workflow

package
v1.30.1 Latest Latest
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 Go to latest Published: May 15, 2026 License: Apache-2.0 Imports: 12 Imported by: 0

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Index

Constants

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const END = "END"

END is a pseudo-node indicating that the workflow should terminate. Use it as the target of a transition to mark a terminal path.

Variables

This section is empty.

Functions

func FilterState 

func FilterState(state map[string]any, declared []string) map[string]any

FilterState returns a subset of state based on declared field names. nil or empty = pass nothing. ["*"] = pass everything. Named fields = pass only those fields.

func MergeState 

func MergeState(state any, changes any, reducers map[string]Reducer) (map[string]any, error)

MergeState applies changes on top of state, using the provided reducers for fields that have one. For fields without an explicit reducer, the reducer is inferred from the field name's prefix (sum*, list*, set*); fields not matching a convention prefix use replace semantics.

The set* prefix is polymorphic: it dispatches to union when the value is a JSON array and to merge when the value is a JSON object. Explicit reducer configuration via SetReducer is strict and does not polymorph.

State, changes and the result are map[string]any or nil.

Types

type Flow 

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

Flow is the carrier object passed to tasks. It holds the state and control signals for a single step in a workflow execution.

func NewFlow 

func NewFlow() *Flow

NewFlow creates a new Flow with initialized maps.

func (*Flow) Get 

func (f *Flow) Get(key string, target any) error

Get unmarshals a state field into the target. Use this for complex types (structs, maps, etc.).

func (*Flow) GetBool 

func (f *Flow) GetBool(key string) bool

GetBool returns a state field as a bool.

func (*Flow) GetDuration 

func (f *Flow) GetDuration(key string) time.Duration

GetDuration returns a state field as a time.Duration.

func (*Flow) GetFloat 

func (f *Flow) GetFloat(key string) float64

GetFloat returns a state field as a float64.

func (*Flow) GetInt 

func (f *Flow) GetInt(key string) int

GetInt returns a state field as an int.

func (*Flow) GetString 

func (f *Flow) GetString(key string) string

GetString returns a state field as a string.

func (*Flow) GetStrings 

func (f *Flow) GetStrings(key string) []string

GetStrings returns a state field as a string slice.

func (*Flow) Goto 

func (f *Flow) Goto(taskName string)

Goto overrides transition routing. The orchestrator skips condition evaluation and follows the specified task instead.

func (*Flow) GotoRequested 

func (f *Flow) GotoRequested() string

GotoRequested returns the task URL set by Goto, or empty if not set.

func (*Flow) Has 

func (f *Flow) Has(key string) bool

Has reports whether a state field exists.

func (*Flow) Interrupt 

func (f *Flow) Interrupt(payload any)

Interrupt pauses the flow execution and requests external input. The payload is propagated up through the surgraph chain and surfaced via State() so the caller can see what data the task needs. The task should return normally after calling Interrupt.

func (*Flow) InterruptRequested 

func (f *Flow) InterruptRequested() (map[string]any, bool)

InterruptRequested returns the interrupt payload and true if Interrupt was called.

func (*Flow) MarshalJSON 

func (f *Flow) MarshalJSON() ([]byte, error)

MarshalJSON serializes the Flow including private fields.

func (*Flow) ParseState 

func (f *Flow) ParseState(target any) error

ParseState unmarshals state fields into the target struct. Fields are matched by their JSON tag names. Fields in state that are not in the struct are ignored.

func (*Flow) Retry 

func (f *Flow) Retry(maxAttempts int, initialDelay time.Duration, multiplier float64, maxDelay time.Duration) bool

Retry requests the orchestrator to retry this task with exponential backoff. Returns true if a retry will be scheduled (attempts remaining), false if exhausted. When true, the task should return nil. When false, the task should return its error. The delay for attempt N is min(initialDelay * multiplier^N, maxDelay).

Example: 

result, err := callExternalAPI(ctx)
if err != nil {
    if flow.Retry(5, 1*time.Second, 2.0, 30*time.Second) {
        return result, nil // retry scheduled, don't report error
    }
    return result, err // retries exhausted, report the error
}

func (*Flow) RetryNow 

func (f *Flow) RetryNow() bool

RetryNow signals the orchestrator to re-execute this task immediately with no limit. Equivalent to Retry(math.MaxInt32, 0, 0, 0).

func (*Flow) RetryNowOnTimeout added in v1.30.0 

func (f *Flow) RetryNowOnTimeout(err error) bool

RetryNowOnTimeout retries the task immediately on HTTP 408 with no attempt limit and no delay, and returns false for any other error so the caller can surface it. Equivalent to RetryOnTimeout(err, math.MaxInt32, 0, 0, 0).

func (*Flow) RetryOnTimeout added in v1.30.0 

func (f *Flow) RetryOnTimeout(err error, maxAttempts int, initialDelay time.Duration, multiplier float64, maxDelay time.Duration) bool

RetryOnTimeout retries the task only when err carries HTTP status 408 (Request Timeout), and otherwise returns false so the caller can surface the error to the workflow. Returns true exactly when Retry would schedule another attempt; the caller should return nil in that case.

