Merge pull request #2012 from prometheus/context-consolidation

api: Consolidate web API contexts

vendor/github.com/prometheus/common/route/route.go

@@ -32,10 +32,38 @@ func WithParam(ctx context.Context, p, v string) context.Context {
 	return context.WithValue(ctx, param(p), v)
 }
 
-// handle turns a Handle into httprouter.Handle
-func handle(h http.HandlerFunc) httprouter.Handle {
-	return func(w http.ResponseWriter, r *http.Request, params httprouter.Params) {
-		ctx, cancel := context.WithCancel(context.Background())
+type contextFn func(r *http.Request) context.Context
+
+// Router wraps httprouter.Router and adds support for prefixed sub-routers
+// and per-request context injections.
+type Router struct {
+	rtr    *httprouter.Router
+	prefix string
+	ctxFn  contextFn
+}
+
+// New returns a new Router.
+func New(ctxFn contextFn) *Router {
+	if ctxFn == nil {
+		ctxFn = func(r *http.Request) context.Context {
+			return context.Background()
+		}
+	}
+	return &Router{
+		rtr:   httprouter.New(),
+		ctxFn: ctxFn,
+	}
+}
+
+// WithPrefix returns a router that prefixes all registered routes with prefix.
+func (r *Router) WithPrefix(prefix string) *Router {
+	return &Router{rtr: r.rtr, prefix: r.prefix + prefix, ctxFn: r.ctxFn}
+}
+
+// handle turns a HandlerFunc into an httprouter.Handle.
+func (r *Router) handle(h http.HandlerFunc) httprouter.Handle {
+	return func(w http.ResponseWriter, req *http.Request, params httprouter.Params) {
+		ctx, cancel := context.WithCancel(r.ctxFn(req))
 		defer cancel()
 
 		for _, p := range params {
@@ -43,56 +71,40 @@ func handle(h http.HandlerFunc) httprouter.Handle {
 		}
 
 		mtx.Lock()
-		ctxts[r] = ctx
+		ctxts[req] = ctx
 		mtx.Unlock()
 
-		h(w, r)
+		h(w, req)
 
 		mtx.Lock()
-		delete(ctxts, r)
+		delete(ctxts, req)
 		mtx.Unlock()
 	}
 }
 
-// Router wraps httprouter.Router and adds support for prefixed sub-routers.
-type Router struct {
-	rtr    *httprouter.Router
-	prefix string
-}
-
-// New returns a new Router.
-func New() *Router {
-	return &Router{rtr: httprouter.New()}
-}
-
-// WithPrefix returns a router that prefixes all registered routes with prefix.
-func (r *Router) WithPrefix(prefix string) *Router {
-	return &Router{rtr: r.rtr, prefix: r.prefix + prefix}
-}
-
 // Get registers a new GET route.
 func (r *Router) Get(path string, h http.HandlerFunc) {
-	r.rtr.GET(r.prefix+path, handle(h))
+	r.rtr.GET(r.prefix+path, r.handle(h))
 }
 
 // Options registers a new OPTIONS route.
 func (r *Router) Options(path string, h http.HandlerFunc) {
-	r.rtr.OPTIONS(r.prefix+path, handle(h))
+	r.rtr.OPTIONS(r.prefix+path, r.handle(h))
 }
 
 // Del registers a new DELETE route.
 func (r *Router) Del(path string, h http.HandlerFunc) {
-	r.rtr.DELETE(r.prefix+path, handle(h))
+	r.rtr.DELETE(r.prefix+path, r.handle(h))
 }
 
 // Put registers a new PUT route.
 func (r *Router) Put(path string, h http.HandlerFunc) {
-	r.rtr.PUT(r.prefix+path, handle(h))
+	r.rtr.PUT(r.prefix+path, r.handle(h))
 }
 
 // Post registers a new POST route.
 func (r *Router) Post(path string, h http.HandlerFunc) {
-	r.rtr.POST(r.prefix+path, handle(h))
+	r.rtr.POST(r.prefix+path, r.handle(h))
 }
 
