feat(Spanner): Add the built in metrics feature

.github/run-package-tests.sh

@@ -70,7 +70,8 @@ for DIR in ${DIRS}; do
         "PubSub,cloud-pubsub"
         "Storage,cloud-storage"
         "ShoppingCommonProtos,shopping-common-protos"
-        "GeoCommonProtos,geo-common-protos,0.1"
+        "GeoCommonProtos,geo-common-protos,0.1",
+        "Monitoring,cloud-monitoring"
     )
     for i in "${PACKAGE_DEPENDENCIES[@]}"; do
         IFS="," read -r PKG_DIR PKG_NAME PKG_VERSION <<< "$i"

Spanner/composer.json

@@ -7,7 +7,9 @@
         "php": "^8.1",
         "ext-grpc": "*",
         "google/cloud-core": "^1.68",
-        "google/gax": "^1.40.0"
+        "google/gax": "^1.40.0",
+        "google/cloud-monitoring": "^2.2",
+        "open-telemetry/sdk": "^1.13"
     },
     "require-dev": {
         "phpunit/phpunit": "^9.6",
@@ -23,6 +25,7 @@
     },
     "suggest": {
         "ext-protobuf": "Provides a significant increase in throughput over the pure PHP protobuf implementation. See https://cloud.google.com/php/grpc for installation instructions.",
+        "ext-opentelemetry": "Provides a significant increase in performance for OpenTelemetry metrics collection.",
         "brick/math": "Perform arithmetic on NUMERIC values."
     },
     "extra": {

