X-Git-Url: https://git.xandkar.net/?a=blobdiff_plain;f=x5%2Fkhatus.c;h=2445c1b918298fdfcaf7a76d4d41927c17adfafd;hb=51e63a6f4abb7090146eff8a0294375ec9525205;hp=382c8731aaeee3c6494955567ecbd806468bb783;hpb=900b9a6b1cf64ec6fc67bca260784ab93aec4fa1;p=khatus.git

diff --git a/x5/khatus.c b/x5/khatus.c
index 382c873..2445c1b 100644
--- a/x5/khatus.c
+++ b/x5/khatus.c
@@ -24,6 +24,7 @@
 }
 #define ERRMSG "ERROR"
 
+
 static const char errmsg[] = ERRMSG;
 static const int  errlen   = sizeof(ERRMSG) - 1;
 
@@ -60,8 +61,23 @@ enum read_status {
 	FAILURE
 };
 
+Slot *
+slots_rev(Slot *old)
+{
+	Slot *tmp = NULL;
+	Slot *new = NULL;
+
+	while (old) {
+		tmp       = old->next;
+		old->next = new;
+		new       = old;
+		old       = tmp;
+	}
+	return new;
+}
+
 void
-slot_print_one(Slot *s)
+slot_print(Slot *s)
 {
 	khlib_info("Slot "
 	    "{"
@@ -90,13 +106,227 @@ slot_print_one(Slot *s)
 }
 
 void
-slot_print_all(Slot *head)
+slots_print(Slot *head)
 {
 	for (Slot *s = head; s; s = s->next) {
-		slot_print_one(s);
+		slot_print(s);
+	}
+}
+
+void
+slot_expire(Slot *s, struct timespec t, char *buf)
+{
+	struct timespec td;
+
+	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_width);
+		khlib_warn("Slot expired: \"%s\"\n", s->in_fifo);
+	}
+}
+
+void
+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: */
+	memset(b + i, '_', s->out_width - i);
+}
+
+enum read_status
+slot_read(Slot *s, char *buf)
+{
+	char c;  /* Character read. */
+	int  r;  /* Remaining unused positions in buffer range. */
+
+	for (;;) {
+		switch (read(s->in_fd, &c, 1)) {
+		case -1:
+			khlib_error(
+			    "Failed to read: \"%s\". errno: %d, msg: %s\n",
+			    s->in_fifo,
+			    errno,
+			    strerror(errno)
+			);
+			switch (errno) {
+			case EINTR:
+			case EAGAIN:
+				return RETRY;
+			default:
+				return FAILURE;
+			}
+		case  0:
+			khlib_debug("%s: End of FILE\n", s->in_fifo);
+			s->out_pos_cur = s->out_pos_lo;
+			return END_OF_FILE;
+		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) + 1;
+				if (r > 0)
+					memset(buf + s->out_pos_cur, ' ', r);
+				return END_OF_MESSAGE;
+			} else {
+				if (s->out_pos_cur <= s->out_pos_hi)
+					buf[s->out_pos_cur++] = c;
+				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:
+			assert(0);
+		}
 	}
 }
 
