k2-coroutines-example.ipynb

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   "source": [
    "// Without coroutine API's can still declare suspend functions (but they cannot be called)\n",
    "// This works today\n",
    "suspend fun main() {\n",
    "    println(\"Hello, world!\")\n",
    "}"
   ],
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   "source": [
    "// Include coroutine APIs\n",
    "%use coroutines"
   ],
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   "source": [
    "// Example 1: Call suspend functions\n",
    "suspend fun main() {\n",
    "    delay(500.milliseconds)\n",
    "    println(\"Hello, world!\")\n",
    "}\n",
    "\n",
    "main()"
   ],
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   "source": [
    "// Example 2: Join multiple tasks\n",
    "suspend fun performTask(name: String): String {\n",
    "    delay(1000L)\n",
    "    return \"Task $name completed\"\n",
    "}\n",
    "\n",
    "val job1 = async { performTask(\"A\") }\n",
    "val job2 = async { performTask(\"B\") }\n",
    "awaitAll(job1, job2)"
   ],
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   "source": [
    "// Example 3: Cell will block until all children completes\n",
    "launch {\n",
    "    delay(1000L)\n",
    "    println(\"Task A completed\")\n",
    "}\n"
   ],
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   "outputs": [],
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   "source": [
    "// Example 4: Flows will block the cell if collected on the top-level\n",
    "fun numbersFlow(): Flow<Int> = flow {\n",
    "    for (i in 1..3) {\n",
    "        delay(100)\n",
    "        println(\"Emitting $i on ${Thread.currentThread().name}\")\n",
    "        emit(i)\n",
    "    }\n",
    "}.flowOn(Dispatchers.Default)\n",
    "\n",
    "numbersFlow().collect { value ->\n",
    "    println(\"Collected $value on ${Thread.currentThread().name}\")\n",
    "}"
   ],
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   "outputs": [],
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  },
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   "cell_type": "code",
   "source": [
    "// Example 5: Exceptions should be shown as Cell output stacktraces\n",
    "suspend fun performTask(name: String): String {\n",
    "    delay(1000L)\n",
    "    throw RuntimeException(\"Error performing task $name\")\n",
    "}\n",
    "\n",
    "performTask(\"Check Error\")"
   ],
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   "outputs": [],
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  },
  {
   "metadata": {},
   "cell_type": "code",
   "source": [
    "// Example 6: runblocking should work\n",
    "runBlocking {\n",
    "    main()\n",
    "}"
   ],
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   "outputs": [],
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  },
  {
   "metadata": {},
   "cell_type": "code",
   "source": [
    "// Example 7: Create your own scopes. Cell is blocked until it completes\n",
    "coroutineScope(Dispatchers.Default) {\n",
    "    main()\n",
    "}"
   ],
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   "source": [
    "// Example 7a: There will be ways where the Cell finishes before the child scope is done\n",
    "// This is similar to what can be accomplished using ThreadPools in K1 Notebooks, so probably acceptable\n",
    "suspend fun work() {\n",
    "    delay(1000L)\n",
    "    println(\"Done!\")\n",
    "}\n",
    "suspend fun outer() = coroutineScope {\n",
    "    val innerScope = CoroutineScope(SupervisorJob() + Dispatchers.Default)\n",
    "    innerScope.launch { work() } // NOT a child of outer\n",
    "} // outer can finish while inner still runs\n",
    "\n",
    "runBlocking { outer() }"
   ],
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