machine

package
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 Go to latest Published: Jun 2, 2024 License: MIT Imports: 15 Imported by: 8

Documentation

Overview

Package machine is a dependency-free implementation of AsyncMachine in Golang using channels and context. It aims at simplicity and speed.

It can be used as a lightweight in-memory Temporal 1 alternative, worker for Asynq 2, or to write simple consensus engines, stateful firewalls, telemetry, bots, etc.

asyncmachine-go is a general purpose state machine for managing complex async workflows in a safe and structured way.

Index

Examples

Constants

View Source 
const (
	// EventTransitionEnd transition ended
	EventTransitionEnd = "transition-end"
	// EventTransitionInit transition being initialized
	EventTransitionInit = "transition-init"
	// EventTransitionStart transition started
	EventTransitionStart = "transition-start"
	// EventTransitionCancel transition canceled
	EventTransitionCancel = "transition-cancel"
	// EventQueueEnd queue fully drained
	EventQueueEnd = "queue-end"
	// EventQueueAdd new mutation queued
	EventQueueAdd = "queue-add"
	// EventStructChange machine's states structure have changed
	EventStructChange = "struct-change"
	// EventTick active states changed, at least one state clock increased
	EventTick = "tick"
	// EventException Exception state becomes active
	EventException = "exception"
)
View Source 
const Exception = "Exception"

Exception is the Exception state name

Variables

View Source 
var (
	// ErrStateUnknown indicates that the state is unknown.
	ErrStateUnknown = errors.New("state unknown")
	// ErrCanceled can be used to indicate a canceled Transition. Not used ATM.
	ErrCanceled = errors.New("transition canceled")
	// ErrQueued can be used to indicate a queued Transition. Not used ATM.
	ErrQueued = errors.New("transition queued")
	// ErrInvalidArgs can be used to indicate invalid arguments. Not used ATM.
	ErrInvalidArgs = errors.New("invalid arguments")
	// ErrTimeout can be used to indicate timed out mutation. Not used ATM.
	ErrTimeout = errors.New("timeout")
)

Functions

func IsActiveTick added in v0.5.0 

func IsActiveTick(tick uint64) bool

IsActiveTick returns true if the tick represents an active state (odd number).

func IsTimeAfter 

func IsTimeAfter(time1, time2 T) bool

IsTimeAfter checks if time1 is after time2. Requires a deterministic states order, e.g. by using Machine.VerifyStates.

func NewArgsMapper added in v0.5.0 

func NewArgsMapper(names []string, maxlen int) func(args A) map[string]string

NewArgsMapper returns a matcher function for LogArgs. Useful for debugging untyped argument maps.

maxlen: maximum length of the string representation of the argument (default=20).

func NormalizeID added in v0.5.0 

func NormalizeID(id string) string

Types

type A 

type A map[string]any

A (arguments) is a map of named arguments for a Mutation.

type Clocks added in v0.3.0 

type Clocks map[string]uint64

Clocks is a map of state names to their clocks.

type DefaultRelationsResolver 

type DefaultRelationsResolver struct {
	Machine    *Machine
	Transition *Transition
}

DefaultRelationsResolver is the default implementation of the RelationsResolver with Add, Remove, Require and After. It can be overridden using Opts.Resolver.

func (*DefaultRelationsResolver) GetAutoMutation 

func (rr *DefaultRelationsResolver) GetAutoMutation() *Mutation

GetAutoMutation implements RelationsResolver.GetAutoMutation.

func (*DefaultRelationsResolver) GetRelationsBetween added in v0.5.0 

func (rr *DefaultRelationsResolver) GetRelationsBetween(
	fromState, toState string,
) ([]Relation, error)

GetRelationsBetween returns a list of relation types between the given states. Not thread safe.

func (*DefaultRelationsResolver) GetRelationsOf added in v0.5.0 

func (rr *DefaultRelationsResolver) GetRelationsOf(fromState string) (
	[]Relation, error,
)

GetRelationsOf returns a list of relation types of the given state. Not thread safe.

func (*DefaultRelationsResolver) GetTargetStates 

func (rr *DefaultRelationsResolver) GetTargetStates(
	t *Transition, calledStates S,
) S

