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Kotlin/Native
CA.kt #3 @stormcat24
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stormcat24
‣ CyberAgent, Inc.
‣ FRESH! https://freshlive.tv
‣ https://blog.stormcat.io
‣ Docker Comedian
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Ice Break?
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Written by @ngsw_taro
Congratulations!
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I reviewed 2nd, 3rd parts.
‣SparkFramework with Kotlin
‣Spring Boot with Kotlin
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Kotlin/Native
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What?
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No content
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“Kotlin/Native that compiles
Kotlin directly to machine.”
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“without any virtual machine.”
(standalone executables)
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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
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Setup
$ git clone [email protected]: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
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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
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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 {
}
}
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Native Library
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Today’s Example
HTTP GET Request By using libcurl
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Create *.def file
‣Library definition file
‣Link Kotlin/Native to Native libraries
‣Generate interoperability stubs
‣Define in build.gradle
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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'
}
}
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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")
}
}
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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
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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
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Interoperability
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Interop types
‣Int => kotlin.Int
‣T* => CPointer
‣void* => COpaquePointer?
‣
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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…?
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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
}
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Use IDEA
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<- Uncheck Java
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Code Completion
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Impressions
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Impressions
‣Very experimental and challenging
‣Interoperability is difficult
‣Lack of Ecosystem, fundamental libraries
‣Not enough code completion
‣If gRPC support Kotlin/Native?
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Thanks✋