711465ccec
Summary: Added a couple functions to WriteBatchWithIndex to make it easier to query the value of a key including reading pending writes from a batch. (This is needed for transactions). I created write_batch_with_index_internal.h to use to store an internal-only helper function since there wasn't a good place in the existing class hierarchy to store this function (and it didn't seem right to stick this function inside WriteBatchInternal::Rep). Since I needed to access the WriteBatchEntryComparator, I moved some helper classes from write_batch_with_index.cc into write_batch_with_index_internal.h/.cc. WriteBatchIndexEntry, ReadableWriteBatch, and WriteBatchEntryComparator are all unchanged (just moved to a different file(s)). Test Plan: Added new unit tests. Reviewers: rven, yhchiang, sdong, igor Reviewed By: igor Subscribers: dhruba, leveldb Differential Revision: https://reviews.facebook.net/D38037
97 lines
3.7 KiB
C++
97 lines
3.7 KiB
C++
// Copyright (c) 2015, 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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#include <limits>
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#include <string>
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#include <unordered_map>
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#include "rocksdb/comparator.h"
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#include "rocksdb/iterator.h"
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#include "rocksdb/slice.h"
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#include "rocksdb/status.h"
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#include "rocksdb/utilities/write_batch_with_index.h"
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namespace rocksdb {
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class MergeContext;
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struct Options;
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// Key used by skip list, as the binary searchable index of WriteBatchWithIndex.
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struct WriteBatchIndexEntry {
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WriteBatchIndexEntry(size_t o, uint32_t c)
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: offset(o), column_family(c), search_key(nullptr) {}
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WriteBatchIndexEntry(const Slice* sk, uint32_t c)
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: offset(0), column_family(c), search_key(sk) {}
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// If this flag appears in the offset, it indicates a key that is smaller
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// than any other entry for the same column family
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static const size_t kFlagMin = std::numeric_limits<size_t>::max();
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size_t offset; // offset of an entry in write batch's string buffer.
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uint32_t column_family; // column family of the entry
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const Slice* search_key; // if not null, instead of reading keys from
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// write batch, use it to compare. This is used
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// for lookup key.
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};
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class ReadableWriteBatch : public WriteBatch {
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public:
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explicit ReadableWriteBatch(size_t reserved_bytes = 0)
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: WriteBatch(reserved_bytes) {}
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// Retrieve some information from a write entry in the write batch, given
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// the start offset of the write entry.
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Status GetEntryFromDataOffset(size_t data_offset, WriteType* type, Slice* Key,
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Slice* value, Slice* blob) const;
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};
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class WriteBatchEntryComparator {
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public:
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WriteBatchEntryComparator(const Comparator* _default_comparator,
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const ReadableWriteBatch* write_batch)
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: default_comparator_(_default_comparator), write_batch_(write_batch) {}
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// Compare a and b. Return a negative value if a is less than b, 0 if they
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// are equal, and a positive value if a is greater than b
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int operator()(const WriteBatchIndexEntry* entry1,
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const WriteBatchIndexEntry* entry2) const;
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int CompareKey(uint32_t column_family, const Slice& key1,
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const Slice& key2) const;
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void SetComparatorForCF(uint32_t column_family_id,
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const Comparator* comparator) {
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cf_comparator_map_[column_family_id] = comparator;
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}
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const Comparator* default_comparator() { return default_comparator_; }
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private:
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const Comparator* default_comparator_;
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std::unordered_map<uint32_t, const Comparator*> cf_comparator_map_;
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const ReadableWriteBatch* write_batch_;
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};
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class WriteBatchWithIndexInternal {
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public:
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enum Result { kFound, kDeleted, kNotFound, kMergeInProgress, kError };
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// If batch contains a value for key, store it in *value and return kFound.
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// If batch contains a deletion for key, return Deleted.
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// If batch contains Merge operations as the most recent entry for a key,
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// and the merge process does not stop (not reaching a value or delete),
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// prepend the current merge operands to *operands,
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// and return kMergeInProgress
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// If batch does not contain this key, return kNotFound
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// Else, return kError on error with error Status stored in *s.
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static WriteBatchWithIndexInternal::Result GetFromBatch(
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const DBOptions& options, WriteBatchWithIndex* batch,
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ColumnFamilyHandle* column_family, const Slice& key,
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MergeContext* merge_context, WriteBatchEntryComparator* cmp,
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std::string* value, Status* s);
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};
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} // namespace rocksdb
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