GetTargetStates implements RelationsResolver.GetTargetStates.

func (*DefaultRelationsResolver) SortStates 

func (rr *DefaultRelationsResolver) SortStates(states S)

SortStates implements RelationsResolver.SortStates.

type Event 

type Event struct {
	// Name of the event / handler
	Name string
	// Machine is the machine that the event belongs to, it can be used to access
	// the current Transition and Mutation.
	Machine *Machine
	// Args is a map of named arguments for a Mutation.
	Args A
	// contains filtered or unexported fields
}

Event struct represents a single event of a Mutation withing a Transition. One event can have 0-n handlers.

func (*Event) Mutation added in v0.5.0 

func (e *Event) Mutation() *Mutation

Mutation returns the Mutation of an Event.

func (*Event) Transition added in v0.5.0 

func (e *Event) Transition() *Transition

Transition returns the Transition of an Event.

type ExceptionArgsPanic 

type ExceptionArgsPanic struct {
	CalledStates S
	StatesBefore S
	Transition   *Transition
	LastStep     *Step
	StackTrace   []byte
}

ExceptionArgsPanic is an optional argument ["panic"] for the Exception state which describes a panic within a Transition handler.

type ExceptionHandler 

type ExceptionHandler struct{}

ExceptionHandler provide a basic Exception state support, as should be embedded into handler structs in most of the cases.

func (*ExceptionHandler) ExceptionState 

func (eh *ExceptionHandler) ExceptionState(e *Event)

ExceptionState is a final entry handler for the Exception state. Args: - err error: The error that caused the Exception state. - panic *ExceptionArgsPanic: Optional details about the panic.

type LogLevel 

type LogLevel int

LogLevel enum 

const (
	// LogNothing means no logging, including external msgs.
	LogNothing LogLevel = iota
	// LogChanges means logging state changes and external msgs.
	LogChanges
	// LogOps means LogChanges + logging all the operations.
	LogOps
	// LogDecisions means LogOps + logging all the decisions behind them.
	LogDecisions
	// LogEverything means LogDecisions + all event and emitter names, and more.
	LogEverything
)

func (LogLevel) String added in v0.3.0 

func (l LogLevel) String() string

type Logger 

type Logger func(level LogLevel, msg string, args ...any)

Logger is a logging function for the machine.

type Machine 

type Machine struct {
	// Unique ID of this machine. Default: random ID.
	ID string
	// Time for a handler to execute. Default: time.Second
	HandlerTimeout time.Duration
	// If true, the machine will print all exceptions to stdout. Default: true.
	// Requires an ExceptionHandler binding and Machine.PanicToException set.
	PrintExceptions bool
	// If true, the machine will catch panic and trigger the Exception state.
	// Default: true.
	PanicToException bool
	// If true, logs will start with machine's ID (5 chars).
	// Default: true.
	LogID bool
	// Relations resolver, used to produce target states of a transition.
	// Default: *DefaultRelationsResolver. Read-only.
	Resolver RelationsResolver
	// Ctx is the context of the machine. Read-only.
	Ctx context.Context
	// Err is the last error that occurred. Read-only.
	Err error
	// Maximum number of mutations that can be queued. Default: 1000.
	QueueLimit int
	// Currently executing transition (if any). Read-only.
	Transition *Transition
	// List of all the registered state names. Read-only.
	StateNames S
	// Confirms the states have been ordered using VerifyStates. Read-only.
	StatesVerified bool
	// Tracers are optional tracers for telemetry integrations.
	Tracers []Tracer
	// If true, the machine has been Disposed and is no-op. Read-only.
	Disposed bool
	// Channel closing when the machine finished disposal. Read-only.
	WhenDisposed chan struct{}
	// ParentID is the ID of the parent machine (if any).
	ParentID string
	// Tags are optional tags for telemetry integrations etc.
	Tags []string
	// contains filtered or unexported fields
}

Machine represent states, provides mutation methods, helpers methods and info about the current and scheduled transitions (if any).

func New 

func New(ctx context.Context, statesStruct Struct, opts *Opts) *Machine

New creates a new Machine instance, bound to context and modified with optional Opts.

