Have KeepAliveGatt state backed by StateFlow

JuulLabs · May 21, 2020 · a07a298 · a07a298
1 parent 874cbd3
commit a07a298
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Showing 3 changed files with 81 additions and 131 deletions.
diff --git a/gradle/dependencies.gradle b/gradle/dependencies.gradle
@@ -7,7 +7,7 @@ ext.versions = [
 ext.deps = [
     kotlin: [
         stdlib: "org.jetbrains.kotlin:kotlin-stdlib",
-        coroutines: "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.5",
+        coroutines: "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.7",
         junit: "org.jetbrains.kotlin:kotlin-test-junit",
     ],
 

diff --git a/keep-alive/src/main/java/KeepAliveGatt.kt b/keep-alive/src/main/java/KeepAliveGatt.kt
@@ -22,7 +22,6 @@ import com.juul.able.gatt.OnDescriptorWrite
 import com.juul.able.gatt.OnMtuChanged
 import com.juul.able.gatt.OnReadRemoteRssi
 import com.juul.able.gatt.WriteType
-import com.juul.able.keepalive.KeepAliveGatt.Configuration
 import com.juul.able.keepalive.State.Connected
 import com.juul.able.keepalive.State.Connecting
 import com.juul.able.keepalive.State.Disconnected
@@ -32,9 +31,10 @@ import kotlin.coroutines.CoroutineContext
 import kotlin.coroutines.EmptyCoroutineContext
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CompletionHandler
-import kotlinx.coroutines.CoroutineExceptionHandler
 import kotlinx.coroutines.CoroutineName
 import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.CoroutineStart
+import kotlinx.coroutines.CoroutineStart.UNDISPATCHED
 import kotlinx.coroutines.DisposableHandle
 import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.Job
@@ -43,13 +43,11 @@ import kotlinx.coroutines.SupervisorJob
 import kotlinx.coroutines.cancelAndJoin
 import kotlinx.coroutines.channels.BroadcastChannel
 import kotlinx.coroutines.channels.Channel.Factory.BUFFERED
-import kotlinx.coroutines.channels.Channel.Factory.CONFLATED
-import kotlinx.coroutines.channels.SendChannel
-import kotlinx.coroutines.channels.consume
 import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.asFlow
-import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
@@ -70,58 +68,43 @@ enum class State {
 fun CoroutineScope.keepAliveGatt(
     androidContext: Context,
     bluetoothDevice: BluetoothDevice,
-    configuration: Configuration
+    disconnectTimeoutMillis: Long,
+    onConnectAction: ConnectAction? = null
 ) = KeepAliveGatt(
     parentCoroutineContext = coroutineContext,
     androidContext = androidContext,
     bluetoothDevice = bluetoothDevice,
-    configuration = configuration
+    disconnectTimeoutMillis = disconnectTimeoutMillis,
+    onConnectAction = onConnectAction
 )
 
 class KeepAliveGatt(
     parentCoroutineContext: CoroutineContext = EmptyCoroutineContext,
     androidContext: Context,
     private val bluetoothDevice: BluetoothDevice,
-    configuration: Configuration
+    private val disconnectTimeoutMillis: Long,
+    private val onConnectAction: ConnectAction? = null
 ) : GattIo {
 
-    data class Configuration(
-        val disconnectTimeoutMillis: Long,
-        val exceptionHandler: CoroutineExceptionHandler? = null,
-        val onConnectAction: ConnectAction? = null,
-        internal val stateCapacity: Int = CONFLATED
-    )
-
     private val applicationContext = androidContext.applicationContext
 
     private val job = SupervisorJob(parentCoroutineContext[Job])
-    private val scope = CoroutineScope(
-        parentCoroutineContext + job + (configuration.exceptionHandler ?: EmptyCoroutineContext)
-    )
+    private val scope = CoroutineScope(parentCoroutineContext + job)
 
     private val isRunning = AtomicBoolean()
 
