Documentation changes.

client/thimble.cc

+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static void spawn_stern_thread(pthread_t *t);
+static int act_goofy(void);
+static void *be_stern(void *);
+
+static struct {
+  pthread_mutex_t lock;
+  pthread_cond_t  cond;
+  int msg;
+} comm = { PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER, 0 };
+
+int
+main(void)
+{
+  pthread_t t;
+  spawn_stern_thread(&t);
+
+  while (act_goofy() != 0)
+    /* do nothing */;
+
+  pthread_exit(NULL);
+
+  /* notreached */
+  return EXIT_SUCCESS;
+}
+
+static void spawn_stern_thread(pthread_t *t)
+{
+  pthread_attr_t attr;
+
+  pthread_attr_init(&attr);
+  pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+
+  if (pthread_create(t, &attr, be_stern, NULL) != 0)
+    exit(EXIT_FAILURE);
+
+  pthread_attr_destroy(&attr);
+}
+
+static int act_goofy(void)
+{
+  int  ret;
+  char buf[30];
+
+  fputs("Are you ready to act goofy (Y/n)? ", stdout); fflush(stdout);
+  fgets(buf, sizeof(buf), stdin);
+  pthread_mutex_lock(&comm.lock);
+  if (buf[0] == 'y' || buf[0] == '\n') {
+    fputs("** Waawlwalkwwwaa!!\n", stdout); fflush(stdout);
+    ++comm.msg;
+    ret = 1;
+  }
+  else {
+    fputs("OK, I hate you.  Let me go.\n", stdout); fflush(stdout);
+    comm.msg = -1;
+    ret = 0;
+  }
+  pthread_mutex_unlock(&comm.lock);
+  pthread_cond_signal(&comm.cond);
+
+  return ret;
+}
+
+static void *be_stern(void *v __attribute((unused)))
+{
+  int msg;
+  for (;;) {
+    pthread_mutex_lock(&comm.lock);
+    while (comm.msg == 0)
+      pthread_cond_wait(&comm.cond, &comm.lock);
+    msg = comm.msg;
+    comm.msg = 0;
+    pthread_mutex_unlock(&comm.lock);
+
+    if (msg < 0)
+      break;  /* the goofy one learned a lesson! */
+
+    fputs("I HAVE TO BE STERN WITH YOU!\n", stderr);
+    fprintf(stderr, "I should give you %d lashes.\n", msg);
+    sleep(msg);
+  }
+
+  fputs("You are NOTHING!\n", stderr);
+  return NULL;
+}