Implement the data expiry check

diff --git a/x5/khatus.c b/x5/khatus.c
index 62b3774..e804642 100644 (file)
--- a/x5/khatus.c
+++ b/x5/khatus.c
@@ -31,8 +31,8 @@ struct Fifo {
        char   *name;
        int     fd;
        int     width;
-       int     last_read;
-       int     ttl;
+       struct timespec last_read;
+       struct timespec ttl;
        int     pos_init;  /* Initial position on the output buffer. */
        int     pos_curr;  /* Current position on the output buffer. */
        int     pos_final; /* Final   position on the output buffer. */
@@ -71,8 +71,8 @@ fifo_print_one(Fifo *f)
            " name = %s,"
            " fd = %d,"
            " width = %d,"
-           " last_read = %d,"
-           " ttl = %d,"
+           " last_read = {tv_sec = %ld, tv_nsec = %ld}"
+           " ttl = {tv_sec = %ld, tv_nsec = %ld},"
            " pos_init = %d,"
            " pos_curr = %d,"
            " pos_final = %d,"
@@ -81,8 +81,10 @@ fifo_print_one(Fifo *f)
            f->name,
            f->fd,
            f->width,
-           f->last_read,
-           f->ttl,
+           f->last_read.tv_sec,
+           f->last_read.tv_nsec,
+           f->ttl.tv_sec,
+           f->ttl.tv_nsec,
            f->pos_init,
            f->pos_curr,
            f->pos_final,
@@ -155,13 +157,13 @@ print_usage()
            "  SPEC       = FILE_PATH DATA_WIDTH DATA_TTL\n"
            "  FILE_PATH  = string\n"
            "  DATA_WIDTH = int  (* (positive) number of characters *)\n"
-           "  DATA_TTL   = int  (* (positive) number of seconds *)\n"
+           "  DATA_TTL   = float  (* (positive) number of seconds *)\n"
            "  OPTION     = -i INTERVAL\n"
            "             | -s SEPARATOR\n"
            "             | -x (* Output to X root window *)\n"
            "             | -l LOG_LEVEL\n"
            "  SEPARATOR  = string\n"
-           "  INTERVAL   = int  (* (positive) number of seconds *)\n"
+           "  INTERVAL   = float  (* (positive) number of seconds *)\n"
            "  LOG_LEVEL  = int  (* %d through %d *)\n"
            "\n",
            argv0,
@@ -255,17 +257,21 @@ parse_opts_spec(Config *cfg, int argc, char *argv[], int i)
        char *w = argv[i++];
        char *t = argv[i++];
 
+       struct timespec last_read;
+
        if (!is_pos_num(w))
                usage("[spec] Invalid width: \"%s\", for fifo \"%s\"\n", w, n);
-       if (!is_pos_num(t))
+       if (!is_decimal(t))
                usage("[spec] Invalid TTL: \"%s\", for fifo \"%s\"\n", t, n);
+       last_read.tv_sec  = 0;
+       last_read.tv_nsec = 0;
        Fifo *f = calloc(1, sizeof(struct Fifo));
        if (f) {
                f->name      = n;
                f->fd        = -1;
                f->width     = atoi(w);
-               f->ttl       = atoi(t);
-               f->last_read = 0;
+               f->ttl       = timespec_of_float(atof(t));
+               f->last_read = last_read;
                f->pos_init  = cfg->total_width;
                f->pos_curr  = f->pos_init;
                f->pos_final = f->pos_init + f->width - 1;
@@ -309,6 +315,28 @@ opts_parse(Config *cfg, int argc, char *argv[])
        }
 }
 
+void
+fifo_expire_one(Fifo *f, struct timespec t, char *buf)
+{
+       struct timespec td;
+
+       timespecsub(&t, &(f->last_read), &td);
+       if (timespeccmp(&td, &(f->ttl), >=)) {
+               /* TODO: Maybe configurable expiry character. */
+               memset(buf + f->pos_init, '_', f->pos_final - f->pos_init);
+               warn("Data source expired: \"%s\"\n", f->name);
+       }
+}
+
+void
+fifo_expire_all(Config *cfg, struct timespec t, char *buf)
+{
+       Fifo *f;
+
+       for (f = cfg->fifos; f; f = f->next)
+               fifo_expire_one(f, t, buf);
+}
+
 void
 fifo_read_error(Fifo *f, char *buf)
 {
@@ -326,7 +354,7 @@ fifo_read_error(Fifo *f, char *buf)
 }
 
 enum read_status
-fifo_read_one(Fifo *f, char *buf)
+fifo_read_one(Fifo *f, struct timespec t, char *buf)
 {
        char c;  /* Character read. */
        int  r;  /* Remaining unused slots in buffer range. */
@@ -354,6 +382,7 @@ fifo_read_one(Fifo *f, char *buf)
                                if (r > 0)
                                        memset(buf + f->pos_curr, ' ', r);
                                f->pos_curr = f->pos_init;
+                               f->last_read = t;
                                return END_OF_MESSAGE;
                        } else {
                                if (f->pos_curr <= f->pos_final)
@@ -365,11 +394,10 @@ fifo_read_one(Fifo *f, char *buf)
                        assert(0);
                }
        }
-       /* TODO Record timestamp read */
 }
 
 void
-fifo_read_all(Config *cfg, char *buf)
+fifo_read_all(Config *cfg, struct timespec t, char *buf)
 {
        fd_set fds;
        int maxfd = -1;
@@ -417,7 +445,7 @@ fifo_read_all(Config *cfg, char *buf)
                for (Fifo *f = cfg->fifos; f; f = f->next) {
                        if (FD_ISSET(f->fd, &fds)) {
                                debug("reading: %s\n", f->name);
-                               switch (fifo_read_one(f, buf)) {
+                               switch (fifo_read_one(f, t, buf)) {
                                /*
                                 * ### MESSAGE LOSS ###
                                 * is introduced by closing at EOM in addition
@@ -527,13 +555,11 @@ main(int argc, char *argv[])
        /* TODO: Handle signals */
        for (;;) {
                clock_gettime(CLOCK_MONOTONIC, &t0); // FIXME: check errors
-               /* TODO: Cache expiration. i.e. use the TTL */
-               /* TODO: How to trigger TTL check? On select? Alarm signal? */
                /* TODO: Set timeout on fifo_read_all based on diff of last time of
-                *       fifo_read_all and desired time of next TTL check.
+                *       fifo_read_all and desired time of next TTL check?
                 */
                /* TODO: How long to wait on IO? Max TTL? */
-               fifo_read_all(cfg, buf);
+               fifo_read_all(cfg, t0, buf);
                if (cfg->output_to_x_root_window) {
                        if (XStoreName(display, DefaultRootWindow(display), buf) < 0)
                                fatal("XStoreName failed.\n");
@@ -542,6 +568,14 @@ main(int argc, char *argv[])
                        puts(buf);
                        fflush(stdout);
                }
+
+               /*
+                * This is a good place for expiry check, since we're about to
+                * sleep anyway and the time taken by the check will be
+                * subtracted from the sleep period.
+                */
+               fifo_expire_all(cfg, t0, buf);
+
                clock_gettime(CLOCK_MONOTONIC, &t1); // FIXME: check errors
                timespecsub(&t1, &t0, &td);
                debug("td {tv_sec = %ld, tv_nsec = %ld}\n", td.tv_sec, td.tv_nsec);