tdb: test and resolultion for tdb_lockall starvation.

[ccan] / ccan / tdb / tools / starvation.c

diff --git a/ccan/tdb/tools/starvation.c b/ccan/tdb/tools/starvation.c
new file mode 100644 (file)
index 0000000..5f8c23d
--- /dev/null
+++ b/ccan/tdb/tools/starvation.c
@@ -0,0 +1,138 @@
+/* Demonstrate starvation of tdb_lockall */
+#include <ccan/tdb/tdb.h>
+#include <err.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <time.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/time.h>
+
+static void usage(const char *extra)
+{
+       errx(1, "%s%s"
+            "Usage: starvation [lockall|gradual] <num> <worktime-in-ms>\n"
+            "  Each locker holds lock for between 1/2 and 1 1/2 times\n"
+            "  worktime, then sleeps for one second.\n\n"
+            "  Main process tries tdb_lockall or tdb_lockall_gradual.",
+            extra ? extra : "", extra ? "\n" : "");
+}
+
+static void run_and_sleep(struct tdb_context *tdb, int parentfd, unsigned time)
+{
+       char c;
+       struct timespec hold;
+       unsigned rand, randtime;
+       TDB_DATA key;
+
+       key.dptr = (void *)&rand;
+       key.dsize = sizeof(rand);
+
+       while (read(parentfd, &c, 1) != 0) {
+               /* Lock a random key. */
+               rand = random();
+               if (tdb_chainlock(tdb, key) != 0)
+                       errx(1, "chainlock failed: %s", tdb_errorstr(tdb));
+
+               /* Hold it for some variable time. */
+               randtime = time / 2 + (random() % time);
+               hold.tv_sec = randtime / 1000;
+               hold.tv_nsec = (randtime % 1000) * 1000000;
+               nanosleep(&hold, NULL);
+
+               if (tdb_chainunlock(tdb, key) != 0)
+                       errx(1, "chainunlock failed: %s", tdb_errorstr(tdb));
+
+               /* Wait for a second without the lock. */
+               sleep(1);
+       }
+       exit(0);
+}
+
+static void logfn(struct tdb_context *tdb,
+                 enum tdb_debug_level level,
+                 const char *fmt, ...)
+{
+           va_list ap;
+
+           va_start(ap, fmt);
+          vfprintf(stderr, fmt, ap);
+          va_end(ap);
+}
+
+int main(int argc, char *argv[])
+{
+       int (*lockall)(struct tdb_context *);
+       unsigned int num, worktime, i;
+       int pfd[2];
+       struct tdb_context *tdb;
+       struct tdb_logging_context log = { logfn, NULL };
+       struct timeval start, end, duration;
+
+       if (argc != 4)
+               usage(NULL);
+
+       if (strcmp(argv[1], "lockall") == 0)
+               lockall = tdb_lockall;
+       else if (strcmp(argv[1], "gradual") == 0)
+               lockall = tdb_lockall_gradual;
+       else
+               usage("Arg1 should be 'lockall' or 'gradual'");
+
+       num = atoi(argv[2]);
+       worktime = atoi(argv[3]);
+
+       if (!num || !worktime)
+               usage("Number of threads and worktime must be non-zero");
+
+       if (pipe(pfd) != 0)
+               err(1, "Creating pipe");
+
+       tdb = tdb_open_ex("/tmp/starvation.tdb", 10000, TDB_DEFAULT,
+                         O_RDWR|O_CREAT|O_TRUNC, 0600, &log, NULL);
+       if (!tdb)
+               err(1, "Opening tdb /tmp/starvation.tdb");
+
+       for (i = 0; i < num; i++) {
+               switch (fork()) {
+               case 0:
+                       close(pfd[1]);
+                       fcntl(pfd[0], F_SETFL,
+                             fcntl(pfd[0], F_GETFL)|O_NONBLOCK);
+                       srandom(getpid() + i);
+                       if (tdb_reopen(tdb) != 0)
+                               err(1, "Reopening tdb %s", tdb_name(tdb));
+
+                       run_and_sleep(tdb, pfd[0], worktime);
+               case -1:
+                       err(1, "forking");
+               }
+               /* Stagger the children. */
+               usleep(random() % (1000000 / num));
+       }
+
+       close(pfd[0]);
+       sleep(1);
+       gettimeofday(&start, NULL);
+       if (lockall(tdb) != 0)
+               errx(1, "lockall failed: %s", tdb_errorstr(tdb));
+       gettimeofday(&end, NULL);
+
+       duration.tv_sec = end.tv_sec - start.tv_sec;
+       duration.tv_usec = end.tv_usec - start.tv_usec;
+       if (duration.tv_usec < 0) {
+               --duration.tv_sec;
+               duration.tv_usec += 1000000;
+       }
+
+       if (tdb_unlockall(tdb) != 0)
+               errx(1, "unlockall failed: %s", tdb_errorstr(tdb));
+       tdb_close(tdb);
+       unlink("/tmp/starvation.tdb");
+
+       printf("Took %lu.%06lu seconds\n", duration.tv_sec, duration.tv_usec);
+       return 0;
+}