Attachment 104838 Details for Bug 82711 – patch v2

[patch] patch v2

0001-factor-40-speedup-v2.patch (text/plain), 3.64 KB, created by Jann Horn on 2014-08-18 18:02:13 UTC

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Creator: Jann Horn

Created: 2014-08-18 18:02:13 UTC

Size: 3.64 KB

patch

obsolete

>From ae2fcecc4ccc0a3b995d1558793fd0545495a53e Mon Sep 17 00:00:00 2001
>From: Jann Horn <jann@thejh.net>
>Date: Mon, 18 Aug 2014 20:01:13 +0200
>Subject: [PATCH] ~factor 40 speedup
>
>First write all files, then sync all filesystems, then move all files.
>The original behavior was very slow for two reasons:
>
> - After every file creation, we had to wait for the harddisk to complete
>   the write.
> - We told the kernel and the harddisk in which order writes should happen.
>
>This reduces the time needed on my harddisk from 44-45s to 0.9-1.4s.
>---
> update-mime-database.c | 57 +++++++++++++++++++++++++++++++++++++++++++-------
> 1 file changed, 49 insertions(+), 8 deletions(-)
>
>diff --git a/update-mime-database.c b/update-mime-database.c
>index be4aba2..158dd09 100644
>--- a/update-mime-database.c
>+++ b/update-mime-database.c
>@@ -85,6 +85,13 @@ struct _Type {
> 	char *media;
> 	char *subtype;
> 
>+	/* Contains the path under which the temporary file describing the
>+         * type has been written. Only set to a meaningful value between
>+         * file creation (write_out_type_tmpfile) and the file getting
>+         * moved to its final name (move_type_file).
>+         */
>+	char *filename;
>+
> 	/* Contains xmlNodes for elements that are being copied to the output.
> 	 * That is, <comment>, <sub-class-of> and <alias> nodes, and anything
> 	 * with an unknown namespace.
>@@ -1014,11 +1021,11 @@ out:
> }
> 
> /* Write out an XML file for one type */
>-static void write_out_type(gpointer key, gpointer value, gpointer data)
>+static void write_out_type_tmpfile(gpointer key, gpointer value, gpointer data)
> {
> 	Type *type = (Type *) value;
> 	const char *mime_dir = (char *) data;
>-	char *media, *filename;
>+	char *media;
> 	GError *local_error = NULL;
> 	char *lower;
> 
>@@ -1032,18 +1039,49 @@ static void write_out_type(gpointer key, gpointer value, gpointer data)
> #endif
> 
> 	lower = g_ascii_strdown(type->subtype, -1);
>-	filename = g_strconcat(media, "/", lower, ".xml.new", NULL);
>+	type->filename = g_strconcat(media, "/", lower, ".xml.new", NULL);
> 	g_free(lower);
> 	g_free(media);
> 	media = NULL;
> 
>-	if (!save_xml_file(type->output, filename, &local_error))
>+	if (!save_xml_file(type->output, type->filename, &local_error))
> 		fatal_gerror(local_error);
>+}
> 
>-	if (!atomic_update(filename, &local_error))
>-		fatal_gerror(local_error);
>+/* Move the XML file to its correct name */
>+static void move_type_file(gpointer key, gpointer value, gpointer data)
>+{
>+	Type *type = (Type *) value;
>+	gchar *new_name = NULL;
>+	int len;
>+	GError *error = NULL;
>+
>+	/* Actually, we already synced the file with sync() - here we
>+           check whether the sync was successful. */
>+	if (sync_file(type->filename, &error) == -1)
>+		fatal_gerror(error);
>+
>+	len = strlen(type->filename);
> 
>-	g_free(filename);
>+	if (strcmp(type->filename + len - 4, ".new") != 0)
>+		g_error("expected temporary filename to end with .new");
>+
>+	new_name = g_strndup(type->filename, len - 4);
>+
>+#ifdef _WIN32
>+	/* we need to remove the old file first! */
>+	remove(new_name);
>+#endif
>+	if (rename(type->filename, new_name) == -1)
>+	{
>+		g_printerr("Failed to rename %s as %s: %s\n", type->filename, new_name,
>+			    g_strerror(errno));
>+		exit (EXIT_FAILURE);
>+	}
>+
>+	g_free(new_name);
>+	g_free(type->filename);
>+	type->filename = NULL;
> }
> 
> /* Comparison function to get the magic rules in priority order */
>@@ -3697,7 +3735,10 @@ int main(int argc, char **argv)
> 
> 	delete_old_types(mime_dir);
> 
>-	g_hash_table_foreach(types, write_out_type, (gpointer) mime_dir);
>+	g_hash_table_foreach(types, write_out_type_tmpfile, (gpointer) mime_dir);
>+	if (sync_enabled())
>+		sync();
>+	g_hash_table_foreach(types, move_type_file, NULL);
> 
> 	{
> 		FILE *globs;
>-- 
>2.0.1
>

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