feat(PubSub): Added samples for Exactly Once Delivery (GoogleCloudPlatform#1672)

* PubSub: Added samples for Exactly Once Delivery

* Pubsub: Added tests for excatly once delivery samples

* PubSub: Addressed PR comments

Author: saranshdhingra

pubsub/api/src/create_subscription_with_exactly_once_delivery.php

@@ -0,0 +1,59 @@
+
+/**
+ * Copyright 2022 Google Inc.
+ *
+ * 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.
+ */
+
+/**
+ * For instructions on how to run the full sample:
+ *
+ * @see https://github.com/GoogleCloudPlatform/php-docs-samples/blob/master/pubsub/api/README.md
+ */
+
+namespace Google\Cloud\Samples\PubSub;
+
+# [START pubsub_create_subscription_with_exactly_once_delivery]
+use Google\Cloud\PubSub\PubSubClient;
+
+/**
+ * Creates a Pub/Sub subscription with `Exactly Once Delivery` enabled.
+ *
+ * @param string $projectId  The Google project ID.
+ * @param string $topicName  The Pub/Sub topic name.
+ * @param string $subscriptionName  The Pub/Sub subscription name.
+ */
+function create_subscription_with_exactly_once_delivery(
+    string $projectId,
+    string $topicName,
+    string $subscriptionName
+): void {
+    $pubsub = new PubSubClient([
+        'projectId' => $projectId,
+    ]);
+    $topic = $pubsub->topic($topicName);
+    $subscription = $topic->subscription($subscriptionName);
+    $subscription->create([
+        'enableExactlyOnceDelivery' => true
+    ]);
+
+    // Exactly Once Delivery status for the subscription
+    $status = $subscription->info()['enableExactlyOnceDelivery'];
+
+    printf('Subscription created with exactly once delivery status: %s' . PHP_EOL, $status ? 'true' : 'false');
+}
+# [END pubsub_create_subscription_with_exactly_once_delivery]
+
+// The following 2 lines are only needed to run the samples
+require_once __DIR__ . '/../../../testing/sample_helpers.php';
+\Google\Cloud\Samples\execute_sample(__FILE__, __NAMESPACE__, $argv);

pubsub/api/src/subscribe_exactly_once_delivery.php

@@ -0,0 +1,66 @@
+
+/**
+ * Copyright 2022 Google LLC
+ *
+ * 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.
+ */
+
+/**
+ * For instructions on how to run the full sample:
+ *
+ * @see https://github.com/GoogleCloudPlatform/php-docs-samples/blob/master/pubsub/api/README.md
+ */
+namespace Google\Cloud\Samples\PubSub;
+
+# [START pubsub_subscriber_exactly_once]
+use Google\Cloud\PubSub\PubSubClient;
+
+/**
+ * Subscribe and pull messages from a subscription
+ * with `Exactly Once Delivery` enabled.
+ *
+ * @param string $projectId
+ * @param string $subscriptionId
+ */
+function subscribe_exactly_once_delivery(
+    string $projectId,
+    string $subscriptionId
+): void {
+    $pubsub = new PubSubClient([
+        'projectId' => $projectId,
+    ]);
+
+    $subscription = $pubsub->subscription($subscriptionId);
+    $messages = $subscription->pull();
+
+    foreach ($messages as $message) {
+        // When exactly once delivery is enabled on the subscription,
+        // the message is guaranteed to not be delivered again if the ack succeeds.
+        // Passing the `returnFailures` flag retries any temporary failures received
+        // while acking the msg and also returns any permanently failed msgs.
+        // Passing this flag on a subscription with exactly once delivery disabled
+        // will always return an empty array.
+        $failedMsgs = $subscription->acknowledge($message, ['returnFailures' => true]);
+
+        if (empty($failedMsgs)) {
+            printf('Acknowledged message: %s' . PHP_EOL, $message->data());
+        } else {
+            // Either log or store the $failedMsgs to be retried later
+        }
+    }
+}
+# [END pubsub_subscriber_exactly_once]
+
+// The following 2 lines are only needed to run the samples
+require_once __DIR__ . '/../../../testing/sample_helpers.php';
+\Google\Cloud\Samples\execute_sample(__FILE__, __NAMESPACE__, $argv);

pubsub/api/test/pubsubTest.php

@@ -31,6 +31,13 @@ class PubSubTest extends TestCase
     use ExecuteCommandTrait;
     use EventuallyConsistentTestTrait;
 
+    private static $eodSubscriptionId;
+
+    public static function setUpBeforeClass(): void
+    {
+        self::$eodSubscriptionId = 'test-eod-subscription-' . rand();
+    }
+
     public function testSubscriptionPolicy()
     {
         $subscription = $this->requireEnv('GOOGLE_PUBSUB_SUBSCRIPTION');
@@ -225,6 +232,20 @@ public function testCreateAndDeleteSubscriptionWithFilter()
         ), $output);
     }
 
+    public function testCreateSubscriptionWithExactlyOnceDelivery()
+    {
+        $topic = $this->requireEnv('GOOGLE_PUBSUB_TOPIC');
+        $subscription = self::$eodSubscriptionId;
+
+        $output = $this->runFunctionSnippet('create_subscription_with_exactly_once_delivery', [
+            self::$projectId,
+            $topic,
+            $subscription
+        ]);
+
+        $this->assertStringContainsString('Subscription created with exactly once delivery status: true', $output);
+    }
+
     public function testCreateAndDeletePushSubscription()
     {
         $topic = $this->requireEnv('GOOGLE_PUBSUB_TOPIC');
@@ -332,4 +353,36 @@ public function testPullMessagesBatchPublisher()
         shell_exec('kill -9 ' . $pid);
         putenv('IS_BATCH_DAEMON_RUNNING=');
     }
+
+    /**
+     * @depends testCreateSubscriptionWithExactlyOnceDelivery
+     */
+    public function testSubscribeExactlyOnceDelivery()
+    {
+        $topic = $this->requireEnv('GOOGLE_PUBSUB_TOPIC');
+        $subscription = self::$eodSubscriptionId;
+
+        $output = $this->runFunctionSnippet('publish_message', [
+            self::$projectId,
+            $topic,
+            'This is a test message',
+        ]);
+
+        $this->runEventuallyConsistentTest(function () use ($subscription) {
+            $output = $this->runFunctionSnippet('subscribe_exactly_once_delivery', [
+                self::$projectId,
+                $subscription,
+            ]);
+
+            // delete the subscription
+            $this->runFunctionSnippet('delete_subscription', [
+                self::$projectId,
+                $subscription,
+            ]);
+
+            // There should be at least one acked message
+            // pulled from the subscription.
+            $this->assertRegExp('/Acknowledged message:/', $output);
+        });
+    }
 }