+void
+slots_read(Config *cfg, struct timespec *ti, char *buf)
+{
+	fd_set fds;
+	int maxfd = -1;
+	int ready = 0;
+	struct stat st;
+	struct timespec t;
+	Slot *s;
+
+	FD_ZERO(&fds);
+	for (s = cfg->slots; s; s = s->next) {
+		/* TODO: Create the FIFO if it doesn't already exist. */
+		if (lstat(s->in_fifo, &st) < 0) {
+			khlib_error(
+			    "Cannot stat \"%s\". Error: %s\n",
+			    s->in_fifo,
+			    strerror(errno)
+			);
+			slot_set_error(s, buf);
+			continue;
+		}
+		if (!(st.st_mode & S_IFIFO)) {
+			khlib_error("\"%s\" is not a FIFO\n", s->in_fifo);
+			slot_set_error(s, buf);
+			continue;
+		}
+		if (s->in_fd < 0) {
+			khlib_debug(
+			    "%s: closed. opening. in_fd: %d\n",
+			    s->in_fifo,
+			    s->in_fd
+			);
+			s->in_fd = open(s->in_fifo, O_RDONLY | O_NONBLOCK);
+		} else {
+			khlib_debug(
+			    "%s: already openned. in_fd: %d\n",
+			    s->in_fifo,
+			    s->in_fd
+			);
+		}
+		if (s->in_fd == -1) {
+			/* TODO Consider backing off retries for failed slots */
+			khlib_error("Failed to open \"%s\"\n", s->in_fifo);
+			slot_set_error(s, buf);
+			continue;
+		}
+		khlib_debug("%s: open. in_fd: %d\n", s->in_fifo, s->in_fd);
+		if (s->in_fd > maxfd)
+			maxfd = s->in_fd;
+		FD_SET(s->in_fd, &fds);
+	}
+	khlib_debug("selecting...\n");
+	ready = pselect(maxfd + 1, &fds, NULL, NULL, ti, NULL);
+	khlib_debug("ready: %d\n", ready);
+	clock_gettime(CLOCK_MONOTONIC, &t);
+	if (ready == -1) {
+		switch (errno) {
+		case EINTR:
+			khlib_error(
+			    "pselect temp failure: %d, errno: %d, msg: %s\n",
+			    ready,
+			    errno,
+			    strerror(errno)
+			);
+			/* TODO: Reconsider what to do here. */
+			return;
+		default:
+			khlib_fatal(
+			    "pselect failed: %d, errno: %d, msg: %s\n",
+			    ready,
+			    errno,
+			    strerror(errno)
+			);
+		}
+	}
+	/* 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, buf)) {
+				/*
+				 * ### MESSAGE LOSS ###
+				 * is introduced by closing at EOM in addition
+				 * to EOF, since there may be unread messages
+				 * remaining in the pipe. However,
+				 *
+				 * ### INTER-MESSAGE PUSHBACK ###
+				 * is also gained, since pipes block at the
+				 * "open" call.
+				 *
+				 * 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_last_read = t;
+					s->out_pos_cur  = s->out_pos_lo;
+					ready--;
+					break;
+				case RETRY:
+					break;
+				default:
+					assert(0);
+				}
+			} else {
+				slot_expire(s, t, buf);
+			}
+		}
+	} while (ready);
+	assert(ready == 0);
+}
+
 void
 config_print(Config *cfg)
 {
@@ -114,7 +344,7 @@ config_print(Config *cfg)
 	    cfg->slot_count,
 	    cfg->total_width
 	);
-	slot_print_all(cfg->slots);
+	slots_print(cfg->slots);
 }
 
 int
@@ -252,35 +482,41 @@ parse_opts_opt(Config *cfg, int argc, char *argv[], int i)
 void
 parse_opts_spec(Config *cfg, int argc, char *argv[], int i)
 {
+	char *n;
+	char *w;
+	char *t;
+	struct timespec in_last_read;
+	Slot *s;
+
 	if ((i + 3) > argc)
 		usage(
 		    "[spec] Parameter(s) missing for fifo \"%s\".\n",
 		    argv[i]
 		);
 
-	char *n = argv[i++];
-	char *w = argv[i++];
-	char *t = argv[i++];
-
-	struct timespec in_last_read;
+	n = argv[i++];
+	w = argv[i++];
+	t = argv[i++];
 
 	if (!is_pos_num(w))
 		usage("[spec] Invalid width: \"%s\", for fifo \"%s\"\n", w, n);
 	if (!is_decimal(t))
 		usage("[spec] Invalid TTL: \"%s\", for fifo \"%s\"\n", t, n);
+
 	in_last_read.tv_sec  = 0;
 	in_last_read.tv_nsec = 0;
-	Slot *s = calloc(1, sizeof(struct Slot));
+	s = calloc(1, sizeof(struct Slot));
+
 	if (s) {
 		s->in_fifo      = n;
 		s->in_fd        = -1;
-		s->out_width     = atoi(w);
-		s->out_ttl       = khlib_timespec_of_float(atof(t));
+		s->out_width    = atoi(w);
+		s->out_ttl      = khlib_timespec_of_float(atof(t));
 		s->in_last_read = in_last_read;
-		s->out_pos_lo  = cfg->total_width;
+		s->out_pos_lo   = cfg->total_width;
 		s->out_pos_cur  = s->out_pos_lo;
-		s->out_pos_hi = s->out_pos_lo + s->out_width - 1;
-		s->next      = cfg->slots;
+		s->out_pos_hi   = s->out_pos_lo + s->out_width - 1;
+		s->next		= cfg->slots;
 
