client

package
v0.8.0 Latest Latest
Warning

This package is not in the latest version of its module.

 Go to latest Published: Jun 30, 2023 License: Apache-2.0 Imports: 23 Imported by: 0

Documentation

Index

Constants

View Source 
const (
	// ClosedEvent txn closed event
	ClosedEvent = EventType(0)
)

Variables

This section is empty.

Functions

func RunTxnTests added in v0.8.0 

func RunTxnTests(fn func(TxnClient, rpc.TxnSender), opts ...TxnClientCreateOption)

RunTxnTests runs txn tests.

func SetupRuntimeTxnOptions added in v0.8.0 

func SetupRuntimeTxnOptions(
	rt runtime.Runtime,
	m txn.TxnMode,
	iso txn.TxnIsolation)

SetupRuntimeTxnOptions setup runtime based txn options

Types

type DebugableTxnOperator added in v0.6.0 

type DebugableTxnOperator interface {
	TxnOperator

	// Debug send debug request to DN, after use, SendResult needs to call the Release
	// method.
	Debug(ctx context.Context, ops []txn.TxnRequest) (*rpc.SendResult, error)
}

DebugableTxnOperator debugable txn operator

type EventType added in v0.8.0 

type EventType int

TxnEvent txn events

type EventableTxnOperator added in v0.8.0 

type EventableTxnOperator interface {
	TxnOperator

	// AppendEventCallback append callback. All append callbacks will be called sequentially
	// if event happend.
	AppendEventCallback(event EventType, callbacks ...func(txn.TxnMeta))
}

CallbackTxnOperator callback txn operator

type TimestampWaiter added in v0.8.0 

type TimestampWaiter interface {
	// GetTimestamp get the latest commit ts as snapshot ts of the new txn. It will keep
	// blocking if latest commit timestamp received from DN is less than the given value.
	GetTimestamp(context.Context, timestamp.Timestamp) (timestamp.Timestamp, error)
	// NotifyLatestCommitTS notify the latest timestamp that received from DN. A applied logtail
	// commit ts is corresponds to an epoch. Whenever the connection of logtail of cn and dn is
	// reset, the epoch will be reset and all the ts of the old epoch should be invalidated.
	NotifyLatestCommitTS(appliedTS timestamp.Timestamp)
	// Close close the timestamp waiter
	Close()
}

TimestampWaiter is used to wait for the timestamp to reach a specified timestamp. In the Push mode of LogTail's Event, the DN pushes the logtail to the subscribed CN once a transaction has been Committed. So there is a actual wait (last push commit ts >= start ts). This is unfriendly to TP, so we can lose some freshness and use the latest commit ts received from the current DN push as the start ts of the transaction, which eliminates this physical wait.

func NewTimestampWaiter added in v0.8.0 

func NewTimestampWaiter() TimestampWaiter

NewTimestampWaiter create timestamp waiter

type TxnClient 

type TxnClient interface {
	// Minimum Active Transaction Timestamp
	MinTimestamp() timestamp.Timestamp
	// New returns a TxnOperator to handle read and write operation for a
	// transaction.
	New(ctx context.Context, commitTS timestamp.Timestamp, options ...TxnOption) (TxnOperator, error)
	// NewWithSnapshot create a txn operator from a snapshot. The snapshot must
	// be from a CN coordinator txn operator.
	NewWithSnapshot(snapshot []byte) (TxnOperator, error)
	// AbortAllRunningTxn set all running txn to be aborted.
	AbortAllRunningTxn()
	// Close closes client.sender
	Close() error
	// WaitLogTailAppliedAt wait log tail applied at ts
	WaitLogTailAppliedAt(ctx context.Context, ts timestamp.Timestamp) (timestamp.Timestamp, error)
}

TxnClient transaction client, the operational entry point for transactions. Each CN node holds one instance of TxnClient.

func NewTxnClient 

func NewTxnClient(
	sender rpc.TxnSender,
	options ...TxnClientCreateOption) TxnClient

NewTxnClient create a txn client with TxnSender and Options

type TxnClientCreateOption 

type TxnClientCreateOption func(*txnClient)

TxnClientCreateOption options for create txn

func WithEnableCNBasedConsistency added in v0.8.0 

func WithEnableCNBasedConsistency() TxnClientCreateOption

WithEnableCNBasedConsistency let all transactions on a CN see writes committed by other transactions before them. When this feature is enabled, the client maintains a CN-Based commit timestamp, and when opening a new transaction, it adjusts the transaction's snapshot timestamp to at least >= lastCommitTimestamp, so that it can see the writes of the previously committed transaction

func WithEnableLeakCheck added in v0.8.0 

func WithEnableLeakCheck(
	maxActiveAges time.Duration,
	leakHandleFunc func(txnID []byte, createAt time.Time, createBy string)) TxnClientCreateOption

