progress so far

fetcher.go

@@ -40,13 +40,15 @@ type fetcher struct {
 }
 
 func NewFetcher(ctx context.Context /*options ...FetcherOption*/) Fetcher {
-	var nworkers int
+	nworkers := 1
 
 	incoming := make(chan *FetchRequest)
 	for i := 0; i < nworkers; i++ {
 		go runFetchWorker(ctx, incoming)
 	}
-	return &fetcher{}
+	return &fetcher{
+		requests: incoming,
+	}
 }
 
 // Fetch requests that a HTTP request be made on behalf of the caller,

go.mod

@@ -3,12 +3,14 @@ module github.com/lestrrat-go/httprc
 go 1.17
 
 require (
+	github.com/lestrrat-go/httpcc v1.0.0
 	github.com/lestrrat-go/option v1.0.0
 	github.com/stretchr/testify v1.7.1
 )
 
 require (
 	github.com/davecgh/go-spew v1.1.0 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
 )

go.sum

@@ -1,7 +1,11 @@
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/lestrrat-go/httpcc v1.0.0 h1:FszVC6cKfDvBKcJv646+lkh4GydQg2Z29scgUfkOpYc=
+github.com/lestrrat-go/httpcc v1.0.0/go.mod h1:tGS/u00Vh5N6FHNkExqGGNId8e0Big+++0Gf8MBnAvE=
 github.com/lestrrat-go/option v1.0.0 h1:WqAWL8kh8VcSoD6xjSH34/1m8yxluXQbDeKNfvFeEO4=
 github.com/lestrrat-go/option v1.0.0/go.mod h1:5ZHFbivi4xwXxhxY9XHDe2FHo6/Z7WWmtT7T5nBBp3I=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=

httprc.go

@@ -35,9 +35,17 @@ type Cache struct {
 	// Cached(string) bool
 }
 
-func New(ctx context.Context) *Cache {
+func New(ctx context.Context, options ...NewOption) *Cache {
+	refreshWindow := 15 * time.Minute
+	for _, option := range options {
+		//nolint:forcetypeassert
+		switch option.Ident() {
+		case identRefreshWindow{}:
+			refreshWindow = option.Value().(time.Duration)
+		}
+	}
 	fetch := NewFetcher(ctx)
-	queue := NewQueue(ctx, 5*time.Minute, fetch)
+	queue := NewQueue(ctx, refreshWindow, fetch)
 
 	return &Cache{
 		queue: queue,

httprc_test.go

@@ -0,0 +1,65 @@
+package httprc_test
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/lestrrat-go/httprc"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCache(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	var called int
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		select {
+		case <-ctx.Done():
+			return
+		default:
+		}
+
+		t.Logf("HTTP handler")
+		called++
+		w.Header().Set(`Cache-Control`, fmt.Sprintf(`max-age=%d`, 3))
+		w.WriteHeader(http.StatusOK)
+	}))
+	c := httprc.New(ctx, httprc.WithRefreshWindow(time.Second))
+
+	c.Register(srv.URL, httprc.WithHTTPClient(srv.Client()), httprc.WithMinRefreshInterval(time.Second))
+	/*
+		if !assert.True(t, c.IsRegistered(srv.URL)) {
+			return
+		}
+	*/
+
+	for i := 0; i < 3; i++ {
+		_, err := c.Get(ctx, srv.URL)
+		if !assert.NoError(t, err, `c.Get should succeed`) {
+			return
+		}
+	}
+	if !assert.Equal(t, 1, called, `there should only be one fetch request`) {
+		return
+	}
+
+	time.Sleep(4 * time.Second)
+	for i := 0; i < 3; i++ {
+		_, err := c.Get(ctx, srv.URL)
+		if !assert.NoError(t, err, `c.Get should succeed`) {
+			return
+		}
+	}
+	if !assert.Equal(t, 2, called, `there should only be one fetch request`) {
+		return
+	}
+
+	cancel()
+
+	time.Sleep(5 * time.Second)
+}

options.yaml

@@ -2,14 +2,17 @@ package_name: httprc
 output: options_gen.go
 interfaces:
   - name: RegisterOption
-  - name: MemoryCacheOption
+  - name: NewOption
 options:
   - ident: HTTPClient
     interface: RegisterOption
     argument_type: HTTPClient
+  - ident: MinRefreshInterval
+    interface: RegisterOption
+    argument_type: time.Duration
   - ident: RefreshInterval
     interface: RegisterOption
     argument_type: time.Duration
   - ident: RefreshWindow
-    interface: MemoryCacheOption
+    interface: NewOption
     argument_type: time.Duration

options_gen.go

@@ -10,16 +10,16 @@ import (
 
 type Option = option.Interface
 
-type MemoryCacheOption interface {
+type NewOption interface {
 	Option
-	memoryCacheOption()
+	newOption()
 }
 
-type memoryCacheOption struct {
+type newOption struct {
 	Option
 }
 
-func (*memoryCacheOption) memoryCacheOption() {}
+func (*newOption) newOption() {}
 
 type RegisterOption interface {
 	Option
@@ -33,13 +33,18 @@ type registerOption struct {
 func (*registerOption) registerOption() {}
 
 type identHTTPClient struct{}
+type identMinRefreshInterval struct{}
 type identRefreshInterval struct{}
 type identRefreshWindow struct{}
 
 func (identHTTPClient) String() string {
 	return "WithHTTPClient"
 }
 
+func (identMinRefreshInterval) String() string {
+	return "WithMinRefreshInterval"
+}
+
 func (identRefreshInterval) String() string {
 	return "WithRefreshInterval"
 }
@@ -52,10 +57,14 @@ func WithHTTPClient(v HTTPClient) RegisterOption {
 	return &registerOption{option.New(identHTTPClient{}, v)}
 }
 
+func WithMinRefreshInterval(v time.Duration) RegisterOption {
+	return &registerOption{option.New(identMinRefreshInterval{}, v)}
+}
+
 func WithRefreshInterval(v time.Duration) RegisterOption {
 	return &registerOption{option.New(identRefreshInterval{}, v)}
 }
 
-func WithRefreshWindow(v time.Duration) MemoryCacheOption {
-	return &memoryCacheOption{option.New(identRefreshWindow{}, v)}
+func WithRefreshWindow(v time.Duration) NewOption {
+	return &newOption{option.New(identRefreshWindow{}, v)}
 }

options_gen_test.go

@@ -10,6 +10,7 @@ import (
 
 func TestOptionIdent(t *testing.T) {
 	require.Equal(t, "WithHTTPClient", identHTTPClient{}.String())
+	require.Equal(t, "WithMinRefreshInterval", identMinRefreshInterval{}.String())
 	require.Equal(t, "WithRefreshInterval", identRefreshInterval{}.String())
 	require.Equal(t, "WithRefreshWindow", identRefreshWindow{}.String())
 }