tasks/service/history/hsm/registry.go

// The MIT License
//
// Copyright (c) 2024 Temporal Technologies Inc.  All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package hsm

import (
	"context"
	"errors"
	"fmt"
	"reflect"

	enumspb "go.temporal.io/api/enums/v1"
)

// ErrDuplicateRegistration is returned by a [Registry] when it detects duplicate registration.
var ErrDuplicateRegistration = errors.New("duplicate registration")

// ErrNotRegistered is returned by a [Registry] when trying to get a type that is not registered.
var ErrNotRegistered error = notRegisteredError{"not registered"}

// notRegisteredError is returned by a [Registry] when trying to get a type that is not registered.
type notRegisteredError struct {
	Message string
}

func (e notRegisteredError) Error() string {
	return e.Message
}

func (notRegisteredError) IsTerminalTaskError() bool {
	return true
}

// Registry maintains a mapping from state machine type to a [StateMachineDefinition] and task type to [TaskSerializer].
// Registry methods are **not** protected by a lock and all registration is expected to happen in a single thread on
// startup for performance reasons.
type Registry struct {
	machines map[int32]StateMachineDefinition
	tasks    map[int32]TaskSerializer
	// This is mapped to any because of Go's limited generics support.
	// The actual value is Executor[T].
	executors map[int32]any
	events    map[enumspb.EventType]EventDefinition
}

// NewRegistry creates a new [Registry].
func NewRegistry() *Registry {
	return &Registry{
		machines:  make(map[int32]StateMachineDefinition),
		tasks:     make(map[int32]TaskSerializer),
		executors: make(map[int32]any),
		events:    make(map[enumspb.EventType]EventDefinition),
	}
}

// RegisterMachine registers a [StateMachineDefinition] by its type.
// Returns an [ErrDuplicateRegistration] if the state machine type has already been registered.
func (r *Registry) RegisterMachine(sm StateMachineDefinition) error {
	t := sm.Type().ID
	if existing, ok := r.machines[t]; ok {
		return fmt.Errorf("%w: state machine already registered for %v - %v", ErrDuplicateRegistration, sm.Type(), existing.Type())
	}
	r.machines[t] = sm
	return nil
}

// Machine returns a [StateMachineDefinition] for a given type and a boolean indicating whether it was found.
func (r *Registry) Machine(t int32) (def StateMachineDefinition, ok bool) {
	def, ok = r.machines[t]
	return
}

// RegisterTaskSerializer registers a [TaskSerializer] for a given type.
// Returns an [ErrDuplicateRegistration] if a serializer for this task type has already been registered.
func (r *Registry) RegisterTaskSerializer(t int32, def TaskSerializer) error {
	if exising, ok := r.tasks[t]; ok {
		return fmt.Errorf("%w: task already registered for %v: %v", ErrDuplicateRegistration, t, exising)
	}
	r.tasks[t] = def
	return nil
}

// TaskSerializer returns a [TaskSerializer] for a given type and a boolean indicating whether it was found.
func (r *Registry) TaskSerializer(t int32) (d TaskSerializer, ok bool) {
	d, ok = r.tasks[t]
	return
}

// RegisterExecutor registers an [Executor] for the given task type.
// Returns an [ErrDuplicateRegistration] if an executor for the type has already been registered.
func RegisterExecutor[T Task](r *Registry, t int32, exec Executor[T]) error {
	if existing, ok := r.executors[t]; ok {
		return fmt.Errorf("%w: executor already registered for %v: %v", ErrDuplicateRegistration, t, existing)
	}
	r.executors[t] = exec
	return nil
}

// Execute gets an [Executor] from the registry and invokes it.
// Returns [ErrNotRegistered] if an executor is not registered for the given task's type.
func Execute(ctx context.Context, r *Registry, env Environment, ref Ref, task Task) error {
	executor, ok := r.executors[task.Type().ID]
	if !ok {
		return fmt.Errorf("%w: executor for task type %v", ErrNotRegistered, task.Type())
	}
	fn := reflect.ValueOf(executor)
	values := fn.Call([]reflect.Value{reflect.ValueOf(ctx), reflect.ValueOf(env), reflect.ValueOf(ref), reflect.ValueOf(task)})
	if !values[0].IsNil() {
		//nolint:revive // type cast result is unchecked
		return values[0].Interface().(error)
	}
	return nil
}

// RegisterEventDefinition registers an [EventDefinition] for the given event type.
// Returns an [ErrDuplicateRegistration] if a definition for the type has already been registered.
func (r *Registry) RegisterEventDefinition(def EventDefinition) error {
	t := def.Type()
	prev, ok := r.events[t]
	if ok {
		return fmt.Errorf("%w: event definition for event type %v: %v", ErrDuplicateRegistration, t, prev)
	}
	r.events[t] = def
	return nil
}

// EventDefinition returns an [EventDefinition] for a given type and a boolean indicating whether it was found.
func (r *Registry) EventDefinition(t enumspb.EventType) (def EventDefinition, ok bool) {
	def, ok = r.events[t]
	return
}