add mmv version 2 support

client.go

@@ -165,6 +165,11 @@ func (c *PCPClient) initializeInstanceAndInstanceDomainOffsets(instanceoffset, i
 		for _, i := range indom.instances {
 			i.offset = instanceoffset
 			instanceoffset += InstanceLength
+
+			if c.r.version2 {
+				i.name.offset = *stringsoffset
+				*stringsoffset += StringLength
+			}
 		}
 
 		if indom.shortDescription.val != "" {
@@ -367,7 +372,17 @@ func (c *PCPClient) writeInstanceAndInstanceDomainBlock() {
 			c.buffer.MustWriteInt64(int64(indom.offset))
 			c.buffer.MustWriteInt32(0)
 			c.buffer.MustWriteUint32(i.id)
-			c.buffer.MustWriteString(i.name)
+
+			if c.r.version2 {
+				c.buffer.MustWriteUint64(uint64(i.name.offset))
+
+				pos := c.buffer.Pos()
+				c.buffer.MustSetPos(i.name.offset)
+				c.buffer.MustWriteString(i.name.val)
+				c.buffer.MustSetPos(pos)
+			} else {
+				c.buffer.MustWriteString(i.name.val)
+			}
 		}
 	}
 }

client_test.go

@@ -366,8 +366,8 @@ func matchInstance(i *mmvdump.Instance, pi *pcpInstance, id *PCPInstanceDomain,
 		t.Errorf("expected indom offset to be %d, got %d", i.Indom, id.offset)
 	}
 
-	if in := i.External[:len(pi.name)]; pi.name != string(in) {
-		t.Errorf("expected instance name to be %v, got %v", pi.name, in)
+	if in := i.External[:len(pi.name.val)]; pi.name.val != string(in) {
+		t.Errorf("expected instance name to be %v, got %v", pi.name.val, in)
 	}
 }
 

instance.go

@@ -5,7 +5,7 @@ type Instances map[string]interface{}
 
 // pcpInstance wraps a PCP compatible Instance
 type pcpInstance struct {
-	name   string
+	name   *pcpString
 	id     uint32
 	offset int
 }
@@ -17,10 +17,10 @@ type pcpInstance struct {
 // but instead added using the AddInstance method of InstanceDomain
 func newpcpInstance(name string) *pcpInstance {
 	return &pcpInstance{
-		name, hash(name, 0), 0,
+		newpcpString(name), hash(name, 0), 0,
 	}
 }
 
 func (i *pcpInstance) String() string {
-	return "Instance: " + i.name
+	return "Instance: " + i.name.val
 }

instance_domain.go

@@ -1,6 +1,9 @@
 package speed
 
-import "errors"
+import (
+	"errors"
+	"fmt"
+)
 
 // InstanceDomain defines the interface for an instance domain
 type InstanceDomain interface {
@@ -9,6 +12,7 @@ type InstanceDomain interface {
 	Description() string          // description for the instance domain
 	HasInstance(name string) bool // checks if an instance is in the indom
 	InstanceCount() int           // returns the number of instances in the indom
+	Instances() []string          // returns a slice of instances in the instance domain
 }
 
 // PCPInstanceDomainBitLength is the maximum bit length of a PCP Instance Domain
@@ -52,6 +56,10 @@ func NewPCPInstanceDomain(name string, instances []string, desc ...string) (*PCP
 	imap := make(map[string]*pcpInstance)
 
 	for _, instance := range instances {
+		if len(instance) > StringLength {
+			return nil, fmt.Errorf("instance name %v is too long", instance)
+		}
+
 		imap[instance] = newpcpInstance(instance)
 	}
 
@@ -81,6 +89,15 @@ func (indom *PCPInstanceDomain) InstanceCount() int {
 	return len(indom.instances)
 }
 
+// Instances returns a slice of defined instances for the instance domain
+func (indom *PCPInstanceDomain) Instances() []string {
+	var ans []string
+	for k := range indom.instances {
+		ans = append(ans, k)
+	}
+	return ans
+}
+
 // MatchInstances returns true if the passed InstanceDomain
 // has exactly the same instances as the passed array
 func (indom *PCPInstanceDomain) MatchInstances(ins []string) bool {
@@ -107,13 +124,5 @@ func (indom *PCPInstanceDomain) Description() string {
 }
 
 func (indom *PCPInstanceDomain) String() string {
-	s := "InstanceDomain: " + indom.name
-	if len(indom.instances) > 0 {
-		s += "["
-		for _, i := range indom.instances {
-			s += i.name + ","
-		}
-		s += "]"
-	}
-	return s
+	return fmt.Sprintf("%s%v", indom.name, indom.Instances())
 }

pcp.go

@@ -11,5 +11,3 @@ type pcpString struct {
 func newpcpString(s string) *pcpString {
 	return &pcpString{s, 0}
 }
-
-func (s *pcpString) String() string { return s.val }

registry.go

@@ -108,7 +108,7 @@ func (r *PCPRegistry) ValuesCount() int { return r.valueCount }
 // StringCount returns the number of strings in the registry
 func (r *PCPRegistry) StringCount() int {
 	if r.version2 {
-		return r.stringcount + r.MetricCount()
+		return r.stringcount + r.MetricCount() + r.InstanceCount()
 	}
 
 	return r.stringcount
@@ -148,6 +148,14 @@ func (r *PCPRegistry) AddInstanceDomain(indom InstanceDomain) error {
 	r.instanceDomains[indom.Name()] = indom.(*PCPInstanceDomain)
 	r.instanceCount += indom.InstanceCount()
 
+	if !r.version2 {
+		for _, v := range indom.Instances() {
+			if len(v) > MaxV1MetricNameLength {
+				r.version2 = true
+			}
+		}
+	}
+
 	log.WithFields(logrus.Fields{
 		"prefix":        "registry",
 		"name":          indom.Name(),