sagas

package
v0.0.0-...-b22a335 Latest Latest
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 Go to latest Published: Apr 25, 2017 License: MIT Imports: 5 Imported by: 0

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Index

Constants

View Source 
const (
	TaskStarted flag = 1 << iota
	TaskCompleted
	CompTaskStarted
	CompTaskCompleted
)

Variables

This section is empty.

Functions

func FatalErr 

func FatalErr(err error) bool

Checks the error returned by updating saga state. Returns true if the error is a FatalErr. Returns false if the error is transient and a retry might succeed

func GenId 

func GenId() gopter.Gen

Generator for a valid SagaId or TaskId

func GenSagaState 

func GenSagaState() gopter.Gen

Generator for a Valid Saga State

func GenSagaStateAndTaskId 

func GenSagaStateAndTaskId() gopter.Gen

Generator for a SagaState and TaskId, returns a StateTaskPair SagaState is always valid. TaskId may or may not be part of the saga

func NewInternalLogError 

func NewInternalLogError(msg string) error

func NewInvalidRequestError 

func NewInvalidRequestError(msg string) error

func NewInvalidSagaMessageError 

func NewInvalidSagaMessageError(msg string) error

func NewInvalidSagaStateError 

func NewInvalidSagaStateError(msg string) error

Types

type InternalLogError 

type InternalLogError struct {
	// contains filtered or unexported fields
}

InternalLogError should be returned by the SagaLog when the request failed, but may succeed on retry this is equivalent to an HTTP 500

func (InternalLogError) Error 

func (e InternalLogError) Error() string

type InvalidRequestError 

type InvalidRequestError struct {
	// contains filtered or unexported fields
}

InvalidRequestError should be returned by the SagaLog when the request is invalid and the same request will fail on restart, equivalent to an HTTP 400

func (InvalidRequestError) Error 

func (e InvalidRequestError) Error() string

type InvalidSagaMessageError 

type InvalidSagaMessageError struct {
	// contains filtered or unexported fields
}

InvalidSagaMessageError signifies that the SagaMessage was not valid

func (InvalidSagaMessageError) Error 

func (e InvalidSagaMessageError) Error() string

type InvalidSagaStateError 

type InvalidSagaStateError struct {
	// contains filtered or unexported fields
}

InvalidSagaStateError signifies that an illegal SagaState would occur from the requested action.

func (InvalidSagaStateError) Error 

func (e InvalidSagaStateError) Error() string

type MockSagaLog 

type MockSagaLog struct {
	// contains filtered or unexported fields
}

Mock of SagaLog interface

func NewMockSagaLog 

func NewMockSagaLog(ctrl *gomock.Controller) *MockSagaLog

func (*MockSagaLog) EXPECT 

func (_m *MockSagaLog) EXPECT() *_MockSagaLogRecorder

func (*MockSagaLog) GetActiveSagas 

func (_m *MockSagaLog) GetActiveSagas() ([]string, error)

func (*MockSagaLog) GetMessages 

func (_m *MockSagaLog) GetMessages(sagaId string) ([]SagaMessage, error)

func (*MockSagaLog) LogMessage 

func (_m *MockSagaLog) LogMessage(message SagaMessage) error

func (*MockSagaLog) StartSaga 

func (_m *MockSagaLog) StartSaga(sagaId string, job []byte) error

type Saga 

type Saga struct {
	// contains filtered or unexported fields
}

Concurrent Object Representing a Saga, to allow for the concurrent execution of tasks Methods update the state of the saga.

func (*Saga) AbortSaga 

func (s *Saga) AbortSaga() error

Log an AbortSaga message. This indicates that the Saga has failed and all execution should be stopped and compensating transactions should be applied.

Returns an error if it fails

func (*Saga) EndCompensatingTask 

func (s *Saga) EndCompensatingTask(taskId string, results []byte) error

Log an End Compensating Task Message to the log when a Compensating Task has been successfully completed. Returns an error if it fails.

