Add RedisTxn storage adapter.

.gitignore

@@ -1,6 +1,7 @@
 /vendor/
 *.iml
 /.idea/
+benchmark.csv
 composer.lock
 composer.phar
 .phpunit.result.cache

docker-compose.yml

@@ -5,6 +5,8 @@ services:
       - php-fpm
     ports:
       - 8080:80
+    environment:
+      - REDIS_HOST=redis
 
   php-fpm:
     build: php-fpm/

examples/flush_adapter.php

@@ -16,6 +16,8 @@
     $adapter = new Prometheus\Storage\APCng();
 } elseif ($adapterName === 'in-memory') {
     $adapter = new Prometheus\Storage\InMemory();
+} elseif ($adapterName === 'redistxn') {
+    $adapter = new Prometheus\Storage\RedisTxn(['host' => $_SERVER['REDIS_HOST'] ?? '127.0.0.1']);
 }
 
 $adapter->wipeStorage();

examples/metrics.php

@@ -17,6 +17,8 @@
     $adapter = new Prometheus\Storage\APCng();
 } elseif ($adapter === 'in-memory') {
     $adapter = new Prometheus\Storage\InMemory();
+} elseif ($adapter === 'redistxn') {
+    $adapter = new Prometheus\Storage\RedisTxn(['host' => $_SERVER['REDIS_HOST'] ?? '127.0.0.1']);
 }
 $registry = new CollectorRegistry($adapter);
 $renderer = new RenderTextFormat();

examples/some_counter.php

@@ -16,6 +16,8 @@
     $adapter = new Prometheus\Storage\APCng();
 } elseif ($adapter === 'in-memory') {
     $adapter = new Prometheus\Storage\InMemory();
+} elseif ($adapter === 'redistxn') {
+    $adapter = new Prometheus\Storage\RedisTxn(['host' => $_SERVER['REDIS_HOST'] ?? '127.0.0.1']);
 }
 $registry = new CollectorRegistry($adapter);
 

examples/some_gauge.php

@@ -19,6 +19,8 @@
     $adapter = new Prometheus\Storage\APCng();
 } elseif ($adapter === 'in-memory') {
     $adapter = new Prometheus\Storage\InMemory();
+} elseif ($adapter === 'redistxn') {
+    $adapter = new Prometheus\Storage\RedisTxn(['host' => $_SERVER['REDIS_HOST'] ?? '127.0.0.1']);
 }
 $registry = new CollectorRegistry($adapter);
 

examples/some_histogram.php

@@ -18,6 +18,8 @@
     $adapter = new Prometheus\Storage\APCng();
 } elseif ($adapter === 'in-memory') {
     $adapter = new Prometheus\Storage\InMemory();
+} elseif ($adapter === 'redistxn') {
+    $adapter = new Prometheus\Storage\RedisTxn(['host' => $_SERVER['REDIS_HOST'] ?? '127.0.0.1']);
 }
 $registry = new CollectorRegistry($adapter);
 

examples/some_summary.php

@@ -18,6 +18,8 @@
     $adapter = new Prometheus\Storage\APCng();
 } elseif ($adapter === 'in-memory') {
     $adapter = new Prometheus\Storage\InMemory();
+} elseif ($adapter === 'redistxn') {
+    $adapter = new Prometheus\Storage\RedisTxn(['host' => $_SERVER['REDIS_HOST'] ?? '127.0.0.1']);
 }
 $registry = new CollectorRegistry($adapter);
 

php-fpm/Dockerfile

@@ -1,7 +1,14 @@
 FROM php:8.1-fpm
 
-RUN pecl install redis && docker-php-ext-enable redis
-RUN pecl install apcu && docker-php-ext-enable apcu
+RUN apt-get -y install git libzip-dev zip unzip php-zip
+RUN pecl install redis && docker-php-ext-enable redis \
+  && pecl install apcu && docker-php-ext-enable apcu \
+  && pecl install zip && docker-php-ext-enable zip
+RUN cd /var/www/html \
+    && curl -sS https://getcomposer.org/installer -o composer-setup.php \
+    && php composer-setup.php \
+    && rm composer-setup.php \
+    && composer.phar install
 
