Add support for writing without response on Apple

JuulLabs · Apr 10, 2022 · 8ae50e0 · 8ae50e0
1 parent aea9303
commit 8ae50e0
Show file tree

Hide file tree

Showing 3 changed files with 22 additions and 20 deletions.
diff --git a/core/src/appleMain/kotlin/Connection.kt b/core/src/appleMain/kotlin/Connection.kt
@@ -1,12 +1,15 @@
 package com.juul.kable
 
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.sync.Semaphore
 import kotlinx.coroutines.sync.withPermit
 
 internal class Connection(
     val delegate: PeripheralDelegate,
 ) {
 
+    val canSendWriteWithoutResponse = MutableStateFlow(false)
+
     // Using Semaphore as Mutex never relinquished lock when multiple concurrent `withLock`s are executed.
     val semaphore = Semaphore(1)
 

diff --git a/core/src/appleMain/kotlin/Peripheral.kt b/core/src/appleMain/kotlin/Peripheral.kt
@@ -44,12 +44,14 @@ import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.filter
 import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.flow.getAndUpdate
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.mapNotNull
 import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.flow.onSubscription
 import kotlinx.coroutines.flow.takeWhile
+import kotlinx.coroutines.flow.updateAndGet
 import kotlinx.coroutines.job
 import kotlinx.coroutines.sync.withPermit
 import kotlinx.coroutines.withContext
@@ -60,7 +62,6 @@ import platform.CoreBluetooth.CBCentralManagerStateResetting
 import platform.CoreBluetooth.CBCentralManagerStateUnauthorized
 import platform.CoreBluetooth.CBCentralManagerStateUnknown
 import platform.CoreBluetooth.CBCentralManagerStateUnsupported
-import platform.CoreBluetooth.CBCharacteristicWriteType
 import platform.CoreBluetooth.CBCharacteristicWriteWithResponse
 import platform.CoreBluetooth.CBCharacteristicWriteWithoutResponse
 import platform.CoreBluetooth.CBErrorConnectionFailed
@@ -155,6 +156,8 @@ public class ApplePeripheral internal constructor(
             .launchIn(scope)
     }
 
+    private val canSendWriteWithoutResponse = MutableStateFlow(cbPeripheral.canSendWriteWithoutResponse)
+
     private val _discoveredServices = atomic<List<DiscoveredService>?>(null)
     private val discoveredServices: List<DiscoveredService>
         get() = _discoveredServices.value
@@ -187,7 +190,7 @@ public class ApplePeripheral internal constructor(
 
         try {
             // todo: Create in `connectPeripheral`.
-            val delegate = PeripheralDelegate(logging, cbPeripheral.identifier.UUIDString)
+            val delegate = PeripheralDelegate(canSendWriteWithoutResponse, logging, cbPeripheral.identifier.UUIDString)
 
             val connection = centralManager.connectPeripheral(cbPeripheral, delegate).also {
                 _connection.value = it
@@ -297,8 +300,16 @@ public class ApplePeripheral internal constructor(
         }
 
         val platformCharacteristic = discoveredServices.obtain(characteristic, writeType.properties)
-        connection.execute<DidWriteValueForCharacteristic> {
-            centralManager.write(cbPeripheral, data, platformCharacteristic, writeType.cbWriteType)
+        when (writeType) {
+            WithResponse -> connection.execute<DidWriteValueForCharacteristic> {
+                centralManager.write(cbPeripheral, data, platformCharacteristic, CBCharacteristicWriteWithResponse)
+            }
+            WithoutResponse -> connection.semaphore.withPermit {
+                if (!canSendWriteWithoutResponse.updateAndGet { cbPeripheral.canSendWriteWithoutResponse }) {
+                    canSendWriteWithoutResponse.first { it }
+                }
+                centralManager.write(cbPeripheral, data, platformCharacteristic, CBCharacteristicWriteWithoutResponse)
+            }
         }
     }
 
@@ -408,12 +419,6 @@ public class ApplePeripheral internal constructor(
     override fun toString(): String = "Peripheral(cbPeripheral=$cbPeripheral)"
 }
 
-private val WriteType.cbWriteType: CBCharacteristicWriteType
-    get() = when (this) {
-        WithResponse -> CBCharacteristicWriteWithResponse
-        WithoutResponse -> CBCharacteristicWriteWithoutResponse
-    }
-
 private suspend fun Flow<DidUpdateValueForCharacteristic>.firstOrThrow(
     predicate: suspend (Data) -> Boolean,
 ): NSData = when (val value = first { it !is Data || predicate.invoke(it) }) {

diff --git a/core/src/appleMain/kotlin/PeripheralDelegate.kt b/core/src/appleMain/kotlin/PeripheralDelegate.kt
@@ -6,7 +6,6 @@ import com.juul.kable.PeripheralDelegate.Response.DidReadRssi
 import com.juul.kable.PeripheralDelegate.Response.DidUpdateNotificationStateForCharacteristic
 import com.juul.kable.PeripheralDelegate.Response.DidUpdateValueForDescriptor
 import com.juul.kable.PeripheralDelegate.Response.DidWriteValueForCharacteristic
-import com.juul.kable.PeripheralDelegate.Response.IsReadyToSendWriteWithoutResponse
 import com.juul.kable.logs.LogMessage
 import com.juul.kable.logs.Logger
 import com.juul.kable.logs.Logging
@@ -15,6 +14,7 @@ import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.channels.Channel.Factory.BUFFERED
 import kotlinx.coroutines.channels.ReceiveChannel
 import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.asSharedFlow
 import platform.CoreBluetooth.CBCharacteristic
 import platform.CoreBluetooth.CBDescriptor
@@ -30,8 +30,9 @@ import platform.darwin.NSObject
 
 // https://developer.apple.com/documentation/corebluetooth/cbperipheraldelegate
 internal class PeripheralDelegate(
+    private val canSendWriteWithoutResponse: MutableStateFlow<Boolean>,
     logging: Logging,
-    identifier: String
+    identifier: String,
 ) : NSObject(), CBPeripheralDelegateProtocol {
 
     sealed class Response {
@@ -68,11 +69,6 @@ internal class PeripheralDelegate(
             override val error: NSError?,
         ) : Response()
 
-        data class IsReadyToSendWriteWithoutResponse(
-            override val peripheralIdentifier: NSUUID,
-            override val error: NSError?,
-        ) : Response()
-
         data class DidReadRssi(
             override val peripheralIdentifier: NSUUID,
             val rssi: NSNumber,
@@ -252,9 +248,7 @@ internal class PeripheralDelegate(
         logger.debug {
             message = "${peripheral.identifier} peripheralIsReadyToSendWriteWithoutResponse"
         }
-        _response.sendBlocking(
-            IsReadyToSendWriteWithoutResponse(peripheral.identifier, error = null)
-        )
+        canSendWriteWithoutResponse.value = true
     }
 
     /* Managing Notifications for a Characteristic’s Value */