⚡ Optimize camera initialization to prevent main thread blocking

app/build.gradle

@@ -63,13 +63,13 @@ dependencies {
     implementation project(':utils')
 
     // Kotlin lang
-    implementation 'androidx.core:core-ktx:1.2.0'
+    implementation 'androidx.core:core-ktx:1.10.1'
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
-    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.4'
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3'
 
     // App compat and UI things
     implementation 'androidx.appcompat:appcompat:1.1.0'
-    implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.2.0'
+    implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.6.2'
     implementation "androidx.viewpager2:viewpager2:1.0.0"
     implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
 
@@ -87,4 +87,9 @@ dependencies {
 
     implementation "io.ktor:ktor-server-core:2.3.3"
     implementation "io.ktor:ktor-server-netty:2.3.3"
+
+    testImplementation 'junit:junit:4.13.2'
+    testImplementation 'org.mockito:mockito-core:3.12.4'
+    testImplementation 'org.mockito:mockito-inline:3.12.4'
+    testImplementation "org.jetbrains.kotlinx:kotlinx-coroutines-test:1.6.4"
 }

app/src/main/java/com/samsung/android/scan3d/serv/Cam.kt

@@ -17,14 +17,24 @@ import com.samsung.android.scan3d.CameraActivity
 import com.samsung.android.scan3d.R
 import com.samsung.android.scan3d.fragments.CameraFragment
 import com.samsung.android.scan3d.http.HttpService
-import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
 
 
 class Cam : Service() {
     var engine: CamEngine? = null
     var http: HttpService? = null
     val CHANNEL_ID = "REMOTE_CAM"
 
+    private val serviceScope = CoroutineScope(Dispatchers.Main + SupervisorJob())
+    private val cameraMutex = Mutex()
+
 
     override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
         Log.i("CAM", "onStartCommand " + intent?.action)
@@ -81,42 +91,64 @@ class Cam : Service() {
             }
 
             "onPause" -> {
-                engine?.insidePause = true
-                if (engine?.isShowingPreview == true) {
-                    engine?.restart()
+                serviceScope.launch {
+                    cameraMutex.withLock {
+                        engine?.insidePause = true
+                        if (engine?.isShowingPreview == true) {
+                            engine?.restart()
+                        }
+                    }
                 }
-
             }
 
             "onResume" -> {
                 engine?.insidePause = false;
             }
 
             "start_camera_engine" -> {
-                engine = CamEngine(this)
-                engine?.http = http
-                runBlocking { engine?.initializeCamera() }
+                serviceScope.launch {
+                    cameraMutex.withLock {
+                        val newEngine = withContext(Dispatchers.IO) {
+                            CamEngine(this@Cam)
+                        }
+                        newEngine.http = http
+                        engine = newEngine
+                        newEngine.initializeCamera()
+                    }
+                }
             }
 
             "new_view_state" -> {
-
-                val old = engine?.viewState!!
                 val new : CameraFragment.Companion.ViewState = intent.extras?.getParcelable("data")!!
                 Log.i("CAM", "new_view_state: " + new)
-                Log.i("CAM", "from:           " + old)
-                engine?.viewState =  new
-                if (old != new) {
-                    Log.i("CAM", "diff")
-                    engine?.restart()
+
+                serviceScope.launch {
+                    cameraMutex.withLock {
+                        val old = engine?.viewState
+                        if (old == null) {
+                            // Engine not ready or null
+                            return@withLock
+                        }
+                        Log.i("CAM", "from:           " + old)
+                        engine?.viewState = new
+                        if (old != new) {
+                            Log.i("CAM", "diff")
+                            engine?.restart()
+                        }
+                    }
                 }
             }
 
             "new_preview_surface" -> {
                 val surface: Surface? = intent.extras?.getParcelable("surface")
-                // Toast.makeText(this, "SURFACE", Toast.LENGTH_SHORT).show()
-                engine?.previewSurface = surface
-                if (engine?.viewState?.preview == true) {
-                    runBlocking { engine?.initializeCamera() }
+                serviceScope.launch {
+                    cameraMutex.withLock {
+                        // Toast.makeText(this, "SURFACE", Toast.LENGTH_SHORT).show()
+                        engine?.previewSurface = surface
+                        if (engine?.viewState?.preview == true) {
+                            engine?.initializeCamera()
+                        }
+                    }
                 }
             }
 
@@ -141,6 +173,7 @@ class Cam : Service() {
     override fun onDestroy() {
         super.onDestroy()
         Log.i("CAM", "OnDestroy")
+        serviceScope.cancel()
         kill()
     }
 

app/src/main/java/com/samsung/android/scan3d/serv/CamEngine.kt

@@ -24,8 +24,9 @@ import android.view.Surface
 import com.samsung.android.scan3d.fragments.CameraFragment
 import com.samsung.android.scan3d.http.HttpService
 import com.samsung.android.scan3d.util.Selector
-import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.suspendCancellableCoroutine
+import kotlinx.coroutines.withContext
 import kotlinx.parcelize.Parcelize
 import kotlin.coroutines.resume
 import kotlin.coroutines.resumeWithException
@@ -125,9 +126,9 @@ class CamEngine(val context: Context) {
         }
     }
 
-    fun restart() {
+    suspend fun restart() {
         stopRunning()
-        runBlocking { initializeCamera() }
+        initializeCamera()
 
     }
 
@@ -185,7 +186,7 @@ class CamEngine(val context: Context) {
         }, handler)
     }
 
-    suspend fun initializeCamera() {
+    suspend fun initializeCamera() = withContext(Dispatchers.IO) {
         Log.i("CAMERA", "initializeCamera")
         Log.i("CAMERA", "RTSP: ${viewState.rtsp}, Encoding: ${viewState.encoding}")
 

build.gradle

@@ -18,15 +18,15 @@
 
 buildscript {
     // Top-level variables used for versioning
-    ext.kotlin_version = '1.6.21'
-    ext.java_version = JavaVersion.VERSION_1_8
+    ext.kotlin_version = '1.9.22'
+    ext.java_version = JavaVersion.VERSION_17
 
     repositories {
         google()
         mavenCentral()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:8.1.0'
+        classpath 'com.android.tools.build:gradle:8.3.0'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
         classpath 'androidx.navigation:navigation-safe-args-gradle-plugin:2.7.0'
 

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.0-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists