generator: Change the signature of the Cron Job Handler

README.md

@@ -7,6 +7,7 @@ Ultimately, kun may support the following communication types:
 - In-process function call
 - RPC (e.g., HTTP and gRPC)
 - Asynchronous messaging
+- Cron Jobs
 
 中文博客：[Go 服务通信工具 Kun](http://russellluo.com/2021/12/kun.html)。
 
@@ -44,7 +45,7 @@ Ultimately, kun may support the following communication types:
         + [x] Event Subscriber
         + [x] Event Publisher
    - [x] Cron
-       + [x] Cron Job Handler
+       + [x] Cron Jobs
 
 2. Useful Packages
 
@@ -856,7 +857,7 @@ See the [OAS Schema](https://github.com/RussellLuo/kun/blob/master/pkg/oas2/sche
     ```go
     type Service interface {
         //kun:cron expr='@every 5s'
-        SendEmail()
+        SendEmail(ctx context.Context) error
     }
 
     // job: {"name": "send_email", "expr": "@every 5s"}
@@ -867,7 +868,7 @@ See the [OAS Schema](https://github.com/RussellLuo/kun/blob/master/pkg/oas2/sche
     ```go
     type Service interface {
         //kun:cron name=send expr='@every 5s'
-        SendEmail()
+        SendEmail(ctx context.Context) error
     }
 
     // job: {"name": "send", "expr": "@every 5s"}

examples/cronsvc/service.go

@@ -1,6 +1,7 @@
 package cronsvc
 
 import (
+	"context"
 	"log"
 )
 
@@ -9,11 +10,12 @@ import (
 // Service is used for handling cron jobs.
 type Service interface {
 	//kun:cron expr='@every 5s'
-	SendEmail()
+	SendEmail(ctx context.Context) error
 }
 
 type Handler struct{}
 
-func (h *Handler) SendEmail() {
+func (h *Handler) SendEmail(ctx context.Context) error {
 	log.Println("Sending an email")
+	return nil
 }

gen/cron/generator/generator.go

@@ -32,7 +32,7 @@ func NewCronJobs(svc {{$.Data.SrcPkgQualifier}}{{$.Data.InterfaceName}}) []micro
 		{
 			Name: "{{getJobName .GoMethodName}}",
 			Expr: "{{getJobExpr .GoMethodName}}",
-			Task: svc.{{.Name}},
+			Handler: svc.{{.Name}},
 		},
 		{{end -}} {{/* range .Spec.Operations */ -}}
 	}

gen/cron/parser/parser.go

@@ -2,6 +2,7 @@ package parser
 
 import (
 	"fmt"
+	"go/types"
 	"regexp"
 
 	"github.com/RussellLuo/kun/gen/util/annotation"
@@ -23,8 +24,9 @@ func Parse(data *ifacetool.Data, snakeCase bool) (map[string]*Job, error) {
 	c := make(map[string]*Job)
 
 	for _, m := range data.Methods {
-		job := new(Job)
-		c[m.Name] = job
+		if !validateSignature(m) {
+			return nil, fmt.Errorf("the signature of method %s must be `func(context.Context) error` when annotated by %s directive", m.Name, annotation.DirectiveCron)
+		}
 
 		for _, comment := range m.Doc {
 			if annotation.Directive(comment).Dialect() != annotation.DialectCron {
@@ -41,6 +43,8 @@ func Parse(data *ifacetool.Data, snakeCase bool) (map[string]*Job, error) {
 				return nil, err
 			}
 
+			job := new(Job)
+
 			for _, pair := range pairs {
 				switch pair.Key {
 				case "name":
@@ -52,6 +56,8 @@ func Parse(data *ifacetool.Data, snakeCase bool) (map[string]*Job, error) {
 				}
 			}
 
+			// Here we assume that all annotation keys are specified in the same line.
+
 			if job.Name == "" {
 				job.Name = caseconv.ToLowerCamelCase(m.Name)
 				if snakeCase {
@@ -62,8 +68,29 @@ func Parse(data *ifacetool.Data, snakeCase bool) (map[string]*Job, error) {
 			if job.Expr == "" {
 				return nil, fmt.Errorf(`missing key "expr" for %s directive in comment: %s`, annotation.DirectiveCron, comment)
 			}
+
+			c[m.Name] = job
+			break // No need to continue since we have found the annotation.
 		}
 	}
 
 	return c, nil
 }
+
+func validateSignature(m *ifacetool.Method) bool {
+	if len(m.Params) != 1 || len(m.Returns) != 1 {
+		return false
+	}
+
+	p := m.Params[0]
+	if _, ok := p.Type.Underlying().(*types.Interface); !ok || p.TypeString != "context.Context" {
+		return false
+	}
+
+	r := m.Returns[0]
+	if _, ok := r.Type.Underlying().(*types.Interface); !ok || r.TypeString != "error" {
+		return false
+	}
+
+	return true
+}

go.mod

@@ -4,7 +4,7 @@ go 1.16
 
 require (
 	github.com/RussellLuo/appx v0.0.0-20221005075435-c578768595db
-	github.com/RussellLuo/micron v0.0.0-20221008065742-31d1b4e95230
+	github.com/RussellLuo/micron v0.0.0-20221009070337-abf7aee8c3d5
 	github.com/RussellLuo/validating/v2 v2.1.1
 	github.com/go-chi/chi v4.1.2+incompatible
 	github.com/go-kit/kit v0.10.0

go.sum

@@ -4,8 +4,8 @@ github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03
 github.com/Knetic/govaluate v3.0.1-0.20171022003610-9aa49832a739+incompatible/go.mod h1:r7JcOSlj0wfOMncg0iLm8Leh48TZaKVeNIfJntJ2wa0=
 github.com/RussellLuo/appx v0.0.0-20221005075435-c578768595db h1:apVxO5ghwD7dOEzeCuBOuEIF9zqiffW0/8RoghDn4vw=
 github.com/RussellLuo/appx v0.0.0-20221005075435-c578768595db/go.mod h1:BYiSO63uqNy81Mlv9EfnJ+wNr+vkgAohKMgeDyhWu1s=
-github.com/RussellLuo/micron v0.0.0-20221008065742-31d1b4e95230 h1:B2qSHwpUWyIa7BGJHNLNPu/eOmT8ocLEeOQ5V+TvBJE=
-github.com/RussellLuo/micron v0.0.0-20221008065742-31d1b4e95230/go.mod h1:dSJ4Da5HdXgw8m9O8V0T5p+HQNEblPx01mXpV8tX2NY=
+github.com/RussellLuo/micron v0.0.0-20221009070337-abf7aee8c3d5 h1:9C+0p+Ixdh7lZEbzX4VnIV39Jx6pCj1aQRUULcZbIGY=
+github.com/RussellLuo/micron v0.0.0-20221009070337-abf7aee8c3d5/go.mod h1:dSJ4Da5HdXgw8m9O8V0T5p+HQNEblPx01mXpV8tX2NY=
 github.com/RussellLuo/validating/v2 v2.1.1 h1:lIqtzIgoeW1Rs4Oouo6Twk0HRxFjKgEZARMuOlT4hh0=
 github.com/RussellLuo/validating/v2 v2.1.1/go.mod h1:FCrcxiiCo8FXMbKoALpXAHkGXZoVh5pWVboC+GVruiI=
 github.com/Shopify/sarama v1.19.0/go.mod h1:FVkBWblsNy7DGZRfXLU0O9RCGt5g3g3yEuWXgklEdEo=