Swallowed cancellation exception fixes (#913)

* add detekt plugin

* Rethrow cancellation exceptions for coroutines

* Fix potential leak for StreamSender caused by exceptions

* spotless

* Migrate withTimeout to withDeadline

withTimeout throws a cancellation exception, cancelling the coroutine

* Detekt rule for NoWithTimeout

* spotless

* Cleanup

Author: davidliu

.changeset/breezy-mugs-raise.md

@@ -0,0 +1,5 @@
+---
+"client-sdk-android": patch
+---
+
+Fix potential leak for StreamSender caused by exceptions

.changeset/eight-numbers-fold.md

@@ -0,0 +1,5 @@
+---
+"client-sdk-android": patch
+---
+
+Rethrow cancellation exceptions for coroutines

.github/workflows/android.yml

@@ -49,9 +49,6 @@ jobs:
     - name: Grant execute permission for gradlew
       run: chmod +x gradlew
 
-    - name: Gradle clean
-      run: ./gradlew clean
-
     - name: Spotless check
       if: github.event_name == 'pull_request'
       run: |

build.gradle

@@ -24,6 +24,7 @@ buildscript {
 
 plugins {
     id("io.github.gradle-nexus.publish-plugin") version "2.0.0"
+    alias(libs.plugins.detekt) apply false
 }
 
 subprojects {
@@ -32,6 +33,8 @@ subprojects {
         return
     }
 
+    def isDetektRulesModule = project.name == "livekit-detekt-rules"
+
     apply plugin: "com.diffplug.spotless"
     spotless {
         // optional: limit format enforcement to just the files changed by this feature branch
@@ -75,6 +78,28 @@ subprojects {
         }
     }
 
+    if (!isDetektRulesModule) {
+        apply plugin: "io.gitlab.arturbosch.detekt"
+        detekt {
+            parallel = true
+            buildUponDefaultConfig = true
+            allRules = false
+            config.from(files("$rootDir/config/detekt/detekt.yml"))
+            reports {
+                html.required.set(true)
+                md.required.set(true)
+            }
+        }
+
+        dependencies {
+            detektPlugins project(":livekit-detekt-rules")
+        }
+
+        tasks.withType(io.gitlab.arturbosch.detekt.Detekt).configureEach {
+            pluginClasspath.setFrom(configurations.detektPlugins)
+        }
+    }
+
     // From Gradle 8 onwards, Kapt no longer automatically picks up jvmTarget
     // from normal KotlinOptions. Must be manually set.
     // JvmToolchain should not be used since it changes the actual JDK used.

config/detekt/detekt.yml

@@ -0,0 +1,23 @@
+# Detekt: smell-oriented checks only. Formatting and naming conventions are handled by Spotless/ktlint.
+config:
+  validation: true
+  warningsAsErrors: true
+  excludes: ''
+
+style:
+  active: false
+
+naming:
+  active: false
+
+coroutines:
+  SuspendFunSwallowedCancellation:
+    active: true
+
+livekit-rules:
+  NoWithTimeout:
+    active: true
+
+exceptions:
+  TooGenericExceptionCaught:
+    active: false

gradle.properties

@@ -21,6 +21,15 @@ android.enableJetifier=false
 kotlin.code.style=official
 
 org.gradle.caching=true
+org.gradle.configuration-cache=true
+org.gradle.configureondemand=true
+org.gradle.daemon=true
+
+kotlin.incremental=true
+kapt.incremental.apt=true
+kapt.use.worker.api=true
+
+
 ###############################################################
 
 GROUP=io.livekit
@@ -62,8 +71,3 @@ RELEASE_SIGNING_ENABLED=true
 livekitUrl=
 livekitApiKey=
 livekitApiSecret=
-
-org.gradle.configuration-cache=true
-kotlin.incremental=true
-org.gradle.configureondemand=true
-org.gradle.daemon=true

gradle/libs.versions.toml

@@ -10,6 +10,7 @@ androidx-lifecycle = "2.8.0"
 audioswitch = "70efa204dda4f468f989b4b3e1b5ecb6ffe56ceb"
 autoService = '1.0.1'
 coroutines = "1.6.0"
+detekt = "1.23.8"
 dagger = "2.46"
 groupie = "2.9.0"
 junit-lib = "4.13.2"
@@ -29,6 +30,8 @@ material = "1.12.0"
 viewpager2 = "1.0.0"
 noise = "2.0.0"
 lifecycleProcess = "2.8.7"
+agp = "8.7.2"
+kotlin = "1.9.25"
 
