Create an MLoggerFactory

Summary:
Previously, we just had one `MLogger` for the whole `MoQServer`. Instead, we'd like to have one `MLogger` per `MoQSession`, which is similar to how we have one `QLogger` for each QUIC connection in mvfst.

In order to do this, I'm creating an `MLoggerFactory` member of the `MoQServer` that would allow us to create a new `MLogger` whenever a new session is created.

Reviewed By: sandarsh

Differential Revision: D89325703

fbshipit-source-id: 0abfa5e980c238b73ca850210ad1a6e3edfc6b29

Author: Aman Sharma

moxygen/mlog/FileMLoggerFactory.h

@@ -0,0 +1,33 @@
+/*
+ *  Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ *  This source code is licensed under the MIT license found in the LICENSE
+ *  file in the root directory of this source tree.
+ *
+ */
+
+#pragma once
+
+#include <string>
+#include "moxygen/mlog/MLoggerFactory.h"
+
+namespace moxygen {
+
+// Creates an MLogger that writes to a file
+class FileMLoggerFactory : public MLoggerFactory {
+ public:
+  FileMLoggerFactory(const std::string& path, VantagePoint vantagePoint)
+      : path_(path), vantagePoint_(vantagePoint) {}
+
+  std::shared_ptr<MLogger> createMLogger() override {
+    auto logger = std::make_shared<MLogger>(vantagePoint_);
+    logger->setPath(path_);
+    return logger;
+  }
+
+ private:
+  std::string path_;
+  VantagePoint vantagePoint_;
+};
+
+} // namespace moxygen

moxygen/mlog/MLoggerFactory.h

@@ -0,0 +1,23 @@
+/*
+ *  Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ *  This source code is licensed under the MIT license found in the LICENSE
+ *  file in the root directory of this source tree.
+ *
+ */
+
+#pragma once
+
+#include <memory>
+#include "moxygen/mlog/MLogger.h"
+
+namespace moxygen {
+
+class MLoggerFactory {
+ public:
+  virtual ~MLoggerFactory() = default;
+
+  virtual std::shared_ptr<MLogger> createMLogger() = 0;
+};
+
+} // namespace moxygen