[lib] Bug #134: threads should be more robust against backward time jumps
2006-08-25 Paul Jakma <paul.jakma@sun.com>
* thread.c: (general) Add support for monotonic clock, it may still
jump forward by huge amounts, but should be immune to going
backwards. Fixes bug #134.
(quagga_gettimeofday_relative_adjust) helper, does what name
says - adjusts gettimeofday based relative timer.
(quagga_gettimeofday) helper to keep recent_time up to date.
(quagga_get_relative) helper, update and getch the relative
timer using gettimeofday(). POSIX CLOCK_MONOTONIC is also
supported, but the code is not enabled yet nor tested.
(quagga_real_stabilised) helper, retrieve absolute time but
stabilised so as to never decrease.
(quagga_gettime) Exported interface, analogous to POSIX
clock_gettime() in interface, supporting several clocks.
(quagga_time) Exported interface, analogous to traditional
time(), will never decrease.
(recent_relative_time) Convenience function to retrieve
relative_time timeval, similar to existing recent_time absolute
timeval, for when an approximately recent value will do.
(remainder) Update to use above helpers.
(thread_getrusage) Previously was a macro, but needs to be
a function to twiddle with thread.c private stuff.
* thread.c: Point the GETRUSAGE macro at previous function.
Export quagga_gettime, quagga_time and recent_relative_time for
general use.
diff --git a/lib/thread.h b/lib/thread.h
index 0670a89..1c324d8 100644
--- a/lib/thread.h
+++ b/lib/thread.h
@@ -31,14 +31,7 @@
};
#define RUSAGE_T struct rusage_t
-#ifdef HAVE_RUSAGE
-#define GETRUSAGE(X) \
- getrusage(RUSAGE_SELF, &((X)->cpu)); \
- gettimeofday(&recent_time, NULL); (X)->real = recent_time
-#else
-#define GETRUSAGE(X) \
- gettimeofday(&recent_time, NULL); (X)->real = recent_time
-#endif /* HAVE_RUSAGE */
+#define GETRUSAGE(X) thread_getrusage(X)
/* Linked list of thread. */
struct thread_list
@@ -99,6 +92,13 @@
unsigned char types;
};
+/* Clocks supported by Quagga */
+enum quagga_clkid {
+ QUAGGA_CLK_REALTIME = 0, /* ala gettimeofday() */
+ QUAGGA_CLK_MONOTONIC, /* monotonic, against an indeterminate base */
+ QUAGGA_CLK_REALTIME_STABILISED, /* like realtime, but non-decrementing */
+};
+
/* Thread types. */
#define THREAD_READ 0
#define THREAD_WRITE 1
@@ -192,8 +192,17 @@
extern unsigned long thread_timer_remain_second (struct thread *);
extern int thread_should_yield (struct thread *);
+/* Internal libzebra exports */
+extern void thread_getrusage (RUSAGE_T *);
extern struct cmd_element show_thread_cpu_cmd;
+/* replacements for the system gettimeofday(), clock_gettime() and
+ * time() functions, providing support for non-decrementing clock on
+ * all systems, and fully monotonic on /some/ systems.
+ */
+extern int quagga_gettime (enum quagga_clkid, struct timeval *);
+extern time_t quagga_time (time_t *);
+
/* Returns elapsed real (wall clock) time. */
extern unsigned long thread_consumed_time(RUSAGE_T *after, RUSAGE_T *before,
unsigned long *cpu_time_elapsed);
@@ -202,5 +211,6 @@
be used instead of calling gettimeofday if a recent value is sufficient.
This is guaranteed to be refreshed before a thread is called. */
extern struct timeval recent_time;
-
+/* Similar to recent_time, but a monotonically increasing time value */
+extern struct timeval recent_relative_time (void);
#endif /* _ZEBRA_THREAD_H */