 [libraries]
 android-jain-sip-ri = { module = "javax.sip:android-jain-sip-ri", version.ref = "androidJainSipRi" }
@@ -109,5 +112,11 @@ androidx-ui-test-junit4 = { group = "androidx.compose.ui", name = "ui-test-junit
 androidx-material3 = { group = "androidx.compose.material3", name = "material3" }
 lifecycle-process = { group = "androidx.lifecycle", name = "lifecycle-process", version.ref = "lifecycleProcess" }
 
+detekt-api = { module = "io.gitlab.arturbosch.detekt:detekt-api", version.ref = "detekt" }
+detekt-test = { module = "io.gitlab.arturbosch.detekt:detekt-test", version.ref = "detekt" }
+
 [plugins]
+detekt = { id = "io.gitlab.arturbosch.detekt", version.ref = "detekt" }
+android-library = { id = "com.android.library", version.ref = "agp" }
+kotlin-android = { id = "org.jetbrains.kotlin.android", version.ref = "kotlin" }
 

livekit-android-sdk/src/main/java/io/livekit/android/audio/PreconnectAudioBuffer.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2025 LiveKit, Inc.
+ * Copyright 2025-2026 LiveKit, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,9 +24,11 @@ import io.livekit.android.events.collect
 import io.livekit.android.room.ConnectionState
 import io.livekit.android.room.Room
 import io.livekit.android.room.datastream.StreamBytesOptions
+import io.livekit.android.room.datastream.outgoing.useStreamSender
 import io.livekit.android.room.participant.Participant
 import io.livekit.android.util.LKLog
 import io.livekit.android.util.flow
+import io.livekit.android.util.rethrowIfCancellationSignal
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.cancel
@@ -150,14 +152,15 @@ internal constructor(timeout: Duration) : AudioTrackSink {
             ),
         )
 
-        try {
-            val result = sender.write(audioData)
+        val sendResult = useStreamSender(sender) {
+            val result = write(audioData)
             if (result.isFailure) {
                 result.exceptionOrNull()?.let { throw it }
             }
-            sender.close()
-        } catch (e: Exception) {
-            sender.close(e.localizedMessage)
+            close()
+        }
+        if (sendResult.isFailure) {
+            return
         }
 
         val samples = audioData.size / (numberOfChannels * bitsPerSample / 8)
@@ -257,6 +260,7 @@ suspend fun <T> Room.withPreconnectAudio(
                         )
                         sentIdentities.add(identity)
                     } catch (e: Exception) {
+                        e.rethrowIfCancellationSignal()
                         LKLog.w(e) { "Error occurred while sending the audio preconnect data." }
                         onError?.invoke(e)
                     }
@@ -295,6 +299,7 @@ suspend fun <T> Room.withPreconnectAudio(
     try {
         retValue = operation.invoke()
     } catch (e: Exception) {
+        e.rethrowIfCancellationSignal()
         cancel()
         throw e
     }
@@ -361,6 +366,7 @@ internal suspend fun Room.startPreconnectAudioJob(
                         )
                         sentIdentities.add(identity)
                     } catch (e: Exception) {
+                        e.rethrowIfCancellationSignal()
                         LKLog.w(e) { "Error occurred while sending the audio preconnect data." }
                     }
                 }

livekit-android-sdk/src/main/java/io/livekit/android/room/RTCEngine.kt

@@ -47,7 +47,9 @@ import io.livekit.android.util.TTLMap
 import io.livekit.android.util.flow
 import io.livekit.android.util.flowDelegate
 import io.livekit.android.util.nullSafe
+import io.livekit.android.util.rethrowIfCancellationSignal
 import io.livekit.android.util.withCheckLock
+import io.livekit.android.util.withDeadline
 import io.livekit.android.webrtc.DataChannelManager
 import io.livekit.android.webrtc.DataPacketBuffer
 import io.livekit.android.webrtc.DataPacketItem
@@ -71,7 +73,6 @@ import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.suspendCancellableCoroutine
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
-import kotlinx.coroutines.withTimeout
 import kotlinx.coroutines.withTimeoutOrNull
 import kotlinx.coroutines.yield
 import livekit.LivekitModels
@@ -397,7 +398,7 @@ internal constructor(
         }
 
