gRPC integration (#12)

* Add initial stats API.

* fixed readme.md file

* fixed readme.md file

* fixing yaml file

* fixing yaml file

* remove go 1.7 and 1.6 from yaml file as we use 'sort.Slice' that is only supportted in 1.8 and above

* Added to README.md a section about modifying the reporting interval.

* Using inheritence instead of type switch for creating aggregationValue and aggregator. Also added equality as an interface to aggregationValue

* Deleted not used directories

* implemented automatic registration for measures on creation

* implemented codec for tags to be used in GRPC

* implemented codec for tags to be used in GRPC

* implemented codec for tags to be used in GRPC

* Fixed readme.md typos. Changed API to create a tagSet builder

* added convenience methods to various structs: String(), Equal(), Contains()... Also renamed some methods to be more succint and fixed some documentation issues

* added getter methods to interfaces and made some fields public to eventually support conversions to other formats

* addressed commnets for the pull request. Fixed both method names and readme.md.

* added installation and prereq comments to readme.md

* Fixed aggregationDistirbution to include oldest bucket in interval stats

* Added plugin interceptor for grpc stats

* Added all defaults measures and views to be collected for grpc stats

* Addressed PR comments. Modified readme.md to mention the requirement for Go1.9 to integrate with libraries still using golang.org/x/net/context.Context. Fixed the license headings to refer to opencensus instead of google.

* Made serverHandler and clientHandler private and added exported constructor for them.

* Requires Go 1.9 to take advantage of context type aliasing.

* Requiring Go 1.9 seems quite limiting. So I went ahead and replaced context by golang.org/x/net/context and reduced the requirement to 1.8

* Reworded comments for NewTestingAggregationDistributionValue

* Renamed NewTestingAggregationDistributionValue to NewDoNotUseTestingAggregationDistributionValue

* Fixed naming NewTestingAggregationDistributionValue to NewDoNotUseTestingAggregationDistributionValue in server_handler_test.go

* Added gofmt to .travis script. Fixed formatting issues

.travis.yml

@@ -16,5 +16,6 @@ before_script:
   - PKGS=$(go list ./... | grep -v /vendor/)             # All the import paths, excluding vendor/ if any
 
 script:
+  - gofmt -w ./
   - go test -v -race $PKGS            # Run all the tests with the race detector enabled
   - 'if [[ $TRAVIS_GO_VERSION = 1.8* ]]; then ! golint ./... | grep -vE "(_mock|_string|\.pb)\.go:"; fi'

README.md

@@ -20,7 +20,7 @@ To install this package, you need to install Go and setup your Go workspace on y
 $ go get -u github.com/census-instrumentation/opencensus-go
 
 ## Prerequisites
-This requires Go 1.8 or later as it uses the convenience function sort.Slice(...) in few places.
+This requires Go 1.8 or later as it uses the convenience function sort.Slice(...) introduced in Go 1.8.
 