Typical usage: 

result, err := svc.doWork(ctx)
if err != nil {
    if flow.RetryOnTimeout(err, 5, 2*time.Second, 2.0, time.Minute) {
        return result, nil // retry scheduled, suppress the timeout
    }
    return result, errors.Trace(err) // non-timeout, or attempts exhausted
}

func (*Flow) RetryRequested 

func (f *Flow) RetryRequested() (maxAttempts int, initialDelay time.Duration, multiplier float64, maxDelay time.Duration, ok bool)

RetryRequested returns the backoff parameters and true if Retry was called. The foreman uses these to compute the sleep delay and check the attempt limit.

func (*Flow) Set 

func (f *Flow) Set(key string, value any) error

Set sets a state field and tracks the change. Use this for complex types (structs, maps, etc.).

func (*Flow) SetBool 

func (f *Flow) SetBool(key string, value bool)

SetBool sets a state bool field and tracks the change.

func (*Flow) SetChanges 

func (f *Flow) SetChanges(source any, snap map[string]any) error

SetChanges marshals the source struct back to state, comparing against the provided snapshot. Only fields whose JSON value differs from the snapshot are recorded as changes. Changed fields are written to both the state and changes maps, so that subsequent reads (including transition condition evaluation) see the updated values.

func (*Flow) SetDuration 

func (f *Flow) SetDuration(key string, value time.Duration)

SetDuration sets a state time.Duration field and tracks the change.

func (*Flow) SetFloat 

func (f *Flow) SetFloat(key string, value float64)

SetFloat sets a state float64 field and tracks the change.

func (*Flow) SetInt 

func (f *Flow) SetInt(key string, value int)

SetInt sets a state int field and tracks the change.

func (*Flow) SetState 

func (f *Flow) SetState(source any) error

SetState marshals the source struct fields into state without tracking changes. Fields are matched by their JSON tag names.

func (*Flow) SetString 

func (f *Flow) SetString(key string, value string)

SetString sets a state string field and tracks the change.

func (*Flow) SetStrings 

func (f *Flow) SetStrings(key string, value []string)

SetStrings sets a state string slice field and tracks the change.

func (*Flow) Sleep 

func (f *Flow) Sleep(duration time.Duration)

Sleep tells the orchestrator to wait for the given duration before the next execution.

func (*Flow) SleepRequested 

func (f *Flow) SleepRequested() time.Duration

SleepRequested returns the duration set by Sleep, or zero if not set.

func (*Flow) Snapshot 

func (f *Flow) Snapshot() map[string]any

Snapshot captures a read-only copy of the flow's current state (including any changes applied so far). Pass the returned snapshot to SetChanges to record only the fields that differ.

func (*Flow) Subgraph 

func (f *Flow) Subgraph(workflowURL string, input map[string]any)

Subgraph signals the orchestrator to create and run a child workflow before this step completes. The step is parked until the child finishes - similar to how Interrupt pauses until Resume is called. When the child completes, its final state is filtered through the child's DeclareOutputs and merged into this step's changes using the parent graph's reducers, then the task is re-executed. On re-entry the task sees the child's output in its state and should return normally without calling Subgraph again.

The child's initial state is built from the parent's full state plus the surgraph step's accumulated changes; the explicit input map is then merged on top using the child graph's reducers, and the result is filtered through the child's DeclareInputs.

func (*Flow) SubgraphRequested 

func (f *Flow) SubgraphRequested() (workflowURL string, input map[string]any, ok bool)

SubgraphRequested returns the workflow URL, input state, and true if Subgraph was called.

func (*Flow) UnmarshalJSON 

func (f *Flow) UnmarshalJSON(data []byte) error

UnmarshalJSON deserializes the Flow including private fields.

type Graph 

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

Graph is the definition of a workflow. It describes the tasks, transitions between them, and reducers for merging state during fan-in.

func NewGraph 

func NewGraph(name string) *Graph

NewGraph creates a new workflow graph with the given name.

func (*Graph) AddSubgraph 

func (g *Graph) AddSubgraph(name, workflowURL string)

AddSubgraph registers a child workflow as a subgraph node in the graph under the given name, with the given URL as the dispatch target. Same registration semantics as AddTask.

func (*Graph) AddTask 

func (g *Graph) AddTask(name, url string)

AddTask registers a task node in the graph under the given name, with the given URL as the dispatch target. The first node added becomes the default entry point unless SetEntryPoint is called explicitly. The pseudo-node END is not registered. Re-registering the same name is a no-op.

