+++ /dev/null
-/*\r
- * timing.c\r
- * \r
- * This module tracks any timers set up by schedule_timer(). It\r
- * keeps all the currently active timers in a list; it informs the\r
- * front end of when the next timer is due to go off if that\r
- * changes; and, very importantly, it tracks the context pointers\r
- * passed to schedule_timer(), so that if a context is freed all\r
- * the timers associated with it can be immediately annulled.\r
- */\r
-\r
-#include <assert.h>\r
-#include <stdio.h>\r
-\r
-#include "putty.h"\r
-#include "tree234.h"\r
-\r
-struct timer {\r
- timer_fn_t fn;\r
- void *ctx;\r
- long now;\r
-};\r
-\r
-static tree234 *timers = NULL;\r
-static tree234 *timer_contexts = NULL;\r
-static long now = 0L;\r
-\r
-static int compare_timers(void *av, void *bv)\r
-{\r
- struct timer *a = (struct timer *)av;\r
- struct timer *b = (struct timer *)bv;\r
- long at = a->now - now;\r
- long bt = b->now - now;\r
-\r
- if (at < bt)\r
- return -1;\r
- else if (at > bt)\r
- return +1;\r
-\r
- /*\r
- * Failing that, compare on the other two fields, just so that\r
- * we don't get unwanted equality.\r
- */\r
-#ifdef __LCC__\r
- /* lcc won't let us compare function pointers. Legal, but annoying. */\r
- {\r
- int c = memcmp(&a->fn, &b->fn, sizeof(a->fn));\r
- if (c < 0)\r
- return -1;\r
- else if (c > 0)\r
- return +1;\r
- }\r
-#else \r
- if (a->fn < b->fn)\r
- return -1;\r
- else if (a->fn > b->fn)\r
- return +1;\r
-#endif\r
-\r
- if (a->ctx < b->ctx)\r
- return -1;\r
- else if (a->ctx > b->ctx)\r
- return +1;\r
-\r
- /*\r
- * Failing _that_, the two entries genuinely are equal, and we\r
- * never have a need to store them separately in the tree.\r
- */\r
- return 0;\r
-}\r
-\r
-static int compare_timer_contexts(void *av, void *bv)\r
-{\r
- char *a = (char *)av;\r
- char *b = (char *)bv;\r
- if (a < b)\r
- return -1;\r
- else if (a > b)\r
- return +1;\r
- return 0;\r
-}\r
-\r
-static void init_timers(void)\r
-{\r
- if (!timers) {\r
- timers = newtree234(compare_timers);\r
- timer_contexts = newtree234(compare_timer_contexts);\r
- now = GETTICKCOUNT();\r
- }\r
-}\r
-\r
-long schedule_timer(int ticks, timer_fn_t fn, void *ctx)\r
-{\r
- long when;\r
- struct timer *t, *first;\r
-\r
- init_timers();\r
-\r
- when = ticks + GETTICKCOUNT();\r
-\r
- /*\r
- * Just in case our various defences against timing skew fail\r
- * us: if we try to schedule a timer that's already in the\r
- * past, we instead schedule it for the immediate future.\r
- */\r
- if (when - now <= 0)\r
- when = now + 1;\r
-\r
- t = snew(struct timer);\r
- t->fn = fn;\r
- t->ctx = ctx;\r
- t->now = when;\r
-\r
- if (t != add234(timers, t)) {\r
- sfree(t); /* identical timer already exists */\r
- } else {\r
- add234(timer_contexts, t->ctx);/* don't care if this fails */\r
- }\r
-\r
- first = (struct timer *)index234(timers, 0);\r
- if (first == t) {\r
- /*\r
- * This timer is the very first on the list, so we must\r
- * notify the front end.\r
- */\r
- timer_change_notify(first->now);\r
- }\r
-\r
- return when;\r
-}\r
-\r
-/*\r
- * Call to run any timers whose time has reached the present.\r
- * Returns the time (in ticks) expected until the next timer after\r
- * that triggers.\r
- */\r
-int run_timers(long anow, long *next)\r
-{\r
- struct timer *first;\r
-\r
- init_timers();\r
-\r
-#ifdef TIMING_SYNC\r
- /*\r
- * In this ifdef I put some code which deals with the\r
- * possibility that `anow' disagrees with GETTICKCOUNT by a\r
- * significant margin. Our strategy for dealing with it differs\r
- * depending on platform, because on some platforms\r
- * GETTICKCOUNT is more likely to be right whereas on others\r
- * `anow' is a better gold standard.\r
- */\r
- {\r
- long tnow = GETTICKCOUNT();\r
-\r
- if (tnow + TICKSPERSEC/50 - anow < 0 ||\r
- anow + TICKSPERSEC/50 - tnow < 0\r
- ) {\r
-#if defined TIMING_SYNC_ANOW\r
- /*\r
- * If anow is accurate and the tick count is wrong,\r
- * this is likely to be because the tick count is\r
- * derived from the system clock which has changed (as\r
- * can occur on Unix). Therefore, we resolve this by\r
- * inventing an offset which is used to adjust all\r
- * future output from GETTICKCOUNT.\r
- * \r
- * A platform which defines TIMING_SYNC_ANOW is\r
- * expected to have also defined this offset variable\r
- * in (its platform-specific adjunct to) putty.h.\r
- * Therefore we can simply reference it here and assume\r
- * that it will exist.\r
- */\r
- tickcount_offset += anow - tnow;\r
-#elif defined TIMING_SYNC_TICKCOUNT\r
- /*\r
- * If the tick count is more likely to be accurate, we\r
- * simply use that as our time value, which may mean we\r
- * run no timers in this call (because we got called\r
- * early), or alternatively it may mean we run lots of\r
- * timers in a hurry because we were called late.\r
- */\r
- anow = tnow;\r
-#else\r
-/*\r
- * Any platform which defines TIMING_SYNC must also define one of the two\r
- * auxiliary symbols TIMING_SYNC_ANOW and TIMING_SYNC_TICKCOUNT, to\r
- * indicate which measurement to trust when the two disagree.\r
- */\r
-#error TIMING_SYNC definition incomplete\r
-#endif\r
- }\r
- }\r
-#endif\r
-\r
- now = anow;\r
-\r
- while (1) {\r
- first = (struct timer *)index234(timers, 0);\r
-\r
- if (!first)\r
- return FALSE; /* no timers remaining */\r
-\r
- if (find234(timer_contexts, first->ctx, NULL) == NULL) {\r
- /*\r
- * This timer belongs to a context that has been\r
- * expired. Delete it without running.\r
- */\r
- delpos234(timers, 0);\r
- sfree(first);\r
- } else if (first->now - now <= 0) {\r
- /*\r
- * This timer is active and has reached its running\r
- * time. Run it.\r
- */\r
- delpos234(timers, 0);\r
- first->fn(first->ctx, first->now);\r
- sfree(first);\r
- } else {\r
- /*\r
- * This is the first still-active timer that is in the\r
- * future. Return how long it has yet to go.\r
- */\r
- *next = first->now;\r
- return TRUE;\r
- }\r
- }\r
-}\r
-\r
-/*\r
- * Call to expire all timers associated with a given context.\r
- */\r
-void expire_timer_context(void *ctx)\r
-{\r
- init_timers();\r
-\r
- /*\r
- * We don't bother to check the return value; if the context\r
- * already wasn't in the tree (presumably because no timers\r
- * ever actually got scheduled for it) then that's fine and we\r
- * simply don't need to do anything.\r
- */\r
- del234(timer_contexts, ctx);\r
-}\r
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