 // Redirect takes an absolute path and sends an internal HTTP redirect for it,

vendor/vendor.json

@@ -211,8 +211,8 @@
 		{
 			"checksumSHA1": "CKVJRc1NREmfoAWQLHxqWQlvxo0=",
 			"path": "github.com/prometheus/common/route",
-			"revision": "4402f4e5ea79ec15f3c574773b6a5198fbea215f",
-			"revisionTime": "2016-06-23T15:14:27Z"
+			"revision": "ee21c31a8cbad2a29cce94a8c53855e1dab92bf7",
+			"revisionTime": "2016-09-21T02:27:24+02:00"
 		},
 		{
 			"checksumSHA1": "91KYK0SpvkaMJJA2+BcxbVnyRO0=",

web/api/v1/api.go

@@ -85,7 +85,6 @@ type apiFunc func(r *http.Request) (interface{}, *apiError)
 // API can register a set of endpoints in a router and handle
 // them using the provided storage and query engine.
 type API struct {
-	Context     context.Context
 	Storage     local.Storage
 	QueryEngine *promql.Engine
 
@@ -94,9 +93,8 @@ type API struct {
 }
 
 // NewAPI returns an initialized API type.
-func NewAPI(ctx context.Context, qe *promql.Engine, st local.Storage) *API {
+func NewAPI(qe *promql.Engine, st local.Storage) *API {
 	return &API{
-		Context:     ctx,
 		QueryEngine: qe,
 		Storage:     st,
 		context:     route.Context,
@@ -159,7 +157,7 @@ func (api *API) query(r *http.Request) (interface{}, *apiError) {
 		return nil, &apiError{errorBadData, err}
 	}
 
-	res := qry.Exec(api.Context)
+	res := qry.Exec(api.context(r))
 	if res.Err != nil {
 		switch res.Err.(type) {
 		case promql.ErrQueryCanceled:
@@ -206,7 +204,7 @@ func (api *API) queryRange(r *http.Request) (interface{}, *apiError) {
 		return nil, &apiError{errorBadData, err}
 	}
 
-	res := qry.Exec(api.Context)
+	res := qry.Exec(api.context(r))
 	if res.Err != nil {
 		switch res.Err.(type) {
 		case promql.ErrQueryCanceled:
@@ -228,7 +226,7 @@ func (api *API) labelValues(r *http.Request) (interface{}, *apiError) {
 	if !model.LabelNameRE.MatchString(name) {
 		return nil, &apiError{errorBadData, fmt.Errorf("invalid label name: %q", name)}
 	}
-	vals, err := api.Storage.LabelValuesForLabelName(api.Context, model.LabelName(name))
+	vals, err := api.Storage.LabelValuesForLabelName(api.context(r), model.LabelName(name))
 	if err != nil {
 		return nil, &apiError{errorExec, err}
 	}
@@ -274,7 +272,7 @@ func (api *API) series(r *http.Request) (interface{}, *apiError) {
 		matcherSets = append(matcherSets, matchers)
 	}
 
-	res, err := api.Storage.MetricsForLabelMatchers(api.Context, start, end, matcherSets...)
+	res, err := api.Storage.MetricsForLabelMatchers(api.context(r), start, end, matcherSets...)
 	if err != nil {
 		return nil, &apiError{errorExec, err}
 	}

web/api/v1/api_test.go

@@ -52,7 +52,6 @@ func TestEndpoints(t *testing.T) {
 	api := &API{
 		Storage:     suite.Storage(),
 		QueryEngine: suite.QueryEngine(),
-		Context:     suite.Context(),
 		now:         func() model.Time { return now },
 	}
 
@@ -610,7 +609,7 @@ func TestParseDuration(t *testing.T) {
 }
 
 func TestOptionsMethod(t *testing.T) {
-	r := route.New()
+	r := route.New(nil)
 	api := &API{}
 	api.Register(r)
 

web/web.go

@@ -120,7 +120,9 @@ type Options struct {
 
 // New initializes a new web Handler.
 func New(o *Options) *Handler {
-	router := route.New()
+	router := route.New(func(r *http.Request) context.Context {
+		return o.Context
+	})
 
 	h := &Handler{
 		router:      router,
@@ -138,7 +140,7 @@ func New(o *Options) *Handler {
 		queryEngine:   o.QueryEngine,
 		storage:       o.Storage,
 
-		apiV1: api_v1.NewAPI(o.Context, o.QueryEngine, o.Storage),
+		apiV1: api_v1.NewAPI(o.QueryEngine, o.Storage),
 		now:   model.Now,
 	}