feat(spanner): [Spanner] add cache updates API

Spanner/samples/V1/SpannerClient/fetch_cache_update.php

@@ -0,0 +1,84 @@
+<?php
+/*
+ * Copyright 2026 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
+ *
+ *     https://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.
+ */
+
+/*
+ * GENERATED CODE WARNING
+ * This file was automatically generated - do not edit!
+ */
+
+require_once __DIR__ . '/../../../vendor/autoload.php';
+
+// [START spanner_v1_generated_Spanner_FetchCacheUpdate_sync]
+use Google\ApiCore\ApiException;
+use Google\ApiCore\ServerStream;
+use Google\Cloud\Spanner\V1\CacheUpdate;
+use Google\Cloud\Spanner\V1\Client\SpannerClient;
+use Google\Cloud\Spanner\V1\FetchCacheUpdateRequest;
+
+/**
+ * Retrieves a cache update for a given database.
+ *
+ * This RPC can be used to warm up the client cache by fetching key recipes
+ * and server information for a given database. It is recommended to call
+ * this RPC at the beginning of the client's lifecycle, prior to any other
+ * data plane operations.
+ *
+ * The cache update is returned as a stream because the response can be too
+ * large to fit into a single `CacheUpdate` message.
+ *
+ * @param string $formattedDatabase The database for which to retrieve the cache update. Please see
+ *                                  {@see SpannerClient::databaseName()} for help formatting this field.
+ */
+function fetch_cache_update_sample(string $formattedDatabase): void
+{
+    // Create a client.
+    $spannerClient = new SpannerClient();
+
+    // Prepare the request message.
+    $request = (new FetchCacheUpdateRequest())
+        ->setDatabase($formattedDatabase);
+
+    // Call the API and handle any network failures.
+    try {
+        /** @var ServerStream $stream */
+        $stream = $spannerClient->fetchCacheUpdate($request);
+
+        /** @var CacheUpdate $element */
+        foreach ($stream->readAll() as $element) {
+            printf('Element data: %s' . PHP_EOL, $element->serializeToJsonString());
+        }
+    } catch (ApiException $ex) {
+        printf('Call failed with message: %s' . PHP_EOL, $ex->getMessage());
+    }
+}
+
+/**
+ * Helper to execute the sample.
+ *
+ * This sample has been automatically generated and should be regarded as a code
+ * template only. It will require modifications to work:
+ *  - It may require correct/in-range values for request initialization.
+ *  - It may require specifying regional endpoints when creating the service client,
+ *    please see the apiEndpoint client configuration option for more details.
+ */
+function callSample(): void
+{
+    $formattedDatabase = SpannerClient::databaseName('[PROJECT]', '[INSTANCE]', '[DATABASE]');
+
+    fetch_cache_update_sample($formattedDatabase);
+}
+// [END spanner_v1_generated_Spanner_FetchCacheUpdate_sync]

Spanner/src/V1/Client/SpannerClient.php

@@ -41,6 +41,7 @@
 use Google\Cloud\Spanner\V1\BatchWriteRequest;
 use Google\Cloud\Spanner\V1\BatchWriteResponse;
 use Google\Cloud\Spanner\V1\BeginTransactionRequest;
+use Google\Cloud\Spanner\V1\CacheUpdate;
 use Google\Cloud\Spanner\V1\CommitRequest;
 use Google\Cloud\Spanner\V1\CommitResponse;
 use Google\Cloud\Spanner\V1\CreateSessionRequest;
@@ -49,6 +50,7 @@
 use Google\Cloud\Spanner\V1\ExecuteBatchDmlRequest\Statement;
 use Google\Cloud\Spanner\V1\ExecuteBatchDmlResponse;
 use Google\Cloud\Spanner\V1\ExecuteSqlRequest;
+use Google\Cloud\Spanner\V1\FetchCacheUpdateRequest;
 use Google\Cloud\Spanner\V1\GetSessionRequest;
 use Google\Cloud\Spanner\V1\ListSessionsRequest;
 use Google\Cloud\Spanner\V1\Mutation;
@@ -608,6 +610,36 @@ public function executeStreamingSql(ExecuteSqlRequest $request, array $callOptio
         return $this->startApiCall('ExecuteStreamingSql', $request, $callOptions);
     }
 
