Added metrics for session acquisition, switched from Clone to Copy for standard sessions, updated glide deps

glide.lock

@@ -1,10 +1,22 @@
 hash: a0f08cf80d876deff8376f2c3dfee8b5d2df8117d06e5337b508329ac10dcef2
-updated: 2018-03-27T21:03:11.417994706+02:00
+updated: 2019-07-02T12:22:38.011604+02:00
 imports:
+- name: github.com/beorn7/perks
+  version: 4b2b341e8d7715fae06375aa633dbb6e91b3fb46
+  subpackages:
+  - quantile
 - name: github.com/bwmarrin/snowflake
   version: 3107b1dd8c5258a02e5f63347dc1c30288c75af5
+- name: github.com/golang/protobuf
+  version: 1643683e1b54a9e88ad26d98f81400c8c9d9f4f9
+  subpackages:
+  - proto
+- name: github.com/matttproud/golang_protobuf_extensions
+  version: c12348ce28de40eed0136aa2b644d0ee0650e56c
+  subpackages:
+  - pbutil
 - name: github.com/mitchellh/mapstructure
-  version: f3009df150dadf309fdee4a54ed65c124afad715
+  version: 3536a929edddb9a5b34bd6861dc4a9647cb459fe
 - name: github.com/nbutton23/zxcvbn-go
   version: eafdab6b0663b4b528c35975c8b0e78be6e25261
   subpackages:
@@ -16,23 +28,39 @@ imports:
   - matching
   - scoring
   - utils/math
+- name: github.com/prometheus/client_golang
+  version: c5b7fccd204277076155f10851dad72b76a49317
+  subpackages:
+  - prometheus
+- name: github.com/prometheus/client_model
+  version: fa8ad6fec33561be4280a8f0514318c79d7f6cb6
+  subpackages:
+  - go
+- name: github.com/prometheus/common
+  version: 0d5de9d6d8629cb8bee6d4674da4127cd8b615a3
+  subpackages:
+  - expfmt
+  - internal/bitbucket.org/ww/goautoneg
+  - model
+- name: github.com/prometheus/procfs
+  version: abf152e5f3e97f2fafac028d2cc06c1feb87ffa5
 - name: github.com/sergi/go-diff
   version: 1744e2970ca51c86172c8190fadad617561ed6e7
   subpackages:
   - diffmatchpatch
 - name: github.com/skratchdot/open-golang
-  version: 75fb7ed4208cf72d323d7d02fd1a5964a7a9073c
+  version: 79abb63cd66e41cb1473e26d11ebdcd68b04c8e5
   subpackages:
   - open
 - name: github.com/ventu-io/go-shortid
   version: 6c56cef5189ca1b3d5ef01dc07f4d611dfc0bb33
 - name: golang.org/x/crypto
-  version: c197bcf24cde29d3f73c7b4ac6fd41f4384e8af6
+  version: 88737f569e3a9c7ab309cdc09a07fe7fc87233c3
   subpackages:
   - bcrypt
   - blowfish
 - name: gopkg.in/mgo.v2
-  version: 3f83fa5005286a7fe593b055f0d7771a7dce4655
+  version: 9856a29383ce1c59f308dd1cf0363a79b5bef6b5
   subpackages:
   - bson
   - internal/json
@@ -40,14 +68,18 @@ imports:
   - internal/scram
 testImports:
 - name: github.com/davecgh/go-spew
-  version: 346938d642f2ec3594ed81d874461961cd0faa76
+  version: 8991bc29aa16c548c550c7ff78260e27b9ab7c73
   subpackages:
   - spew
+- name: github.com/docker/docker
+  version: f5ec1e2936dcbe7b5001c2b817188b095c700c27
+  subpackages:
+  - pkg/testutil/assert
 - name: github.com/pmezard/go-difflib
-  version: d8ed2627bdf02c080bf22230dbb337003b7aba2d
+  version: 792786c7400a136282c1664665ae0a8db921c6c2
   subpackages:
   - difflib
 - name: github.com/stretchr/testify
-  version: 12b6f73e6084dad08a7c6e575284b177ecafbc71
+  version: ffdc059bfe9ce6a4e144ba849dbedead332c6053
   subpackages:
   - assert

persistence/metrics.go

@@ -0,0 +1,35 @@
+package persistence
+
+import "github.com/prometheus/client_golang/prometheus"
+
+const (
+	labelDB         = "db"
+	labelCollection = "collection"
+
+	namespace        = "foomo_shop"
+	subsystemService = "persistor"
+)
+
+var (
+	getStandardSessionCounter = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Namespace: namespace,
+			Subsystem: subsystemService,
+			Name:      "get_standard_session_count",
+			Help:      "count of standard session acquirements",
+		}, []string{labelDB, labelCollection},
+	)
+	getGlobalSessionCounter = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Namespace: namespace,
+			Subsystem: subsystemService,
+			Name:      "get_global_session_count",
+			Help:      "count of global session acquirements",
+		}, []string{labelDB, labelCollection},
+	)
+)
+
+func init() {
+	prometheus.MustRegister(getStandardSessionCounter)
+	prometheus.MustRegister(getGlobalSessionCounter)
+}

persistence/persistence.go

@@ -100,8 +100,15 @@ func (p *Persistor) EnsureIndexes(indexes []mgo.Index) error {
 }
 
 func (p *Persistor) GetCollection() (session *mgo.Session, collection *mgo.Collection) {
-	session = p.session.Clone()
+
+	// From the documentation of session.Clone: ..., it also means that long operations may cause other goroutines using the original session to wait.
+	// Lets try using Copy here and observe the impact
+	session = p.session.Copy()
 	collection = session.DB(p.db).C(p.collection)
+
+	// increment metrics for acquiring the STANDARD session
+	getStandardSessionCounter.WithLabelValues(p.db, p.collection).Inc()
+
 	return session, collection
 }
 
@@ -112,6 +119,10 @@ func (p *Persistor) GetGlobalSessionCollection() (collection *mgo.Collection) {
 	if err := p.session.Ping(); err != nil {
 		p.session.Refresh()
 	}
+
+	// increment metrics for acquiring the GLOBAL session
+	getGlobalSessionCounter.WithLabelValues(p.db, p.collection).Inc()
+
 	return p.session.DB(p.db).C(p.collection)
 }