From a7abb429fd7d05cc3a680796d3e0644b360cd79e Mon Sep 17 00:00:00 2001
From: Mark Wooding <mdw@distorted.org.uk>
Date: Sat, 19 May 2018 18:28:15 +0100
Subject: [PATCH] server/tripe.c: Formalize the interval-timer arrangements.

The hard stuff is now (mostly) detached from the main initialization
code.  There's also some machinery, currently unused, for disabling the
interval timer while it's not doing any good, which might be useful in
energy-constrained devices.
---
 server/tripe.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++---------
 server/tripe.h | 26 ++++++++++++++++++++++++++
 2 files changed, 75 insertions(+), 9 deletions(-)

diff --git a/server/tripe.c b/server/tripe.c
index 93d40b9b..e4733bce 100644
--- a/server/tripe.c
+++ b/server/tripe.c
@@ -36,7 +36,10 @@ sel_state sel;
 static sel_timer it;
 #define T_INTERVAL MIN(1)
 
-/*----- Main code ---------------------------------------------------------*/
+static unsigned iv_nreasons = 0;
+static struct timeval iv_next = { 0, 0 };
+
+/*----- The interval timer ------------------------------------------------*/
 
 /* --- @interval@ --- *
  *
@@ -50,15 +53,54 @@ static sel_timer it;
 
 static void interval(struct timeval *tv, void *v)
 {
-  struct timeval tvv;
   T( trace(T_PEER, "peer: interval timer"); )
+  iv_next = *tv;
   rand_seed(RAND_GLOBAL, MAXHASHSZ);
   p_interval();
-  tvv = *tv;
-  tvv.tv_sec += T_INTERVAL;
-  sel_addtimer(&sel, &it, &tvv, interval, v);
+  iv_next.tv_sec += T_INTERVAL;
+  sel_addtimer(&sel, &it, &iv_next, interval, v);
+}
+
+/* --- @iv_addreason@ --- *
+ *
+ * Arguments:	---
+ *
+ * Returns:	---
+ *
+ * Use:		Adds an `interval timer reason'; if there are no others, the
+ *		interval timer is engaged.
+ */
+
+void iv_addreason(void)
+{
+  struct timeval tv;
+
+  if (!iv_nreasons) {
+    gettimeofday(&tv, 0);
+    if (TV_CMP(&tv, >=, &iv_next)) interval(&tv, 0);
+    else sel_addtimer(&sel, &it, &iv_next, interval, 0);
+  }
+  iv_nreasons++;
 }
 
+/* --- @iv_rmreason@ --- *
+ *
+ * Arguments:	---
+ *
+ * Returns:	---
+ *
+ * Use:		Removes an interval timer reason; if there are none left, the
+ *		interval timer is disengaged.
+ */
+
+void iv_rmreason(void)
+{
+  assert(iv_nreasons); iv_nreasons--;
+  if (!iv_nreasons) sel_rmtimer(&it);
+}
+
+/*----- Main code ---------------------------------------------------------*/
+
 /* --- @main@ --- *
  *
  * Arguments:	@int argc@ = number of command line arguments
@@ -127,7 +169,6 @@ int main(int argc, char *argv[])
   int i;
   int err, selerr = 0;
   unsigned af;
-  struct timeval tv;
   uid_t u = -1;
   gid_t g = -1;
 
@@ -331,9 +372,8 @@ int main(int argc, char *argv[])
     a_switcherr();
   }
 
-  tv.tv_sec = time(0) + T_INTERVAL;
-  tv.tv_usec = 0;
-  sel_addtimer(&sel, &it, &tv, interval, 0);
+  gettimeofday(&iv_next, 0); iv_next.tv_sec += T_INTERVAL;
+  iv_addreason();
 
   for (;;) {
     a_preselect();
diff --git a/server/tripe.h b/server/tripe.h
index 9ff54566..a2fdd006 100644
--- a/server/tripe.h
+++ b/server/tripe.h
@@ -1829,6 +1829,32 @@ extern void p_mkiter(peer_iter */*i*/);
 
 extern peer *p_next(peer_iter */*i*/);
 
+/*----- The interval timer ------------------------------------------------*/
+
+/* --- @iv_addreason@ --- *
+ *
+ * Arguments:	---
+ *
+ * Returns:	---
+ *
+ * Use:		Adds an `interval timer reason'; if there are no others, the
+ *		interval timer is engaged.
+ */
+
+extern void iv_addreason(void);
+
+/* --- @iv_rmreason@ --- *
+ *
+ * Arguments:	---
+ *
+ * Returns:	---
+ *
+ * Use:		Removes an interval timer reason; if there are none left, the
+ *		interval timer is disengaged.
+ */
+
+extern void iv_rmreason(void);
+
 /*----- Tunnel drivers ----------------------------------------------------*/
 
 #ifdef TUN_LINUX
-- 
2.11.0