+    /**
+     * Retrieves a cache update for a given database.
+     *
+     * This RPC can be used to warm up the client cache by fetching key recipes
+     * and server information for a given database. It is recommended to call
+     * this RPC at the beginning of the client's lifecycle, prior to any other
+     * data plane operations.
+     *
+     * The cache update is returned as a stream because the response can be too
+     * large to fit into a single `CacheUpdate` message.
+     *
+     * @example samples/V1/SpannerClient/fetch_cache_update.php
+     *
+     * @param FetchCacheUpdateRequest $request     A request to house fields associated with the call.
+     * @param array                   $callOptions {
+     *     Optional.
+     *
+     *     @type int $timeoutMillis
+     *           Timeout to use for this call.
+     * }
+     *
+     * @return ServerStream<CacheUpdate>
+     *
+     * @throws ApiException Thrown if the API call fails.
+     */
+    public function fetchCacheUpdate(FetchCacheUpdateRequest $request, array $callOptions = []): ServerStream
+    {
+        return $this->startApiCall('FetchCacheUpdate', $request, $callOptions);
+    }
+
     /**
      * Gets a session. Returns `NOT_FOUND` if the session doesn't exist.
      * This is mainly useful for determining whether a session is still

Spanner/src/V1/gapic_metadata.json

@@ -55,6 +55,11 @@
                                 "executeStreamingSql"
                             ]
                         },
+                        "FetchCacheUpdate": {
+                            "methods": [
+                                "fetchCacheUpdate"
+                            ]
+                        },
                         "GetSession": {
                             "methods": [
                                 "getSession"

Spanner/src/V1/resources/spanner_client_config.json

@@ -106,6 +106,9 @@
                 "ExecuteStreamingSql": {
                     "timeout_millis": 3600000
                 },
+                "FetchCacheUpdate": {
+                    "timeout_millis": 60000
+                },
                 "GetSession": {
                     "timeout_millis": 30000,
                     "retry_codes_name": "retry_policy_3_codes",

Spanner/src/V1/resources/spanner_descriptor_config.php

@@ -137,6 +137,21 @@
                     ],
                 ],
             ],
+            'FetchCacheUpdate' => [
+                'grpcStreaming' => [
+                    'grpcStreamingType' => 'ServerStreaming',
+                ],
+                'callType' => \Google\ApiCore\Call::SERVER_STREAMING_CALL,
+                'responseType' => 'Google\Cloud\Spanner\V1\CacheUpdate',
+                'headerParams' => [
+                    [
+                        'keyName' => 'database',
+                        'fieldAccessors' => [
+                            'getDatabase',
+                        ],
+                    ],
+                ],
+            ],
             'GetSession' => [
                 'callType' => \Google\ApiCore\Call::UNARY_CALL,
                 'responseType' => 'Google\Cloud\Spanner\V1\Session',

Spanner/src/V1/resources/spanner_rest_client_config.php

@@ -264,6 +264,18 @@
                     ],
                 ],
             ],
+            'FetchCacheUpdate' => [
+                'method' => 'post',
+                'uriTemplate' => '/v1/{database=projects/*/instances/*/databases/*}:cacheUpdate',
+                'body' => '*',
+                'placeholders' => [
+                    'database' => [
+                        'getters' => [
+                            'getDatabase',
+                        ],
+                    ],
+                ],
+            ],
             'GetSession' => [
                 'method' => 'get',
                 'uriTemplate' => '/v1/{name=projects/*/instances/*/databases/*/sessions/*}',