EndCompTask is idempotent with respect to sagaId & taskId. If the data passed changes the last written EndCompTask message will win

Returns an error if it fails

func (*Saga) EndSaga 

func (s *Saga) EndSaga() error

Log an End Saga Message to the log, returns updated SagaState Returns the resulting SagaState or an error if it fails

Once EndSaga is succesfully called, trying to log additional messages will result in a panic.

func (*Saga) EndTask 

func (s *Saga) EndTask(taskId string, results []byte) error

Log an EndTask Message to the log. Indicates that this task has been successfully completed. Returns an error if it fails.

EndTask is idempotent with respect to sagaId & taskId. If the data passed changes the last written EndTask message will win

Returns an error if it fails

func (*Saga) GetEndCompTaskData 

func (s *Saga) GetEndCompTaskData(taskId string) []byte

func (*Saga) GetEndTaskData 

func (s *Saga) GetEndTaskData(taskId string) []byte

func (*Saga) GetStartCompTaskData 

func (s *Saga) GetStartCompTaskData(taskId string) []byte

func (*Saga) GetStartTaskData 

func (s *Saga) GetStartTaskData(taskId string) []byte

func (*Saga) GetTaskIds 

func (s *Saga) GetTaskIds() []string

func (*Saga) IsCompTaskCompleted 

func (s *Saga) IsCompTaskCompleted(taskId string) bool

func (*Saga) IsCompTaskStarted 

func (s *Saga) IsCompTaskStarted(taskId string) bool

func (*Saga) IsSagaAborted 

func (s *Saga) IsSagaAborted() bool

func (*Saga) IsSagaCompleted 

func (s *Saga) IsSagaCompleted() bool

func (*Saga) IsTaskCompleted 

func (s *Saga) IsTaskCompleted(taskId string) bool

func (*Saga) IsTaskStarted 

func (s *Saga) IsTaskStarted(taskId string) bool

func (*Saga) Job 

func (s *Saga) Job() []byte

func (*Saga) SagaId 

func (s *Saga) SagaId() string

Getter Methods for Saga State to ensure concurrent access is safe.

func (*Saga) StartCompensatingTask 

func (s *Saga) StartCompensatingTask(taskId string, data []byte) error

Log a Start Compensating Task Message to the log. Should only be logged after a Saga has been avoided and in Rollback Recovery Mode. Should not be used in ForwardRecovery Mode returns an error if it fails

StartCompTask is idempotent with respect to sagaId & taskId. If the data passed changes the last written StartCompTask message will win

Returns an error if it fails

func (*Saga) StartTask 

func (s *Saga) StartTask(taskId string, data []byte) error

Log a StartTask Message to the log. Returns an error if it fails.

StartTask is idempotent with respect to sagaId & taskId. If the data passed changes the last written StartTask message will win

Returns an error if it fails

type SagaCoordinator 

type SagaCoordinator struct {
	// contains filtered or unexported fields
}

SagaCoordinator organizes a set of Sagas.

func MakeSagaCoordinator 

func MakeSagaCoordinator(log SagaLog) SagaCoordinator

Make a Saga which uses the specied SagaLog interface for durable storage

func (SagaCoordinator) GetActiveSagas 

func (s SagaCoordinator) GetActiveSagas() ([]string, error)

Should be called at SEC Startup Time. Returns a Slice of In Progress SagaIds

func (SagaCoordinator) MakeSaga 

func (s SagaCoordinator) MakeSaga(sagaId string, job []byte) (*Saga, error)

Make a Saga add it to the SagaCoordinator, if a Saga Already exists with the same id, it will overwrite the already existing one.

func (SagaCoordinator) RecoverSagaState 

func (sc SagaCoordinator) RecoverSagaState(sagaId string, recoveryType SagaRecoveryType) (*Saga, error)

Recovers SagaState by reading all logged messages from the log. Utilizes the specified recoveryType to determine if Saga needs to be Aborted or can proceed safely.