The same URL may be registered under multiple names. This is how a workflow author reuses the same task code at distinct positions in the graph with different downstream transitions per position.

func (*Graph) AddTransition 

func (g *Graph) AddTransition(from, to string)

AddTransition adds an unconditional transition between two nodes. Both endpoints are auto-registered as tasks if not already present (see autoRegister).

func (*Graph) AddTransitionForEach 

func (g *Graph) AddTransitionForEach(from, to string, forEach string, as string)

AddTransitionForEach adds a dynamic fan-out transition.

func (*Graph) AddTransitionGoto 

func (g *Graph) AddTransitionGoto(from, to string)

AddTransitionGoto adds a transition that is only taken when the source task calls flow.Goto with a target that resolves to this transition's destination.

func (*Graph) AddTransitionOnError added in v1.30.0 

func (g *Graph) AddTransitionOnError(from, to string)

AddTransitionOnError adds a transition that is taken when the source task returns an error.

func (*Graph) AddTransitionOnTimeout added in v1.30.0 

func (g *Graph) AddTransitionOnTimeout(from, to string)

AddTransitionOnTimeout adds an error transition that is taken only when the source task's error carries HTTP status 408.

func (*Graph) AddTransitionWhen 

func (g *Graph) AddTransitionWhen(from, to string, when string)

AddTransitionWhen adds a conditional transition between two nodes.

func (*Graph) DeclareInputs 

func (g *Graph) DeclareInputs(fields ...string)

DeclareInputs declares which state fields are passed into this graph when used as a subgraph.

func (*Graph) DeclareOutputs 

func (g *Graph) DeclareOutputs(fields ...string)

DeclareOutputs declares which state fields are returned from this graph on completion.

func (*Graph) EntryPoint 

func (g *Graph) EntryPoint() string

EntryPoint returns the node name of the entry point of the graph.

func (*Graph) ErrorTransition 

func (g *Graph) ErrorTransition(name string) (Transition, bool)

ErrorTransition returns the error transition from the given node name, if one exists.

func (*Graph) FanInFor added in v1.30.0 

func (g *Graph) FanInFor(fanOutSource string) string

FanInFor returns the fan-in node that pops the frame pushed by a fan-out at the named source, or "" if the source is not a fan-out. Populated by Validate.

func (*Graph) HasFanIn added in v1.30.0 

func (g *Graph) HasFanIn() bool

HasFanIn reports whether the graph declares any fan-in nexus.

func (*Graph) Inputs 

func (g *Graph) Inputs() []string

Inputs returns the declared input fields.

func (*Graph) IsFanIn added in v1.30.0 

func (g *Graph) IsFanIn(name string) bool

IsFanIn reports whether the named node is a fan-in nexus.

func (*Graph) IsFanOutSource added in v1.30.0 

func (g *Graph) IsFanOutSource(name string) bool

IsFanOutSource reports whether the named node has 2+ non-goto/non-error outgoing transitions, or any forEach outgoing transition.

func (*Graph) IsSubgraph 

func (g *Graph) IsSubgraph(name string) bool

IsSubgraph returns true if the given node name is registered as a subgraph.

func (*Graph) MarshalJSON 

func (g *Graph) MarshalJSON() ([]byte, error)

MarshalJSON serializes the graph to JSON.

func (*Graph) Mermaid 

func (g *Graph) Mermaid() string

Mermaid returns a fully-styled Mermaid flowchart representation of the graph, suitable for writing directly to a .mmd file. The output includes the classDef styles, a title node derived from the graph's URL, and per-node class annotations.

Node shapes encode role: regular tasks are rectangles, subgraphs use the double rectangle, forEach targets use a stacked rectangle ("many of these"), and SetFanIn nodes use an inverted trapezoid ("many converging here"). Edges into a SetFanIn node carry a "fan-in" label.

func (*Graph) Name 

func (g *Graph) Name() string

Name returns the name of the graph.

func (*Graph) NamesForURL added in v1.30.0 

func (g *Graph) NamesForURL(url string) []string

NamesForURL returns all node names whose dispatch URL matches the given URL. Empty result means no node uses that URL. Multiple results mean the URL is reused at distinct graph positions.

func (*Graph) Nodes 

func (g *Graph) Nodes() []Node

Nodes returns the list of nodes in the graph.

func (*Graph) Outputs 

func (g *Graph) Outputs() []string

Outputs returns the declared output fields.

func (*Graph) Reducers 

func (g *Graph) Reducers() map[string]Reducer

Reducers returns the reducer map for state fields.

func (*Graph) SetEntryPoint 

func (g *Graph) SetEntryPoint(name string)

SetEntryPoint sets the entry point of the graph explicitly, overriding the default (first task added). The argument is a node name.

func (*Graph) SetFanIn added in v1.30.0 

func (g *Graph) SetFanIn(name string)