Example

TODO ExampleNew 

t := &testing.T{} // Replace this with actual *testing.T in real test cases
initialState := S{"A"}

mach := NewNoRels(t, initialState)

// Use the machine m here
_ = mach

Output:

func NewCommon added in v0.5.0 

func NewCommon(
	ctx context.Context, id string, statesStruct Struct, stateNames S,
	handlers any, parent *Machine, opts *Opts,
) (*Machine, error)

NewCommon creates a new Machine instance with all the common options set.

Example

TODO ExampleNewCommon 

t := &testing.T{} // Replace this with actual *testing.T in real test cases
initialState := S{"A"}

mach := NewNoRels(t, initialState)

// Use the machine m here
_ = mach

Output:

func (*Machine) ActiveStates 

func (m *Machine) ActiveStates() S

ActiveStates returns a copy of the currently active states.

func (*Machine) Add 

func (m *Machine) Add(states S, args A) Result

Add activates a list of states in the machine, returning the result of the transition (Executed, Queued, Canceled). Like every mutation method, it will resolve relations and trigger handlers.

func (*Machine) Add1 added in v0.5.0 

func (m *Machine) Add1(state string, args A) Result

Add1 is a shorthand method to add a single state with the passed args.

func (*Machine) AddErr 

func (m *Machine) AddErr(err error) Result

AddErr is a shorthand method to add the Exception state with the passed error. Like every mutation method, it will resolve relations and trigger handlers.

func (*Machine) AddErrStr 

func (m *Machine) AddErrStr(err string) Result

AddErrStr is a shorthand method to add the Exception state with the passed error string. Like every mutation method, it will resolve relations and trigger handlers.

func (*Machine) AddFromEv added in v0.5.0 

func (m *Machine) AddFromEv(states S, event *Event, args A) Result

AddFromEv TODO AddFromEv Planned.

func (*Machine) Any 

func (m *Machine) Any(states ...S) bool

Any is group call to Is, returns true if any of the params return true from Is. 

machine.StringAll() // ()[Foo:0 Bar:0 Baz:0]
machine.Add(S{"Foo"})
// is(Foo, Bar) or is(Bar)
machine.Any(S{"Foo", "Bar"}, S{"Bar"}) // false
// is(Foo) or is(Bar)
machine.Any(S{"Foo"}, S{"Bar"}) // true

func (*Machine) Any1 added in v0.5.0 

func (m *Machine) Any1(states ...string) bool

Any1 is group call to Is1(), returns true if any of the params return true from Is1().

func (*Machine) BindHandlers 

func (m *Machine) BindHandlers(handlers any) error

BindHandlers binds a struct of handler methods to the machine's states. Returns a HandlerBinding object, which signals when the binding is ready. TODO verify method signatures early TODO detect handlers for unknown states

func (*Machine) CanAdd added in v0.5.0 

func (m *Machine) CanAdd(states S) bool

CanAdd TODO CanAdd Planned.

func (*Machine) CanRemove added in v0.5.0 

func (m *Machine) CanRemove(states S) bool

CanRemove TODO CanRemove Planned.

func (*Machine) CanSet added in v0.5.0 

func (m *Machine) CanSet(states S) bool

CanSet TODO CanSet Planned.

func (*Machine) Clock 

func (m *Machine) Clock(state string) uint64

Clock return the current tick for a state.

func (*Machine) Clocks added in v0.5.0 

func (m *Machine) Clocks(states S) Clocks

Clocks returns the map of specified cloks or all clocks if states is nil.

func (*Machine) Dispose 

func (m *Machine) Dispose()

Dispose disposes the machine and all its emitters. You can wait for the completion of the disposal with `<-mach.WhenDisposed`.

func (*Machine) DisposeForce added in v0.5.0 

func (m *Machine) DisposeForce()

DisposeForce disposes the machine and all its emitters, without waiting for the queue to drain. Will cause panics.

func (*Machine) DuringTransition 

func (m *Machine) DuringTransition() bool

DuringTransition checks if the machine is currently during a transition.

func (*Machine) Eval added in v0.5.0 

func (m *Machine) Eval(ctx context.Context, fn func(), source string) bool

Eval executes a function on the machine's queue, allowing to avoid using locks for non-handler code. Blocking code should NOT be scheduled here. Eval cannot be called within a handler's critical section, as both are using the same serial queue and will deadlock. Eval has a timeout of HandlerTimeout/2 and will return false in case it happens.

ctx: nil context defaults to machine's context.