Returns the current SagaState

type SagaLog 

type SagaLog interface {

	//
	// Log a Start Saga Message message to the log.
	// Returns an error if it fails.
	//
	StartSaga(sagaId string, job []byte) error

	//
	// Update the State of the Saga by Logging a message.
	// Returns an error if it fails.
	//
	LogMessage(message SagaMessage) error

	//
	// Returns all of the messages logged so far for the
	// specified saga.
	//
	GetMessages(sagaId string) ([]SagaMessage, error)

	//
	// Returns a list of all in progress sagaIds.
	// This MUST include all not completed sagaIds.
	// It may also included completed sagas
	// Returns an error if it fails.
	//
	GetActiveSagas() ([]string, error)
}

SagaLog Interface, Implemented

type SagaMessage 

type SagaMessage struct {
	// contains filtered or unexported fields
}

Data Structure representation of a entry in the SagaLog. Different SagaMessageTypes utilize different fields. Factory Methods are supplied for creation of Saga Messages and should be used instead of directly creatinga sagaMessage struct

func MakeAbortSagaMessage 

func MakeAbortSagaMessage(sagaId string) SagaMessage

AbortSaga SagaMessageType

  • sagaId - id of the Saga

func MakeEndCompTaskMessage 

func MakeEndCompTaskMessage(sagaId string, taskId string, results []byte) SagaMessage

EndCompTask SagaMessageType

  • sagaId - id of the Saga
  • taskId - id of the completed compensating task. Should be the same as the original taskId
  • data - any results from compensating task completion

func MakeEndSagaMessage 

func MakeEndSagaMessage(sagaId string) SagaMessage

EndSaga SagaMessageType

  • sagaId - id of the Saga

func MakeEndTaskMessage 

func MakeEndTaskMessage(sagaId string, taskId string, results []byte) SagaMessage

EndTask SagaMessageType

  • sagaId - id of the Saga
  • taskId - id of the completed Task
  • data - any results from task completion

func MakeStartCompTaskMessage 

func MakeStartCompTaskMessage(sagaId string, taskId string, data []byte) SagaMessage

StartCompTask SagaMessageType

  • sagaId - id of the Saga
  • taskId - id of the started compensating task. Should be the same as the original taskId
  • data - data that is persisted to the log, useful for diagnostic information

func MakeStartSagaMessage 

func MakeStartSagaMessage(sagaId string, job []byte) SagaMessage

StartSaga SagaMessageType

  • sagaId - id of the Saga
  • data - data needed to execute the saga

func MakeStartTaskMessage 

func MakeStartTaskMessage(sagaId string, taskId string, data []byte) SagaMessage

StartTask SagaMessageType

  • sagaId - id of the Saga
  • taskId - id of the started Task
  • data - data that is persisted to the log, useful for diagnostic information

func (SagaMessage) GetData 

func (sm SagaMessage) GetData() []byte

func (SagaMessage) GetMessageType 

func (sm SagaMessage) GetMessageType() SagaMessageType

func (SagaMessage) GetSagaId 

func (sm SagaMessage) GetSagaId() string

func (SagaMessage) GetTaskId 

func (sm SagaMessage) GetTaskId() string

type SagaMessageType 

type SagaMessageType int
const (
	StartSaga SagaMessageType = iota
	EndSaga
	AbortSaga
	StartTask
	EndTask
	StartCompTask
	EndCompTask
)

func (SagaMessageType) String 

func (s SagaMessageType) String() string

type SagaRecoveryType 

type SagaRecoveryType int
const (
	RollbackRecovery SagaRecoveryType = iota
	ForwardRecovery
)

Saga Recovery Types define how to interpret SagaState in RecoveryMode.

ForwardRecovery: all tasks in the saga must be executed at least once. 

tasks MUST BE idempotent

RollbackRecovery: if Saga is Aborted or in unsafe state, compensating 

tasks for all started tasks need to be executed.
compensating tasks MUST BE idempotent.

type SagaState 

type SagaState struct {
	// contains filtered or unexported fields
}

Data Structure representation of the current state of the Saga.

func (*SagaState) String 

func (state *SagaState) String() string

Custom ToString function for SagaState

type StateTaskPair 

type StateTaskPair struct {
	// contains filtered or unexported fields
}

func (StateTaskPair) String 

func (p StateTaskPair) String() string

Source Files

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