Add RTC stats for publisher/subscriber peer connection and tracks (#165)

* Add RTC stats for publisher/subscriber peer connection and tracks

* Documentation

@@ -808,6 +808,14 @@ internal constructor(
 
         client.sendSyncState(syncState)
     }
+
+    fun getPublisherRTCStats(callback: RTCStatsCollectorCallback) {
+        _publisher?.peerConnection?.getStats(callback) ?: callback.onStatsDelivered(RTCStatsReport(0, emptyMap()))
+    }
+
+    fun getSubscriberRTCStats(callback: RTCStatsCollectorCallback) {
+        _subscriber?.peerConnection?.getStats(callback) ?: callback.onStatsDelivered(RTCStatsReport(0, emptyMap()))
+    }
 }
 
 /**

@@ -27,6 +27,7 @@ import io.livekit.android.util.FlowObservable
 import io.livekit.android.util.LKLog
 import io.livekit.android.util.flowDelegate
 import io.livekit.android.util.invoke
+import io.livekit.android.webrtc.getFilteredStats
 import kotlinx.coroutines.*
 import livekit.LivekitModels
 import livekit.LivekitRtc
@@ -874,6 +875,22 @@ constructor(
         }
     }
 
+    /**
+     * Get stats for the publisher peer connection.
+     *
+     * @see getSubscriberRTCStats
+     * @see getFilteredStats
+     */
+    fun getPublisherRTCStats(callback: RTCStatsCollectorCallback) = engine.getPublisherRTCStats(callback)
+
+    /**
+     * Get stats for the subscriber peer connection.
+     *
+     * @see getPublisherRTCStats
+     * @see getFilteredStats
+     */
+    fun getSubscriberRTCStats(callback: RTCStatsCollectorCallback) = engine.getSubscriberRTCStats(callback)
+
     // Debug options
 
     /**

+package io.livekit.android.webrtc
+
+import io.livekit.android.util.LKLog
+import org.webrtc.MediaStreamTrack
+import org.webrtc.RTCStats
+import org.webrtc.RTCStatsReport
+
+/**
+ * Returns an RTCStatsReport with all the relevant information pertaining to a track.
+ *
+ * @param trackIdentifier track, sender, or receiver id
+ */
+fun RTCStatsReport.getFilteredStats(track: MediaStreamTrack): RTCStatsReport {
+    return getFilteredStats(track.id())
+}
+
+/**
+ * Returns an RTCStatsReport with all the relevant information pertaining to a track identifier.
+ *
+ * @param trackIdentifier track, sender, or receiver id
+ */
+fun RTCStatsReport.getFilteredStats(trackIdentifier: String): RTCStatsReport {
+    val rtcStatsReport = this
+    val statsMap = rtcStatsReport.statsMap
+    val filteredStats = mutableSetOf<RTCStats>()
+
+    // Get track stats
+    val trackStats = getTrackStats(trackIdentifier, statsMap)
+    if (trackStats == null) {
+        LKLog.i { "getStats: couldn't find track stats!" }
+        return RTCStatsReport(rtcStatsReport.timestampUs.toLong(), HashMap())
+    }
+    filteredStats.add(trackStats)
+    val trackId = trackStats.id
+
+    // Get stream stats
+    val streamStats = getStreamStats(trackId, statsMap)
+    if (streamStats != null) {
+        filteredStats.add(streamStats)
+    }
+
+    // Get streamType stats and associated information
+    val ssrcs: MutableSet<Long?> = HashSet()
+    val codecIds: MutableSet<String?> = HashSet()
+
+    for (stats in statsMap.values) {
+        if ((stats.type == "inbound-rtp" || stats.type == "outbound-rtp") && trackId == stats.members["trackId"]) {
+            ssrcs.add(stats.members["ssrc"] as Long?)
+            codecIds.add(stats.members["codecId"] as String?)
+            filteredStats.add(stats)
+        }
+    }
+
+    // Get nominated candidate information
+    var candidatePairStats: RTCStats? = null
+    for (stats in statsMap.values) {
+        if (stats.type == "candidate-pair" && stats.members["nominated"] == true) {
+            candidatePairStats = stats
+            break
+        }
+    }
+
+    var localCandidateId: String? = null
+    var remoteCandidateId: String? = null
+    if (candidatePairStats != null) {
+        filteredStats.add(candidatePairStats)
+        localCandidateId = candidatePairStats.members["localCandidateId"] as String?
+        remoteCandidateId = candidatePairStats.members["remoteCandidateId"] as String?
+    }
+
+    // Sweep for any remaining stats we want.
+    filteredStats.addAll(
+        getExtraStats(
+            trackIdentifier,
+            ssrcs,
+            codecIds,
+            localCandidateId,
+            remoteCandidateId,
+            statsMap
+        )
+    )
+    val filteredStatsMap: MutableMap<String, RTCStats> = HashMap()
+    for (stats in filteredStats) {
+        filteredStatsMap[stats.id] = stats
+    }
+
+    return RTCStatsReport(rtcStatsReport.timestampUs.toLong(), filteredStatsMap)
+}
+
+// Note: trackIdentifier can differ from the internal stats trackId
+// trackIdentifier refers to the sender or receiver id
+private fun getTrackStats(trackIdentifier: String, statsMap: Map<String, RTCStats>): RTCStats? {
+    for (stats in statsMap.values) {
+        if (stats.type == "track" && trackIdentifier == stats.members["trackIdentifier"]) {
+            return stats
+        }
+    }
+    return null
+}
+
+
+private fun getStreamStats(trackId: String, statsMap: Map<String, RTCStats>): RTCStats? {
+    for (stats in statsMap.values) {
+        if (stats.type == "stream") {
+            val trackIds = (stats.members["trackIds"] as? Array<*>)?.toList() ?: emptyList()
+            if (trackIds.contains(trackId)) {
+                return stats
+            }
+        }
+    }
+    return null
+}
+
+// Note: trackIdentifier can differ from the internal stats trackId
+// trackIdentifier refers to the sender or receiver id
+private fun getExtraStats(
+    trackIdentifier: String,
+    ssrcs: Set<Long?>,
+    codecIds: Set<String?>,
+    localCandidateId: String?,
+    remoteCandidateId: String?,
+    statsMap: Map<String, RTCStats>
+): Set<RTCStats> {
+    val extraStats: MutableSet<RTCStats> = HashSet()
+    for (stats in statsMap.values) {
+        when (stats.type) {
+            "certificate", "transport" -> extraStats.add(stats)
+        }
+        if (stats.id == localCandidateId || stats.id == remoteCandidateId) {
+            extraStats.add(stats)
+            continue
+        }
+        if (ssrcs.contains(stats.members["ssrc"])) {
+            extraStats.add(stats)
+            continue
+        }
+        if (trackIdentifier == stats.members["trackIdentifier"]) {
+            extraStats.add(stats)
+            continue
+        }
+        if (codecIds.contains(stats.id)) {
+            extraStats.add(stats)
+        }
+    }
+    return extraStats
+}
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