From dfb8bd8c95a5ff8633214f483f358d24071a7d8a Mon Sep 17 00:00:00 2001
From: rodri <rgl@antares-labs.eu>
Date: Wed, 21 Jul 2021 20:08:58 +0000
Subject: implement a primitive VLA to keep connection state.

---
 dat.h   |  8 ++++++++
 muswd.c | 32 ++++++++++++++++++++++++++------
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/dat.h b/dat.h
index 97e0719..66db045 100644
--- a/dat.h
+++ b/dat.h
@@ -2,6 +2,7 @@
 
 typedef struct GameState GameState;
 typedef struct Derivative Derivative;
+typedef struct Conn Conn;
 
 struct GameState
 {
@@ -12,3 +13,10 @@ struct Derivative
 {
 	double dx, dv;
 };
+
+struct Conn
+{
+	int *fds;
+	ulong off;
+	ulong cap;
+};
diff --git a/muswd.c b/muswd.c
index 4ebdb5e..c652b39 100644
--- a/muswd.c
+++ b/muswd.c
@@ -9,8 +9,7 @@ int debug;
 GameState state;
 double t, Δt;
 
-int *conns;
-int nconns;
+Conn conns;
 
 static long
 _iolisten(va_list *arg)
@@ -55,8 +54,15 @@ threadlisten(void *arg)
 			continue;
 		}
 
-		conns = erealloc(conns, ++nconns*sizeof(*conns));
-		conns[nconns-1] = dfd;
+		if(conns.off >= conns.cap){
+			conns.cap += 8;
+			conns.fds = erealloc(conns.fds, conns.cap*sizeof(*conns.fds));
+		}
+		conns.fds[conns.off++] = dfd;
+
+		if(debug)
+			fprint(2, "added conn %d for %lud conns at %lud max\n",
+				dfd, conns.off, conns.cap);
 	}
 }
 
@@ -89,8 +95,19 @@ threadsim(void *)
 		then = now;
 		timeacc += frametime/1e9;
 
-		for(i = 0; i < nconns; i++)
-			fprint(conns[i], "state: x=%g v=%g\n", state.x, state.v);
+		for(i = 0; i < conns.off; i++)
+			if(fprint(conns.fds[i], "state: x=%g v=%g\n", state.x, state.v) < 0){
+				fprint(2, "client #%d hanged up\n", i+1);
+				if(conns.off < conns.cap-1)
+					memmove(&conns.fds[conns.off], &conns.fds[conns.off+1], conns.cap-conns.off - 1);
+				conns.off--;
+
+				if(debug)
+					fprint(2, "removed conn %d for %lud conns at %lud max\n",
+						i, conns.off, conns.cap);
+
+				i--;
+			}
 
 		while(timeacc >= Δt){
 			integrate(&state, t, Δt);
@@ -129,6 +146,9 @@ threadmain(int argc, char *argv[])
 	if(acfd < 0)
 		sysfatal("announce: %r");
 
+	conns.fds = emalloc(2*sizeof(*conns.fds));
+	conns.cap = 2;
+
 	threadcreate(threadlisten, adir, 4096);
 	threadcreate(threadsim, nil, 4096);
 	threadexits(nil);
-- 
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