Add pipeline run coordinator

internal/app/run_coordinator.go

@@ -0,0 +1,131 @@
+package app
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+)
+
+type PipelineRunID string
+
+type PipelineRunStatus string
+
+const (
+	PipelineRunRunning   PipelineRunStatus = "running"
+	PipelineRunSucceeded PipelineRunStatus = "succeeded"
+	PipelineRunFailed    PipelineRunStatus = "failed"
+)
+
+type PipelineRunRecord struct {
+	ID         PipelineRunID     `json:"id"`
+	PipelineID string            `json:"pipeline_id"`
+	Status     PipelineRunStatus `json:"status"`
+	StartedAt  time.Time         `json:"started_at"`
+	FinishedAt *time.Time        `json:"finished_at,omitempty"`
+	Report     RunReport         `json:"report,omitempty"`
+	Error      string            `json:"error,omitempty"`
+}
+
+type DuplicatePipelineRunError struct {
+	PipelineID string
+	RunID      PipelineRunID
+}
+
+func (err DuplicatePipelineRunError) Error() string {
+	if err.RunID == "" {
+		return fmt.Sprintf("pipeline %q already has an active run", err.PipelineID)
+	}
+	return fmt.Sprintf("pipeline %q already has active run %s", err.PipelineID, err.RunID)
+}
+
+func IsDuplicatePipelineRun(err error) bool {
+	var duplicate DuplicatePipelineRunError
+	return errors.As(err, &duplicate)
+}
+
+type PipelineRunCoordinator struct {
+	ctx    context.Context
+	run    pipelineRunFunc
+	now    func() time.Time
+	mu     sync.Mutex
+	nextID uint64
+	active map[string]PipelineRunRecord
+}
+
+type pipelineRunFunc func(context.Context, RunPipelineOptions) (RunReport, error)
+
+func NewPipelineRunCoordinator(ctx context.Context) *PipelineRunCoordinator {
+	return newPipelineRunCoordinator(ctx, RunPipeline)
+}
+
+func newPipelineRunCoordinator(ctx context.Context, run pipelineRunFunc) *PipelineRunCoordinator {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	return &PipelineRunCoordinator{
+		ctx:    ctx,
+		run:    run,
+		now:    time.Now,
+		active: map[string]PipelineRunRecord{},
+	}
+}
+
+func (coordinator *PipelineRunCoordinator) RunPipeline(ctx context.Context, options RunPipelineOptions) (PipelineRunRecord, error) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	if err := ctx.Err(); err != nil {
+		return PipelineRunRecord{}, err
+	}
+	record, err := coordinator.admit(options.PipelineID)
+	if err != nil {
+		return PipelineRunRecord{}, err
+	}
+	defer coordinator.clear(options.PipelineID)
+
+	report, runErr := coordinator.run(coordinator.ctx, options)
+	record.Report = report
+	finishedAt := coordinator.now().UTC()
+	record.FinishedAt = &finishedAt
+	if runErr != nil {
+		record.Status = PipelineRunFailed
+		record.Error = runErr.Error()
+		return record, runErr
+	}
+	record.Status = PipelineRunSucceeded
+	return record, nil
+}
+
+func (coordinator *PipelineRunCoordinator) admit(pipelineID string) (PipelineRunRecord, error) {
+	coordinator.mu.Lock()
+	defer coordinator.mu.Unlock()
+	if active, ok := coordinator.active[pipelineID]; ok {
+		return PipelineRunRecord{}, DuplicatePipelineRunError{
+			PipelineID: pipelineID,
+			RunID:      active.ID,
+		}
+	}
+	coordinator.nextID++
+	record := PipelineRunRecord{
+		ID:         PipelineRunID(fmt.Sprintf("run-%016d", coordinator.nextID)),
+		PipelineID: pipelineID,
+		Status:     PipelineRunRunning,
+		StartedAt:  coordinator.now().UTC(),
+	}
+	coordinator.active[pipelineID] = record
+	return record, nil
+}
+
+func (coordinator *PipelineRunCoordinator) clear(pipelineID string) {
+	coordinator.mu.Lock()
+	defer coordinator.mu.Unlock()
+	delete(coordinator.active, pipelineID)
+}
+
+func (coordinator *PipelineRunCoordinator) activeCount() int {
+	coordinator.mu.Lock()
+	defer coordinator.mu.Unlock()
+	return len(coordinator.active)
+}