SERVER-19584: Implement full-time diagnostic data capture file reader and writer

1 files changed, 147 insertions, 0 deletions

diff --git a/src/mongo/db/ftdc/file_manager.h b/src/mongo/db/ftdc/file_manager.h
new file mode 100644
index 00000000000..3342a1877cf
--- /dev/null
+++ b/src/mongo/db/ftdc/file_manager.h
@@ -0,0 +1,147 @@
+/**
+ * Copyright (C) 2015 MongoDB Inc.
+ *
+ * This program is free software: you can redistribute it and/or  modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * As a special exception, the copyright holders give permission to link the
+ * code of portions of this program with the OpenSSL library under certain
+ * conditions as described in each individual source file and distribute
+ * linked combinations including the program with the OpenSSL library. You
+ * must comply with the GNU Affero General Public License in all respects
+ * for all of the code used other than as permitted herein. If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so. If you do not
+ * wish to do so, delete this exception statement from your version. If you
+ * delete this exception statement from all source files in the program,
+ * then also delete it in the license file.
+ */
+
+#pragma once
+
+#include <boost/filesystem/path.hpp>
+#include <memory>
+#include <tuple>
+#include <vector>
+
+#include "mongo/base/disallow_copying.h"
+#include "mongo/base/status.h"
+#include "mongo/base/string_data.h"
+#include "mongo/db/ftdc/collector.h"
+#include "mongo/db/ftdc/config.h"
+#include "mongo/db/ftdc/file_writer.h"
+#include "mongo/db/ftdc/util.h"
+#include "mongo/db/jsobj.h"
+
+namespace mongo {
+
+class Client;
+
+/**
+ * Manages a directory full of archive files, and an interim file.
+ *
+ * Manages file rotation, and directory size management.
+ */
+class FTDCFileManager {
+    MONGO_DISALLOW_COPYING(FTDCFileManager);
+
+public:
+    ~FTDCFileManager();
+
+    /**
+     * Creates the directory if it does not exist.
+     * NOTE: This must be run on a thread with a Client context, i.e., not a static initializer.
+     *
+     * Collectors are used to collect data to be stored as metadata on file rotation or system
+     * restart.
+     *
+     * Recovers data from the interim file as needed.
+     * Rotates files if needed.
+     */
+    static StatusWith<std::unique_ptr<FTDCFileManager>> create(const FTDCConfig* config,
+                                                               const boost::filesystem::path& path,
+                                                               FTDCCollectorCollection* collection,
+                                                               Client* client);
+
+    /**
+     * Rotates files
+     */
+    Status rotate(Client* client);
+
+    /**
+     * Writes a sample to disk via FTDCFileWriter.
+     *
+     * Rotates files as needed.
+     */
+    Status writeSampleAndRotateIfNeeded(Client* client, const BSONObj& sample);
+
+    /**
+     * Closes the current file manager down.
+     */
+    Status close();
+
+public:
+    /**
+     * Generate a new file name for the archive.
+     * Public for use by unit tests only.
+     */
+    static StatusWith<boost::filesystem::path> generateArchiveFileName(
+        const boost::filesystem::path& path, StringData suffix);
+
+private:
+    FTDCFileManager(const FTDCConfig* config,
+                    const boost::filesystem::path& path,
+                    FTDCCollectorCollection* collection);
+
+    /**
+     * Gets a list of metrics files in a directory.
+     */
+    std::vector<boost::filesystem::path> scanDirectory();
+
+    /**
+     * Recover the interim file.
+     *
+     * Checks if the file is non-empty, and if so appends it the archive file.
+     */
+    std::vector<std::tuple<FTDCBSONUtil::FTDCType, BSONObj>> recoverInterimFile();
+
+    /**
+     * Removes the oldest files if the directory is over quota
+     */
+    void trimDirectory(std::vector<boost::filesystem::path>& files);
+
+    /**
+     * Open a new file for writing.
+     *
+     * Steps:
+     * 1. Writes any recovered interim file samples into the file.
+     * 2. Appends file rotation collectors upon opening the file.
+     */
+    Status openArchiveFile(Client* client,
+                           const boost::filesystem::path& path,
+                           const std::vector<std::tuple<FTDCBSONUtil::FTDCType, BSONObj>>& docs);
+
+private:
+    // config to use
+    const FTDCConfig* const _config;
+
+    // file to log samples to
+    FTDCFileWriter _writer;
+
+    // Path of metrics directory
+    boost::filesystem::path _path;
+
+    // collection of collectors to add to new files on rotation, and server restart
+    FTDCCollectorCollection* const _rotateCollectors;
+};
+
+}  // namespace mongo