-    private val disconnectTimeoutMillis = configuration.disconnectTimeoutMillis
-    private val onConnectAction = configuration.onConnectAction
-
     @Volatile
     private var _gatt: GattIo? = null
     private val gatt: GattIo
         inline get() = _gatt ?: throw NotReady(toString())
 
-    private val _state = BroadcastChannel<State>(configuration.stateCapacity)
+    private val _state = MutableStateFlow(Disconnected)
 
     @FlowPreview
-    val state: Flow<State> = _state.asFlow()
+    val state: Flow<State> = _state
 
     private val _onCharacteristicChanged = BroadcastChannel<OnCharacteristicChanged>(BUFFERED)
 
-    // todo: Replace with `trySend` when Kotlin/kotlinx.coroutines#974 is fixed.
-    // https://github.com/Kotlin/kotlinx.coroutines/issues/974
-    private fun setState(state: State) {
-        _state.offerCatching(state)
-    }
-
     fun connect(): Boolean {
         check(!job.isCancelled) { "Cannot connect, $this is closed" }
         isRunning.compareAndSet(false, true) || return false
@@ -131,7 +114,7 @@ class KeepAliveGatt(
                 try {
                     spawnConnection()
                 } finally {
-                    setState(Disconnected)
+                    _state.value = Disconnected
                 }
             }
         }
@@ -146,7 +129,6 @@ class KeepAliveGatt(
     private fun cancel(cause: CancellationException?) {
         job.cancel(cause)
         _onCharacteristicChanged.cancel()
-        _state.cancel()
     }
 
     fun cancel() {
@@ -156,7 +138,6 @@ class KeepAliveGatt(
     suspend fun cancelAndJoin() {
         job.cancelAndJoin()
         _onCharacteristicChanged.cancel()
-        _state.cancel()
     }
 
     // todo: Fix `@see` documentation link when https://github.com/Kotlin/dokka/issues/80 is fixed.
@@ -166,7 +147,7 @@ class KeepAliveGatt(
     ): DisposableHandle = job.invokeOnCompletion(handler)
 
     private suspend fun spawnConnection() {
-        setState(Connecting)
+        _state.value = Connecting
 
         val gatt = when (val result = bluetoothDevice.connectGatt(applicationContext)) {
             is Success -> result.gatt
@@ -184,14 +165,14 @@ class KeepAliveGatt(
             coroutineScope {
                 gatt.onCharacteristicChanged
                     .onEach(_onCharacteristicChanged::send)
-                    .launchIn(this)
+                    .launchIn(this, start = UNDISPATCHED)
                 onConnectAction?.invoke(gatt)
                 _gatt = gatt
-                setState(Connected)
+                _state.value = Connected
             }
         } finally {
             _gatt = null
-            setState(State.Disconnecting)
+            _state.value = State.Disconnecting
             withContext(NonCancellable) {
                 withTimeoutOrNull(disconnectTimeoutMillis) {
                     gatt.disconnect()
@@ -236,10 +217,12 @@ class KeepAliveGatt(
     override suspend fun readRemoteRssi(): OnReadRemoteRssi = gatt.readRemoteRssi()
 
     override fun toString() =
-        "KeepAliveGatt(device=$bluetoothDevice, gatt=$_gatt, state=${_state.consume { poll() }})"
+        "KeepAliveGatt(device=$bluetoothDevice, gatt=$_gatt, state=${_state.value})"
 }
 
-// https://github.com/Kotlin/kotlinx.coroutines/issues/974
-private fun <E> SendChannel<E>.offerCatching(element: E): Boolean {
-    return runCatching { offer(element) }.getOrDefault(false)
+private fun <T> Flow<T>.launchIn(
+    scope: CoroutineScope,
+    start: CoroutineStart = CoroutineStart.DEFAULT
+): Job = scope.launch(start = start) {
+    collect()
 }