 COPY www.conf /usr/local/etc/php-fpm.d/
 COPY docker-php-ext-apcu-cli.ini /usr/local/etc/php/conf.d/

phpunit.xml.dist

@@ -25,6 +25,7 @@
     <groups>
         <exclude>
             <group>Performance</group>
+            <group>Benchmark</group>
         </exclude>
     </groups>
 </phpunit>

src/Prometheus/Storage/RedisTxn.php

@@ -0,0 +1,300 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Prometheus\Storage;
+
+use Prometheus\Exception\StorageException;
+use Prometheus\Histogram;
+use Prometheus\MetricFamilySamples;
+use Prometheus\Storage\RedisTxn\Collecter\CounterCollecter;
+use Prometheus\Storage\RedisTxn\Collecter\GaugeCollecter;
+use Prometheus\Storage\RedisTxn\Collecter\HistogramCollecter;
+use Prometheus\Storage\RedisTxn\Collecter\SummaryCollecter;
+use Prometheus\Storage\RedisTxn\Updater\CounterUpdater;
+use Prometheus\Storage\RedisTxn\Updater\GaugeUpdater;
+use Prometheus\Storage\RedisTxn\Updater\HistogramUpdater;
+use Prometheus\Storage\RedisTxn\Updater\SummaryUpdater;
+use function \sort;
+
+/**
+ * This is a storage adapter that persists Prometheus metrics in Redis.
+ *
+ * This library currently has two alternative Redis adapters:
+ * - {@see \Prometheus\Storage\Redis}: Initial Redis adapter written for this library.
+ * - {@see \Prometheus\Storage\RedisNg}: "Next-generation" adapter refactored to avoid use of the KEYS command to improve performance.
+ *
+ * While the next-generation adapter was an enormous performance improvement over the first, it still suffers from
+ * performance degradation that scales significantly as the number of metrics grows. This is largely due to the fact
+ * that the "collect" phase for metrics generally involves at least one network request per metric of each type.
+ *
+ * This adapter refactors the {@see \Prometheus\Storage\RedisNg} adapter to generally try and execute the "update" and
+ * "collect" operations of each metric type within a single Redis transaction.
+ *
+ * @todo Reimplement wipeStorage() to account for reorganized keys in Redis.
+ * @todo Reimplement all Redis scripts with redis.pcall() to trap runtime errors that are ignored by redis.call().
+ */
+class RedisTxn implements Adapter
+{
+    /**
+     * @var mixed[]
+     */
+    private static $defaultOptions = [
+        'host' => '127.0.0.1',
+        'port' => 6379,
+        'timeout' => 0.1,
+        'read_timeout' => '10',
+        'persistent_connections' => false,
+        'password' => null,
+    ];
+
+    /**
+     * @var string
+     */
+    private static $prefix = 'PROMETHEUS_';
+
+    /**
+     * @var mixed[]
+     */
+    private $options = [];
+
+    /**
+     * @var \Redis
+     */
+    private $redis;
+
+    /**
+     * @var boolean
+     */
+    private $connectionInitialized = false;
+
+    /**
+     * Redis constructor.
+     * @param mixed[] $options
+     */
+    public function __construct(array $options = [])
+    {
+        $this->options = array_merge(self::$defaultOptions, $options);
+        $this->redis = new \Redis();
+    }
+
+    /**
+     * @param \Redis $redis
+     * @return self
+     * @throws StorageException
+     */
+    public static function fromExistingConnection(\Redis $redis): self
+    {
+        if ($redis->isConnected() === false) {
+            throw new StorageException('Connection to Redis server not established');
+        }
+
+        $self = new self();
+        $self->connectionInitialized = true;
+        $self->redis = $redis;
+
+        return $self;
+    }
+
+    /**
+     * @throws StorageException
+     * @deprecated use replacement method wipeStorage from Adapter interface
+     */
+    public function flushRedis(): void
+    {
+        $this->wipeStorage();
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function wipeStorage(): void
+    {
+        $this->ensureOpenConnection();
+
+        $searchPattern = "";
+
+        $globalPrefix = $this->redis->getOption(\Redis::OPT_PREFIX);
+        // @phpstan-ignore-next-line false positive, phpstan thinks getOptions returns int
+        if (is_string($globalPrefix)) {
+            $searchPattern .= $globalPrefix;
+        }
+
+        $searchPattern .= self::$prefix;
+        $searchPattern .= '*';
+
+        $this->redis->eval(
+            <<<LUA
+local cursor = "0"
+repeat
+    local results = redis.call('SCAN', cursor, 'MATCH', ARGV[1])
+    cursor = results[1]
+    for _, key in ipairs(results[2]) do