 		cfg->slots        = s;
 		cfg->total_width += s->out_width;
@@ -309,211 +545,7 @@ void
 opts_parse(Config *cfg, int argc, char *argv[])
 {
 	opts_parse_any(cfg, argc, argv, 1);
-
-	Slot *last = cfg->slots;
-	cfg->slots = NULL;
-	for (Slot *s = last; s; ) {
-		Slot *next = s->next;
-		s->next = cfg->slots;
-		cfg->slots = s;
-		s = next;
-	}
-}
-
-void
-slot_expire(Slot *s, struct timespec t, char *buf)
-{
-	struct timespec td;
-
-	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);
-		khlib_warn("Slot expired: \"%s\"\n", s->in_fifo);
-	}
-}
-
-void
-slot_read_error(Slot *s, char *buf)
-{
-	char *b;
-	int i;
-
-	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 slots: */
-	for (; i < s->out_width; i++)
-		b[i] = '_';
-}
-
-enum read_status
-slot_read_one(Slot *s, struct timespec t, char *buf)
-{
-	char c;  /* Character read. */
-	int  r;  /* Remaining unused slots in buffer range. */
-
-	for (;;) {
-		switch (read(s->in_fd, &c, 1)) {
-		case -1:
-			khlib_error(
-			    "Failed to read: \"%s\". errno: %d, msg: %s\n",
-			    s->in_fifo,
-			    errno,
-			    strerror(errno)
-			);
-			switch (errno) {
-			case EINTR:
-			case EAGAIN:
-				return RETRY;
-			default:
-				return FAILURE;
-			}
-		case  0:
-			khlib_debug("%s: End of FILE\n", s->in_fifo);
-			s->out_pos_cur = s->out_pos_lo;
-			return END_OF_FILE;
-		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;
-				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.
-				 */
-			}
-			break;
-		default:
-			assert(0);
-		}
-	}
-}
-
-void
-slot_read_all(Config *cfg, struct timespec *ti, char *buf)
-{
-	fd_set fds;
-	int maxfd = -1;
-	int ready = 0;
-	struct stat st;
-	struct timespec t;
-
-	FD_ZERO(&fds);
-	for (Slot *s = cfg->slots; s; s = s->next) {
-		/* TODO: Create the FIFO if it doesn't already exist. */
-		if (lstat(s->in_fifo, &st) < 0) {
-			khlib_error(
-			    "Cannot stat \"%s\". Error: %s\n",
-			    s->in_fifo,
-			    strerror(errno)
-			);
-			slot_read_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);
-			continue;
-		}
-		if (s->in_fd < 0) {
-			khlib_debug(
-			    "%s: closed. opening. in_fd: %d\n",
-			    s->in_fifo,
-			    s->in_fd
-			);
-			s->in_fd = open(s->in_fifo, O_RDONLY | O_NONBLOCK);
-		} else {
-			khlib_debug(
-			    "%s: already openned. in_fd: %d\n",
-			    s->in_fifo,
-			    s->in_fd
-			);
-		}
-		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);
-			continue;
-		}
-		khlib_debug("%s: open. in_fd: %d\n", s->in_fifo, s->in_fd);
-		if (s->in_fd > maxfd)
-			maxfd = s->in_fd;
-		FD_SET(s->in_fd, &fds);
-	}
-	khlib_debug("selecting...\n");
-	ready = pselect(maxfd + 1, &fds, NULL, NULL, ti, NULL);
-	khlib_debug("ready: %d\n", ready);
-	clock_gettime(CLOCK_MONOTONIC, &t);
-	if (ready == -1) {
-		switch (errno) {
-		case EINTR:
-			khlib_error(
-			    "pselect temp failure: %d, errno: %d, msg: %s\n",
-			    ready,
-			    errno,
-			    strerror(errno)
-			);
-			/* TODO: Reconsider what to do here. */
-			return;
-		default:
-			khlib_fatal(
-			    "pselect failed: %d, errno: %d, msg: %s\n",
-			    ready,
-			    errno,
-			    strerror(errno)
-			);
-		}
-	}
-	/* At-least-once ensures that expiries are still checked on timeouts. */
-	do {
-		for (Slot *s = cfg->slots; s; s = s->next) {
-			if (FD_ISSET(s->in_fd, &fds)) {
-				khlib_debug("reading: %s\n", s->in_fifo);
-				switch (slot_read_one(s, t, buf)) {
-				/*
-				 * ### MESSAGE LOSS ###
-				 * is introduced by closing at EOM in addition
-				 * to EOF, since there may be unread messages
-				 * remaining in the pipe. However,
-				 *
-				 * ### INTER-MESSAGE PUSHBACK ###
-				 * is also gained, since pipes block at the
-				 * "open" call.
-				 *
-				 * This is an acceptable trade-off because we
-				 * are a stateless reporter of a _most-recent_
-				 * status, not a stateful accumulator.
-				 */
-				case END_OF_MESSAGE:
-				case END_OF_FILE:
-				case FAILURE:
-					close(s->in_fd);
-					s->in_fd = -1;
-					ready--;
-					break;
-				case RETRY:
-					break;
-				default:
-					assert(0);
-				}
-			} else {
-				slot_expire(s, t, buf);
-			}
-		}
-	} while (ready);
-	assert(ready == 0);
+	cfg->slots = slots_rev(cfg->slots);
 }
 
