feat: support external HttpClient via IO.Options

README.md

@@ -39,6 +39,7 @@ kotlin {
 ```kotlin
 val opt = IO.Options()
 // opt.trustAllCerts = true
+// opt.httpClient = yourSharedHttpClient
 IO.socket("http://localhost:3000", opt) { socket ->
     socket.on(Socket.EVENT_CONNECT) { args ->
         println("on connect ${args.joinToString()}")
@@ -53,6 +54,10 @@ IO.socket("http://localhost:3000", opt) { socket ->
 }
 ```
 
+If you set `opt.httpClient`, kmp-socketio will reuse this externally managed Ktor `HttpClient`
+for both polling and websocket transports.
+When websocket transport is enabled, make sure your shared client installs the Ktor `WebSockets` plugin.
+
 Most of the APIs are the same as socket.io-client-java, here are some differences:
 
 - Create socket is asynchronous, to make it's easier to guarantee thread safety.

kmp-socketio/src/commonMain/kotlin/com/piasy/kmp/socketio/engineio/EngineSocket.kt

@@ -218,6 +218,7 @@ class EngineSocket(
         opts.timestampParam = options?.timestampParam ?: opt.timestampParam
         opts.extraHeaders = opt.extraHeaders
         opts.trustAllCerts = opt.trustAllCerts
+        opts.httpClient = options?.httpClient ?: opt.httpClient
 
         val transport = factory.create(name, opts, scope, rawMessage)
         emit(EVENT_TRANSPORT, transport)

kmp-socketio/src/commonMain/kotlin/com/piasy/kmp/socketio/engineio/Transport.kt

@@ -3,6 +3,7 @@ package com.piasy.kmp.socketio.engineio
 import com.piasy.kmp.socketio.emitter.Emitter
 import com.piasy.kmp.xlog.Logging
 import com.piasy.kmp.socketio.parseqs.ParseQS
+import io.ktor.client.HttpClient
 import io.ktor.util.date.*
 import kotlinx.coroutines.CoroutineScope
 import org.hildan.socketio.EngineIOPacket
@@ -42,6 +43,12 @@ abstract class Transport(
 
         @JvmField
         var trustAllCerts: Boolean = false
+
+        /**
+         * Optional externally managed ktor HttpClient to reuse.
+         */
+        @JvmField
+        var httpClient: HttpClient? = null
     }
 
     protected var state = State.INIT

kmp-socketio/src/commonMain/kotlin/com/piasy/kmp/socketio/engineio/transports/PollingXHR.kt

@@ -17,7 +17,10 @@ open class PollingXHR(
     opt: Options,
     scope: CoroutineScope,
     private val ioScope: CoroutineScope = CoroutineScope(Dispatchers.Default),
-    private val factory: HttpClientFactory = DefaultHttpClientFactory(trustAllCerts = opt.trustAllCerts),
+    private val factory: HttpClientFactory = DefaultHttpClientFactory(
+        externalHttpClient = opt.httpClient,
+        trustAllCerts = opt.trustAllCerts,
+    ),
     rawMessage: Boolean,
 ) : Transport(opt, scope, NAME, rawMessage) {
     private var polling = false

kmp-socketio/src/commonMain/kotlin/com/piasy/kmp/socketio/engineio/transports/WebSocket.kt

@@ -23,7 +23,10 @@ open class WebSocket(
     opt: Options,
     scope: CoroutineScope,
     private val ioScope: CoroutineScope = CoroutineScope(Dispatchers.Default),
-    private val factory: HttpClientFactory = DefaultHttpClientFactory(trustAllCerts = opt.trustAllCerts),
+    private val factory: HttpClientFactory = DefaultHttpClientFactory(
+        externalHttpClient = opt.httpClient,
+        trustAllCerts = opt.trustAllCerts,
+    ),
     rawMessage: Boolean,
 ) : Transport(opt, scope, NAME, rawMessage) {
     private var ws: WebSocketSession? = null

kmp-socketio/src/commonMain/kotlin/com/piasy/kmp/socketio/engineio/transports/transport.kt

@@ -60,21 +60,24 @@ interface HttpClientFactory {
 }
 
 class DefaultHttpClientFactory(
+    externalHttpClient: HttpClient? = null,
     trustAllCerts: Boolean = false,
 ): HttpClientFactory {
-    private val wsClient = httpClient(
-        trustAllCerts = trustAllCerts,
-    ) {
-        install(Logging) {
-            logger = object : Logger {
-                override fun log(message: String) {
-                    com.piasy.kmp.xlog.Logging.info("Net", message)
+    private val wsClient = externalHttpClient ?: run {
+        httpClient(
+            trustAllCerts = trustAllCerts,
+        ) {
+            install(Logging) {
+                logger = object : Logger {
+                    override fun log(message: String) {
+                        com.piasy.kmp.xlog.Logging.info("Net", message)
+                    }
                 }
+                level = LogLevel.ALL
+            }
+            install(WebSockets) {
+                pingIntervalMillis = 20_000
             }
-            level = LogLevel.ALL
-        }
-        install(WebSockets) {
-            pingIntervalMillis = 20_000
         }
     }
     // Linux curl engine doesn't work for simultaneous websocket and http request.

kmp-socketio/src/jvmTest/kotlin/com/piasy/kmp/socketio/engineio/EngineSocketTest.kt

@@ -3,8 +3,10 @@ package com.piasy.kmp.socketio.engineio
 import com.piasy.kmp.socketio.engineio.transports.PollingXHR
 import com.piasy.kmp.socketio.engineio.transports.TransportFactory
 import com.piasy.kmp.socketio.engineio.transports.WebSocket
+import io.ktor.client.HttpClient
 import io.mockk.every
 import io.mockk.mockk
+import io.mockk.slot
 import io.mockk.spyk
 import io.mockk.verify
 import kotlinx.coroutines.*
@@ -19,6 +21,7 @@ import org.hildan.socketio.SocketIOPacket
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertFalse
+import kotlin.test.assertSame
 
 class EngineSocketTest : BaseTest() {
 
@@ -116,6 +119,25 @@ class EngineSocketTest : BaseTest() {
         assertEquals(listOf(EngineSocket.EVENT_TRANSPORT), sock.events)
     }
 
+    @Test
+    fun openWithExternalHttpClient() = runTest {
+        val opt = EngineSocket.Options()
+        opt.transports = listOf(PollingXHR.NAME)
+        val externalHttpClient = mockk<HttpClient>(relaxed = true)
+        opt.httpClient = externalHttpClient
+
+        val transport = spyk(TestTransport(Transport.Options(), this, PollingXHR.NAME))
+        val factory = mockk<TransportFactory>()
+        val transportOpt = slot<Transport.Options>()
+        every { factory.create(any(), capture(transportOpt), any(), any()) } returns transport
+
+        val socket = EngineSocket("http://localhost", opt, this, factory)
+        socket.open()
+        advanceUntilIdle()
+
+        assertSame(externalHttpClient, transportOpt.captured.httpClient)
+    }
+
     @Test
     fun openSuccess() = runTest {
         val sock = prepareSocket(listOf(WebSocket.NAME), this)