Note: usage of Eval is discouraged.

func (*Machine) GetLogArgs added in v0.5.0 

func (m *Machine) GetLogArgs() func(args A) map[string]string

GetLogArgs returns the current log args function.

func (*Machine) GetLogLevel added in v0.3.0 

func (m *Machine) GetLogLevel() LogLevel

GetLogLevel returns the log level of the machine.

func (*Machine) GetLogger added in v0.3.0 

func (m *Machine) GetLogger() Logger

GetLogger returns the current custom logger function, or nil.

func (*Machine) GetStruct added in v0.5.0 

func (m *Machine) GetStruct() Struct

GetStruct returns a copy of machine's state structure.

func (*Machine) Has 

func (m *Machine) Has(states S) bool

Has return true is passed states are registered in the machine. TODO test

func (*Machine) Has1 added in v0.5.0 

func (m *Machine) Has1(state string) bool

Has1 is a shorthand for Has. It returns true if the passed state is registered in the machine.

func (*Machine) HasStateChanged 

func (m *Machine) HasStateChanged(before S) bool

HasStateChanged checks current active states have changed from the passed ones.

func (*Machine) HasStateChangedSince added in v0.5.0 

func (m *Machine) HasStateChangedSince(clocks Clocks) bool

HasStateChangedSince checks if the machine has changed since the passed clocks. Returns true if at least one state has changed.

func (*Machine) Inspect 

func (m *Machine) Inspect(states S) string

Inspect returns a multi-line string representation of the machine (states, relations, clocks). states: param for ordered or partial results.

func (*Machine) Is 

func (m *Machine) Is(states S) bool

Is checks if all the passed states are currently active. 

machine.StringAll() // ()[Foo:0 Bar:0 Baz:0]
machine.Add(S{"Foo"})
machine.Is(S{"Foo"}) // true
machine.Is(S{"Foo", "Bar"}) // false

func (*Machine) Is1 added in v0.5.0 

func (m *Machine) Is1(state string) bool

Is1 is a shorthand method to check if a single state is currently active. See Is().

func (*Machine) IsClock 

func (m *Machine) IsClock(state string, tick uint64) bool

IsClock checks if the passed state's clock equals the passed tick. 

tick := m.Clock("A")
m.Remove("A")
m.Add("A")
m.Is("A", tick) // -> false

func (*Machine) IsErr 

func (m *Machine) IsErr() bool

IsErr checks if the machine has the Exception state currently active.

func (*Machine) IsQueued 

func (m *Machine) IsQueued(mutationType MutationType, states S,
	withoutArgsOnly bool, statesStrictEqual bool, startIndex int,
) int

IsQueued checks if a particular mutation has been queued. Returns an index of the match or -1 if not found.

mutationType: add, remove, set

states: list of states used in the mutation

withoutParamsOnly: matches only mutation without the arguments object

statesStrictEqual: states of the mutation have to be exactly like `states` and not a superset. TODO test

func (*Machine) Log 

func (m *Machine) Log(msg string, args ...any)

Log logs an [extern] message unless LogNothing is set (default). Optionally redirects to a custom logger from SetLogger.

func (*Machine) MustParseStates 

func (m *Machine) MustParseStates(states S) S

MustParseStates parses the states and returns them as a list. Panics when a state is not defined. It's an usafe equivalent of VerifyStates.

func (*Machine) NewStateCtx added in v0.5.0 

func (m *Machine) NewStateCtx(state string) context.Context

NewStateCtx returns a new sub-context, bound to the current clock's tick of the passed state.

Context cancels when the state has been de-activated, or right away, if it isn't currently active.

