feat(core): persist tasks and recover them after restart

database/task.go

@@ -0,0 +1,92 @@
+package database
+
+import (
+	"context"
+	"errors"
+	"time"
+)
+
+var errNotInitialized = errors.New("database not initialized")
+
+type TaskStatus string
+
+const (
+	TaskStatusQueued    TaskStatus = "queued"
+	TaskStatusRunning   TaskStatus = "running"
+	TaskStatusFailed    TaskStatus = "failed"
+	TaskStatusCancelled TaskStatus = "cancelled"
+)
+
+// Task is the persisted record of a queued or running task, used to recover
+// unfinished work after a process restart. Completed tasks are deleted on
+// finish, so the table only ever holds queued/running rows.
+type Task struct {
+	ID        string `gorm:"primaryKey;size:64"`
+	Type      string `gorm:"size:32;index"`
+	Payload   []byte
+	Status    string `gorm:"size:16;index"`
+	Error     string
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+func CreateTask(ctx context.Context, task *Task) error {
+	if db == nil {
+		return errNotInitialized
+	}
+	return db.WithContext(ctx).Create(task).Error
+}
+
+// UpsertTask inserts the task or replaces the existing row with the same ID.
+func UpsertTask(ctx context.Context, task *Task) error {
+	if db == nil {
+		return errNotInitialized
+	}
+	return db.WithContext(ctx).Save(task).Error
+}
+
+func UpdateTaskStatus(ctx context.Context, id string, status TaskStatus, errMsg string) error {
+	if db == nil {
+		return errNotInitialized
+	}
+	return db.WithContext(ctx).Model(&Task{}).
+		Where("id = ?", id).
+		Updates(map[string]any{
+			"status":     status,
+			"error":      errMsg,
+			"updated_at": time.Now(),
+		}).Error
+}
+
+func DeleteTask(ctx context.Context, id string) error {
+	if db == nil {
+		return errNotInitialized
+	}
+	return db.WithContext(ctx).Delete(&Task{}, "id = ?", id).Error
+}
+
+// GetUnfinishedTasks returns all tasks that were not finished when the
+// process stopped, i.e. tasks that must be re-enqueued on startup.
+func GetUnfinishedTasks(ctx context.Context) ([]Task, error) {
+	if db == nil {
+		return nil, errNotInitialized
+	}
+	var tasks []Task
+	err := db.WithContext(ctx).
+		Where("status IN ?", []string{string(TaskStatusQueued), string(TaskStatusRunning)}).
+		Order("created_at").
+		Find(&tasks).Error
+	return tasks, err
+}
+
+func CountUnfinishedTasks(ctx context.Context) (int64, error) {
+	if db == nil {
+		return 0, errNotInitialized
+	}
+	var count int64
+	err := db.WithContext(ctx).
+		Model(&Task{}).
+		Where("status IN ?", []string{string(TaskStatusQueued), string(TaskStatusRunning)}).
+		Count(&count).Error
+	return count, err
+}