WithEnableLeakCheck enable txn leak check. Used to found any txn is not committed or rollbacked.

func WithEnableRefreshExpression added in v0.8.0 

func WithEnableRefreshExpression() TxnClientCreateOption

WithEnableRefreshExpression in RC mode, in the event of a conflict, the later transaction needs to see the latest data after the previous transaction commits. At this time we need to re-read the data, re-read the latest data, and re-compute the expression.

func WithEnableSacrificingFreshness added in v0.8.0 

func WithEnableSacrificingFreshness() TxnClientCreateOption

When making this optimization, there are some scenarios where data consistency must be guaranteed, such as a database connection in a session where the latter transaction must be able to read the data committed by the previous transaction, then it is necessary to maintain a Session-level transaction last commit time, and the start time of the next transaction cannot be less than this value.

If we need to ensure that all the transactions on a CN can read the writes of the previous committed transaction, then we can use WithEenableCNBasedConsistency to turn on.

func WithLockService added in v0.8.0 

func WithLockService(lockService lockservice.LockService) TxnClientCreateOption

WithLockService setup lock service

func WithTimestampWaiter added in v0.8.0 

func WithTimestampWaiter(waiter TimestampWaiter) TxnClientCreateOption

WithTimestampWaiter setup timestamp waiter to get the latest applied committed timestamp from logtail.

func WithTxnIDGenerator 

func WithTxnIDGenerator(generator TxnIDGenerator) TxnClientCreateOption

WithTxnIDGenerator setup txn id generator

type TxnClientWithCtl added in v0.8.0 

type TxnClientWithCtl interface {
	TxnClient

	// GetLatestCommitTS get latest commit timestamp
	GetLatestCommitTS() timestamp.Timestamp
	// SetLatestCommitTS set latest commit timestamp
	SetLatestCommitTS(timestamp.Timestamp)
}

TxnClientWithCtl TxnClient to support ctl command.

type TxnClientWithFeature added in v0.8.0 

type TxnClientWithFeature interface {
	TxnClient
	// Pause the txn client to prevent new txn from being created.
	Pause()
	// Resume the txn client to allow new txn to be created.
	Resume()
	// RefreshExpressionEnabled return true if refresh expression feature enabled
	RefreshExpressionEnabled() bool
	// CNBasedConsistencyEnabled return true if cn based consistency feature enabled
	CNBasedConsistencyEnabled() bool
}

TxnClientWithFeature is similar to TxnClient, except that some methods have been added to determine whether certain features are supported.

type TxnIDGenerator 

type TxnIDGenerator interface {
	// Generate returns a unique transaction id
	Generate() []byte
}

TxnIDGenerator txn id generator

type TxnOperator 

type TxnOperator interface {
	// Txn returns the current txn metadata
	Txn() txn.TxnMeta
	// TxnRef returns pointer of current txn metadata. In RC mode, txn's snapshot ts
	// will updated before statement executed.
	TxnRef() *txn.TxnMeta
	// Snapshot a snapshot of the transaction handle that can be passed around the
	// network. In some scenarios, operations of a transaction are executed on multiple
	// CN nodes for performance acceleration. But with only one CN coordinator, Snapshot
	// can be used to recover the transaction operation handle at a non-CN coordinator
	// node, or it can be used to pass information back to the transaction coordinator
	// after the non-CN coordinator completes the transaction operation.
	Snapshot() ([]byte, error)
	// UpdateSnapshot in some scenarios, we need to boost the snapshotTimestamp to eliminate
	// the w-w conflict.
	// If ts is empty, it will use the latest commit timestamp which is received from DN.
	UpdateSnapshot(ctx context.Context, ts timestamp.Timestamp) error
	// ApplySnapshot CN coordinator applies a snapshot of the non-coordinator's transaction
	// operation information.
	ApplySnapshot(data []byte) error
	// Read transaction read operation, the operator routes the message based
	// on the given DN node information and waits for the read data synchronously.
	// The transaction has been aborted if ErrTxnAborted returned.
	// After use, SendResult needs to call the Release method
	Read(ctx context.Context, ops []txn.TxnRequest) (*rpc.SendResult, error)
	// Write transaction write operation, and the operator will record the DN
	// nodes written by the current transaction, and when it finds that multiple
	// DN nodes are written, it will start distributed transaction processing.
	// The transaction has been aborted if ErrTxnAborted returned.
	// After use, SendResult needs to call the Release method
	Write(ctx context.Context, ops []txn.TxnRequest) (*rpc.SendResult, error)
	// WriteAndCommit is similar to Write, but commit the transaction after write.
	// After use, SendResult needs to call the Release method
	WriteAndCommit(ctx context.Context, ops []txn.TxnRequest) (*rpc.SendResult, error)
	// Commit the transaction. If data has been written to multiple DN nodes, a
	// 2pc distributed transaction commit process is used.
	Commit(ctx context.Context) error
	// Rollback the transaction.
	Rollback(ctx context.Context) error

