add example illustrating sleep functionality

examples/Makefile.subdir

-bin_PROGRAMS += examples/client examples/server examples/server-hang examples/client-timeout
+bin_PROGRAMS += examples/client examples/server examples/server-hang examples/client-timeout examples/sleep
 
 examples_server_SOURCES = \
  examples/server.c \

examples/sleep.c

@@ -7,11 +7,14 @@
 #include <stdio.h>
 #include <assert.h>
 #include <unistd.h>
+#include <stdlib.h>
+#include <ctype.h>
 #include <abt.h>
 #include <abt-snoozer.h>
 #include <margo.h>
 
-static int use_abt_sleep;
+static int use_abt_sleep = 0;
+static int sleep_seconds = 2;
 
 static void sleep_fn(void *arg);
 
@@ -27,20 +30,27 @@ int main(int argc, char **argv)
     hg_context_t *hg_context;
     hg_class_t *hg_class;
 
-    if(argc == 1)
+    int arg_ndx = 1;
+    if(argc > 1)
     {
-        use_abt_sleep = 0;
+        if(isdigit(argv[1][0]))
+        {
+            sleep_seconds = atoi(argv[1]);
+            arg_ndx++;
         }
-    else if((argc == 2) && (strcmp(argv[1], "ABT") == 0))
+        if((arg_ndx < argc) && (strcmp(argv[arg_ndx], "ABT") == 0))
         {
             use_abt_sleep = 1;
+            arg_ndx++;
         }
-    else
+        if(arg_ndx != argc)
         {
-        fprintf(stderr, "Usage: %s [ABT]\n", argv[0]);
+            fprintf(stderr, "Usage: %s [sleep_seconds] [ABT]\n", argv[0]);
+            fprintf(stderr, "\tsleep_seconds: number of seconds for each thread to sleep.\n");
             fprintf(stderr, "\tABT: use ABT sleep mechanism, rather than POSIX sleep.\n");
             return(-1);
         }
+    }
 
     /* boilerplate HG initialization steps */
     /***************************************/
@@ -90,11 +100,8 @@ int main(int argc, char **argv)
     }
 
     /* actually start margo */
-    /* provide argobots pools for driving communication progress and
-     * executing rpc handlers as well as class and context for Mercury
-     * communication.  The rpc handler pool is null in this example program
-     * because this is a pure client that will not be servicing rpc requests.
-     */
+    /* use a single pool for progress and sleeper threads */
+    /* NOTE: no rpc handler threads are needed */
     /***************************************/
     mid = margo_init(pool, ABT_POOL_NULL, hg_context, hg_class);
     for(i=0; i<4; i++)
@@ -147,9 +154,9 @@ static void sleep_fn(void *arg)
     int my_tid = *(int *)arg;
 
     if(use_abt_sleep)
-        margo_thread_sleep(2*1000.0);
+        margo_thread_sleep(sleep_seconds*1000.0);
     else
-        sleep(2);
+        sleep(sleep_seconds);
 
     printf("TID: %d sleep end\n", my_tid);