fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph
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103 lines
3.6 KiB
103 lines
3.6 KiB
// 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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#pragma once
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#ifndef ROCKSDB_LITE
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#include <string>
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#include <unordered_map>
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#include "db/dbformat.h"
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#include "db/read_callback.h"
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#include "rocksdb/db.h"
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#include "rocksdb/slice.h"
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#include "rocksdb/status.h"
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#include "rocksdb/types.h"
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namespace ROCKSDB_NAMESPACE {
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struct TransactionKeyMapInfo {
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// Earliest sequence number that is relevant to this transaction for this key
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SequenceNumber seq;
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uint32_t num_writes;
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uint32_t num_reads;
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bool exclusive;
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explicit TransactionKeyMapInfo(SequenceNumber seq_no)
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: seq(seq_no), num_writes(0), num_reads(0), exclusive(false) {}
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// Used in PopSavePoint to collapse two savepoints together.
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void Merge(const TransactionKeyMapInfo& info) {
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assert(seq <= info.seq);
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num_reads += info.num_reads;
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num_writes += info.num_writes;
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exclusive |= info.exclusive;
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}
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};
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using TransactionKeyMap =
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std::unordered_map<uint32_t,
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std::unordered_map<std::string, TransactionKeyMapInfo>>;
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class DBImpl;
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struct SuperVersion;
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class WriteBatchWithIndex;
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class TransactionUtil {
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public:
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// Verifies there have been no commits to this key in the db since this
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// sequence number.
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//
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// If cache_only is true, then this function will not attempt to read any
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// SST files. This will make it more likely this function will
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// return an error if it is unable to determine if there are any conflicts.
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//
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// See comment of CheckKey() for explanation of `snap_seq`, `snap_checker`
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// and `min_uncommitted`.
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//
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// Returns OK on success, BUSY if there is a conflicting write, or other error
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// status for any unexpected errors.
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static Status CheckKeyForConflicts(
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DBImpl* db_impl, ColumnFamilyHandle* column_family,
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const std::string& key, SequenceNumber snap_seq, bool cache_only,
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ReadCallback* snap_checker = nullptr,
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SequenceNumber min_uncommitted = kMaxSequenceNumber);
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// For each key,SequenceNumber pair in the TransactionKeyMap, this function
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// will verify there have been no writes to the key in the db since that
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// sequence number.
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//
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// Returns OK on success, BUSY if there is a conflicting write, or other error
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// status for any unexpected errors.
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//
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// REQUIRED: this function should only be called on the write thread or if the
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// mutex is held.
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static Status CheckKeysForConflicts(DBImpl* db_impl,
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const TransactionKeyMap& keys,
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bool cache_only);
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private:
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// If `snap_checker` == nullptr, writes are always commited in sequence number
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// order. All sequence number <= `snap_seq` will not conflict with any
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// write, and all keys > `snap_seq` of `key` will trigger conflict.
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// If `snap_checker` != nullptr, writes may not commit in sequence number
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// order. In this case `min_uncommitted` is a lower bound.
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// seq < `min_uncommitted`: no conflict
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// seq > `snap_seq`: applicable to conflict
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// `min_uncommitted` <= seq <= `snap_seq`: call `snap_checker` to determine.
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static Status CheckKey(DBImpl* db_impl, SuperVersion* sv,
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SequenceNumber earliest_seq, SequenceNumber snap_seq,
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const std::string& key, bool cache_only,
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ReadCallback* snap_checker = nullptr,
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SequenceNumber min_uncommitted = kMaxSequenceNumber);
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};
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} // namespace ROCKSDB_NAMESPACE
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#endif // ROCKSDB_LITE
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