SetFanIn marks a node as a fan-in nexus. Opts the graph into the lineage validator.

func (*Graph) SetReducer 

func (g *Graph) SetReducer(field string, reducer Reducer)

SetReducer sets the merge strategy for a state field during fan-in.

func (*Graph) SetTimeBudget 

func (g *Graph) SetTimeBudget(name string, budget time.Duration)

SetTimeBudget sets the execution time budget for a specific node, by name.

func (*Graph) TimeBudget 

func (g *Graph) TimeBudget(name string) time.Duration

TimeBudget returns the execution time budget for a node by name, or 0 if not set.

func (*Graph) Transitions 

func (g *Graph) Transitions() []Transition

Transitions returns the list of transitions in the graph.

func (*Graph) URLOf added in v1.30.0 

func (g *Graph) URLOf(name string) string

URLOf returns the dispatch URL for a node identified by name. Returns the empty string if the name is not registered. END maps to itself.

func (*Graph) UnmarshalJSON 

func (g *Graph) UnmarshalJSON(data []byte) error

UnmarshalJSON deserializes the graph from JSON.

func (*Graph) Validate 

func (g *Graph) Validate() error

Validate checks the graph for structural errors.

type Node 

type Node struct {
	Name       string
	URL        string
	TimeBudget time.Duration
	Subgraph   bool
}

Node describes a task or subgraph node registered in a workflow graph. Name is the node's identifier within the graph and the value stored on step rows (microbus_steps.task_name). URL is the dispatch target the foreman calls when the node is reached.

type RawFlow 

type RawFlow struct {
	Flow
}

RawFlow wraps Flow with additional methods used by the foreman orchestrator. Task endpoints should use Flow directly; RawFlow is for internal orchestration use only.

func NewRawFlow 

func NewRawFlow() *RawFlow

NewRawFlow creates a new RawFlow with initialized maps.

func (*RawFlow) ClearChanges 

func (f *RawFlow) ClearChanges()

ClearChanges resets the changes map. Called by the orchestrator after persisting changes.

func (*RawFlow) ClearControl 

func (f *RawFlow) ClearControl()

ClearControl resets all control signals. Called by the orchestrator after processing them.

func (*RawFlow) RawChanges 

func (f *RawFlow) RawChanges() map[string]any

RawChanges returns a copy of the raw changes map.

func (*RawFlow) RawState 

func (f *RawFlow) RawState() map[string]any

RawState returns a copy of the raw state map.

func (*RawFlow) SetAttempt 

func (f *RawFlow) SetAttempt(attempt int)

SetAttempt sets the attempt counter on the flow. Called by the orchestrator before dispatching a task so that Retry can check whether attempts are exhausted.

func (*RawFlow) SetRawChanges 

func (f *RawFlow) SetRawChanges(changes map[string]any)

SetRawChanges replaces the entire changes map with the given raw map.

func (*RawFlow) SetRawState 

func (f *RawFlow) SetRawState(state map[string]any)

SetRawState replaces the entire state with the given raw map, without tracking changes.

type Reducer 

type Reducer string

Reducer defines how concurrent state modifications from parallel tasks are merged during fan-in. 

const (
	ReducerReplace Reducer = "replace" // Last write wins (default)
	ReducerAppend  Reducer = "append"  // Concatenate arrays
	ReducerAdd     Reducer = "add"     // Sum numeric values
	ReducerUnion   Reducer = "union"   // Merge arrays, deduplicate
	ReducerMerge   Reducer = "merge"   // Merge objects, new key wins
)

func ReducerForFieldName added in v1.29.0 

func ReducerForFieldName(name string) Reducer

ReducerForFieldName returns the reducer inferred from a state field name. Returns empty (replace) if no convention prefix matches.

Conventions: 

sum*  - numeric add
list* - array append
set*  - polymorphic: array union, object merge

The character right after the prefix must be uppercase to avoid matching English words like "summary", "listening", or "setup".

func (Reducer) Reduce 

func (r Reducer) Reduce(existing, incoming any) (any, error)

Reduce applies the reducer to merge an incoming value into an existing value. Both existing and incoming are JSON-compatible values (json.RawMessage or native Go types). The result is the merged value.

type Transition 

type Transition struct {
	From       string `json:"from"`
	To         string `json:"to"`
	When       string `json:"when,omitzero"`
	WithGoto   bool   `json:"withGoto,omitzero"`
	ForEach    string `json:"forEach,omitzero"` // dynamic fan-out over a state field
	As         string `json:"as,omitzero"`      // alias for the current element during forEach fan-out
	OnError    bool   `json:"onError,omitzero"` // taken when the source task returns an error
	StatusCode int    `json:"statusCode,omitzero"`
}

Transition defines a possible transition between two nodes in a workflow graph. From and To are node names, not URLs.

Source Files

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