State contexts are used to check state expirations and should be checked often inside goroutines. TODO reuse existing ctxs

func (*Machine) Not 

func (m *Machine) Not(states S) bool

Not checks if **none** of the passed states are currently active. 

machine.StringAll()
// -> ()[A:0 B:0 C:0 D:0]
machine.Add(S{"A", "B"})

// not(A) and not(C)
machine.Not(S{"A", "C"})
// -> false

// not(C) and not(D)
machine.Not(S{"C", "D"})
// -> true

func (*Machine) Not1 added in v0.5.0 

func (m *Machine) Not1(state string) bool

Not1 is a shorthand method to check if a single state is currently inactive. See Not().

func (*Machine) OnEvent added in v0.5.0 

func (m *Machine) OnEvent(events []string, ctx context.Context) chan *Event

OnEvent returns a channel that will be notified with *Event, when any of the passed events happen. It's a quick substitute for predefined transition handlers, although it does not support negotiation.

ctx: optional context to dispose the emitter early.

It's not supported to nest OnEvent() calls, as it would cause a deadlock. Using OnEvent is recommended only in special cases, like test assertions.

func (*Machine) Queue 

func (m *Machine) Queue() []*Mutation

Queue returns a copy of the currently active states.

func (*Machine) RegisterDisposalHandler added in v0.5.0 

func (m *Machine) RegisterDisposalHandler(fn func())

RegisterDisposalHandler adds a function to be called when the machine is disposed. This function will block before mach.WhenDispose is closed.

func (*Machine) Remove 

func (m *Machine) Remove(states S, args A) Result

Remove de-activates a list of states in the machine, returning the result of the transition (Executed, Queued, Canceled). Like every mutation method, it will resolve relations and trigger handlers.

func (*Machine) Remove1 added in v0.5.0 

func (m *Machine) Remove1(state string, args A) Result

Remove1 is a shorthand method to remove a single state with the passed args. See Remove().

func (*Machine) RemoveFromEv added in v0.5.0 

func (m *Machine) RemoveFromEv(states S, event *Event, args A) Result

RemoveFromEv TODO RemoveFromEv Planned.

func (*Machine) Set 

func (m *Machine) Set(states S, args A) Result

Set de-activates a list of states in the machine, returning the result of the transition (Executed, Queued, Canceled). Like every mutation method, it will resolve relations and trigger handlers.

func (*Machine) SetFromEv added in v0.5.0 

func (m *Machine) SetFromEv(states S, event *Event, args A) Result

SetFromEv TODO SetFromEv Planned.

func (*Machine) SetLogArgs added in v0.5.0 

func (m *Machine) SetLogArgs(matcher func(args A) map[string]string)

SetLogArgs accepts a function which decides which mutation arguments to log. See NewArgsMapper or create your own manually.

func (*Machine) SetLogLevel 

func (m *Machine) SetLogLevel(level LogLevel)

SetLogLevel sets the log level of the machine.

func (*Machine) SetLogger 

func (m *Machine) SetLogger(fn Logger)

SetLogger sets a custom logger function.

func (*Machine) SetStruct added in v0.5.0 

func (m *Machine) SetStruct(statesStruct Struct, names S) error

SetStruct sets the machine's state structure. It will automatically call VerifyStates with the names param and emit EventStructChange if successful. Note: it's not recommended to change the states structure of a machine which has already produced transitions.

func (*Machine) SetTestLogger added in v0.5.0 

func (m *Machine) SetTestLogger(
	logf func(format string, args ...any), level LogLevel,
)

SetTestLogger hooks into the testing.Logf and set the log level in one call. Useful for testing. Requires LogChanges log level to produce any output.

func (*Machine) String 

func (m *Machine) String() string

String returns a one line representation of the currently active states, with their clock values. Inactive states are omitted. Eg: (Foo:1 Bar:3)

func (*Machine) StringAll 

func (m *Machine) StringAll() string

StringAll returns a one line representation of all the states, with their clock values. Inactive states are in square brackets. Eg: (Foo:1 Bar:3)[Baz:2]

func (*Machine) Switch added in v0.3.0 

func (m *Machine) Switch(states ...string) string

Switch returns the first state from the passed list that is currently active, making it useful for switch statements. 

