Module tikv::storage

This module contains TiKV’s transaction layer. It lowers high-level, transactional commands to low-level (raw key-value) interactions with persistent storage.

This module is further split into layers: txn lowers transactional commands to key-value operations on an MVCC abstraction. mvcc is our MVCC implementation. kv is an abstraction layer over persistent storage.

Other responsibilities of this module are managing latches (see latch), deadlock and wait handling (see lock_manager), scheduling command execution (see txn::scheduler), and handling commands from the raw and versioned APIs (in the Storage struct).

For more information about TiKV’s transactions, see the sig-txn docs.

Some important types are:

• the Engine trait and related traits, which abstracts over underlying storage,
• the MvccTxn struct, which is the primary object in the MVCC implementation,
• the commands in the commands module, which are how each command is implemented,
• the Storage struct, which is the primary entry point for this module.

Related code:

• the kv module, which is the interface for TiKV’s APIs,
• the `lock_manager, which takes part in lock and deadlock management,
• gc_worker, which drives garbage collection of old values,
• the `txn_types crate, some important types for this module’s interface,
• the kvproto crate, which defines TiKV’s protobuf API and includes some documentation of the commands implemented here,
• the test_storage crate, integration tests for this module,
• the engine_traits crate, more detail of the engine abstraction.

Re-exports

pub use self::errors::get_error_kind_from_header;

pub use self::errors::get_tag_from_header;

pub use self::errors::Error;

pub use self::errors::ErrorHeaderKind;

pub use self::errors::ErrorInner;

pub use self::raw::TTLSnapshot;

pub use self::txn::ProcessResult;

Modules

config	Storage configuration.
errors	Types for storage related errors and associated helper methods.
kv
lock_manager
metrics	Prometheus metrics for storage functionality.
mvcc	Multi-version concurrency control functionality.
raw
read_pool	Distinct thread pools to handle read commands having different priority levels.
test_util
txn	Storage Transactions
types	Core data types.

Structs

CbContext
CfStatistics	Statistics collects the ops taken when fetching data.
Cursor
CursorBuilder	A handy utility to build a snapshot cursor according to various configurations.
FlowStatistics
LatchLock	Lock required for a command.
Latches	Latches which are used for concurrency control in the scheduler.
PerfStatisticsDelta	Store statistics we need. Data comes from RocksDB’s PerfContext. This statistics store delta values between two instant statistics.
PerfStatisticsInstant	Store statistics we need. Data comes from RocksDB’s PerfContext. This statistics store instant values.
PrewriteResult
RocksEngine	The RocksEngine is based on RocksDB.
SnapshotStore
Statistics
Storage	Storage implements transactional KV APIs and raw KV APIs on a given Engine. An Engine provides low level KV functionality. Engine has multiple implementations. When a TiKV server is running, a RaftKv will be the underlying Engine of Storage. The other two types of engines are for test purpose.
TestEngineBuilder	A builder to build a temporary RocksEngine.
TestStorageBuilder	A builder to build a temporary Storage<E>.

Enums

PessimisticLockRes
RawStore
ScanMode
SecondaryLocksStatus
StorageCallback
TxnStatus	Represents the status of a transaction.

Traits

Engine	Engine defines the common behaviour for a storage engine type.
FlowStatsReporter
Iterator
ResponseBatchConsumer
Scanner	Scanners allow retrieving items or batches from a scan result.
Snapshot	A Snapshot is a consistent view of the underlying engine at a given point in time.
Store

Functions

build_read_pool	Build respective thread pools to handle read commands of different priority levels.
build_read_pool_for_test	Build a thread pool that has default tick behavior for testing.
get_priority_tag
need_check_locks_in_replica_read
point_key_range
prepare_snap_ctx

Type Definitions

Callback
Result