Untuk pekerjaan latar belakang, Anda sering kali perlu memastikan bahwa hanya satu instans orkestrator tertentu yang berjalan pada satu waktu, mencegah orkestrasi duplikat berjalan secara bersamaan. Anda dapat menerapkan pola singleton ini di Durable Functions atau SDK Tugas Durable dengan menetapkan ID instans tertentu ke orkestrator saat membuatnya, lalu memeriksa apakah instans dengan ID tersebut sudah berjalan sebelum memulai yang baru.
Artikel ini memperlihatkan cara mengimplementasikan orkestrator singleton dengan contoh kode untuk setiap bahasa yang didukung.
Prasyarat
Nota
Ada potensi kondisi perlombaan dalam pola singleton. Jika dua klien menjalankan logika periksa-dan-mulai secara bersamaan, kedua panggilan mungkin melaporkan keberhasilan, tetapi hanya satu instance orkestrasi yang benar-benar memulai. Tergantung pada kebutuhan Anda, ini mungkin memiliki efek samping yang tidak diinginkan. Jika jaminan instans tunggal yang ketat diperlukan, pertimbangkan untuk menambahkan mekanisme penguncian tambahan.
Penting
Saat ini, PowerShell Durable Task SDK tidak tersedia.
Contoh orkestrator singleton
Contoh berikut menunjukkan fungsi pemicu HTTP yang membuat orkestrasi pekerjaan latar belakang singleton. Kode mencoba memastikan bahwa hanya satu instans aktif yang ada untuk ID instans tertentu.
[Function("HttpStartSingle")]
public static async Task<HttpResponseData> RunSingle(
[HttpTrigger(AuthorizationLevel.Function, "post", Route = "orchestrators/{functionName}/{instanceId}")] HttpRequestData req,
[DurableClient] DurableTaskClient starter,
string functionName,
string instanceId,
FunctionContext executionContext)
{
ILogger logger = executionContext.GetLogger("HttpStartSingle");
// Check if an instance with the specified ID already exists or an existing one stopped running(completed/failed/terminated).
OrchestrationMetadata? existingInstance = await starter.GetInstanceAsync(instanceId, getInputsAndOutputs: false);
if (existingInstance == null
|| existingInstance.RuntimeStatus == OrchestrationRuntimeStatus.Completed
|| existingInstance.RuntimeStatus == OrchestrationRuntimeStatus.Failed
|| existingInstance.RuntimeStatus == OrchestrationRuntimeStatus.Terminated)
{
// An instance with the specified ID doesn't exist or an existing one stopped running, create one.
string requestBody = await new StreamReader(req.Body).ReadToEndAsync();
await starter.ScheduleNewOrchestrationInstanceAsync(functionName, requestBody, new StartOrchestrationOptions { InstanceId = instanceId });
logger.LogInformation($"Started orchestration with ID = '{instanceId}'.");
return await starter.CreateCheckStatusResponseAsync(req, instanceId);
}
else
{
// An instance with the specified ID exists or an existing one still running, don't create one.
var response = req.CreateResponse(HttpStatusCode.Conflict);
await response.WriteStringAsync($"An instance with ID '{instanceId}' already exists.");
return response;
}
}
Nota
Kode C# sebelumnya adalah untuk model pekerja terisolasi, yang merupakan model yang direkomendasikan untuk aplikasi .NET. Untuk informasi selengkapnya tentang perbedaan antara model pekerja dalam proses dan terisolasi, lihat artikel versi Durable Functions.
Penting
Contoh JavaScript ini menggunakan model pemrograman Node.js v3, yang menggunakan function.json. Jika Anda menggunakan model pemrogramanNode.js v4 (default saat ini), gunakan pola code-first v4 sebagai gantinya.
function.json
{
"bindings": [
{
"authLevel": "function",
"name": "req",
"type": "httpTrigger",
"direction": "in",
"route": "orchestrators/{functionName}/{instanceId}",
"methods": ["post"]
},
{
"name": "starter",
"type": "orchestrationClient",
"direction": "in"
},
{
"name": "$return",
"type": "http",
"direction": "out"
}
]
}
index.js
const df = require("durable-functions");
module.exports = async function(context, req) {
const client = df.getClient(context);
const instanceId = req.params.instanceId;
const functionName = req.params.functionName;
// Check if an instance with the specified ID already exists or an existing one stopped running(completed/failed/terminated).