switch mach.Switch(ss.GroupPlaying...) {
case "Playing":
case "Paused":
case "Stopped":
}

func (*Machine) Time 

func (m *Machine) Time(states S) T

Time returns a list of logical clocks of specified states (or all the states if nil). states: optionally passing a list of states param guarantees a deterministic order of the result.

func (*Machine) TimeSum 

func (m *Machine) TimeSum(states S) uint64

TimeSum returns the sum of logical clocks of specified states (or all states if nil). It's a very inaccurate, yet simple way to measure the machine's time. TODO handle overflow

func (*Machine) VerifyStates added in v0.3.0 

func (m *Machine) VerifyStates(states S) error

VerifyStates verifies an array of state names and returns an error in case at least one isn't defined. It also retains the order and uses it for StateNames (only if all states have been passed). Not thread-safe.

func (*Machine) When 

func (m *Machine) When(states S, ctx context.Context) chan struct{}

When returns a channel that will be closed when all the passed states become active or the machine gets disposed.

ctx: optional context that will close the channel when done. Useful when listening on 2 When() channels within the same `select` to GC the 2nd one. TODO re-use channels with the same state set and context

func (*Machine) When1 added in v0.5.0 

func (m *Machine) When1(state string, ctx context.Context) chan struct{}

When1 is an alias to When() for a single state. See When.

func (*Machine) WhenArgs added in v0.5.0 

func (m *Machine) WhenArgs(
	state string, args A, ctx context.Context,
) chan struct{}

WhenArgs returns a channel that will be closed when the passed state becomes active with all the passed args. Args are compared using the native '=='. It's meant to be used with async Multi states, to filter out a specific completion. TODO better val comparisons

func (*Machine) WhenErr 

func (m *Machine) WhenErr(ctx context.Context) chan struct{}

WhenErr returns a channel that will be closed when the machine is in the Exception state.

ctx: optional context defaults to the machine's context.

func (*Machine) WhenNot 

func (m *Machine) WhenNot(states S, ctx context.Context) chan struct{}

WhenNot returns a channel that will be closed when all the passed states become inactive or the machine gets disposed.

ctx: optional context that will close the channel when done. Useful when listening on 2 WhenNot() channels within the same `select` to GC the 2nd one.

func (*Machine) WhenNot1 added in v0.5.0 

func (m *Machine) WhenNot1(state string, ctx context.Context) chan struct{}

WhenNot1 is an alias to WhenNot() for a single state. See WhenNot.

func (*Machine) WhenQueueEnds added in v0.5.0 

func (m *Machine) WhenQueueEnds(ctx context.Context) <-chan T

WhenQueueEnds writes every time the queue ends with the times from after the last mutation. The channel will close with ctx or Machine.Ctx. TODO WhenQueueEnds Planned.

func (*Machine) WhenTicks added in v0.5.0 

func (m *Machine) WhenTicks(
	state string, ticks int, ctx context.Context,
) chan struct{}

WhenTicks waits N tick for a single state. Uses WhenTime underneath.

func (*Machine) WhenTicksEq added in v0.5.0 

func (m *Machine) WhenTicksEq(
	state string, ticks int, ctx context.Context,
) chan struct{}

WhenTicksEq waits till ticks for a single state equal the given value. Uses WhenTime underneath.

func (*Machine) WhenTime added in v0.5.0 

func (m *Machine) WhenTime(
	states S, times T, ctx context.Context,
) chan struct{}

WhenTime returns a channel that will be closed when all the passed states have passed the specified time. The time is a logical clock of the state. Machine time can be sourced from the Time() method, or Clock() for a specific state.

type Mutation 

type Mutation struct {
	// add, set, remove
	Type MutationType
	// states explicitly passed to the mutation method
	CalledStates S
	// argument map passed to the mutation method (if any).
	Args A
	// this mutation has been triggered by an auto state
	Auto bool
	// specific context for this mutation (optional)
	Ctx context.Context
	// optional eval func, only for MutationEval
	Eval func()
}

