ircd::db: Add a fileinfo wrapping interface.

include/ircd/db/database/database.h

@@ -79,6 +79,7 @@ struct ircd::db::database
 	struct column;
 	struct env;
 	struct cache;
+	struct fileinfo;
 
 	std::string name;
 	uint64_t checkpoint;

include/ircd/db/database/fileinfo.h

@@ -0,0 +1,43 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_DB_DATABASE_FILEINFO_H
+
+/// Database snapshot object. Maintaining this object will maintain a
+/// consistent state of access to the database at the sequence number
+/// from when it's acquired.
+struct ircd::db::database::fileinfo
+{
+	struct vector;
+
+	std::string name;
+	std::string path;
+	std::string column;
+	size_t size {0};
+	uint64_t min_seq {0};
+	uint64_t max_seq {0};
+	std::string min_key;
+	std::string max_key;
+	uint64_t num_reads {0};
+	int level {-1};
+	bool compacting {false};
+
+	fileinfo() = default;
+	fileinfo(rocksdb::LiveFileMetaData &&);
+	fileinfo(const database &, const string_view &filename);
+};
+
+struct ircd::db::database::fileinfo::vector
+:std::vector<fileinfo>
+{
+	vector() = default;
+	explicit vector(const database &);
+};

include/ircd/db/database/rocksdb.h

@@ -33,6 +33,7 @@ namespace rocksdb
 	struct SstFileManager;
 	struct PerfContext;
 	struct IOStatsContext;
+	struct LiveFileMetaData;
 }
 
 //

include/ircd/db/db.h

@@ -69,6 +69,7 @@ enum class ircd::db::pos
 #include "database/database.h"
 #include "database/options.h"
 #include "database/snapshot.h"
+#include "database/fileinfo.h"
 #include "cache.h"
 #include "opts.h"
 #include "column.h"

ircd/db.cc

@@ -2483,6 +2483,68 @@ const noexcept
 	return db::name(*c).c_str();
 }
 
+///////////////////////////////////////////////////////////////////////////////
+//
+// database::fileinfo
+//
+
+//
+// fileinfo::vector
+//
+
+ircd::db::database::fileinfo::vector::vector(const database &d)
+{
+	std::vector<rocksdb::LiveFileMetaData> v;
+	d.d->GetLiveFilesMetaData(&v);
+
+	this->resize(v.size());
+	std::transform(v.begin(), v.end(), this->begin(), []
+	(auto &&info)
+	{
+		return std::move(info);
+	});
+}
+
+//
+// fileinfo::fileinfo
+//
+
+ircd::db::database::fileinfo::fileinfo(const database &d,
+                                       const string_view &filename)
+{
+	std::vector<rocksdb::LiveFileMetaData> v;
+	d.d->GetLiveFilesMetaData(&v);
+
+	for(auto &md : v)
+		if(md.name == filename)
+		{
+			new (this) fileinfo(std::move(md));
+			return;
+		}
+
+	throw not_found
+	{
+		"No file named '%s' is live in database '%s'",
+		filename,
+		d.name
+	};
+}
+
+ircd::db::database::fileinfo::fileinfo(rocksdb::LiveFileMetaData &&md)
+:name{std::move(md.name)}
+,path{std::move(md.db_path)}
+,column{std::move(md.column_family_name)}
+,size{md.size}
+,min_seq{md.smallest_seqno}
+,max_seq{md.largest_seqno}
+,min_key{std::move(md.smallestkey)}
+,max_key{std::move(md.largestkey)}
+,num_reads{md.num_reads_sampled}
+,level{md.level}
+,compacting{md.being_compacted}
+{
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 //
 // database::env