wip Adapter to pipe ext-mongodb logs to a PSR-3 logger

Author: jmikola

src/Client.php

@@ -37,12 +37,14 @@
 use MongoDB\Operation\ListDatabaseNames;
 use MongoDB\Operation\ListDatabases;
 use MongoDB\Operation\Watch;
+use Psr\Log\LoggerAwareInterface;
+use Psr\Log\LoggerInterface;
 use Throwable;
 
 use function is_array;
 use function is_string;
 
-class Client
+class Client implements LoggerAwareInterface
 {
     public const DEFAULT_URI = 'mongodb://127.0.0.1/';
 
@@ -329,6 +331,19 @@ public function selectDatabase(string $databaseName, array $options = [])
         return new Database($this->manager, $databaseName, $options);
     }
 
+    public function setLogger(LoggerInterface $logger): void
+    {
+        /* TODO: lazily initialize a PsrLogAdapter for this client and register
+         * it with PHPC. Consider what happens if multiple clients instances in
+         * an app register the same PSR logger. That logger will likely receive
+         * duplicate messages, since PHPC's own checks would only prevent the
+         * same PsrLogAdapter instance from being registered multiple times.
+         *
+         * Perhaps we can work around this by making PsrLogAdapter a singleton
+         * or utilize a static map of PSR loggers.
+         */
+    }
+
     /**
      * Start a new client session.
      *

src/PsrLogAdapter.php

@@ -0,0 +1,72 @@
+<?php
+/*
+ * Copyright 2023-present MongoDB, 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
+ *
+ *   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.
+ */
+
+namespace MongoDB;
+
+use MongoDB\Driver\Logging\Logger as DriverLoggerInterface;
+use Psr\Log\LoggerInterface as PsrLoggerInterface;
+use Psr\Log\LogLevel as PsrLogLevel;
+
+class PsrLogAdapter implements DriverLoggerInterface
+{
+    private PsrLoggerInterface $psrLogger;
+
+    public function __construct(PsrLoggerInterface $psrLogger)
+    {
+        $this->psrLogger = $psrLogger;
+    }
+
+    public function log(int $level, string $domain, string $message): void
+    {
+        $this->psrLogger->log(
+            $this->driverLevelToPsrLevel($level),
+            $domain . ': ' . $message,
+        );
+    }
+
+    // TODO: Refactor this method as a private const array map on PsrLogAdapter
+    private function driverLevelToPsrLevel(int $level): string
+    {
+        switch ($level) {
+            /* libmongoc considers "critical" less severe than "error" so route
+             * both levels to "error" in the PSR logger. */
+            case DriverLoggerInterface::LEVEL_ERROR:
+            case DriverLoggerInterface::LEVEL_CRITICAL:
+                return PsrLogLevel::ERROR;
+
+            case DriverLoggerInterface::LEVEL_WARNING:
+                return PsrLogLevel::WARNING;
+
+            case DriverLoggerInterface::LEVEL_MESSAGE:
+                return PsrLogLevel::NOTICE;
+
+            case DriverLoggerInterface::LEVEL_INFO:
+                return PsrLogLevel::INFO;
+
+            /* PSR does not define a "trace" level, so route both levels to
+             * "debug". That said, trace logging is very verbose and should not
+             * be encouraged when using a PSR logger. */
+            case DriverLoggerInterface::LEVEL_DEBUG:
+            case DriverLoggerInterface::LEVEL_TRACE:
+                return PsrLogLevel::DEBUG;
+
+            /* A default case is intentionally not handled since libmongoc and
+             * PHPC should avoid emitting bogus levels; however, we can consider
+             * throwing an UnexpectedValueException here. */
+        }
+    }
+}