store last vector clock instead of just last clock in the tracing server

Author: shayanh

go.mod

@@ -3,6 +3,6 @@ module github.com/DistributedClocks/tracing
 go 1.14
 
 require (
-	github.com/DistributedClocks/GoVector v0.0.0-20210401191024-1400ef02f9b0
+	github.com/DistributedClocks/GoVector v0.0.0-20210402100930-db949c81a0af
 	github.com/google/go-cmp v0.5.4
 )

go.sum

@@ -1,5 +1,7 @@
 github.com/DistributedClocks/GoVector v0.0.0-20210401191024-1400ef02f9b0 h1:HRWExv6qm+GjZGmsRmw2pyOLvPZn3CjHr+KopnaGBV8=
 github.com/DistributedClocks/GoVector v0.0.0-20210401191024-1400ef02f9b0/go.mod h1:KhO62KYM3s2gEKM3ESiiI4pgvEPHz96Y1R1ceFpyVBg=
+github.com/DistributedClocks/GoVector v0.0.0-20210402100930-db949c81a0af h1:dZA/5RPZb4h+6EPdMIyQ1SE62NBBGIp6O1UNowh+Ozg=
+github.com/DistributedClocks/GoVector v0.0.0-20210402100930-db949c81a0af/go.mod h1:KhO62KYM3s2gEKM3ESiiI4pgvEPHz96Y1R1ceFpyVBg=
 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/daviddengcn/go-colortext v1.0.0 h1:ANqDyC0ys6qCSvuEK7l3g5RaehL/Xck9EX8ATG8oKsE=

server.go

@@ -2,6 +2,7 @@ package tracing
 
 import (
 	"encoding/json"
+	"errors"
 	"io/ioutil"
 	"log"
 	"net"
@@ -32,8 +33,8 @@ type TracingServer struct {
 	shivizRecordFile *os.File
 	shivizLogger     *shivizLogger
 
-	lock   sync.RWMutex
-	lastVC vclock.VClock
+	lock    sync.RWMutex
+	lastVCs map[string]vclock.VClock
 }
 
 // RPCProvider is an abstraction to prevent registering non-RPC functions
@@ -72,7 +73,7 @@ func NewTracingServer(config TracingServerConfig) *TracingServer {
 	tracingServer := &TracingServer{
 		acceptDone: make(chan struct{}),
 		Config:     &config,
-		lastVC:     vclock.New(),
+		lastVCs:    make(map[string]vclock.VClock),
 	}
 	return tracingServer
 }
@@ -189,7 +190,7 @@ func (rp *RPCProvider) RecordAction(arg RecordActionArg, result *RecordActionRes
 	}
 
 	rp.server.lock.Lock()
-	rp.server.lastVC.Merge(arg.VectorClock)
+	rp.server.lastVCs[arg.TracerIdentity] = arg.VectorClock
 	rp.server.lock.Unlock()
 
 	if err := rp.server.recordEncoder.Encode(wrappedRecord); err != nil {
@@ -201,19 +202,18 @@ func (rp *RPCProvider) RecordAction(arg RecordActionArg, result *RecordActionRes
 	return nil
 }
 
-type GetLastClockArg string
+type GetLastVCArg string
 
-type GetLastClockResult uint64
+type GetLastVCResult vclock.VClock
 
-func (rp *RPCProvider) GetLastClock(arg GetLastClockArg, result *GetLastClockResult) error {
+func (rp *RPCProvider) GetLastVC(arg GetLastVCArg, result *GetLastVCResult) error {
 	rp.server.lock.RLock()
 	defer rp.server.lock.RUnlock()
 
-	value, ok := rp.server.lastVC.FindTicks(string(arg))
+	vc, ok := rp.server.lastVCs[string(arg)]
 	if !ok {
-		*result = GetLastClockResult(0)
-	} else {
-		*result = GetLastClockResult(value)
+		return errors.New("not found")
 	}
+	*result = GetLastVCResult(vc)
 	return nil
 }

tracer.go

@@ -13,6 +13,7 @@ import (
 	"net/rpc"
 
 	"github.com/DistributedClocks/GoVector/govec"
+	"github.com/DistributedClocks/GoVector/govec/vclock"
 )
 
 // TracingToken is an abstract token to be used when tracing
@@ -70,16 +71,15 @@ func NewTracer(config TracerConfig) *Tracer {
 		log.Fatal("dialing server: ", err)
 	}
 
-	// TODO: make this call optional
-	var initialClock uint64 = 0
-	err = client.Call("RPCProvider.GetLastClock", config.TracerIdentity, &initialClock)
-	if err != nil {
-		log.Println("cannot fetch intial clock value from tracing server:", err)
-	}
-
 	goLogConfig := govec.GetDefaultConfig()
 	goLogConfig.LogToFile = false
-	goLogConfig.InitialClock = initialClock
+
+	// TODO: make this call optional
+	var initialVC vclock.VClock
+	err = client.Call("RPCProvider.GetLastVC", config.TracerIdentity, &initialVC)
+	if err == nil {
+		goLogConfig.InitialVC = initialVC.Copy()
+	}
 
 	tracer := &Tracer{
 		client:      client,

tracing_test.go

@@ -459,17 +459,10 @@ func TestTracerRejoin(t *testing.T) {
 		})
 		defer cRejoined.Close()
 
-		clock, ok := c.logger.GetCurrentVC().FindTicks(tracerIdentity)
-		if !ok {
-			t.Fatal("tracerIdentity not found in vector clock")
-		}
-
-		rejoinedClock, ok := cRejoined.logger.GetCurrentVC().FindTicks(tracerIdentity)
-		if !ok {
-			t.Fatal("tracerIdentity not found in vector clock")
-		}
+		vc := c.logger.GetCurrentVC()
+		rejoinedVC := cRejoined.logger.GetCurrentVC()
 
-		if clock != rejoinedClock {
+		if !cmp.Equal(vc, rejoinedVC) {
 			t.Fatal("rejoined tracer clock value is not equal to intial tracer clock value")
 		}
 	})()