creates a hash table
+// from key prefixes to offset of the output file. IndexedTable will decide
+// whether it points to the data offset of the first key with the key prefix
+// or the offset of it. If there are too many keys share this prefix, it will
+// create a binary search-able index from the suffix to offset on disk.
+//
+// The implementation of IndexedTableReader requires output file is mmaped
+class PlainTableReader: public TableReader {
+ public:
+  static Status Open(const Options& options, const EnvOptions& soptions,
+                     const InternalKeyComparator& internal_comparator,
+                     unique_ptr<RandomAccessFile>&& file, uint64_t file_size,
+                     unique_ptr<TableReader>* table,
+                     const int bloom_bits_per_key, double hash_table_ratio,
+                     size_t index_sparseness, size_t huge_page_tlb_size,
+                     bool full_scan_mode);
+
+  Iterator* NewIterator(const ReadOptions&, Arena* arena = nullptr) override;
+
+  void Prepare(const Slice& target);
+
+  Status Get(const ReadOptions&, const Slice& key, void* arg,
+             bool (*result_handler)(void* arg, const ParsedInternalKey& k,
+                                    const Slice& v),
+             void (*mark_key_may_exist)(void*) = nullptr);
+
+  uint64_t ApproximateOffsetOf(const Slice& key);
+
+  uint32_t GetIndexSize() const { return index_.GetIndexSize(); }
+  void SetupForCompaction();
+
+  std::shared_ptr<const TableProperties> GetTableProperties() const {
+    return table_properties_;
+  }
+
+  virtual size_t ApproximateMemoryUsage() const override {
+    return arena_.MemoryAllocatedBytes();
+  }
+
+  PlainTableReader(const Options& options, unique_ptr<RandomAccessFile>&& file,
+                   const EnvOptions& storage_options,
+                   const InternalKeyComparator& internal_comparator,
+                   EncodingType encoding_type, uint64_t file_size,
+                   const TableProperties* table_properties);
+  virtual ~PlainTableReader();
+
+ protected:
+  // Check bloom filter to see whether it might contain this prefix.
+  // The hash of the prefix is given, since it can be reused for index lookup
+  // too.
+  virtual bool MatchBloom(uint32_t hash) const;
+
+  // PopulateIndex() builds index of keys. It must be called before any query
+  // to the table.
+  //
+  // props: the table properties object that need to be stored. Ownership of
+  //        the object will be passed.
+  //
+
+  Status PopulateIndex(TableProperties* props, int bloom_bits_per_key,
+                       double hash_table_ratio, size_t index_sparseness,
+                       size_t huge_page_tlb_size);
+
+  Status MmapDataFile();
+
+ private:
+  const InternalKeyComparator internal_comparator_;
+  EncodingType encoding_type_;
+  // represents plain table's current status.
+  Status status_;
+  Slice file_data_;
+
+  PlainTableIndex index_;
+  bool full_scan_mode_;
+
+  // data_start_offset_ and data_end_offset_ defines the range of the
+  // sst file that stores data.
+  const uint32_t data_start_offset_ = 0;
+  const uint32_t data_end_offset_;
+  const size_t user_key_len_;
+  const SliceTransform* prefix_extractor_;
+
+  static const size_t kNumInternalBytes = 8;
+
+  // Bloom filter is used to rule out non-existent key
+  bool enable_bloom_;
+  DynamicBloom bloom_;
+  Arena arena_;
+
+  const Options& options_;
+  unique_ptr<RandomAccessFile> file_;
+  uint32_t file_size_;
+  std::shared_ptr<const TableProperties> table_properties_;
+
+  bool IsFixedLength() const {
+    return user_key_len_ != kPlainTableVariableLength;
+  }
+
+  size_t GetFixedInternalKeyLength() const {
+    return user_key_len_ + kNumInternalBytes;
+  }
+
+  Slice GetPrefix(const Slice& target) const {
+    assert(target.size() >= 8);  // target is internal key
+    return GetPrefixFromUserKey(GetUserKey(target));
+  }
+
+  Slice GetPrefix(const ParsedInternalKey& target) const {
+    return GetPrefixFromUserKey(target.user_key);
+  }
+
+  Slice GetUserKey(const Slice& key) const {
+    return Slice(key.data(), key.size() - 8);
+  }
+
+  Slice GetPrefixFromUserKey(const Slice& user_key) const {
+    if (!IsTotalOrderMode()) {
+      return prefix_extractor_->Transform(user_key);
+    } else {
+      // Use empty slice as prefix if prefix_extractor is not set.
+      // In that case,
+      // it falls back to pure binary search and
+      // total iterator seek is supported.
+      return Slice();
+    }
+  }
+
+  friend class TableCache;
+  friend class PlainTableIterator;
+
+  // Internal helper function to generate an IndexRecordList object from all
+  // the rows, which contains index records as a list.
+  // If bloom_ is not null, all the keys' full-key hash will be added to the
+  // bloom filter.
+  Status PopulateIndexRecordList(PlainTableIndexBuilder* index_builder,
+                                 vector<uint32_t>* prefix_hashes);
+
+  // Internal helper function to allocate memory for bloom filter and fill it
+  void AllocateAndFillBloom(int bloom_bits_per_key, int num_prefixes,
+                            size_t huge_page_tlb_size,
+                            vector<uint32_t>* prefix_hashes);
+
+  void FillBloom(vector<uint32_t>* prefix_hashes);
+
+  // Read the key and value at `offset` to parameters for keys, the and
+  // `seekable`.
+  // On success, `offset` will be updated as the offset for the next key.
+  // `parsed_key` will be key in parsed format.
+  // if `internal_key` is not empty, it will be filled with key with slice
+  // format.
+  // if `seekable` is not null, it will return whether we can directly read
+  // data using this offset.
+  Status Next(PlainTableKeyDecoder* decoder, uint32_t* offset,
+              ParsedInternalKey* parsed_key, Slice* internal_key, Slice* value,
+              bool* seekable = nullptr) const;
+  // Get file offset for key target.
+  // return value prefix_matched is set to true if the offset is confirmed
+  // for a key with the same prefix as target.
+  Status GetOffset(const Slice& target, const Slice& prefix,
+                   uint32_t prefix_hash, bool& prefix_matched,
+                   uint32_t* offset) const;
+
+  bool IsTotalOrderMode() const { return (prefix_extractor_ == nullptr); }
+
+  // No copying allowed
+  explicit PlainTableReader(const TableReader&) = delete;
+  void operator=(const TableReader&) = delete;
+};
+}  // namespace rocksdb
+#endif  // ROCKSDB_LITE