Initial commit for proposed query handlers refactoring:

 * updated CustomHandler interface
 * unified how query routes are added. no need to pass router around and wrapping is done in one place.
 * routes are registered with names so they could be easily found later when custom handlers are registered.

src/query/api/v1/handler/database/common.go

@@ -27,10 +27,7 @@ import (
 	dbconfig "github.com/m3db/m3/src/cmd/services/m3dbnode/config"
 	"github.com/m3db/m3/src/cmd/services/m3query/config"
 	"github.com/m3db/m3/src/query/api/v1/handler/prometheus/handleroptions"
-	"github.com/m3db/m3/src/query/util/logging"
 	"github.com/m3db/m3/src/x/instrument"
-
-	"github.com/gorilla/mux"
 )
 
 // Handler represents a generic handler for namespace endpoints.
@@ -43,31 +40,23 @@ type Handler struct {
 
 // RegisterRoutes registers the namespace routes
 func RegisterRoutes(
-	r *mux.Router,
+	addRoute func(path string, handler http.Handler, methods ...string),
 	client clusterclient.Client,
 	cfg config.Configuration,
 	embeddedDbCfg *dbconfig.DBConfiguration,
 	defaults []handleroptions.ServiceOptionsDefault,
 	instrumentOpts instrument.Options,
 ) error {
-	wrapped := func(n http.Handler) http.Handler {
-		return logging.WithResponseTimeAndPanicErrorLogging(n, instrumentOpts)
-	}
-
 	createHandler, err := NewCreateHandler(client, cfg, embeddedDbCfg,
 		defaults, instrumentOpts)
 	if err != nil {
 		return err
 	}
 
-	r.HandleFunc(CreateURL,
-		wrapped(createHandler).ServeHTTP).
-		Methods(CreateHTTPMethod)
-
 	// Register the same handler under two different endpoints. This just makes explaining things in
 	// our documentation easier so we can separate out concepts, but share the underlying code.
-	r.HandleFunc(CreateURL, wrapped(createHandler).ServeHTTP).Methods(CreateHTTPMethod)
-	r.HandleFunc(CreateNamespaceURL, wrapped(createHandler).ServeHTTP).Methods(CreateNamespaceHTTPMethod)
+	addRoute(CreateURL, createHandler, CreateHTTPMethod)
+	addRoute(CreateNamespaceURL, createHandler, CreateNamespaceHTTPMethod)
 
 	return nil
 }

src/query/api/v1/handler/namespace/common.go

@@ -33,11 +33,8 @@ import (
 	"github.com/m3db/m3/src/dbnode/namespace"
 	"github.com/m3db/m3/src/query/api/v1/handler/prometheus/handleroptions"
 	"github.com/m3db/m3/src/query/storage/m3"
-	"github.com/m3db/m3/src/query/util/logging"
 	"github.com/m3db/m3/src/x/instrument"
 	xhttp "github.com/m3db/m3/src/x/net/http"
-
-	"github.com/gorilla/mux"
 )
 
 const (
@@ -104,15 +101,12 @@ func Metadata(store kv.Store) ([]namespace.Metadata, int, error) {
 
 // RegisterRoutes registers the namespace routes.
 func RegisterRoutes(
-	r *mux.Router,
+	addRoute func(path string, handler http.Handler, methods ...string),
 	client clusterclient.Client,
 	clusters m3.Clusters,
 	defaults []handleroptions.ServiceOptionsDefault,
 	instrumentOpts instrument.Options,
 ) {
-	wrapped := func(n http.Handler) http.Handler {
-		return logging.WithResponseTimeAndPanicErrorLogging(n, instrumentOpts)
-	}
 	applyMiddleware := func(
 		f func(svc handleroptions.ServiceNameAndDefaults,
 			w http.ResponseWriter, r *http.Request),
@@ -128,40 +122,32 @@ func RegisterRoutes(
 	}
 
 	// Get M3DB namespaces.
-	getHandler := wrapped(
-		applyMiddleware(NewGetHandler(client, instrumentOpts).ServeHTTP, defaults))
-	r.HandleFunc(M3DBGetURL, getHandler.ServeHTTP).Methods(GetHTTPMethod)
+	getHandler := applyMiddleware(NewGetHandler(client, instrumentOpts).ServeHTTP, defaults)
+	addRoute(M3DBGetURL, getHandler, GetHTTPMethod)
 
