util: simplify column caching logic

src/cgtop/cgtop.c

@@ -447,7 +447,7 @@ static int display(Hashmap *a) {
         if (rows <= 0)
                 rows = 25;
 
-        path_columns = columns_uncached() - 42;
+        path_columns = columns() - 42;
         if (path_columns < 10)
                 path_columns = 10;
 
@@ -653,6 +653,8 @@ int main(int argc, char *argv[]) {
                 goto finish;
         }
 
+        signal(SIGWINCH, columns_cache_reset);
+
         while (!quit) {
                 Hashmap *c;
                 usec_t t;

src/shared/util.c

@@ -72,7 +72,7 @@
 int saved_argc = 0;
 char **saved_argv = NULL;
 
-static int parsed_columns = 0;
+static volatile unsigned cached_columns = 0;
 
 size_t page_size(void) {
         static __thread size_t pgsz = 0;
@@ -3793,46 +3793,31 @@ int fd_columns(int fd) {
         return ws.ws_col;
 }
 
-static unsigned columns_cached(bool cached) {
-        static __thread int env_columns = -1;
-        const char *e;
-
-        if (_likely_(parsed_columns > 0 && cached))
-                return parsed_columns;
-
-        if (_unlikely_(env_columns == -1)) {
-                e = getenv("COLUMNS");
-                if (e)
-                        env_columns = atoi(e);
-                else
-                        env_columns = 0;
-        }
-
-        if (env_columns > 0) {
-                parsed_columns = env_columns;
-                return parsed_columns;
-        }
-
-        if (parsed_columns <= 0 || !cached)
-                parsed_columns = fd_columns(STDOUT_FILENO);
-
-        if (parsed_columns <= 0)
-                parsed_columns = 80;
-
-        return parsed_columns;
-}
-
 unsigned columns(void) {
-        return columns_cached(true);
-}
+        const char *e;
+        unsigned c;
 
-unsigned columns_uncached(void) {
-        return columns_cached(false);
+        if (_likely_(cached_columns > 0))
+                return cached_columns;
+
+        c = 0;
+        e = getenv("COLUMNS");
+        if (e)
+                safe_atou(e, &c);
+
+        if (c <= 0)
+                c = fd_columns(STDOUT_FILENO);
+
+        if (c <= 0)
+                c = 80;
+
+        cached_columns = c;
+        return c;
 }
 
 /* intended to be used as a SIGWINCH sighandler */
 void columns_cache_reset(int signum) {
-        parsed_columns = 0;
+        cached_columns = 0;
 }
 
 int fd_lines(int fd) {

src/shared/util.h

@@ -384,7 +384,6 @@ int status_welcome(void);
 
 int fd_columns(int fd);
 unsigned columns(void);
-unsigned columns_uncached(void);
 void columns_cache_reset(int _unused_ signum);
 
 int fd_lines(int fd);