From f271b1aadb4af330f5b1f11211545cc5a32098ae Mon Sep 17 00:00:00 2001
From: Mathis Engelbart <mathis.engelbart@gmail.com>
Date: Thu, 16 Dec 2021 12:59:57 +0100
Subject: [PATCH] Add callback to get bandwith estimator on new PC

---
 pkg/gcc/interceptor.go | 67 +++++++++++++++++++-----------------------
 1 file changed, 30 insertions(+), 37 deletions(-)

diff --git a/pkg/gcc/interceptor.go b/pkg/gcc/interceptor.go
index 1127410c..0ddc8f4f 100644
--- a/pkg/gcc/interceptor.go
+++ b/pkg/gcc/interceptor.go
@@ -2,7 +2,6 @@ package gcc
 
 import (
 	"errors"
-	"fmt"
 	"sync"
 	"time"
 
@@ -18,6 +17,14 @@ const transportCCURI = "http://www.ietf.org/id/draft-holmer-rmcat-transport-wide
 // ErrUnknownSession indicates that a session ID was not assigned
 var ErrUnknownSession = errors.New("unknown session ID")
 
+// Pacer is the interface implemented by packet pacers
+type Pacer interface {
+	interceptor.RTPWriter
+	AddStream(ssrc uint32, writer interceptor.RTPWriter)
+	SetTargetBitrate(int)
+	Close() error
+}
+
 // Option can be used to set initial options on GCC interceptors
 type Option func(*Interceptor) error
 
@@ -36,25 +43,32 @@ func SetPacer(pacer Pacer) Option {
 	}
 }
 
+type BandwidthEstimator interface {
+	GetTargetBitrate() int
+	GetStats() map[string]interface{}
+}
+
+type NewPeerConnectionCallback func(id string, estimator BandwidthEstimator)
+
 // InterceptorFactory is a factory for GCC interceptors
 type InterceptorFactory struct {
-	opts         []Option
-	interceptors map[string]*Interceptor
+	opts              []Option
+	addPeerConnection NewPeerConnectionCallback
 }
 
 // NewInterceptor returns a new GCC interceptor factory
 func NewInterceptor(opts ...Option) (*InterceptorFactory, error) {
 	return &InterceptorFactory{
-		opts:         opts,
-		interceptors: map[string]*Interceptor{},
+		opts: opts,
 	}, nil
 }
 
+func (f *InterceptorFactory) OnNewPeerConnection(cb NewPeerConnectionCallback) {
+	f.addPeerConnection = cb
+}
+
 // NewInterceptor returns a new GCC interceptor
 func (f *InterceptorFactory) NewInterceptor(id string) (interceptor.Interceptor, error) {
-	if i, ok := f.interceptors[id]; ok {
-		return i, nil
-	}
 	i := &Interceptor{
 		NoOp:            interceptor.NoOp{},
 		lock:            sync.Mutex{},
@@ -82,17 +96,11 @@ func (f *InterceptorFactory) NewInterceptor(id string) (interceptor.Interceptor,
 	i.loss = newLossBasedBWE(i.bitrate)
 	i.delay = newDelayBasedBWE(i.bitrate)
 
-	f.interceptors[id] = i
 	go i.loop()
-	return i, nil
-}
-
-// GetTargetBitrate returns the target bitrate for the connection with id
-func (f *InterceptorFactory) GetTargetBitrate(id string) (int, error) {
-	if i, ok := f.interceptors[id]; ok {
-		return i.getTargetBitrate(), nil
+	if f.addPeerConnection != nil {
+		f.addPeerConnection(id, i)
 	}
-	return 0, fmt.Errorf("%w: %v", ErrUnknownSession, id)
+	return i, nil
 }
 
 // Stats contains internal statistics of the bandwidth estimator
@@ -101,23 +109,6 @@ type Stats struct {
 	DelayStats
 }
 
-// GetStats returns a sample of the internal statistics of the interceptor
-// running on the connection with id
-func (f *InterceptorFactory) GetStats(id string) (*Stats, error) {
-	if i, ok := f.interceptors[id]; ok {
-		return i.getStats(), nil
-	}
-	return nil, fmt.Errorf("%w: %v", ErrUnknownSession, id)
-}
-
-// Pacer is the interface implemented by packet pacers
-type Pacer interface {
-	interceptor.RTPWriter
-	AddStream(ssrc uint32, writer interceptor.RTPWriter)
-	SetTargetBitrate(int)
-	Close() error
-}
-
 type packetAndAttributes struct {
 	header     rtp.Header
 	payload    []byte
@@ -145,14 +136,16 @@ type Interceptor struct {
 	close    chan struct{}
 }
 
-func (c *Interceptor) getTargetBitrate() int {
+func (c *Interceptor) GetTargetBitrate() int {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 	return c.bitrate
 }
 
-func (c *Interceptor) getStats() *Stats {
-	return c.latestStats
+func (c *Interceptor) GetStats() map[string]interface{} {
+	return map[string]interface{}{
+		"gcc": c.latestStats,
+	}
 }
 
 // BindRTCPReader lets you modify any incoming RTCP packets. It is called once