 	// Add M3DB namespaces.
-	addHandler := wrapped(
-		applyMiddleware(NewAddHandler(client, instrumentOpts).ServeHTTP, defaults))
-	r.HandleFunc(M3DBAddURL, addHandler.ServeHTTP).Methods(AddHTTPMethod)
+	addHandler := applyMiddleware(NewAddHandler(client, instrumentOpts).ServeHTTP, defaults)
+	addRoute(M3DBAddURL, addHandler, AddHTTPMethod)
 
 	// Update M3DB namespaces.
-	updateHandler := wrapped(
-		applyMiddleware(NewUpdateHandler(client, instrumentOpts).ServeHTTP, defaults))
-	r.HandleFunc(M3DBUpdateURL, updateHandler.ServeHTTP).Methods(UpdateHTTPMethod)
+	updateHandler := applyMiddleware(NewUpdateHandler(client, instrumentOpts).ServeHTTP, defaults)
+	addRoute(M3DBUpdateURL, updateHandler, UpdateHTTPMethod)
 
 	// Delete M3DB namespaces.
-	deleteHandler := wrapped(
-		applyMiddleware(NewDeleteHandler(client, instrumentOpts).ServeHTTP, defaults))
-	r.HandleFunc(M3DBDeleteURL, deleteHandler.ServeHTTP).Methods(DeleteHTTPMethod)
+	deleteHandler := applyMiddleware(NewDeleteHandler(client, instrumentOpts).ServeHTTP, defaults)
+	addRoute(M3DBDeleteURL, deleteHandler, DeleteHTTPMethod)
 
 	// Deploy M3DB schemas.
-	schemaHandler := wrapped(
-		applyMiddleware(NewSchemaHandler(client, instrumentOpts).ServeHTTP, defaults))
-	r.HandleFunc(M3DBSchemaURL, schemaHandler.ServeHTTP).Methods(SchemaDeployHTTPMethod)
+	schemaHandler := applyMiddleware(NewSchemaHandler(client, instrumentOpts).ServeHTTP, defaults)
+	addRoute(M3DBSchemaURL, schemaHandler, SchemaDeployHTTPMethod)
 
 	// Reset M3DB schemas.
-	schemaResetHandler := wrapped(
-		applyMiddleware(NewSchemaResetHandler(client, instrumentOpts).ServeHTTP, defaults))
-	r.HandleFunc(M3DBSchemaURL, schemaResetHandler.ServeHTTP).Methods(DeleteHTTPMethod)
+	schemaResetHandler := applyMiddleware(NewSchemaResetHandler(client, instrumentOpts).ServeHTTP, defaults)
+	addRoute(M3DBSchemaURL, schemaResetHandler, DeleteHTTPMethod)
 
 	// Mark M3DB namespace as ready.
-	readyHandler := wrapped(
-		applyMiddleware(NewReadyHandler(client, clusters, instrumentOpts).ServeHTTP, defaults))
-	r.HandleFunc(M3DBReadyURL, readyHandler.ServeHTTP).Methods(ReadyHTTPMethod)
-
+	readyHandler := applyMiddleware(NewReadyHandler(client, clusters, instrumentOpts).ServeHTTP, defaults)
+	addRoute(M3DBReadyURL, readyHandler, ReadyHTTPMethod)
 }
 
 func validateNamespaceAggregationOptions(mds []namespace.Metadata) error {

src/query/api/v1/handler/placement/common.go

@@ -42,8 +42,6 @@ import (
 	xerrors "github.com/m3db/m3/src/x/errors"
 	"github.com/m3db/m3/src/x/instrument"
 	xhttp "github.com/m3db/m3/src/x/net/http"
-
-	"github.com/gorilla/mux"
 )
 
 const (
@@ -222,7 +220,7 @@ func ConvertInstancesProto(instancesProto []*placementpb.Instance) ([]placement.
 