 int
@@ -542,6 +574,7 @@ main(int argc, char *argv[])
 		ti,  /* time interval desired    (t1 - t0) */
 		td,  /* time interval measured   (t1 - t0) */
 		tc;  /* time interval correction (ti - td) when td < ti */
+	Slot *s;
 
 	argv0 = argv[0];
 
@@ -555,7 +588,7 @@ main(int argc, char *argv[])
 		usage("No slot specs were given!\n");
 
 	/* 1st pass to check file existence and type */
-	for (Slot *s = cfg.slots; s; s = s->next) {
+	for (s = cfg.slots; s; s = s->next) {
 		if (lstat(s->in_fifo, &st) < 0) {
 			khlib_error(
 			    "Cannot stat \"%s\". Error: %s\n",
@@ -580,7 +613,7 @@ main(int argc, char *argv[])
 	seplen = strlen(cfg.separator);
 
 	/* 2nd pass to make space for separators */
-	for (Slot *s = cfg.slots; s; s = s->next) {
+	for (s = cfg.slots; s; s = s->next) {
 		s->out_pos_lo  += prefix;
 		s->out_pos_hi += prefix;
 		s->out_pos_cur = s->out_pos_lo;
@@ -597,7 +630,7 @@ main(int argc, char *argv[])
 	memset(buf, ' ', width);
 	buf[width] = '\0';
 	/* 3rd pass to set the separators */
-	for (Slot *s = cfg.slots; s; s = s->next) {
+	for (s = cfg.slots; s; s = s->next) {
 		if (s->out_pos_lo) {  /* Skip the first, left-most */
 			/* Copying only seplen ensures we omit the '\0' byte. */
 			strncpy(
@@ -613,7 +646,7 @@ main(int argc, char *argv[])
 	/* TODO: Handle signals */
 	for (;;) {
 		clock_gettime(CLOCK_MONOTONIC, &t0); // FIXME: check errors
-		slot_read_all(&cfg, &ti, buf);
+		slots_read(&cfg, &ti, buf);
 		if (cfg.output_to_x_root_window) {
 			if (XStoreName(d, DefaultRootWindow(d), buf) < 0)
 				khlib_fatal("XStoreName failed.\n");
@@ -630,16 +663,13 @@ main(int argc, char *argv[])
 		    td.tv_nsec
 		);
 		if (timespeccmp(&td, &ti, <)) {
-			/* Pushback on data producers by refusing to read the
+			/*
+			 * Pushback on data producers by refusing to read the
 			 * pipe more frequently than the interval.
 			 */
 			timespecsub(&ti, &td, &tc);
-			khlib_debug("khlib_sleep YES\n");
 			khlib_sleep(&tc);
-		} else {
-			khlib_debug("khlib_sleep NO\n");
 		}
 	}
-
 	return EXIT_SUCCESS;
 }