Move icon cache to a separate file; protect cache with file locks

CMakeLists.txt

@@ -118,6 +118,7 @@ set( SOURCES src/config.c
              src/util/common.c
              src/util/strnatcmp.c
              src/util/timer.c
+             src/util/cache.c
              src/util/window.c )
 
 if( ENABLE_BATTERY )

src/launcher/icon-theme-common.c

@@ -27,6 +27,7 @@
 
 #include "apps-common.h"
 #include "common.h"
+#include "cache.h"
 
 #define ICON_DIR_TYPE_SCALABLE 0
 #define ICON_DIR_TYPE_FIXED 1
@@ -317,7 +318,7 @@ void free_themes(IconThemeWrapper *wrapper)
 	}
 	g_slist_free(wrapper->themes_fallback);
 	g_slist_free_full(wrapper->_queued, free);
-	g_hash_table_destroy(wrapper->_cache);
+	free_cache(&wrapper->_cache);
 	free(wrapper);
 }
 
@@ -452,72 +453,9 @@ gchar *get_icon_cache_path()
 	return g_build_filename(g_get_user_cache_dir(), "tint2", "icon.cache", NULL);
 }
 
-void load_cache(GHashTable **cache, gchar *cache_path)
-{
-	*cache = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, g_free);
-
-	FILE *f = fopen(cache_path, "rt");
-	if (!f)
-		return;
-
-	char *line = NULL;
-	size_t line_size;
-
-	while (getline(&line, &line_size, f) >= 0) {
-		char *key, *value;
-
-		size_t line_len = strlen(line);
-		gboolean has_newline = FALSE;
-		if (line_len >= 1) {
-			if (line[line_len - 1] == '\n') {
-				line[line_len - 1] = '\0';
-				line_len--;
-				has_newline = TRUE;
-			}
-		}
-		if (!has_newline)
-			break;
-
-		if (line_len == 0)
-			continue;
-
-		if (parse_theme_line(line, &key, &value)) {
-			g_hash_table_insert(*cache, g_strdup(key), g_strdup(value));
-		}
-	}
-	free(line);
-	fclose(f);
-}
-
-void write_cache_line(gpointer key, gpointer value, gpointer user_data)
-{
-	gchar *k = key;
-	gchar *v = value;
-	FILE *f = user_data;
-
-	fprintf(f, "%s=%s\n", k, v);
-}
-
-void save_cache(GHashTable *cache, gchar *cache_path)
-{
-	FILE *f = fopen(cache_path, "w");
-	if (!f) {
-		gchar *dir_path = g_path_get_dirname(cache_path);
-		g_mkdir_with_parents(dir_path, 0700);
-		g_free(dir_path);
-		f = fopen(cache_path, "w");
-		if (!f) {
-			fprintf(stderr, RED "Could not save icon theme cache!" RESET "\n");
-			return;
-		}
-	}
-	g_hash_table_foreach(cache, write_cache_line, f);
-	fclose(f);
-}
-
 void load_icon_cache(IconThemeWrapper *wrapper)
 {
-	if (wrapper->_cache)
+	if (wrapper->_cache.loaded)
 		return;
 
 	fprintf(stderr, GREEN "Loading icon theme cache..." RESET "\n");
@@ -529,12 +467,12 @@ void load_icon_cache(IconThemeWrapper *wrapper)
 
 void save_icon_cache(IconThemeWrapper *wrapper)
 {
-	if (!wrapper || !wrapper->_cache || !wrapper->_cache_dirty)
+	if (!wrapper || !wrapper->_cache.dirty)
 		return;
 
 	fprintf(stderr, GREEN "Saving icon theme cache..." RESET "\n");
 	gchar *cache_path = get_icon_cache_path();
-	save_cache(wrapper->_cache, cache_path);
+	save_cache(&wrapper->_cache, cache_path);
 	g_free(cache_path);
 }
 
