/
engine.go
313 lines (248 loc) · 6.98 KB
/
engine.go
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package cte
import (
"context"
"github.com/jamestrandung/go-concurrency/async"
"golang.org/x/sync/errgroup"
"reflect"
)
type registeredComputer struct {
computer ImpureComputer
metadata parsedMetadata
}
type Engine struct {
computers map[string]registeredComputer
plans map[string]analyzedPlan
}
func NewEngine() Engine {
return Engine{
computers: make(map[string]registeredComputer),
plans: make(map[string]analyzedPlan),
}
}
func (e Engine) AnalyzePlan(p Plan) {
planName := extractFullNameFromValue(p)
if _, ok := e.plans[planName]; ok {
return
}
val := reflect.ValueOf(p)
if val.Kind() != reflect.Pointer {
panic(ErrPlanMustUsePointerReceiver.Err(reflect.TypeOf(p)))
}
pa := planAnalyzer{
engine: e,
plan: p,
planValue: val.Elem(),
}
ap := pa.analyze()
e.plans[planName] = ap
}
func (e Engine) registerComputer(mp MetadataProvider) {
computerID := extractFullNameFromValue(mp)
if _, ok := e.computers[computerID]; ok {
return
}
metadata := extractMetadata(mp, true)
computerType := func() reflect.Type {
cType, ok := metadata.getComputerType()
if !ok {
panic(ErrComputerMetaMissing.Err(reflect.TypeOf(mp)))
}
if cType.Kind() == reflect.Pointer {
return cType.Elem()
}
return cType
}()
computer := reflect.New(computerType).Interface()
switch c := computer.(type) {
case ImpureComputer:
e.computers[computerID] = registeredComputer{
computer: c,
metadata: metadata,
}
case SideEffectComputer:
e.computers[computerID] = registeredComputer{
computer: bridgeComputer{
se: c,
},
metadata: metadata,
}
case SwitchComputer:
e.computers[computerID] = registeredComputer{
computer: bridgeComputer{
sw: c,
},
metadata: metadata,
}
default:
panic(ErrInvalidComputerType.Err(computerType))
}
}
func (e Engine) ExecuteMasterPlan(ctx context.Context, p MasterPlan) error {
// Plan implementations always use pointer receivers.
// Should be safe to extract value.
planValue := reflect.ValueOf(p).Elem()
planName := extractFullNameFromType(planValue.Type())
if err := e.doExecutePlan(ctx, planName, p, planValue, p.IsSequentialCTEPlan()); err != nil {
return swallowErrPlanExecutionEndingEarly(err)
}
return nil
}
func (e Engine) doExecutePlan(ctx context.Context, planName string, p MasterPlan, curPlanValue reflect.Value, isSequential bool) error {
ap := e.findAnalyzedPlan(planName, curPlanValue)
for _, h := range ap.preHooks {
if err := h.hook.PreExecute(p); err != nil {
return err
}
}
err := func() error {
if isSequential {
return e.doExecuteSync(ctx, p, curPlanValue, ap.components)
}
return e.doExecuteAsync(ctx, p, curPlanValue, ap.components)
}()
if err != nil {
return err
}
for _, h := range ap.postHooks {
if err := h.hook.PostExecute(p); err != nil {
return err
}
}
return nil
}
func (e Engine) doExecuteComputer(ctx context.Context, c ImpureComputer, p MasterPlan) (any, error) {
result, err := c.Compute(ctx, p)
if tep, ok := result.(toExecutePlan); ok {
if err != nil {
return tep.mp, err
}
return tep.mp, tep.mp.Execute(ctx)
}
return result, err
}
func (e Engine) doExecuteSync(ctx context.Context, p MasterPlan, curPlanValue reflect.Value, components []parsedComponent) error {
for _, component := range components {
if c, ok := e.computers[component.id]; ok {
task := async.NewTask(
func(taskCtx context.Context) (any, error) {
return e.doExecuteComputer(taskCtx, c.computer, p)
},
)
result, err := task.RunSync(ctx).Outcome()
// Register Result/SyncResult in a sequential plan's field
if component.requireSet {
field := curPlanValue.Field(component.fieldIdx)
casted := func() reflect.Value {
if component.isSyncResult {
return reflect.ValueOf(newSyncResult(result)).Convert(component.fieldType)
}
return reflect.ValueOf(newResult(task)).Convert(component.fieldType)
}()
resultTakingIntoAccountPointerType := func() reflect.Value {
if !component.isPointerType {
return casted
}
rv := reflect.New(component.fieldType)
rv.Elem().Set(casted)
return rv
}()
field.Set(resultTakingIntoAccountPointerType)
}
if err != nil {
return err
}
continue
}
// Nested plan gets executed synchronously
if ap, ok := e.plans[component.id]; ok {
// Nested plan is always a value, never a pointer. Hence, no need to call Elem().
nestedPlanValue := curPlanValue.Field(component.fieldIdx)
err := e.doExecutePlan(ctx, component.id, p, nestedPlanValue, ap.isSequential)
if err != nil && err != ErrPlanExecutionEndingEarly {
return err
}
}
}
return nil
}
func (e Engine) doExecuteAsync(ctx context.Context, p MasterPlan, curPlanValue reflect.Value, components []parsedComponent) error {
tasks := make([]async.SilentTask, 0, len(components))
for _, component := range components {
componentID := component.id
if c, ok := e.computers[componentID]; ok {
task := async.NewTask(
func(taskCtx context.Context) (any, error) {
return e.doExecuteComputer(taskCtx, c.computer, p)
},
)
tasks = append(tasks, task)
// Register Result in a parallel plan's field
if component.requireSet {
field := curPlanValue.Field(component.fieldIdx)
resultTakingIntoAccountPointerType := func() reflect.Value {
casted := reflect.ValueOf(newResult(task)).Convert(component.fieldType)
if !component.isPointerType {
return casted
}
rv := reflect.New(component.fieldType)
rv.Elem().Set(casted)
return rv
}()
field.Set(resultTakingIntoAccountPointerType)
}
continue
}
// Nested plan gets executed asynchronously by wrapping it inside a task
if ap, ok := e.plans[componentID]; ok {
// Nested plan is always a value, never a pointer. Hence, no need to call Elem().
nestedPlanValue := curPlanValue.Field(component.fieldIdx)
task := async.NewSilentTask(
func(taskCtx context.Context) error {
err := e.doExecutePlan(taskCtx, componentID, p, nestedPlanValue, ap.isSequential)
if err != nil && err != ErrPlanExecutionEndingEarly {
return err
}
return nil
},
)
tasks = append(tasks, task)
}
}
g, groupCtx := errgroup.WithContext(ctx)
for _, task := range tasks {
t := task
g.Go(
func() error {
return t.ExecuteSync(groupCtx).Error()
},
)
}
return g.Wait()
}
func (e Engine) VerifyConfigurations() error {
for _, p := range e.plans {
if p.isMasterPlan {
rp := reflect.New(p.pType)
if err := isComplete(e, rp); err != nil {
return err
}
}
}
return nil
}
func (e Engine) findExistingPlanOrCreate(planName string) analyzedPlan {
if existing, ok := e.plans[planName]; ok {
return existing
}
return analyzedPlan{}
}
func (e Engine) findAnalyzedPlan(planName string, curPlanValue reflect.Value) analyzedPlan {
if len(planName) == 0 {
panic(ErrPlanNotAnalyzed.Err(curPlanValue.Type()))
}
ap, ok := e.plans[planName]
if !ok || len(ap.components) == 0 {
panic(ErrPlanNotAnalyzed.Err(planName))
}
return ap
}