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코드 샘플
C#
using CloudNative.CloudEvents;
using Google.Cloud.Functions.Framework;
using Google.Events.Protobuf.Cloud.PubSub.V1;
using Microsoft.Extensions.Logging;
using System;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
namespace Retry;
public class Function : ICloudEventFunction<MessagePublishedData>
{
private readonly ILogger _logger;
public Function(ILogger<Function> logger) =>
_logger = logger;
public Task HandleAsync(CloudEvent cloudEvent, MessagePublishedData data, CancellationToken cancellationToken)
{
bool retry = false;
string text = data.Message?.TextData;
// Get the value of the "retry" JSON parameter, if one exists.
if (!string.IsNullOrEmpty(text))
{
JsonElement element = JsonSerializer.Deserialize<JsonElement>(data.Message.TextData);
retry = element.TryGetProperty("retry", out var property) &&
property.ValueKind == JsonValueKind.True;
}
// Throwing an exception causes the execution to be retried.
if (retry)
{
throw new InvalidOperationException("Retrying...");
}
else
{
_logger.LogInformation("Not retrying...");
}
return Task.CompletedTask;
}
}Go
// Package tips contains tips for writing Cloud Functions in Go.
package tips
import (
"context"
"errors"
"log"
)
// PubSubMessage is the payload of a Pub/Sub event.
// See the documentation for more details:
// https://cloud.google.com/pubsub/docs/reference/rest/v1/PubsubMessage
type PubSubMessage struct {
Data []byte `json:"data"`
}
// RetryPubSub demonstrates how to toggle using retries.
func RetryPubSub(ctx context.Context, m PubSubMessage) error {
name := string(m.Data)
if name == "" {
name = "World"
}
// A misconfigured client will stay broken until the function is redeployed.
client, err := MisconfiguredDataClient()
if err != nil {
log.Printf("MisconfiguredDataClient (retry denied): %v", err)
// A nil return indicates that the function does not need a retry.
return nil
}
// Runtime error might be resolved with a new attempt.
if err = FailedWriteOperation(client, name); err != nil {
log.Printf("FailedWriteOperation (retry expected): %v", err)
// A non-nil return indicates that a retry is needed.
return err
}
return nil
}
Java
import com.google.cloud.functions.BackgroundFunction;
import com.google.cloud.functions.Context;
import com.google.gson.Gson;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import functions.eventpojos.PubsubMessage;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
import java.util.logging.Logger;
public class RetryPubSub implements BackgroundFunction<PubsubMessage> {
private static final Logger logger = Logger.getLogger(RetryPubSub.class.getName());
// Use Gson (https://github.com/google/gson) to parse JSON content.
private static final Gson gson = new Gson();
@Override
public void accept(PubsubMessage message, Context context) {
String bodyJson = new String(
Base64.getDecoder().decode(message.getData()), StandardCharsets.UTF_8);
JsonElement bodyElement = gson.fromJson(bodyJson, JsonElement.class);
// Get the value of the "retry" JSON parameter, if one exists
boolean retry = false;
if (bodyElement != null && bodyElement.isJsonObject()) {
JsonObject body = bodyElement.getAsJsonObject();
if (body.has("retry") && body.get("retry").getAsBoolean()) {
retry = true;
}
}
// Retry if appropriate
if (retry) {
// Throwing an exception causes the execution to be retried
throw new RuntimeException("Retrying...");
} else {
logger.info("Not retrying...");
}
}
}Node.js
/**
* Background Cloud Function that demonstrates
* how to toggle retries using a promise
*
* @param {object} event The Cloud Functions event.
* @param {object} event.data Data included with the event.
* @param {object} event.data.retry User-supplied parameter that tells the function whether to retry.
*/
exports.retryPromise = event => {
const tryAgain = !!event.data.retry;
if (tryAgain) {
throw new Error('Retrying...');
} else {
console.error('Not retrying...');
return Promise.resolve();
}
};
/**
* Background Cloud Function that demonstrates
* how to toggle retries using a callback
*
* @param {object} event The Cloud Functions event.
* @param {object} event.data Data included with the event.
* @param {object} event.data.retry User-supplied parameter that tells the function whether to retry.
* @param {function} callback The callback function.
*/
exports.retryCallback = (event, callback) => {
const tryAgain = !!event.data.retry;
const err = new Error('Error!');
if (tryAgain) {
console.error('Retrying:', err);
callback(err);
} else {
console.error('Not retrying:', err);
callback();
}
};PHP
use Google\CloudFunctions\CloudEvent;
function tipsRetry(CloudEvent $event): void
{
$cloudEventData = $event->getData();
$pubSubData = $cloudEventData['message']['data'];
$json = json_decode(base64_decode($pubSubData), true);
// Determine whether to retry the invocation based on a parameter
$tryAgain = $json['some_parameter'];
if ($tryAgain) {
/**
* Functions with automatic retries enabled should throw exceptions to
* indicate intermittent failures that a retry might fix. In this
* case, a thrown exception will cause the original function
* invocation to be re-sent.
*/
throw new Exception('Intermittent failure occurred; retrying...');
}
/**
* If a function with retries enabled encounters a non-retriable
* failure, it should return *without* throwing an exception.
*/
$log = fopen(getenv('LOGGER_OUTPUT') ?: 'php://stderr', 'wb');
fwrite($log, 'Not retrying' . PHP_EOL);
}Python
from google.cloud import error_reporting
error_client = error_reporting.Client()
def retry_or_not(data, context):
"""Background Cloud Function that demonstrates how to toggle retries.
Args:
data (dict): The event payload.
context (google.cloud.functions.Context): The event metadata.
Returns:
None; output is written to Stackdriver Logging
"""
# Retry based on a user-defined parameter
try_again = data.data.get('retry') is not None
try:
raise RuntimeError('I failed you')
except RuntimeError:
error_client.report_exception()
if try_again:
raise # Raise the exception and try again
else:
pass # Swallow the exception and don't retryRuby
require "functions_framework"
FunctionsFramework.cloud_event "retry_or_not" do |event|
try_again = event.data["retry"]
begin
# Simulate a failure
raise "I failed!"
rescue RuntimeError => e
logger.warn "Caught an error: #{e}"
if try_again
# Raise an exception to return a 500 and trigger a retry.
logger.info "Trying again..."
raise ex
else
# Return normally to end processing of this event.
logger.info "Giving up."
end
end
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