top: change default allow/suppress define for SIGWINCH

No top #define is enabled and that constitutes default
behavior. So whenever a default behavior should change
the define must be changed too if it is to remain off.

This commit simply changes top's default behavior with
respect to allowing/suppressing any potential flood of
SIGWINCH during resize operations, if running under X.

Formerly top would block those signals to reduce costs
of repeated refreshes. That yields a requirement where
the user would have to provide another keystroke for a
final display update. That keystroke may not always be
needed now, but it ultimately depends on some terminal
emulator's scrollback buffer. In any case, the cost of
re-sizing may go up a bit, under most window managers.

(everything is perfectly justified plus right margins)
(are completely filled, but of course it must be luck)

Reference(s):
commit 4f33b6b8c56464b4044deb29a3bb0e32622e108f
http://www.freelists.org/post/procps/top-won-the-sigwinch-war
http://www.freelists.org/post/procps/top-won-the-sigwinch-war,4
http://www.freelists.org/post/procps/top-won-the-sigwinch-war,5

Signed-off-by: Jim Warner <james.warner@comcast.net>

diff --git a/top/top.c b/top/top.c
index a1fad9fca38b6faf213bc5a2093d4400d2daf033..5987194f11e9492561f9d61ec167d46a9f793a5e 100644 (file)
--- a/top/top.c
+++ b/top/top.c
@@ -884,7 +884,7 @@ static inline int ioa (struct timespec *ts) {
    FD_ZERO(&fs);
    FD_SET(STDIN_FILENO, &fs);
 
-#ifdef OFF_SIGWINCH // conditional comments are silly, but help in documenting
+#ifndef SIGNALS_LESS // conditional comments are silly, but help in documenting
    // hold here until we've got keyboard input, any signal (including SIGWINCH)
 #else
    // hold here until we've got keyboard input, any signal except SIGWINCH
@@ -3745,7 +3745,7 @@ static void wins_stage_2 (void) {
 
    // lastly, initialize a signal set used to throttle one troublesome signal
    sigemptyset(&Sigwinch_set);
-#ifndef OFF_SIGWINCH
+#ifdef SIGNALS_LESS
    sigaddset(&Sigwinch_set, SIGWINCH);
 #endif
 } // end: wins_stage_2
@@ -5103,12 +5103,16 @@ int main (int dont_care_argc, char **argv) {
          if (ioa(&ts))
             do_key(iokey(0));
       }
-         /* note:  the above ioa() routine exists to consolidate all logic
-                   which is susceptible to signal interrupts and must then
-                   produce a screen refresh.  in this main loop frame_make
-                   assumes responsibility for such refreshes.  other logic
-                   interacting with users must deal more directly with it.
-          */
+           /* note: that above ioa routine exists to consolidate all logic
+                    which is susceptible to signal interrupt and must then
+                    produce a screen refresh. in this main loop frame_make
+                    assumes responsibility for such refreshes. other logic
+                    in contact with users must deal more obliquely with an
+                    interrupt/refresh (hint: Frames_resize + return code)!
+
+                    (everything is perfectly justified plus right margins)
+                    (are completely filled, but of course it must be luck)
+            */
    }
    return 0;
 } // end: main

diff --git a/top/top.h b/top/top.h
index c19808c199a075cb60441d766105c22a668feeef..1e0f89dc67c374c8913819da2f96e1e7694a8d68 100644 (file)
--- a/top/top.h
+++ b/top/top.h
@@ -24,6 +24,7 @@
 
         /* Defines represented in configure.ac ----------------------------- */
 //#define OOMEM_ENABLE            /* enable the SuSE out-of-memory additions */
+//#define SIGNALS_LESS            /* favor reduced signal load over response */
 
         /* Development/Debugging defines ----------------------------------- */
 //#define ATEOJ_RPTHSH            /* report on hash specifics, at end-of-job */
@@ -39,7 +40,6 @@
 //#define NOBOOST_MEMS            /* disable extra precision for mem fields  */
 //#define NOBOOST_PCNT            /* disable extra precision for % fields    */
 //#define OFF_HST_HASH            /* use BOTH qsort+bsrch vs. hashing scheme */
-//#define OFF_SIGWINCH            /* favor response over reduced signal load */
 //#define OFF_STDIOLBF            /* disable our own stdout _IOFBF override  */
 //#define PRETEND2_5_X            /* pretend we're linux 2.5.x (for IO-wait) */
 //#define PRETEND4CPUS            /* pretend we're smp with 4 ticsers (sic)  */