feat: Introduce LogMessageProcessors and their factory

Logging/src/LogMessageProcessor.php

@@ -0,0 +1,33 @@
+<?php
+/**
+ * Copyright 2022 Google Inc. All Rights Reserved.
+ *
+ * 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.
+ */
+
+namespace Google\Cloud\Logging;
+
+/**
+ * Interface representing a Message Processor used by the {@see PsrLogger}
+ */
+interface LogMessageProcessor
+{
+    /**
+     * @param string|\Stringable $message
+     * @param array $context
+     *
+     * @phpstan-return array{message: string, context: array}
+     * @return array
+     */
+    public function processLogMessage($message, $context);
+}

Logging/src/LogMessageProcessor/MonologMessageProcessor.php

@@ -0,0 +1,55 @@
+<?php
+/**
+ * Copyright 2022 Google Inc. All Rights Reserved.
+ *
+ * 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.
+ */
+
+namespace Google\Cloud\Logging\LogMessageProcessor;
+
+use Google\Cloud\Logging\LogMessageProcessor;
+use Monolog\Formatter\NormalizerFormatter;
+use Monolog\Processor\PsrLogMessageProcessor;
+
+/**
+ * Uses the Monolog 1/2 PsrLogMessageProcessor to process a
+ * record's message according to PSR-3 rules.
+ */
+final class MonologMessageProcessor implements LogMessageProcessor
+{
+    /**
+     * @var NormalizerFormatter
+     */
+    private $formatter;
+
+    /**
+     * @var PsrLogMessageProcessor
+     */
+    private $processor;
+
+    public function __construct()
+    {
+        $this->formatter = new NormalizerFormatter();
+        $this->processor = new PsrLogMessageProcessor();
+    }
+
+    public function processLogMessage($message, $context)
+    {
+        $processor = $this->processor;
+
+        return $processor([
+            'message' => (string) $message,
+            'context' => $this->formatter->format($context)
+        ]);
+    }
+}

Logging/src/LogMessageProcessor/MonologV3MessageProcessor.php

@@ -0,0 +1,60 @@
+<?php
+/**
+ * Copyright 2022 Google Inc. All Rights Reserved.
+ *
+ * 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.
+ */
+
+namespace Google\Cloud\Logging\LogMessageProcessor;
+
+use Google\Cloud\Logging\LogMessageProcessor;
+use Monolog\Level;
+use Monolog\LogRecord;
+use Monolog\Processor\PsrLogMessageProcessor;
+
+/**
+ * Uses the Monolog 3 PsrLogMessageProcessor to process a
+ * record's message according to PSR-3 rules.
+ */
+final class MonologV3MessageProcessor implements LogMessageProcessor
+{
+    /**
+     * @var PsrLogMessageProcessor
+     */
+    private $processor;
+
+    public function __construct()
+    {
+        $this->processor = new PsrLogMessageProcessor();
+    }
+
+    public function processLogMessage($message, $context)
+    {
+        // The datetime, channel, and level are required but not relevant here
+        $logRecord = new LogRecord(
+            new \DateTimeImmutable(),
+            'channel',
+            Level::Info,
+            (string) $message,
+            $context
+        );
+
+        $processor = $this->processor;
+        $processed = $processor($logRecord);
+
+        return [
+            'message' => $processed['message'],
+            'context' => $processed['context'],
+        ];
+    }
+}

Logging/src/LogMessageProcessorFactory.php

@@ -0,0 +1,47 @@
+<?php
+/**
+ * Copyright 2022 Google Inc. All Rights Reserved.
+ *
+ * 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.
+ */
+
+namespace Google\Cloud\Logging;
+
+use Google\Cloud\Logging\LogMessageProcessor\MonologMessageProcessor;
+use Google\Cloud\Logging\LogMessageProcessor\MonologV3MessageProcessor;
+use Monolog\Logger as MonologLogger;
+use RuntimeException;
+
+/**
+ * Returns a LogMessageProcessor that can be used with the currently install Monolog version
+ */
+class LogMessageProcessorFactory
+{
+    /**
+     * @return LogMessageProcessor
+     */
+    public static function build()
+    {
+        $version = defined('\Monolog\Logger::API') ? MonologLogger::API : 1;
+
+        switch ($version) {
+            case 1:
+            case 2:
+                return new MonologMessageProcessor();
+            case 3:
+                return new MonologV3MessageProcessor();
+            default:
+                throw new RuntimeException('Version not supported');
+        }
+    }
+}

Logging/src/PsrLogger.php

@@ -23,8 +23,6 @@
 use Google\Cloud\Core\Report\MetadataProviderInterface;
 use Google\Cloud\Core\Report\MetadataProviderUtils;
 use Google\Cloud\Core\Timestamp;
-use Monolog\Formatter\NormalizerFormatter;
-use Monolog\Processor\PsrLogMessageProcessor;
 use Psr\Log\InvalidArgumentException;
 use Psr\Log\LoggerInterface;
 
@@ -89,6 +87,11 @@ class PsrLogger implements LoggerInterface, \Serializable
      */
     private $logName;
 
+    /**
+     * @var LogMessageProcessor
+     */
+    private $logMessageProcessor;
+
     /**
      * @param Logger $logger The logger used to write entries.
      * @param string $messageKey The key in the `jsonPayload` used to contain
@@ -138,6 +141,7 @@ public function __construct(
     ) {
         $this->logger = $logger;
         $this->logName = $logger->name();
+        $this->logMessageProcessor = LogMessageProcessorFactory::build();
         $this->messageKey = $messageKey ?: 'message';
         $this->metadataProvider = isset($options['metadataProvider'])
             ? $options['metadataProvider']
@@ -383,12 +387,7 @@ public function log($level, $message, array $context = [])
             unset($context['stackdriverOptions']);
         }
 
-        $formatter = new NormalizerFormatter();
-        $processor = new PsrLogMessageProcessor();
-        $processedData = $processor([
-            'message' => (string) $message,
-            'context' => $formatter->format($context)
-        ]);
+        $processedData = $this->logMessageProcessor->processLogMessage($message, $context);
         $jsonPayload = [$this->messageKey => $processedData['message']];
 
         // Adding labels for log request correlation.

Logging/tests/Unit/PsrLoggerTest.php

@@ -17,13 +17,10 @@
 
 namespace Google\Cloud\Logging\Tests\Unit;
 
-use Google\Cloud\Core\Batch\BatchRunner;
-use Google\Cloud\Core\Batch\OpisClosureSerializer;
 use Google\Cloud\Core\Report\EmptyMetadataProvider;
 use Google\Cloud\Logging\Logger;
 use Google\Cloud\Logging\PsrLogger;
 use Google\Cloud\Logging\Connection\ConnectionInterface;
-use Prophecy\Argument;
 use Yoast\PHPUnitPolyfills\TestCases\TestCase;
 use Yoast\PHPUnitPolyfills\Polyfills\ExpectException;