 ## Tags
 

plugins/grpc/handlers.go

@@ -0,0 +1,75 @@
+// Copyright 2017, OpenCensus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+package grpc
+
+import (
+	"golang.org/x/net/context"
+
+	"google.golang.org/grpc/stats"
+)
+
+// Handlers is a composite type implementing the "google.golang.org/grpc/stats.Handler"
+// interface to process lifecycle events from a GRPC client or server. Its only
+// purpose is to allow for chaining others types implementing the "google.golang.org/grpc/stats.Handler"
+// interface. In this package it allows both stats and tracing subHandlers to be chained together.
+type Handlers struct {
+	subHandlers []stats.Handler
+}
+
+// TagConn can attach some information to the given context. The returned
+// context will be used for stats handling. For conn stats handling, the
+// context used in HandleConn for this connection will be derived from the
+// context returned.
+// For client RPC stats handling, the context used in HandleRPC is not derived
+// from the context returned.
+// For server RPC stats handling, the context used in HandleRPC for all RPCs on
+// this connection will be derived from this returned context.
+func (h Handlers) TagConn(ctx context.Context, info *stats.ConnTagInfo) context.Context {
+	for _, sh := range h.subHandlers {
+		ctx = sh.TagConn(ctx, info)
+	}
+	return ctx
+}
+
+// HandleConn calls all registered connection subHandlers.
+func (h Handlers) HandleConn(ctx context.Context, s stats.ConnStats) {
+	for _, sh := range h.subHandlers {
+		sh.HandleConn(ctx, s)
+	}
+}
+
+// TagRPC can attach some information to the given context. The returned
+// context is used in the rest lifetime of the RPC.
+func (h Handlers) TagRPC(ctx context.Context, info *stats.RPCTagInfo) context.Context {
+	for _, sh := range h.subHandlers {
+		ctx = sh.TagRPC(ctx, info)
+	}
+	return ctx
+}
+
+// HandleRPC calls all registered RPC subHandlers.
+func (h Handlers) HandleRPC(ctx context.Context, s stats.RPCStats) {
+	for _, sh := range h.subHandlers {
+		sh.HandleRPC(ctx, s)
+	}
+}
+
+// AddHandler adds a handler to the list of registered subHandlers. This list
+// contains all the subhandlers that will be called during HandleConn and
+// HandleRPC.
+func (h Handlers) AddHandler(sh stats.Handler) {
+	h.subHandlers = append(h.subHandlers, sh)
+}