 // RegisterRoutes registers the placement routes
 func RegisterRoutes(
-	r *mux.Router,
+	addRoute func(path string, handler http.Handler, methods ...string),
 	defaults []handleroptions.ServiceOptionsDefault,
 	opts HandlerOptions,
 ) {
@@ -231,63 +229,64 @@ func RegisterRoutes(
 		initHandler = NewInitHandler(opts)
 		initFn      = applyMiddleware(initHandler.ServeHTTP, defaults, opts.instrumentOptions)
 	)
-	r.HandleFunc(M3DBInitURL, initFn).Methods(InitHTTPMethod)
-	r.HandleFunc(M3AggInitURL, initFn).Methods(InitHTTPMethod)
-	r.HandleFunc(M3CoordinatorInitURL, initFn).Methods(InitHTTPMethod)
+
+	addRoute(M3DBInitURL, initFn, InitHTTPMethod)
+	addRoute(M3AggInitURL, initFn, InitHTTPMethod)
+	addRoute(M3CoordinatorInitURL, initFn, InitHTTPMethod)
 
 	// Get
 	var (
 		getHandler = NewGetHandler(opts)
 		getFn      = applyMiddleware(getHandler.ServeHTTP, defaults, opts.instrumentOptions)
 	)
-	r.HandleFunc(M3DBGetURL, getFn).Methods(GetHTTPMethod)
-	r.HandleFunc(M3AggGetURL, getFn).Methods(GetHTTPMethod)
-	r.HandleFunc(M3CoordinatorGetURL, getFn).Methods(GetHTTPMethod)
+	addRoute(M3DBGetURL, getFn, GetHTTPMethod)
+	addRoute(M3AggGetURL, getFn, GetHTTPMethod)
+	addRoute(M3CoordinatorGetURL, getFn, GetHTTPMethod)
 
 	// Delete all
 	var (
 		deleteAllHandler = NewDeleteAllHandler(opts)
 		deleteAllFn      = applyMiddleware(deleteAllHandler.ServeHTTP, defaults, opts.instrumentOptions)
 	)
-	r.HandleFunc(M3DBDeleteAllURL, deleteAllFn).Methods(DeleteAllHTTPMethod)
-	r.HandleFunc(M3AggDeleteAllURL, deleteAllFn).Methods(DeleteAllHTTPMethod)
-	r.HandleFunc(M3CoordinatorDeleteAllURL, deleteAllFn).Methods(DeleteAllHTTPMethod)
+	addRoute(M3DBDeleteAllURL, deleteAllFn, DeleteAllHTTPMethod)
+	addRoute(M3AggDeleteAllURL, deleteAllFn, DeleteAllHTTPMethod)
+	addRoute(M3CoordinatorDeleteAllURL, deleteAllFn, DeleteAllHTTPMethod)
 
 	// Add
 	var (
 		addHandler = NewAddHandler(opts)
 		addFn      = applyMiddleware(addHandler.ServeHTTP, defaults, opts.instrumentOptions)
 	)
-	r.HandleFunc(M3DBAddURL, addFn).Methods(AddHTTPMethod)
-	r.HandleFunc(M3AggAddURL, addFn).Methods(AddHTTPMethod)
-	r.HandleFunc(M3CoordinatorAddURL, addFn).Methods(AddHTTPMethod)
+	addRoute(M3DBAddURL, addFn, AddHTTPMethod)
+	addRoute(M3AggAddURL, addFn, AddHTTPMethod)
+	addRoute(M3CoordinatorAddURL, addFn, AddHTTPMethod)
 
 	// Delete
 	var (
 		deleteHandler = NewDeleteHandler(opts)
 		deleteFn      = applyMiddleware(deleteHandler.ServeHTTP, defaults, opts.instrumentOptions)
 	)
-	r.HandleFunc(M3DBDeleteURL, deleteFn).Methods(DeleteHTTPMethod)
-	r.HandleFunc(M3AggDeleteURL, deleteFn).Methods(DeleteHTTPMethod)
-	r.HandleFunc(M3CoordinatorDeleteURL, deleteFn).Methods(DeleteHTTPMethod)
+	addRoute(M3DBDeleteURL, deleteFn, DeleteHTTPMethod)
+	addRoute(M3AggDeleteURL, deleteFn, DeleteHTTPMethod)
+	addRoute(M3CoordinatorDeleteURL, deleteFn, DeleteHTTPMethod)
 
 	// Replace
 	var (
 		replaceHandler = NewReplaceHandler(opts)
 		replaceFn      = applyMiddleware(replaceHandler.ServeHTTP, defaults, opts.instrumentOptions)
 	)
-	r.HandleFunc(M3DBReplaceURL, replaceFn).Methods(ReplaceHTTPMethod)
-	r.HandleFunc(M3AggReplaceURL, replaceFn).Methods(ReplaceHTTPMethod)
-	r.HandleFunc(M3CoordinatorReplaceURL, replaceFn).Methods(ReplaceHTTPMethod)
+	addRoute(M3DBReplaceURL, replaceFn, ReplaceHTTPMethod)
+	addRoute(M3AggReplaceURL, replaceFn, ReplaceHTTPMethod)
+	addRoute(M3CoordinatorReplaceURL, replaceFn, ReplaceHTTPMethod)
 