	// AddLockTable for pessimistic transactions, if the current transaction is successfully
	// locked, the metadata corresponding to the lockservice needs to be recorded to the txn, and
	// at transaction commit time, the metadata of all lockservices accessed by the transaction
	// will be committed to dn to check. If the metadata of the lockservice changes in [lock, commit],
	// the transaction will be rolled back.
	AddLockTable(locktable lock.LockTable) error

	// AddWorkspace for the transaction
	AddWorkspace(workspace Workspace)
	// GetWorkspace from the transaction
	GetWorkspace() Workspace
}

TxnOperator operator for transaction clients, handling read and write requests for transactions, and handling distributed transactions across DN nodes. Note: For Error returned by Read/Write/WriteAndCommit/Commit/Rollback, need to check if it is a moerr.ErrDNShardNotFound error, if so, the DN information held is out of date and needs to be reloaded by HAKeeper.

type TxnOption 

type TxnOption func(*txnOperator)

TxnOption options for setup transaction FIXME(fagongzi): refactor TxnOption to avoid mem alloc

func WithSnapshotTS added in v0.7.0 

func WithSnapshotTS(ts timestamp.Timestamp) TxnOption

WithSnapshotTS use a spec snapshot timestamp to build TxnOperator.

func WithTxnCNCoordinator 

func WithTxnCNCoordinator() TxnOption

WithTxnCNCoordinator set cn txn coordinator

func WithTxnCacheWrite 

func WithTxnCacheWrite() TxnOption

WithTxnCacheWrite Set cache write requests, after each Write call, the request will not be sent to the DN node immediately, but stored in the Coordinator's memory, and the Coordinator will choose the right time to send the cached requests. The following scenarios trigger the sending of requests to DN:

  1. Before read, because the Coordinator is not aware of the format and content of the written data, it is necessary to send the cached write requests to the corresponding DN node each time Read is called, used to implement "read your write".
  2. Before commit, obviously, the cached write requests needs to be sent to the corresponding DN node before commit.

func WithTxnCreateBy added in v0.8.0 

func WithTxnCreateBy(createBy string) TxnOption

WithTxnCreateBy set txn create by.Used to check leak txn

func WithTxnDisable1PCOpt 

func WithTxnDisable1PCOpt() TxnOption

WithTxnDisable1PCOpt disable 1pc opt on distributed transaction. By default, mo enables 1pc optimization for distributed transactions. For write operations, if all partitions' prepares are executed successfully, then the transaction is considered committed and returned directly to the client. Partitions' prepared data are committed asynchronously.

func WithTxnIsolation added in v0.8.0 

func WithTxnIsolation(value txn.TxnIsolation) TxnOption

WithTxnIsolation set txn isolation

func WithTxnLockService added in v0.8.0 

func WithTxnLockService(lockService lockservice.LockService) TxnOption

WithTxnLockService set txn lock service

func WithTxnMode added in v0.8.0 

func WithTxnMode(value txn.TxnMode) TxnOption

WithTxnMode set txn mode

func WithTxnReadyOnly 

func WithTxnReadyOnly() TxnOption

WithTxnReadyOnly setup readonly flag

type Workspace added in v0.8.0 

type Workspace interface {
	// IncrStatementID incr the execute statement id. It maintains the statement id, first statement is 1,
	// second is 2, and so on. If in rc mode, snapshot will updated to latest applied commit ts from dn. And
	// workspace will update snapshot data for later read request.
	IncrStatementID(ctx context.Context, commit bool) error
	// RollbackLastStatement rollback the last statement.
	RollbackLastStatement(ctx context.Context) error

	Commit(ctx context.Context) error
	Rollback(ctx context.Context) error
}

Source Files

View all Source files

Jump to

Keyboard shortcuts

? : This menu
/ : Search site
f or F : Jump to
y or Y : Canonical URL
go.dev uses cookies from Google to deliver and enhance the quality of its services and to analyze traffic. Learn more.