Major Update/Refactor to Support IETF 02

Beginning of a release candidate for support for IETF 02 tag of the
responsiveness spec.

4 files changed, 47 insertions, 5 deletions

diff --git a/lgc/collection.go b/lgc/collection.go
index 7560186..cd6a87d 100644
--- a/lgc/collection.go
+++ b/lgc/collection.go
@@ -16,6 +16,7 @@ package lgc
 
 import (
 	"fmt"
+	"math/rand"
 	"sync"
 )
 
@@ -33,10 +34,10 @@ func (collection *LoadGeneratingConnectionCollection) Get(idx int) (*LoadGenerat
 		collection.Lock.Unlock()
 		return nil, fmt.Errorf("collection is unlocked")
 	}
+	return collection.lockedGet(idx)
+}
 
-	if idx > len(*collection.LGCs) {
-		return nil, fmt.Errorf("index too large")
-	}
+func (collection *LoadGeneratingConnectionCollection) lockedGet(idx int) (*LoadGeneratingConnection, error) {
 	return &(*collection.LGCs)[idx], nil
 }
 
@@ -49,6 +50,22 @@ func (collection *LoadGeneratingConnectionCollection) Append(conn LoadGenerating
 	return nil
 }
 
-func (collection *LoadGeneratingConnectionCollection) Len() int {
-	return len(*collection.LGCs)
+func (collection *LoadGeneratingConnectionCollection) Len() (int, error) {
+	if collection.Lock.TryLock() {
+		collection.Lock.Unlock()
+		return -1, fmt.Errorf("collection is unlocked")
+	}
+	return len(*collection.LGCs), nil
+}
+
+func (collection *LoadGeneratingConnectionCollection) GetRandom() (*LoadGeneratingConnection, error) {
+	if collection.Lock.TryLock() {
+		collection.Lock.Unlock()
+		return nil, fmt.Errorf("collection is unlocked")
+	}
+
+	idx := int(rand.Uint32())
+	idx = idx % len(*collection.LGCs)
+
+	return collection.lockedGet(idx)
 }
diff --git a/lgc/download.go b/lgc/download.go
index a73cc37..c13a1b1 100644
--- a/lgc/download.go
+++ b/lgc/download.go
@@ -64,6 +64,10 @@ func NewLoadGeneratingConnectionDownload(url string, keyLogger io.Writer, connec
 	return lgd
 }
 
+func (lgd *LoadGeneratingConnectionDownload) Direction() LgcDirection {
+	return LGC_DOWN
+}
+
 func (lgd *LoadGeneratingConnectionDownload) WaitUntilStarted(ctxt context.Context) bool {
 	conditional := func() bool { return lgd.status != LGC_STATUS_NOT_STARTED }
 	go utilities.ContextSignaler(ctxt, 500*time.Millisecond, &conditional, lgd.statusWaiter)
diff --git a/lgc/lgc.go b/lgc/lgc.go
index db73efa..3b77015 100644
--- a/lgc/lgc.go
+++ b/lgc/lgc.go
@@ -31,6 +31,23 @@ type LoadGeneratingConnection interface {
 	ClientId() uint64
 	Stats() *stats.TraceStats
 	WaitUntilStarted(context.Context) bool
+	Direction() LgcDirection
+}
+
+type LgcDirection int
+
+const (
+	LGC_DOWN LgcDirection = iota
+	LGC_UP
+)
+
+func (direction LgcDirection) String() string {
+	if direction == LGC_DOWN {
+		return "Download"
+	} else if direction == LGC_UP {
+		return "Upload"
+	}
+	return "Invalid load-generating connection direction"
 }
 
 type LgcStatus int
diff --git a/lgc/upload.go b/lgc/upload.go
index 5175fe0..e4518b8 100644
--- a/lgc/upload.go
+++ b/lgc/upload.go
@@ -90,6 +90,10 @@ func (lgu *LoadGeneratingConnectionUpload) Status() LgcStatus {
 	return lgu.status
 }
 
+func (lgd *LoadGeneratingConnectionUpload) Direction() LgcDirection {
+	return LGC_UP
+}
+
 type syntheticCountingReader struct {
 	n   *uint64
 	ctx context.Context