Kotlin/Native CA.kt #3 @stormcat24

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Ice Break?

Written by @ngsw_taro Congratulations!

I reviewed 2nd, 3rd parts. ‣SparkFramework with Kotlin ‣Spring Boot with Kotlin

Kotlin/Native

What?

No content

“Kotlin/Native that compiles Kotlin directly to machine.”

“without any virtual machine.” (standalone executables)

Kotlin/Native is ‣Compiles directly to native code via LLVM ‣Call native libraries ‣Cross Platform ‣Windows/Linux/macOS/iOS/Android/Raspberry Pi ‣Version 0.3

Setup $ git clone git@github.com:JetBrains/kotlin-native.git $ cd kotlin-native (kotlin-native)$ git checkout v0.3.4 Get Kotlin/Native Build (kotlin-native)$ ./gradlew dependencies:update (kotlin-native)$ ./gradlew dist (kotlin-native)$ ./gradlew cross_dist Path $ export PATH=$PATH:path-to-path/kotlin-native/dist/bin

Try Quickly fun main(args: Array) { // Not System.out.println() println(“Hello! Kotlin/Native“) } hello.kt compile $ kotlinc hello.kt -o hello KtFile: hello.kt Execute $ ./hello.kexe Hello! Kotlin/Native

build.gradle buildscript { repositories { mavenCentral() maven { url "https://dl.bintray.com/jetbrains/kotlin-native-dependencies" } } dependencies { classpath "org.jetbrains.kotlin:kotlin-native-gradle-plugin:0.3.3" } } apply plugin: 'konan' konanArtifacts { KonanExample { } }

Native Library

Today’s Example HTTP GET Request By using libcurl

Create *.def file ‣Library definition file ‣Link Kotlin/Native to Native libraries ‣Generate interoperability stubs ‣Define in build.gradle

Define *.def file headers = curl/curl.h compilerOpts=-I/usr/local/include linkerOpts.osx = -L/opt/local/lib -L/usr/local/opt/curl/lib -lcurl src/main/c_interop/libcurl.def build.gradle apply plugin: 'konan' konanInterop { Libcurl { includeDirs '/usr/local/opt/curl/include', '.' } } konanArtifacts { KonanExample { useInterop 'libcurl' } }

Implementation curl.kt import kotlinx.cinterop.* import libcurl.* fun main(args: Array): Unit { if (args.size == 0) { return } val url = args.first() val curl = curl_easy_init() curl_easy_setopt(curl, CURLOPT_URL, url) val res = curl_easy_perform(curl) when (res) { CURLE_OK -> println("HTTP Request OK") else -> println("HTTP Request NG") } }

Call Library In C #include CURLcode curl_easy_perform(CURL * easy_handle); fun curl_easy_perform(curl: COpaquePointer?): CURLcode { return kniBridge40(curl.rawValue) } typealias CURLcode = kotlin.Int val CURLE_OK: CURLcode = 0 val CURLE_UNSUPPORTED_PROTOCOL: CURLcode = 1 val CURLE_FAILED_INIT: CURLcode = 2 … Stub in Kotlin/Native

Execute Build Execute $ ./gradlew build $ ls build/konan/bin Curl.kexe Curl.kt.bc $ build/konan/bin/Curl.kexe https://blog.stormcat.io (...) HTTP Request OK

Interoperability

Interop types ‣Int => kotlin.Int ‣T* => CPointer ‣void* => COpaquePointer? ‣

Memory Management ‣Automated memory management by Cycle Collector ‣https://github.com/JetBrains/kotlin-native/blob/master/ runtime/src/main/cpp/Memory.cpp ‣When using Native Library…?

Memory allocation Allocate memory val buffer = nativeHeap.allocArray(size) ... nativeHeap.free(buffer) memScoped val fileSize = memScoped { val statBuf = alloc() val error = stat("/", statBuf.ptr) statBuf.st_size }

Use IDEA

<- Uncheck Java

Code Completion

Impressions

Impressions ‣Very experimental and challenging ‣Interoperability is difficult ‣Lack of Ecosystem, fundamental libraries ‣Not enough code completion ‣If gRPC support Kotlin/Native?

Thanks✋