@@ -761,8 +699,9 @@ char *get_icon_path_from_cache(IconThemeWrapper *wrapper, const char *icon_name,
 	load_icon_cache(wrapper);
 
 	gchar *key = g_strdup_printf("%s\t%s\t%d", wrapper->icon_theme_name, icon_name, size);
-	gchar *value = g_hash_table_lookup(wrapper->_cache, key);
+	const gchar *value = get_from_cache(&wrapper->_cache, key);
 	g_free(key);
+
 	if (!value) {
 		fprintf(stderr,
 		        YELLOW "Icon path not found in cache: theme = %s, icon = %s, size = %d" RESET "\n",
@@ -787,13 +726,8 @@ void add_icon_path_to_cache(IconThemeWrapper *wrapper, const char *icon_name, in
 	load_icon_cache(wrapper);
 
 	gchar *key = g_strdup_printf("%s\t%s\t%d", wrapper->icon_theme_name, icon_name, size);
-	gchar *value = g_hash_table_lookup(wrapper->_cache, key);
-	if (value && g_str_equal(value, path)) {
+	add_to_cache(&wrapper->_cache, key, path);
 	g_free(key);
-		return;
-	}
-	g_hash_table_insert(wrapper->_cache, key, g_strdup(path));
-	wrapper->_cache_dirty = TRUE;
 }
 
 char *get_icon_path(IconThemeWrapper *wrapper, const char *icon_name, int size)

src/launcher/icon-theme-common.h

@@ -7,6 +7,7 @@
 #define ICON_THEME_COMMON_H
 
 #include <glib.h>
+#include "cache.h"
 
 typedef struct IconThemeWrapper {
 	// The icon theme name for which this wrapper was created
@@ -19,8 +20,7 @@ typedef struct IconThemeWrapper {
 	GSList *themes_fallback;
 	// Fallback themes are loaded lazily when needed.
 	gboolean _fallback_loaded;
-	GHashTable *_cache;
-	gboolean _cache_dirty;
+	Cache _cache;
 	// List of icon theme names that have been queued for loading.
 	// Used to avoid loading the same theme twice, and to avoid cycles.
 	GSList *_queued;

src/tint2conf/CMakeLists.txt

@@ -21,6 +21,7 @@ include_directories( ../util
 
 set(SOURCES ../util/common.c
             ../util/strnatcmp.c
+            ../util/cache.c
             ../config.c
             ../server.c
             ../launcher/apps-common.c