+        redis.call('DEL', key)
+    end
+until cursor == "0"
+LUA
+            ,
+            [$searchPattern],
+            0
+        );
+    }
+
+    /**
+     * @return MetricFamilySamples[]
+     * @throws StorageException
+     */
+    public function collect(): array
+    {
+        // Ensure Redis connection
+        $this->ensureOpenConnection();
+
+        // Collect all metrics
+        $counters = $this->collectCounters();
+        $histograms = $this->collectHistograms();
+        $gauges = $this->collectGauges();
+        $summaries = $this->collectSummaries();
+        return array_merge(
+            $counters,
+            $histograms,
+            $gauges,
+            $summaries
+        );
+    }
+
+    /**
+     * @throws StorageException
+     */
+    private function ensureOpenConnection(): void
+    {
+        if ($this->connectionInitialized === true) {
+            return;
+        }
+
+        $this->connectToServer();
+
+        if ($this->options['password'] !== null) {
+            $this->redis->auth($this->options['password']);
+        }
+
+        if (isset($this->options['database'])) {
+            $this->redis->select($this->options['database']);
+        }
+
+        $this->redis->setOption(\Redis::OPT_READ_TIMEOUT, $this->options['read_timeout']);
+
+        $this->connectionInitialized = true;
+    }
+
+    /**
+     * @throws StorageException
+     */
+    private function connectToServer(): void
+    {
+        try {
+            $connection_successful = false;
+            if ($this->options['persistent_connections'] !== false) {
+                $connection_successful = $this->redis->pconnect(
+                    $this->options['host'],
+                    (int)$this->options['port'],
+                    (float)$this->options['timeout']
+                );
+            } else {
+                $connection_successful = $this->redis->connect($this->options['host'], (int)$this->options['port'], (float)$this->options['timeout']);
+            }
+            if (!$connection_successful) {
+                throw new StorageException("Can't connect to Redis server", 0);
+            }
+        } catch (\RedisException $e) {
+            throw new StorageException("Can't connect to Redis server", 0, $e);
+        }
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function updateHistogram(array $data): void
+    {
+        // Ensure Redis connection
+        $this->ensureOpenConnection();
+
+        // Update metric
+        $updater = new HistogramUpdater($this->redis);
+        $updater->update($data);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function updateSummary(array $data): void
+    {
+        // Ensure Redis connection
+        $this->ensureOpenConnection();
+
+        // Update metric
+        $updater = new SummaryUpdater($this->redis);
+        $updater->update($data);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function updateGauge(array $data): void
+    {
+        // Ensure Redis connection
+        $this->ensureOpenConnection();
+
+        // Update metric
+        $updater = new GaugeUpdater($this->redis);
+        $updater->update($data);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function updateCounter(array $data): void
+    {
+        // Ensure Redis connection
+        $this->ensureOpenConnection();
+
+        // Update metric
+        $updater = new CounterUpdater($this->redis);
+        $updater->update($data);
+    }
+
+    /**
+     * @return MetricFamilySamples[]
+     */
+    private function collectHistograms(): array
+    {
+        $collector = new HistogramCollecter($this->redis);
+        return $collector->getMetricFamilySamples();
+    }
+
+    /**
+     * @return MetricFamilySamples[]
+     */
+    private function collectSummaries(): array
+    {
+        $collector = new SummaryCollecter($this->redis);
+        return $collector->getMetricFamilySamples();
+    }
+
+    /**
+     * @return MetricFamilySamples[]
+     */
+    private function collectGauges(): array
+    {
+        $collector = new GaugeCollecter($this->redis);
+        return $collector->getMetricFamilySamples();
+    }
+
+    /**
+     * @return MetricFamilySamples[]
+     */
+    private function collectCounters(): array
+    {
+        $collector = new CounterCollecter($this->redis);
+        return $collector->getMetricFamilySamples();
+    }
+}