db_save, state_file: convert to C++

src/StateFile.cxx

@@ -0,0 +1,165 @@
+/*
+ * Copyright (C) 2003-2013 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "StateFile.hxx"
+#include "OutputState.hxx"
+#include "playlist.h"
+#include "PlaylistState.hxx"
+
+extern "C" {
+#include "volume.h"
+#include "text_file.h"
+}
+
+#include <glib.h>
+#include <assert.h>
+#include <string.h>
+#include <errno.h>
+
+#undef G_LOG_DOMAIN
+#define G_LOG_DOMAIN "state_file"
+
+static char *state_file_path;
+
+/** the GLib source id for the save timer */
+static guint save_state_source_id;
+
+/**
+ * These version numbers determine whether we need to save the state
+ * file.  If nothing has changed, we won't let the hard drive spin up.
+ */
+static unsigned prev_volume_version, prev_output_version,
+	prev_playlist_version;
+
+static void
+state_file_write(struct player_control *pc)
+{
+	FILE *fp;
+
+	assert(state_file_path != NULL);
+
+	g_debug("Saving state file %s", state_file_path);
+
+	fp = fopen(state_file_path, "w");
+	if (G_UNLIKELY(!fp)) {
+		g_warning("failed to create %s: %s",
+			  state_file_path, g_strerror(errno));
+		return;
+	}
+
+	save_sw_volume_state(fp);
+	audio_output_state_save(fp);
+	playlist_state_save(fp, &g_playlist, pc);
+
+	fclose(fp);
+
+	prev_volume_version = sw_volume_state_get_hash();
+	prev_output_version = audio_output_state_get_version();
+	prev_playlist_version = playlist_state_get_hash(&g_playlist, pc);
+}
+
+static void
+state_file_read(struct player_control *pc)
+{
+	FILE *fp;
+	bool success;
+
+	assert(state_file_path != NULL);
+
+	g_debug("Loading state file %s", state_file_path);
+
+	fp = fopen(state_file_path, "r");
+	if (G_UNLIKELY(!fp)) {
+		g_warning("failed to open %s: %s",
+			  state_file_path, g_strerror(errno));
+		return;
+	}
+
+	GString *buffer = g_string_sized_new(1024);
+	const char *line;
+	while ((line = read_text_line(fp, buffer)) != NULL) {
+		success = read_sw_volume_state(line) ||
+			audio_output_state_read(line) ||
+			playlist_state_restore(line, fp, buffer,
+					       &g_playlist, pc);
+		if (!success)
+			g_warning("Unrecognized line in state file: %s", line);
+	}
+
+	fclose(fp);
+
+	prev_volume_version = sw_volume_state_get_hash();
+	prev_output_version = audio_output_state_get_version();
+	prev_playlist_version = playlist_state_get_hash(&g_playlist, pc);
+
+
+	g_string_free(buffer, true);
+}
+
+/**
+ * This function is called every 5 minutes by the GLib main loop, and
+ * saves the state file.
+ */
+static gboolean
+timer_save_state_file(gpointer data)
+{
+	struct player_control *pc = (struct player_control *)data;
+
+	if (prev_volume_version == sw_volume_state_get_hash() &&
+	    prev_output_version == audio_output_state_get_version() &&
+	    prev_playlist_version == playlist_state_get_hash(&g_playlist, pc))
+		/* nothing has changed - don't save the state file,
+		   don't spin up the hard disk */
+		return true;
+
+	state_file_write(pc);
+	return true;
+}
+
+void
+state_file_init(const char *path, struct player_control *pc)
+{
+	assert(state_file_path == NULL);
+
+	if (path == NULL)
+		return;
+
+	state_file_path = g_strdup(path);
+	state_file_read(pc);
+
+	save_state_source_id = g_timeout_add_seconds(5 * 60,
+						     timer_save_state_file,
+						     pc);
+}
+
+void
+state_file_finish(struct player_control *pc)
+{
+	if (state_file_path == NULL)
+		/* no state file configured, no cleanup required */
+		return;
+
+	if (save_state_source_id != 0)
+		g_source_remove(save_state_source_id);
+
+	state_file_write(pc);
+
+	g_free(state_file_path);
+}