const existingInstance = await client.getStatus(instanceId);
if (!existingInstance
|| existingInstance.runtimeStatus == "Completed"
|| existingInstance.runtimeStatus == "Failed"
|| existingInstance.runtimeStatus == "Terminated") {
// An instance with the specified ID doesn't exist or an existing one stopped running, create one.
const eventData = req.body;
await client.startNew(functionName, instanceId, eventData);
context.log(`Started orchestration with ID = '${instanceId}'.`);
return client.createCheckStatusResponse(req, instanceId);
} else {
// An instance with the specified ID exists or an existing one still running, don't create one.
return {
status: 409,
body: `An instance with ID '${instanceId}' already exists.`,
};
}
};
function_app.py
import logging
import azure.functions as func
import azure.durable_functions as df
app = df.DFApp(http_auth_level=func.AuthLevel.FUNCTION)
@app.route(route="orchestrators/{functionName}/{instanceId}", methods=["POST"])
@app.durable_client_input(client_name="client")
async def http_start_single(req: func.HttpRequest, client):
instance_id = req.route_params["instanceId"]
function_name = req.route_params["functionName"]
existing_instance = await client.get_status(instance_id)
if not existing_instance or existing_instance.runtime_status in [
df.OrchestrationRuntimeStatus.Completed,
df.OrchestrationRuntimeStatus.Failed,
df.OrchestrationRuntimeStatus.Terminated,
]:
event_data = req.get_body()
instance_id = await client.start_new(function_name, instance_id, event_data)
logging.info(f"Started orchestration with ID = '{instance_id}'.")
return client.create_check_status_response(req, instance_id)
return func.HttpResponse(
body=f"An instance with ID '{instance_id}' already exists.",
status_code=409,
)
using namespace System.Net
param($Request, $TriggerMetadata)
$FunctionName = $Request.Params.FunctionName
$InstanceId = $Request.Params.InstanceId
# Check if an instance with the specified ID already exists
$existingInstance = Get-DurableStatus -InstanceId $InstanceId
if (-not $existingInstance -or
$existingInstance.RuntimeStatus -eq "Completed" -or
$existingInstance.RuntimeStatus -eq "Failed" -or
$existingInstance.RuntimeStatus -eq "Terminated") {
# An instance with the specified ID doesn't exist or stopped running, create one
$InstanceId = Start-DurableOrchestration -FunctionName $FunctionName -InstanceId $InstanceId -Input $Request.Body
Write-Host "Started orchestration with ID = '$InstanceId'."
$Response = New-DurableOrchestrationCheckStatusResponse -Request $Request -InstanceId $InstanceId
Push-OutputBinding -Name Response -Value $Response
}
else {
# An instance with the specified ID exists or still running
Push-OutputBinding -Name Response -Value ([HttpResponseContext]@{
StatusCode = [HttpStatusCode]::Conflict
Body = "An instance with ID '$InstanceId' already exists."
})
}
@FunctionName("HttpStartSingle")
public HttpResponseMessage runSingle(
@HttpTrigger(name = "req", route = "orchestrators/{functionName}/{instanceId}") HttpRequestMessage<?> req,
@DurableClientInput(name = "durableContext") DurableClientContext durableContext) {
String instanceId = req.getHeaders().getOrDefault("instanceId", "singleton-job");
DurableTaskClient client = durableContext.getClient();
// Check to see if an instance with this ID is already running
OrchestrationMetadata metadata = client.getInstanceMetadata(instanceId, false);
if (metadata == null || !metadata.isRunning()) {
// No such instance exists or it finished - create a new one.
// De-dupe is handled automatically in the storage layer if another
// function tries to also use this instance ID.
client.scheduleNewOrchestrationInstance("MyOrchestration", null, instanceId);
return durableContext.createCheckStatusResponse(req, instanceId);
}
return req.createResponseBuilder(HttpStatus.CONFLICT)
.body("An instance with ID '" + instanceId + "' already exists.")