         // Suspend until signal client receives message confirming track publication.
-        return withTimeout(20.seconds) {
+        return withDeadline(20.seconds) {
             suspendCancellableCoroutine { cont ->
                 synchronized(pendingTrackResolvers) {
                     pendingTrackResolvers[cid] = cont
@@ -540,6 +541,7 @@ internal constructor(
                     try {
                         url = regionUrlProvider?.getNextBestRegionUrl() ?: url
                     } catch (e: Exception) {
+                        e.rethrowIfCancellationSignal()
                         LKLog.d(e) { "Exception while getting next best region url while reconnecting." }
                     }
                 }
@@ -589,6 +591,7 @@ internal constructor(
                         listener?.onFullReconnecting()
                         joinImpl(url!!, token, connectOptions, lastRoomOptions ?: RoomOptions())
                     } catch (e: Exception) {
+                        e.rethrowIfCancellationSignal()
                         LKLog.w(e) { "Error during reconnection." }
                         // reconnect failed, retry.
                         continue
@@ -612,6 +615,7 @@ internal constructor(
                         }
                         client.onReadyForResponses()
                     } catch (e: Exception) {
+                        e.rethrowIfCancellationSignal()
                         LKLog.w(e) { "Error during reconnection." }
                         // ws reconnect failed, retry.
                         continue
@@ -716,6 +720,7 @@ internal constructor(
         try {
             ensurePublisherConnected(dataPacket.kind)
         } catch (e: Exception) {
+            e.rethrowIfCancellationSignal()
             return Result.failure(e)
         }
 
@@ -769,6 +774,7 @@ internal constructor(
 
                 channel.send(buf)
             } catch (e: Exception) {
+                e.rethrowIfCancellationSignal()
                 return Result.failure(e)
             }
             return Result.success(Unit)
@@ -802,6 +808,7 @@ internal constructor(
         try {
             ensurePublisherConnected(kind)
         } catch (e: Exception) {
+            e.rethrowIfCancellationSignal()
             return
         }
         val manager = dataChannelManagerForKind(kind) ?: return

livekit-android-sdk/src/main/java/io/livekit/android/room/Room.kt

@@ -75,6 +75,7 @@ import io.livekit.android.util.LKLog
 import io.livekit.android.util.flow
 import io.livekit.android.util.flowDelegate
 import io.livekit.android.util.invoke
+import io.livekit.android.util.rethrowIfCancellationSignal
 import io.livekit.android.webrtc.getFilteredStats
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CoroutineDispatcher
@@ -414,6 +415,7 @@ constructor(
                 connectionWarmer.fetch(url)
             }
         } catch (e: Exception) {
+            e.rethrowIfCancellationSignal()
             LKLog.e(e) { "Error while preparing connection:" }
         }
     }
@@ -498,6 +500,7 @@ constructor(
                     try {
                         regionUrlProvider?.fetchRegionSettings()
                     } catch (e: Exception) {
+                        e.rethrowIfCancellationSignal()
                         LKLog.w(e) { "could not fetch region settings" }
                     }
                 }
@@ -513,9 +516,7 @@ constructor(
                     engine.regionUrlProvider = regionUrlProvider
                     engine.join(connectUrl, token, options, roomOptions)
                 } catch (e: Exception) {
-                    if (e is CancellationException) {
-                        throw e // rethrow to properly cancel.
-                    }
+                    e.rethrowIfCancellationSignal()
 
                     nextUrl = regionUrlProvider?.getNextBestRegionUrl()
                     if (nextUrl != null) {