Mutation represents an atomic change (or an attempt) of machine's active states. Mutation causes a Transition.

func (Mutation) StateWasCalled added in v0.5.0 

func (m Mutation) StateWasCalled(state string) bool

StateWasCalled returns true if the Mutation was called with the passed state (or does it come from relations).

type MutationType 

type MutationType int

MutationType enum 

const (
	MutationAdd MutationType = iota
	MutationRemove
	MutationSet
	MutationEval
)

func (MutationType) String 

func (m MutationType) String() string

type Opts 

type Opts struct {
	// Unique ID of this machine. Default: random ID.
	ID string
	// Time for a handler to execute. Default: time.Second
	HandlerTimeout time.Duration
	// If true, the machine will NOT print all exceptions to stdout.
	DontPrintExceptions bool
	// If true, the machine will die on panics.
	DontPanicToException bool
	// If true, the machine will NOT prefix its logs with its ID.
	DontLogID bool
	// Custom relations resolver. Default: *DefaultRelationsResolver.
	Resolver RelationsResolver
	// Log level of the machine. Default: LogNothing.
	LogLevel LogLevel
	// Tracer for the machine. Default: nil.
	Tracers []Tracer
	// LogArgs matching function for the machine. Default: nil.
	LogArgs func(args A) map[string]string
	// Parent machine, used to inherit certain properties, e.g. tracers.
	// Overrides ParentID. Default: nil.
	Parent *Machine
	// ParentID is the ID of the parent machine. Default: "".
	ParentID string
	// Tags is a list of tags for the machine. Default: nil.
	Tags []string
	// QueueLimit is the maximum number of mutations that can be queued.
	// Default: 1000.
	// TODO per-state QueueLimit
	QueueLimit int
}

Opts struct is used to configure a new Machine.

func OptsWithDebug added in v0.5.0 

func OptsWithDebug(opts *Opts) *Opts

OptsWithDebug returns Opts with debug settings (DontPanicToException, long HandlerTimeout).

func OptsWithParentTracers added in v0.5.0 

func OptsWithParentTracers(opts *Opts, parent *Machine) *Opts

OptsWithParentTracers returns Opts with the parent's Opts.Tracers and Opts.LogArgs.

func OptsWithTracers added in v0.5.0 

func OptsWithTracers(opts *Opts, tracers ...Tracer) *Opts

OptsWithTracers returns Opts with the given tracers. Tracers are inherited by submachines (via Opts.Parent) when env.AM_DEBUG is set.

type Relation 

type Relation int

Relation enum 

const (
	RelationAfter Relation = iota
	RelationAdd
	RelationRequire
	RelationRemove
)

func (Relation) String 

func (r Relation) String() string

type RelationsResolver 

type RelationsResolver interface {
	// GetTargetStates returns the target states after parsing the relations.
	GetTargetStates(t *Transition, calledStates S) S
	// GetAutoMutation returns an (optional) auto mutation which is appended to
	// the queue after the transition is executed.
	GetAutoMutation() *Mutation
	// SortStates sorts the states in the order their handlers should be
	// executed.
	SortStates(states S)
	// GetRelationsOf returns a list of relation types of the given state.
	GetRelationsOf(fromState string) ([]Relation, error)
	// GetRelationsBetween returns a list of relation types between the given
	// states.
	GetRelationsBetween(fromState, toState string) ([]Relation, error)
}

RelationsResolver is an interface for parsing relations between states. Not thread-safe. TODO support custom relation types and additional state properties.

type Result 

type Result int

Result enum is the result of a state Transition 

const (
	// Executed means that the transition was executed immediately and not
	// canceled.
	Executed Result = 1 << iota
	// Canceled means that the transition was canceled, by either relations or a
	// handler.
	Canceled
	// Queued means that the transition was queued for later execution. The
	// following methods can be used to wait for the results:
	// - Machine.When
	// - Machine.WhenNot
	// - Machine.WhenArgs
	// - Machine.WhenTime
	Queued
)

func (Result) String 

func (r Result) String() string

type S 

type S []string

S (state names) is a string list of state names.