.build();
}
Contoh berikut menunjukkan cara membuat orkestrasi singleton menggunakan Durable Task SDK. Kode mencoba memastikan bahwa hanya satu instans aktif yang ada untuk ID instans tertentu.
using Microsoft.DurableTask.Client;
// Check if an instance with the specified ID already exists
string instanceId = "singleton-job";
OrchestrationMetadata? existingInstance = await client.GetInstanceAsync(instanceId, getInputsAndOutputs: false);
if (existingInstance == null ||
existingInstance.RuntimeStatus == OrchestrationRuntimeStatus.Completed ||
existingInstance.RuntimeStatus == OrchestrationRuntimeStatus.Failed ||
existingInstance.RuntimeStatus == OrchestrationRuntimeStatus.Terminated)
{
// An instance with the specified ID doesn't exist or an existing one stopped running, create one.
await client.ScheduleNewOrchestrationInstanceAsync("MyOrchestration", input, new StartOrchestrationOptions(instanceId));
Console.WriteLine($"Started orchestration with ID = '{instanceId}'.");
}
else
{
// An instance with the specified ID exists or an existing one still running.
Console.WriteLine($"An instance with ID '{instanceId}' already exists.");
}
from durabletask.azuremanaged.client import DurableTaskSchedulerClient
instance_id = "singleton-job"
# Check if an instance with the specified ID already exists
existing_instance = client.get_orchestration_state(instance_id)
if (existing_instance is None or
existing_instance.runtime_status in ['COMPLETED', 'FAILED', 'TERMINATED']):
# An instance with the specified ID doesn't exist or an existing one stopped running, create one.
client.schedule_new_orchestration(my_orchestration, input=input_data, instance_id=instance_id)
print(f"Started orchestration with ID = '{instance_id}'.")
else:
# An instance with the specified ID exists or an existing one still running.
print(f"An instance with ID '{instance_id}' already exists.")
import com.microsoft.durabletask.DurableTaskClient;
import com.microsoft.durabletask.OrchestrationMetadata;
String instanceId = "singleton-job";
// Check to see if an instance with this ID is already running
OrchestrationMetadata existingInstance = client.getInstanceMetadata(instanceId, false);
if (existingInstance == null || !existingInstance.isRunning()) {
// An instance doesn't exist or finished - create one
client.scheduleNewOrchestrationInstance("MyOrchestration", input, instanceId);
System.out.println("Started orchestration with ID = '" + instanceId + "'.");
} else {
// An instance with the specified ID exists and is still running
System.out.println("An instance with ID '" + instanceId + "' already exists.");
}
import { createAzureManagedClient } from "@microsoft/durabletask-js-azuremanaged";
import { OrchestrationStatus } from "@microsoft/durabletask-js";
const client = createAzureManagedClient(connectionString);
const instanceId = "singleton-job";
// Check if an instance with the specified ID already exists
const existingInstance = await client.getOrchestrationState(instanceId, false);
if (!existingInstance ||
existingInstance.runtimeStatus === OrchestrationStatus.COMPLETED ||
existingInstance.runtimeStatus === OrchestrationStatus.FAILED ||
existingInstance.runtimeStatus === OrchestrationStatus.TERMINATED) {
// An instance with the specified ID doesn't exist or an existing one stopped running, create one.
await client.scheduleNewOrchestration("MyOrchestration", input, instanceId);
console.log(`Started orchestration with ID = '${instanceId}'.`);
} else {
// An instance with the specified ID exists or an existing one still running.
console.log(`An instance with ID '${instanceId}' already exists.`);
}
SDK Tugas Tahan Lama tidak tersedia untuk PowerShell. Gunakan Durable Functions sebagai gantinya.
Cara kerja pola singleton
Karena ID instans bersifat unik dalam hub tugas, menjadwalkan orkestrasi dengan ID yang sudah diketahui dan tetap serta memeriksa statusnya terlebih dahulu dapat mencegah terjadinya duplikasi eksekusi yang bersamaan. Secara default, ID instans adalah GUID yang dihasilkan secara acak. Namun, dalam contoh sebelumnya, ID instans yang spesifik diteruskan. Kode kemudian mengambil metadata instans orkestrasi untuk memeriksa apakah instans dengan ID tersebut sudah berjalan. Jika tidak ada instans seperti itu yang berjalan, instans baru dibuat dengan ID tersebut.
Fungsi orkestrator itu sendiri dapat menggunakan pola apa pun - fungsi standar yang dimulai dan selesai, atau Orkestrasi Abadi yang berjalan terus menerus. Pola singleton hanya mengontrol berapa banyak instans yang berjalan bersamaan.
Langkah berikutnya