Global state demo. (#1236)

samples/globalState/README.md

@@ -0,0 +1,9 @@
+# Shared global state
+
+ This example shows how one could implement global shared state using interop mechanisms.
+
+To build use `../gradlew build`.
+
+To run use `./build/konan/bin/<platform>/Globals.exe`.
+
+

samples/globalState/build.gradle

@@ -0,0 +1,15 @@
+apply plugin: 'konan'
+
+konan.targets = ['macbook', 'linux', 'mingw']
+
+konanArtifacts {
+    interop('global') {
+        defFile 'src/main/c_interop/global.def'
+    }
+
+    program('Globals') {
+        libraries {
+            artifact 'global'
+        }
+    }
+}

samples/globalState/src/main/c_interop/global.def

@@ -0,0 +1,10 @@
+package = global
+
+---
+typedef struct {
+  int x;
+  float f;
+  char* string;
+} SharedData;
+
+SharedData sharedData;

samples/globalState/src/main/kotlin/Global.kt

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import global.*
+import kotlinx.cinterop.*
+import platform.posix.*
+
+fun Int.ensureUnixCallResult(op: String, predicate: (Int) -> Boolean = { x -> x >= 0} ): Int {
+    if (!predicate(this)) {
+        throw Error("$op: ${strerror(posix_errno())!!.toKString()}")
+    }
+    return this
+}
+
+fun dumpShared(prefix: String) =
+        println("$prefix: ${pthread_self().rawValue} x=${sharedData.x} f=${sharedData.f} s=${sharedData.string!!.toKString()}")
+
+fun main(args: Array<String>) {
+    // Arena owning all native allocs.
+    val arena = Arena()
+
+    // Assign global data.
+    sharedData.x = 239
+    sharedData.f = 0.5f
+    sharedData.string = "Hello Kotlin!".cstr.getPointer(arena)
+    dumpShared("thread1")
+
+    // Start a new thread, that sees the variable.
+    // memScoped is needed to pass thread's local address to pthread_create().
+    memScoped {
+        val thread = alloc<pthread_tVar>()
+        pthread_create(thread.ptr, null, staticCFunction {
+            _ ->
+            initRuntimeIfNeeded()
+            dumpShared("thread2")
+            // Workaround for compiler issue.
+            null as COpaquePointer?
+        }, null).ensureUnixCallResult("pthread_create")
+        pthread_join(thread.value, null).ensureUnixCallResult("pthread_join")
+    }
+
+    // At this moment we do not need data stored in shared data, so clean up the data
+    // and free memory.
+    sharedData.string = null
+    arena.clear()
+}

samples/settings.gradle

@@ -3,6 +3,7 @@
 include ':calculator'
 include ':csvparser'
 include ':gitchurn'
+include ':globalState'
 include ':gtk'
 include ':libcurl'
 include ':nonBlockingEchoServer'