libmainloop/defer.c

   1 /*
   2  * ion/libmainloop/defer.c
   3  *
   4  * Copyright (c) Tuomo Valkonen 1999-2006.
   5  *
   6  * Ion is free software; you can redistribute it and/or modify it under
   7  * the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  */
  11
  12 /* This file contains routines for deferred execution of potentially
  13  * dangerous actions. They're called upon returning to the main
  14  * loop.
  15  */
  16
  17 #include <libtu/obj.h>
  18 #include <libtu/objp.h>
  19 #include <libtu/types.h>
  20 #include <libtu/misc.h>
  21 #include <libtu/dlist.h>
  22 #include <libtu/output.h>
  23 #include <libtu/locale.h>
  24 #include "defer.h"
  25
  26
  27 DECLSTRUCT(WDeferred){
  28     Watch watch;
  29     WDeferredAction *action;
  30     ExtlFn fn;
  31     WDeferred *next, *prev;
  32     WDeferred **list;
  33 };
  34
  35
  36 static WDeferred *deferred=NULL;
  37
  38
  39 #define N_DBUF 16
  40
  41 /* To avoid allocating memory all the time, we use a small
  42  * buffer that should be able to contain the small expected
  43  * number of simultaneous deferred actions.
  44  */
  45 static WDeferred dbuf[N_DBUF];
  46 static int dbuf_used=0;
  47
  48
  49 static WDeferred *alloc_defer()
  50 {
  51     int i;
  52
  53     /* Keeping it simple -- this naive loop should do it
  54      * as N_DBUF is small.
  55      */
  56     for(i=0; i<N_DBUF; i++){
  57         if(!dbuf_used&(1<<i)){
  58             dbuf_used|=(1<<i);
  59             return dbuf+i;
  60         }
  61     }
  62     return ALLOC(WDeferred);
  63 }
  64
  65
  66 static void free_defer(WDeferred *d)
  67 {
  68     if(d>=dbuf && d<dbuf+N_DBUF){
  69         dbuf_used&=~1<<((d-dbuf)/sizeof(WDeferred));
  70         return;
  71     }
  72     FREE(d);
  73 }
  74
  75
  76 static void defer_watch_handler(Watch *w, Obj *obj)
  77 {
  78     WDeferred *d=(WDeferred*)w;
  79
  80     UNLINK_ITEM(*(WDeferred**)(d->list), d, next, prev);
  81
  82     free_defer(d);
  83
  84     warn(TR("Object destroyed while deferred actions are still pending."));
  85 }
  86
  87
  88 bool mainloop_defer_action_on_list(Obj *obj, WDeferredAction *action,
  89                                    WDeferred **list)
  90 {
  91     WDeferred *d;
  92
  93     d=alloc_defer();
  94
  95     if(d==NULL){
  96         warn_err();
  97         return FALSE;
  98     }
  99
 100     d->action=action;
 101     d->list=list;
 102     d->fn=extl_fn_none();
 103
 104     if(obj!=NULL)
 105         watch_setup(&(d->watch), obj, defer_watch_handler);
 106
 107     LINK_ITEM(*list, d, next, prev);
 108
 109     return TRUE;
 110 }
 111
 112
 113 bool mainloop_defer_action(Obj *obj, WDeferredAction *action)
 114 {
 115     return mainloop_defer_action_on_list(obj, action, &deferred);
 116 }
 117
 118
 119 bool mainloop_defer_destroy(Obj *obj)
 120 {
 121     if(OBJ_IS_BEING_DESTROYED(obj))
 122         return FALSE;
 123
 124     return mainloop_defer_action(obj, destroy_obj);
 125 }
 126
 127
 128 bool mainloop_defer_extl_on_list(ExtlFn fn, WDeferred **list)
 129 {
 130     WDeferred *d;
 131
 132     d=alloc_defer();
 133
 134     if(d==NULL){
 135         warn_err();
 136         return FALSE;
 137     }
 138
 139     d->action=NULL;
 140     d->list=list;
 141     d->fn=extl_ref_fn(fn);
 142
 143     watch_init(&(d->watch));
 144
 145     LINK_ITEM(*list, d, next, prev);
 146
 147     return TRUE;
 148 }
 149
 150
 151 /*EXTL_DOC
 152  * Defer execution of \var{fn} until the main loop.
 153  */
 154 EXTL_SAFE
 155 EXTL_EXPORT_AS(mainloop, defer)
 156 bool mainloop_defer_extl(ExtlFn fn)
 157 {
 158     return mainloop_defer_extl_on_list(fn, &deferred);
 159 }
 160
 161
 162 static void do_execute(WDeferred *d)
 163 {
 164     Obj *obj=d->watch.obj;
 165     WDeferredAction *a=d->action;
 166     ExtlFn fn=d->fn;
 167
 168     watch_reset(&(d->watch));
 169     free_defer(d);
 170
 171     if(a!=NULL){
 172         if(obj!=NULL)
 173             a(obj);
 174     }else if(fn!=extl_fn_none()){
 175         extl_call(fn, NULL, NULL);
 176         extl_unref_fn(fn);
 177     }
 178 }
 179
 180
 181 void mainloop_execute_deferred_on_list(WDeferred **list)
 182 {
 183     Obj *obj;
 184     void (*action)(Obj*);
 185
 186     while(*list!=NULL){
 187         WDeferred *d=*list;
 188         UNLINK_ITEM(*list, d, next, prev);
 189         do_execute(d);
 190     }
 191 }
 192
 193
 194 void mainloop_execute_deferred()
 195 {
 196     mainloop_execute_deferred_on_list(&deferred);
 197 }
 198