src/util/cache.c

@@ -0,0 +1,156 @@
+/**************************************************************************
+*
+* Tint2 : cache
+*
+* Copyright (C) 2016 @o9000
+*
+* This program is free software; you can redistribute it and/or
+* modify it under the terms of the GNU General Public License version 2
+* 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 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 "cache.h"
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "common.h"
+
+void init_cache(Cache *cache)
+{
+	if (cache->_table)
+		free_cache(cache);
+	cache->_table = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, g_free);
+	cache->dirty = FALSE;
+	cache->loaded = FALSE;
+}
+
+void free_cache(Cache *cache)
+{
+	if (cache->_table)
+		g_hash_table_destroy(cache->_table);
+	cache->_table = NULL;
+	cache->dirty = FALSE;
+	cache->loaded = FALSE;
+}
+
+void load_cache(Cache *cache, const gchar *cache_path)
+{
+	init_cache(cache);
+
+	int fd = open(cache_path, O_RDONLY);
+	if (fd == -1)
+		return;
+	flock(fd, LOCK_SH);
+
+	FILE *f = fopen(cache_path, "rt");
+	if (!f)
+		goto unlock;
+
+	char *line = NULL;
+	size_t line_size;
+
+	while (getline(&line, &line_size, f) >= 0) {
+		char *key, *value;
+
+		size_t line_len = strlen(line);
+		gboolean has_newline = FALSE;
+		if (line_len >= 1) {
+			if (line[line_len - 1] == '\n') {
+				line[line_len - 1] = '\0';
+				line_len--;
+				has_newline = TRUE;
+			}
+		}
+		if (!has_newline)
+			break;
+
+		if (line_len == 0)
+			continue;
+
+		if (parse_line(line, &key, &value)) {
+			g_hash_table_insert(cache->_table, g_strdup(key), g_strdup(value));
+		}
+	}
+	free(line);
+	fclose(f);
+
+	cache->loaded = TRUE;
+
+unlock:
+	flock(fd, LOCK_UN);
+	close(fd);
+}
+
+void write_cache_line(gpointer key, gpointer value, gpointer user_data)
+{
+	gchar *k = key;
+	gchar *v = value;
+	FILE *f = user_data;
+
+	fprintf(f, "%s=%s\n", k, v);
+}
+
+void save_cache(Cache *cache, const gchar *cache_path)
+{
+	int fd = open(cache_path, O_RDONLY | O_CREAT);
+	if (fd == -1)
+		return;
+	flock(fd, LOCK_EX);
+
+	FILE *f = fopen(cache_path, "w");
+	if (!f) {
+		gchar *dir_path = g_path_get_dirname(cache_path);
+		g_mkdir_with_parents(dir_path, 0700);
+		g_free(dir_path);
+		f = fopen(cache_path, "w");
+		if (!f) {
+			fprintf(stderr, RED "Could not save icon theme cache!" RESET "\n");
+			goto unlock;
+		}
+	}
+	g_hash_table_foreach(cache->_table, write_cache_line, f);
+	fclose(f);
+	cache->dirty = FALSE;
+
+unlock:
+	flock(fd, LOCK_UN);
+	close(fd);
+}
+
+const gchar *get_from_cache(Cache *cache, const gchar *key)
+{
+	if (!cache->_table)
+		return NULL;
+	return g_hash_table_lookup(cache->_table, key);
+}
+
+void add_to_cache(Cache *cache, const gchar *key, const gchar *value)
+{
+	if (!cache->_table)
+		init_cache(cache);
+
+	if (!key || !value)
+		return;
+
+	gchar *old_value = g_hash_table_lookup(cache->_table, key);
+	if (old_value && g_str_equal(old_value, value))
+		return;
+
+	g_hash_table_insert(cache->_table, g_strdup(key), g_strdup(value));
+	cache->dirty = TRUE;
+}

src/util/cache.h

@@ -0,0 +1,39 @@
+#ifndef CACHE_H
+#define CACHE_H
+
+#include <glib.h>
+
+// A cache with string keys and values, backed by a file.
+// The strings must not be NULL and are stripped of any whitespace at start and end.
+typedef struct Cache {
+	gboolean dirty;
+	gboolean loaded;
+	GHashTable *_table;
+} Cache;
+
+// Initializes the cache. You can also call load_cache directly if you set the memory contents to zero first.
+void init_cache(Cache *cache);
+
+// Clears the cache contents and releases all memory, but not the object.
+// You can use init_cache or load_cache afterwards.
+void free_cache(Cache *cache);
+
+// Clears the cache contents and loads new contents from a file.
+// Sets the loaded flag to TRUE.
+void load_cache(Cache *cache, const gchar *cache_path);
+
+// Saves the cache contents to a file.
+// Clears the dirty flag.
+void save_cache(Cache *cache, const gchar *cache_path);
+
+// Returns a pointer to the value in the cache, or NULL if not found.
+// Do not free the returned value!
+const gchar *get_from_cache(Cache *cache, const gchar *key);
+
+// Adds a key-value pair to the cache. NULL keys or values are not allowed.
+// If the key already exists, the old value is and replaced with the new value.
+// Does not take ownership of the pointers (neither key, nor value); instead it makes copies.
+// Sets the dirty flag to TRUE.
+void add_to_cache(Cache *cache, const gchar *key, const gchar *value);
+
+#endif

tint2.files

@@ -177,3 +177,5 @@ tint2.files
 tint2.includes
 tint2.svg
 src/tint2conf/po/ru.po
+src/util/cache.c
+src/util/cache.h