plugins/grpc/stats/client_handler.go

@@ -0,0 +1,178 @@
+// Copyright 2017, OpenCensus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+package stats
+
+import (
+	"strings"
+	"sync/atomic"
+	"time"
+
+	istats "github.com/census-instrumentation/opencensus-go/stats"
+	"github.com/census-instrumentation/opencensus-go/tags"
+	"github.com/golang/glog"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc/stats"
+)
+
+var (
+	// grpcClientConnKey is the key used to store client instrumentation
+	// connection related data into the context.
+	grpcClientConnKey *grpcInstrumentationKey
+	// grpcClientRPCKey is the key used to store client instrumentation RPC
+	// related data into the context.
+	grpcClientRPCKey *grpcInstrumentationKey
+)
+
+// clientHandler is the type implementing the "google.golang.org/grpc/stats.Handler"
+// interface to process lifecycle events from the GRPC client.
+type clientHandler struct{}
+
+// NewClientHandler returns the "google.golang.org/grpc/stats.Handler"
+// implementation for the grpc client.
+func NewClientHandler() stats.Handler {
+	return clientHandler{}
+}
+
+// TagConn adds connection related data to the given context and returns the
+// new context.
+func (ch clientHandler) TagConn(ctx context.Context, info *stats.ConnTagInfo) context.Context {
+	// Do nothing. This is here to satisfy the interface "google.golang.org/grpc/stats.Handler"
+	return ctx
+}
+
+// HandleConn processes the connection events.
+func (ch clientHandler) HandleConn(ctx context.Context, s stats.ConnStats) {
+	// Do nothing. This is here to satisfy the interface "google.golang.org/grpc/stats.Handler"
+}
+
+// TagRPC gets the github.com/census-instrumentation/opencensus-go/tags.TagsSet
+// populated by the application code, serializes its tags into the GRPC
+// metadata in order to be sent to the server.
+func (ch clientHandler) TagRPC(ctx context.Context, info *stats.RPCTagInfo) context.Context {
+	startTime := time.Now()
+	if ctx == nil {
+		if glog.V(2) {
+			glog.Infoln("clientHandler.TagRPC called with nil context")
+		}
+		return ctx
+	}
+
+	if info == nil {
+		if glog.V(2) {
+			glog.Infof("clientHandler.TagRPC called with nil info.", info.FullMethodName)
+		}
+		return ctx
+	}
+	names := strings.Split(info.FullMethodName, "/")
+	if len(names) != 3 {
+		if glog.V(2) {
+			glog.Infof("clientHandler.TagRPC called with info.FullMethodName bad format. got %v, want '/$service/$method/'", info.FullMethodName)
+		}
+		return ctx
+	}
+	serviceName := names[1]
+	methodName := names[2]
+
+	d := &rpcData{
+		startTime: startTime,
+	}
+
+	ts := tags.FromContext(ctx)
+	encoded := tags.EncodeToFullSignature(ts)
+	ctx = stats.SetTags(ctx, encoded)
+
+	tsb := tags.NewTagSetBuilder(ts)
+	tsb.UpsertString(keyService, serviceName)
+	tsb.UpsertString(keyMethod, methodName)
+
+	// TODO(acetechnologist): should we be recording this later? What is the
+	// point of updating d.reqLen & d.reqCount if we update now?
+	ctx = tags.NewContext(ctx, tsb.Build())
+	istats.RecordInt64(ctx, RPCClientStartedCount, 1)
+
+	return context.WithValue(ctx, grpcClientRPCKey, d)
+}
+
+// HandleRPC processes the RPC events.
+func (ch clientHandler) HandleRPC(ctx context.Context, s stats.RPCStats) {
+	switch st := s.(type) {
+	case *stats.Begin, *stats.OutHeader, *stats.InHeader, *stats.InTrailer, *stats.OutTrailer:
+		// do nothing for client
+	case *stats.OutPayload:
+		ch.handleRPCOutPayload(ctx, st)
+	case *stats.InPayload:
+		ch.handleRPCInPayload(ctx, st)
+	case *stats.End:
+		ch.handleRPCEnd(ctx, st)
+	default:
+		glog.Infof("unexpected stats: %T", st)
+	}
+}
+
+func (ch clientHandler) handleRPCOutPayload(ctx context.Context, s *stats.OutPayload) {
+	d, ok := ctx.Value(grpcClientRPCKey).(*rpcData)
+	if !ok {
+		if glog.V(2) {
+			glog.Infoln("clientHandler.handleRPCOutPayload failed to retrieve *rpcData from context")
+		}
+		return
+	}
+
+	istats.RecordInt64(ctx, RPCClientRequestBytes, int64(s.Length))
+	atomic.AddUint64(&d.reqCount, 1)
+}
+
+func (ch clientHandler) handleRPCInPayload(ctx context.Context, s *stats.InPayload) {
+	d, ok := ctx.Value(grpcClientRPCKey).(*rpcData)
+	if !ok {
+		if glog.V(2) {
+			glog.Infoln("clientHandler.handleRPCInPayload failed to retrieve *rpcData from context")
+		}
+		return
+	}
+
+	istats.RecordInt64(ctx, RPCClientResponseBytes, int64(s.Length))
+	atomic.AddUint64(&d.respCount, 1)
+}
+
+func (ch clientHandler) handleRPCEnd(ctx context.Context, s *stats.End) {
+	d, ok := ctx.Value(grpcClientRPCKey).(*rpcData)
+	if !ok {
+		if glog.V(2) {
+			glog.Infoln("clientHandler.handleRPCEnd failed to retrieve *rpcData from context")
+		}
+		return
+	}
+	elapsedTime := time.Since(d.startTime)
+
+	var measurements []istats.Measurement
+	measurements = append(measurements, RPCClientRequestCount.Is(int64(d.reqCount)))
+	measurements = append(measurements, RPCClientResponseCount.Is(int64(d.respCount)))
+	measurements = append(measurements, RPCClientFinishedCount.Is(1))
+	measurements = append(measurements, RPCClientRoundTripLatency.Is(float64(elapsedTime)/float64(time.Millisecond)))
+
+	if s.Error != nil {
+		errorCode := s.Error.Error()
+		ts := tags.FromContext(ctx)
+		tsb := tags.NewTagSetBuilder(ts)
+		tsb.UpsertString(keyOpStatus, errorCode)
+
+		ctx = tags.NewContext(ctx, tsb.Build())
+		measurements = append(measurements, RPCClientErrorCount.Is(1))
+	}
+
+	istats.Record(ctx, measurements...)
+}