src/thread/pthread/SDL_systhread.c
author Sam Lantinga <slouken@libsdl.org>
Wed, 03 Jun 2009 04:37:27 +0000
changeset 3162 dc1eb82ffdaa
parent 2859 99210400e8b9
child 3578 0d1b16ee0bca
permissions -rw-r--r--
Von: Thomas Zimmermann
Betreff: [SDL] [PATCH] Make static variables const
Datum: Tue, 19 May 2009 19:45:37 +0200

Hi,

this is a set of simple changes which make some of SDL's internal static
arrays constant. The purpose is to shrink the number of write-able
static bytes and thus increase the number of memory pages shared between
SDL applications.

The patch set is against trunk@4513. Each of the attached patch files is
specific to a sub-system. The set is completed by a second mail, because
of the list's 40 KiB limit.

The files readelf-r4513.txt and readelf-const-patch.txt where made by
calling 'readelf -S libSDL.so'. They show the difference in ELF sections
without and with the patch. Some numbers measured on my x86-64:

Before

[13] .rodata PROGBITS 00000000000eaaa0 000eaaa0
0000000000008170 0000000000000000 A 0 0 32
[19] .data.rel.ro PROGBITS 00000000003045e0 001045e0
00000000000023d0 0000000000000000 WA 0 0 32
[23] .data PROGBITS 00000000003076e0 001076e0
0000000000004988 0000000000000000 WA 0 0 32

After

[13] .rodata PROGBITS 00000000000eaaa0 000eaaa0
0000000000009a50 0000000000000000 A 0 0 32
[19] .data.rel.ro PROGBITS 0000000000306040 00106040
0000000000002608 0000000000000000 WA 0 0 32
[23] .data PROGBITS 0000000000309360 00109360
0000000000002e88 0000000000000000 WA 0 0 32

The size of the write-able data section decreased considerably. Some
entries became const-after-relocation, while most of its content went
straight into the read-only data section.

Best regards, Thomas
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997-2009 Sam Lantinga
     4 
     5     This library is free software; you can redistribute it and/or
     6     modify it under the terms of the GNU Lesser General Public
     7     License as published by the Free Software Foundation; either
     8     version 2.1 of the License, or (at your option) any later version.
     9 
    10     This library is distributed in the hope that it will be useful,
    11     but WITHOUT ANY WARRANTY; without even the implied warranty of
    12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13     Lesser General Public License for more details.
    14 
    15     You should have received a copy of the GNU Lesser General Public
    16     License along with this library; if not, write to the Free Software
    17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
    18 
    19     Sam Lantinga
    20     slouken@libsdl.org
    21 */
    22 #include "SDL_config.h"
    23 
    24 #include <pthread.h>
    25 #include <signal.h>
    26 
    27 #include "SDL_thread.h"
    28 #include "../SDL_thread_c.h"
    29 #include "../SDL_systhread.h"
    30 
    31 /* List of signals to mask in the subthreads */
    32 static const int sig_list[] = {
    33     SIGHUP, SIGINT, SIGQUIT, SIGPIPE, SIGALRM, SIGTERM, SIGCHLD, SIGWINCH,
    34     SIGVTALRM, SIGPROF, 0
    35 };
    36 
    37 #ifdef __RISCOS__
    38 /* RISC OS needs to know the main thread for
    39  * it's timer and event processing. */
    40 int riscos_using_threads = 0;
    41 Uint32 riscos_main_thread = 0;  /* Thread running events */
    42 #endif
    43 
    44 
    45 static void *
    46 RunThread(void *data)
    47 {
    48     SDL_RunThread(data);
    49     pthread_exit((void *) 0);
    50     return ((void *) 0);        /* Prevent compiler warning */
    51 }
    52 
    53 int
    54 SDL_SYS_CreateThread(SDL_Thread * thread, void *args)
    55 {
    56     pthread_attr_t type;
    57 
    58     /* Set the thread attributes */
    59     if (pthread_attr_init(&type) != 0) {
    60         SDL_SetError("Couldn't initialize pthread attributes");
    61         return (-1);
    62     }
    63     pthread_attr_setdetachstate(&type, PTHREAD_CREATE_JOINABLE);
    64 
    65     /* Create the thread and go! */
    66     if (pthread_create(&thread->handle, &type, RunThread, args) != 0) {
    67         SDL_SetError("Not enough resources to create thread");
    68         return (-1);
    69     }
    70 #ifdef __RISCOS__
    71     if (riscos_using_threads == 0) {
    72         riscos_using_threads = 1;
    73         riscos_main_thread = SDL_ThreadID();
    74     }
    75 #endif
    76 
    77     return (0);
    78 }
    79 
    80 void
    81 SDL_SYS_SetupThread(void)
    82 {
    83     int i;
    84     sigset_t mask;
    85 
    86     /* Mask asynchronous signals for this thread */
    87     sigemptyset(&mask);
    88     for (i = 0; sig_list[i]; ++i) {
    89         sigaddset(&mask, sig_list[i]);
    90     }
    91     pthread_sigmask(SIG_BLOCK, &mask, 0);
    92 
    93 #ifdef PTHREAD_CANCEL_ASYNCHRONOUS
    94     /* Allow ourselves to be asynchronously cancelled */
    95     {
    96         int oldstate;
    97         pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &oldstate);
    98     }
    99 #endif
   100 }
   101 
   102 /* WARNING:  This may not work for systems with 64-bit pid_t */
   103 Uint32
   104 SDL_ThreadID(void)
   105 {
   106     return ((Uint32) pthread_self());
   107 }
   108 
   109 void
   110 SDL_SYS_WaitThread(SDL_Thread * thread)
   111 {
   112     pthread_join(thread->handle, 0);
   113 }
   114 
   115 /* vi: set ts=4 sw=4 expandtab: */