 	// Set
 	var (
 		setHandler = NewSetHandler(opts)
 		setFn      = applyMiddleware(setHandler.ServeHTTP, defaults, opts.instrumentOptions)
 	)
-	r.HandleFunc(M3DBSetURL, setFn).Methods(SetHTTPMethod)
-	r.HandleFunc(M3AggSetURL, setFn).Methods(SetHTTPMethod)
-	r.HandleFunc(M3CoordinatorSetURL, setFn).Methods(SetHTTPMethod)
+	addRoute(M3DBSetURL, setFn, SetHTTPMethod)
+	addRoute(M3AggSetURL, setFn, SetHTTPMethod)
+	addRoute(M3CoordinatorSetURL, setFn, SetHTTPMethod)
 }
 
 func newPlacementCutoverNanosFn(
@@ -386,11 +385,11 @@ func applyMiddleware(
 	f func(svc handleroptions.ServiceNameAndDefaults, w http.ResponseWriter, r *http.Request),
 	defaults []handleroptions.ServiceOptionsDefault,
 	instrumentOpts instrument.Options,
-) func(w http.ResponseWriter, r *http.Request) {
+) http.Handler {
 	return logging.WithResponseTimeAndPanicErrorLoggingFunc(
 		parseServiceMiddleware(f, defaults),
 		instrumentOpts,
-	).ServeHTTP
+	)
 }
 
 func parseServiceMiddleware(

src/query/api/v1/handler/topic/common.go

@@ -29,13 +29,11 @@ import (
 	"github.com/m3db/m3/src/cmd/services/m3query/config"
 	"github.com/m3db/m3/src/msg/topic"
 	"github.com/m3db/m3/src/query/api/v1/handler/prometheus/handleroptions"
-	"github.com/m3db/m3/src/query/util/logging"
 	xerrors "github.com/m3db/m3/src/x/errors"
 	"github.com/m3db/m3/src/x/instrument"
 
 	"github.com/gogo/protobuf/jsonpb"
 	"github.com/gogo/protobuf/proto"
-	"github.com/gorilla/mux"
 )
 
 const (
@@ -71,30 +69,16 @@ func Service(clusterClient clusterclient.Client, opts handleroptions.ServiceOpti
 
 // RegisterRoutes registers the topic routes
 func RegisterRoutes(
-	r *mux.Router,
+	addRoute func(path string, handler http.Handler, methods ...string),
 	client clusterclient.Client,
 	cfg config.Configuration,
 	instrumentOpts instrument.Options,
 ) {
-	wrapped := func(n http.Handler) http.Handler {
-		return logging.WithResponseTimeAndPanicErrorLogging(n, instrumentOpts)
-	}
-
-	r.HandleFunc(InitURL,
-		wrapped(newInitHandler(client, cfg, instrumentOpts)).ServeHTTP).
-		Methods(InitHTTPMethod)
-	r.HandleFunc(GetURL,
-		wrapped(newGetHandler(client, cfg, instrumentOpts)).ServeHTTP).
-		Methods(GetHTTPMethod)
-	r.HandleFunc(AddURL,
-		wrapped(newAddHandler(client, cfg, instrumentOpts)).ServeHTTP).
-		Methods(AddHTTPMethod)
-	r.HandleFunc(UpdateURL,
-		wrapped(newUpdateHandler(client, cfg, instrumentOpts)).ServeHTTP).
-		Methods(UpdateHTTPMethod)
-	r.HandleFunc(DeleteURL,
-		wrapped(newDeleteHandler(client, cfg, instrumentOpts)).ServeHTTP).
-		Methods(DeleteHTTPMethod)
+	addRoute(InitURL, newInitHandler(client, cfg, instrumentOpts), InitHTTPMethod)
+	addRoute(GetURL, newGetHandler(client, cfg, instrumentOpts), GetHTTPMethod)
+	addRoute(AddURL, newAddHandler(client, cfg, instrumentOpts), AddHTTPMethod)
+	addRoute(UpdateURL, newUpdateHandler(client, cfg, instrumentOpts), UpdateHTTPMethod)
+	addRoute(DeleteURL, newDeleteHandler(client, cfg, instrumentOpts), DeleteHTTPMethod)
 }
 
 func topicName(headers http.Header) string {