Spanner/src/Middleware/MetricsAttemptMiddleware.php

@@ -0,0 +1,240 @@
+<?php
+/*
+ * Copyright 2026 Google LLC
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+namespace Google\Cloud\Spanner\Middleware;
+
+use Exception;
+use Google\ApiCore\ApiException;
+use Google\ApiCore\Call;
+use Google\ApiCore\Middleware\MiddlewareInterface;
+use Google\ApiCore\ServerStream;
+use Google\Rpc\Code;
+use GuzzleHttp\Promise\PromiseInterface;
+use OpenTelemetry\API\Metrics\CounterInterface;
+use OpenTelemetry\API\Metrics\HistogramInterface;
+use OpenTelemetry\API\Metrics\MeterInterface;
+
+/**
+ * @internal
+ *
+ * A middleware to be appended inside of the retry loops of GAX.
+ * This middleware handles the recording of Built-in metrics
+ * for an Attempt, where an Attempt is an RPC call as part of an Operation.
+ * If an Operation fails, said Operation may contain multiple attempts depending on the retry configuration.
+ */
+class MetricsAttemptMiddleware implements MiddlewareInterface
+{
+    private HistogramInterface $attemptLatencyHistogram;
+    private CounterInterface $attemptCountCounter;
+    private HistogramInterface $attemptGfeHistogram;
+    private CounterInterface $gfeConnectivityErrorCounter;
+
+    /** @var callable */
+    private $nextHandler;
+    private string $projectId;
+    private string $clientId;
+    private string $clientName;
+
+    private const INSTANCE_CONFIG = 'unknown';
+    private const LOCATION_LABEL = 'global';
+
+    /**
+     * Creates a middleware that tracks all the attempts of an RPC call
+     *
+     * @param callable $nextHandler
+     * @param MeterInterface $meter
+     * @param string $clientId
+     * @param string $projectId
+     * @param string $clientName
+     */
+    public function __construct(
+        callable $nextHandler,
+        MeterInterface $meter,
+        string $clientId,
+        string $projectId,
+        string $clientName,
+    ) {
+        $this->nextHandler = $nextHandler;
+        $this->attemptLatencyHistogram = $meter->createHistogram(
+            'attempt_latencies',
+            'ms',
+            'The latency of an RPC attempt'
+        );
+        $this->attemptCountCounter = $meter->createCounter(
+            'attempt_count',
+            '1',
+            'The number of RPC attempts'
+        );
+        $this->attemptGfeHistogram = $meter->createHistogram(
+            'gfe_latencies',
+            'ms',
+            'Latency between Google\'s network receiving an RPC and reading back the first byte of the response'
+        );
+        $this->gfeConnectivityErrorCounter = $meter->createCounter(
+            'gfe_connectivity_error_count',
+            '1',
+            'Number of RPC attempts that failed to reach the GFE or returned no GFE headers'
+        );
+        $this->clientId = $clientId;
+        $this->projectId = $projectId;
+        $this->clientName = $clientName;
+    }
+
+    public function __invoke(Call $call, array $options)
+    {
+        $next = $this->nextHandler;
+
+        $startTime = microtime(true);
+
+        // In case that something else is using this callback,
+        // we take the original one and call it later.
+        $originalCallback = $options['metadataCallback'] ?? null;
+
+        // This gets the metadata on an ok status meaning we can get the GFE latency header for unary calls
+        $options['metadataCallback'] = function ($metadata) use ($originalCallback, $call, $options) {
+            $this->recordGfeLatency($metadata, $call, $options);
+            if ($originalCallback) {
+                $originalCallback($metadata);
+            }
+        };
+
+        try {
+            $response = $next(
+                $call,
+                $options
+            );
+        } catch (Exception $e) {
+            // In case that the call is not a unary call and it is a streaming call error.
+            $this->recordAttempt($startTime, $e->getCode(), $call->getMethod(), $options);
+            $this->recordGfeError($e, $call, $options);
+            throw $e;
+        }
+
+        if ($response instanceof ServerStream) {
+            $this->recordAttempt($startTime, Code::OK, $call->getMethod(), $options);
+            $this->recordGfeLatency($response->getServerStreamingCall()->getMetadata(), $call, $options);
+        }
+
+        if ($response instanceof PromiseInterface) {
+            return $response->then(
+                function ($response) use ($startTime, $options, $call) {
+                    $this->recordAttempt($startTime, Code::OK, $call->getMethod(), $options);
+                    return $response;
+                },
+                function ($e) use ($startTime, $options, $call) {
+                    $this->recordAttempt($startTime, $e->getCode(), $call->getMethod(), $options);
+                    $this->recordGfeError($e, $call, $options);
+                    throw $e;
+                }
+            );
+        }
+
+        // The response can be a stream
+        return $response;
+    }
+
+    /**
+     * Records an Attempt
+     *
+     * @param array $options The options being used for the middleware layer to communicate amongst middlewares
+     * @param float $startTime The start time of the RPC attempt
+     * @param int $code The resulting code of the attempt
+     * @param string $method The RPC method name that is being called
+     *
+     * @return void
+     */
+    private function recordAttempt(float $startTime, int $code, string $method, array $options): void
+    {
+        $endTime = microtime(true);
+        $duration = ($endTime - $startTime) * 1000; // Convert to MS
+
+        $labels = $this->getMetricLabels($method, $options, $code);
+
+        $this->attemptCountCounter->add(1, $labels);
+        $this->attemptLatencyHistogram->record($duration, $labels);
+    }
+
+    private function recordGfeLatency($metadata, Call $call, array $options): void
+    {
+        $serverTiming = $metadata['server-timing'][0] ?? null;
+        $gfeLatency = null;
+
+        if ($serverTiming) {
+            if (preg_match('/gfet4t7;\s*dur=(\d+(\.\d+)?)/', $serverTiming, $matches)) {
+                $gfeLatency = (float) $matches[1];
+            }
+        }
+
+        $labels = $this->getMetricLabels($call->getMethod(), $options, Code::OK);
+
+        if ($gfeLatency !== null) {
+            $this->attemptGfeHistogram->record($gfeLatency, $labels);
+        } else {
+            $this->gfeConnectivityErrorCounter->add(1, $labels);
+        }
+    }
+
+    private function getMetricLabels(string $method, array $options, int $code): array
+    {
+        $codeName = Code::name($code);
+
+        // Extract resource information from the GAX routing header.
+        $params = $options['headers']['x-goog-request-params'][0] ?? '';
+        $prefix = urldecode($params);
+
+        if (preg_match('/instances\/([^\/]+)\/databases\/([^\/]+)/', $prefix, $matches)) {
+            $instanceId = $matches[1];
+            $databaseId = $matches[2];
+        }
+
+        return [
+            'method' => $method,
+            'status' => $codeName,
+            'instance_id' => $instanceId ?? '',
+            'database' => $databaseId ?? '',
+            'project_id' => $this->projectId,
+            'client_uid' => $this->clientId,
+            'client_name' => $this->clientName,
+            'instance_config' => self::INSTANCE_CONFIG,
+            'location' => self::LOCATION_LABEL
+        ];
+    }
+
+    private function recordGfeError(Exception $e, Call $call, array $options): void
+    {
+        if ($e instanceof ApiException) {
+            $this->recordGfeLatency($e->getMetadata() ?? [], $call, $options);
+        } else {
+            $this->recordGfeLatency([], $call, $options);
+        }
+    }
+}