ircd:Ⓜ️:rooms: Add dump to file util w/ console cmd.

include/ircd/m/rooms.h

@@ -25,6 +25,9 @@ namespace ircd::m::rooms
 	// tools
 	size_t count(const opts & = opts_default);
 	bool has(const opts & = opts_default);
+
+	// util
+	void dump__file(const opts &, const string_view &filename);
 }
 
 /// Arguments structure to rooms::for_each(). This reduces the API surface to

matrix/rooms.cc

@@ -12,6 +12,53 @@ decltype(ircd::m::rooms::opts_default)
 IRCD_MODULE_EXPORT_DATA
 ircd::m::rooms::opts_default;
 
+void
+IRCD_MODULE_EXPORT
+ircd::m::rooms::dump__file(const opts &opts,
+                           const string_view &filename)
+{
+	const fs::fd file
+	{
+		filename, std::ios::out | std::ios::app
+	};
+
+	// POSIX_FADV_DONTNEED
+	fs::evict(file);
+
+	size_t len(0), num(0);
+	for_each(opts, [&](const auto &room_id)
+	{
+		const const_buffer bufs[]
+		{
+			room_id, "\n"_sv
+		};
+
+		len += fs::append(file, bufs);
+		++num;
+
+		char pbuf[48];
+		log::info
+		{
+			log, "dump[%s] rooms:%zu %s %s",
+			filename,
+			num,
+			pretty(pbuf, iec(len)),
+			string_view{room_id},
+		};
+
+		return true;
+	});
+
+	char pbuf[48];
+	log::notice
+	{
+		log, "dump[%s] complete rooms:%zu using %s",
+		filename,
+		num,
+		pretty(pbuf, iec(len)),
+    };
+}
+
 bool
 IRCD_MODULE_EXPORT
 ircd::m::rooms::has(const opts &opts)

modules/console.cc

@@ -8074,6 +8074,33 @@ console_cmd__rooms(opt &out, const string_view &line)
 	return true;
 }
 
+bool
+console_cmd__rooms__dump(opt &out, const string_view &line)
+{
+	const params param{line, " ",
+	{
+		"filename"
+	}};
+
+	const auto filename
+	{
+		param.at(0)
+	};
+
+	static conf::item<size_t>
+	rooms_dump_prefetch
+	{
+		{ "name",     "ircd.console.rooms.dump.prefetch" },
+		{ "default",  16L                                },
+	};
+
+	m::rooms::opts opts;
+	opts.remote_only = true;
+	opts.prefetch = rooms_dump_prefetch;
+	m::rooms::dump__file(opts, filename);
+	return true;
+}
+
 bool
 console_cmd__rooms__public(opt &out, const string_view &line)
 {