func DiffStates 

func DiffStates(states1 S, states2 S) S

DiffStates returns the states that are in states1 but not in states2.

func SMerge added in v0.5.0 

func SMerge(states ...S) S

SMerge merges multiple state lists into one, removing duplicates. Especially useful for merging state group with single states.

type State 

type State struct {
	Auto    bool
	Multi   bool
	Require S
	Add     S
	Remove  S
	After   S
}

State defines a single state of a machine, its properties and relations.

type Step added in v0.5.0 

type Step struct {
	Type StepType
	// optional, unless no ToState
	FromState string
	// optional, unless no FromState
	ToState string
	// eg a transition method name, relation type
	Data any
	// marks a final handler (FooState, FooEnd)
	IsFinal bool
	// marks a self handler (FooFoo)
	IsSelf bool
	// marks an enter handler (FooEnter). Requires IsFinal.
	IsEnter bool
}

Step struct represents a single step within a Transition, either a relation resolving step or a handler call.

type StepType added in v0.5.0 

type StepType int

StepType enum 

const (
	StepRelation StepType = 1 << iota
	StepHandler
	StepSet
	// StepRemove indicates a step where a state goes active->inactive
	StepRemove
	// StepRemoveNotActive indicates a step where a state goes inactive->inactive
	StepRemoveNotActive
	StepRequested
	StepCancel
)

func (StepType) String added in v0.5.0 

func (tt StepType) String() string

type Struct added in v0.5.0 

type Struct = map[string]State

Struct is a map of state names to state definitions.

func CloneStates added in v0.5.0 

func CloneStates(states Struct) Struct

CloneStates deep clones the states struct and returns a copy.

type T 

type T []uint64

T is an ordered list of state clocks. TODO use math/big?

type Tracer added in v0.5.0 

type Tracer interface {
	TransitionInit(transition *Transition)
	TransitionEnd(transition *Transition)
	HandlerStart(transition *Transition, emitter string, handler string)
	HandlerEnd(transition *Transition, emitter string, handler string)
	End()
	MachineInit(mach *Machine)
	MachineDispose(machID string)
	NewSubmachine(parent, mach *Machine)
	Inheritable() bool
}

Tracer is an interface for logging machine transitions and events, used by Opts.Tracers.

type Transition 

type Transition struct {
	ID string
	// List of steps taken by this transition (so far).
	Steps []*Step
	// When true, execution of the transition has been completed.
	IsCompleted bool
	// states before the transition
	StatesBefore S
	// clocks of the states from before the transition
	// TODO timeBefore, produce Clocks via ClockBefore(), add index diffs
	ClocksBefore Clocks
	// clocks of the states from after the transition
	// TODO timeAfter, produce Clocks via ClockAfter(), add index diffs
	ClocksAfter Clocks
	// Struct with "enter" handlers to execute
	Enters S
	// Struct with "exit" handlers to executed
	Exits S
	// target states after parsing the relations
	TargetStates S
	// was the transition accepted (during the negotiation phase)
	Accepted bool
	// Mutation call which cased this transition
	Mutation *Mutation
	// Parent machine
	Machine *Machine
	// Log entries produced during the transition
	LogEntries []string
	// contains filtered or unexported fields
}

Transition represents processing of a single mutation withing a machine.

func (*Transition) Args 

func (t *Transition) Args() A

Args returns the argument map passed to the mutation method (or an empty one).

func (*Transition) CalledStates 

func (t *Transition) CalledStates() S

CalledStates return explicitly called / requested states of the transition.

func (*Transition) IsAuto 

func (t *Transition) IsAuto() bool

IsAuto returns true if the transition was triggered by an auto state. Thus, it cant trigger any other auto state mutations.

func (*Transition) LogArgs added in v0.5.0 

func (t *Transition) LogArgs() string

LogArgs returns a text snippet with arguments which should be logged for this Mutation.

func (*Transition) String 

func (t *Transition) String() string

String representation of the transition and the steps taken so far. TODO: implement, test

func (*Transition) Type 

func (t *Transition) Type() MutationType

Type returns the type of the mutation (add, remove, set).

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