X-Git-Url: https://git.xandkar.net/?a=blobdiff_plain;f=x5%2Fkhatus.c;h=2445c1b918298fdfcaf7a76d4d41927c17adfafd;hb=51e63a6f4abb7090146eff8a0294375ec9525205;hp=5caae33d698edc1d4d4abf1e1a1035c7629ef46f;hpb=4bfac488ba99787df53cf6b8627b0192921309cf;p=khatus.git

diff --git a/x5/khatus.c b/x5/khatus.c
index 5caae33..2445c1b 100644
--- a/x5/khatus.c
+++ b/x5/khatus.c
@@ -121,29 +121,29 @@ slot_expire(Slot *s, struct timespec t, char *buf)
 	timespecsub(&t, &(s->in_last_read), &td);
 	if (timespeccmp(&td, &(s->out_ttl), >=)) {
 		/* TODO: Maybe configurable expiry character. */
-		memset(buf + s->out_pos_lo, '_', s->out_pos_hi - s->out_pos_lo);
+		memset(buf + s->out_pos_lo, '_', s->out_width);
 		khlib_warn("Slot expired: \"%s\"\n", s->in_fifo);
 	}
 }
 
 void
-slot_read_error(Slot *s, char *buf)
+slot_set_error(Slot *s, char *buf)
 {
 	char *b;
 	int i;
 
+	s->in_fd = -1;
 	b = buf + s->out_pos_lo;
 	/* Copy as much of the error message as possible.
 	 * EXCLUDING the terminating \0. */
 	for (i = 0; i < errlen && i < s->out_width; i++)
 		b[i] = errmsg[i];
 	/* Any remaining positions: */
-	for (; i < s->out_width; i++)
-		b[i] = '_';
+	memset(b + i, '_', s->out_width - i);
 }
 
 enum read_status
-slot_read(Slot *s, struct timespec t, char *buf)
+slot_read(Slot *s, char *buf)
 {
 	char c;  /* Character read. */
 	int  r;  /* Remaining unused positions in buffer range. */
@@ -171,21 +171,21 @@ slot_read(Slot *s, struct timespec t, char *buf)
 		case  1:
 			/* TODO: Consider making msg term char a CLI option */
 			if (c == '\n' || c == '\0') {
-				r = s->out_pos_hi - s->out_pos_cur;
+				r = (s->out_pos_hi - s->out_pos_cur) + 1;
 				if (r > 0)
 					memset(buf + s->out_pos_cur, ' ', r);
-				s->out_pos_cur = s->out_pos_lo;
-				s->in_last_read = t;
 				return END_OF_MESSAGE;
 			} else {
 				if (s->out_pos_cur <= s->out_pos_hi)
 					buf[s->out_pos_cur++] = c;
-				/* Drop beyond available range. */
-				/*
-				 * TODO Define max after which we stop reading.
-				 *      To ensure that a rogue large message
-				 *      doesn't trap us here.
-				 */
+				else
+					/*
+					 * Force EOM beyond available range.
+					 * To ensure that a rogue large message
+					 * doesn't trap us here needlessly
+					 * long.
+					 */
+					return END_OF_MESSAGE;
 			}
 			break;
 		default:
@@ -213,12 +213,12 @@ slots_read(Config *cfg, struct timespec *ti, char *buf)
 			    s->in_fifo,
 			    strerror(errno)
 			);
-			slot_read_error(s, buf);
+			slot_set_error(s, buf);
 			continue;
 		}
 		if (!(st.st_mode & S_IFIFO)) {
 			khlib_error("\"%s\" is not a FIFO\n", s->in_fifo);
-			slot_read_error(s, buf);
+			slot_set_error(s, buf);
 			continue;
 		}
 		if (s->in_fd < 0) {
@@ -238,7 +238,7 @@ slots_read(Config *cfg, struct timespec *ti, char *buf)
 		if (s->in_fd == -1) {
 			/* TODO Consider backing off retries for failed slots */
 			khlib_error("Failed to open \"%s\"\n", s->in_fifo);
-			slot_read_error(s, buf);
+			slot_set_error(s, buf);
 			continue;
 		}
 		khlib_debug("%s: open. in_fd: %d\n", s->in_fifo, s->in_fd);
@@ -273,9 +273,11 @@ slots_read(Config *cfg, struct timespec *ti, char *buf)
 	/* At-least-once ensures that expiries are still checked on timeouts. */
 	do {
 		for (s = cfg->slots; s; s = s->next) {
+			if (s->in_fd < 0)
+				continue;
 			if (FD_ISSET(s->in_fd, &fds)) {
 				khlib_debug("reading: %s\n", s->in_fifo);
-				switch (slot_read(s, t, buf)) {
+				switch (slot_read(s, buf)) {
 				/*
 				 * ### MESSAGE LOSS ###
 				 * is introduced by closing at EOM in addition
@@ -289,12 +291,27 @@ slots_read(Config *cfg, struct timespec *ti, char *buf)
 				 * This is an acceptable trade-off because we
 				 * are a stateless reporter of a _most-recent_
 				 * status, not a stateful accumulator.
+				 *
+				 * ### LOSSLESS ALTERNATIVES ###
+				 * - Read each pipe until EOF before reading
+				 *   another.
+				 *   PROBLEM: a fast writer can trap us in the
+				 *   read loop.
+				 *
+				 * - Read each pipe until EOM, but close only
+				 *   at EOF.
+				 *   PROBLEM: a fast writer can fill the pipe
+				 *   faster than we can read it and we end-up
+				 *   displaying stale data.
+				 *
 				 */
 				case END_OF_MESSAGE:
 				case END_OF_FILE:
 				case FAILURE:
 					close(s->in_fd);
-					s->in_fd = -1;
+					s->in_fd        = -1;
+					s->in_last_read = t;
+					s->out_pos_cur  = s->out_pos_lo;
 					ready--;
 					break;
 				case RETRY: