cookbook: allow for setting --delay duration

The CockroachDB test suite currently makes use of charybdefs-nemesis to
induce artificial delays into the filesystem to simulate disk stalls.
Currently, the delay duration is fixed at 50ms. This precludes testing
of faults that last indefinitely.

Change the format of the `--delay` command to take a duration, in
microseconds, allowing for faults of a longer duration.

cookbook/recipes

@@ -4,4 +4,4 @@ if [ ! -d gen-py ]; then
     thrift -r --gen py ../server.thrift &> /dev/null
 fi
 
-python2 recipes.py $1
+python2 recipes.py "$@"

cookbook/recipes.py

@@ -17,7 +17,7 @@ def usage():
           " --full\n"
           " --io-error\n"
           " --quota\n"
-          " --delay\n"
+          " --delay DELAY_MICROS\n"
           " --random\n"
           " --specific-syscalls\n"
           " --probability\n"
@@ -57,7 +57,7 @@ def main():
         client.set_all_fault(False, [errno.EDQUOT], 0, "", False, 0, False)
     elif sys.argv[1] == "--delay":
         print("Simulating delayed IO")
-        client.set_all_fault(False, [], 0, "", False, 50000, False)
+        client.set_all_fault(False, [], 0, "", False, sys.argv[2], False)
     elif sys.argv[1] == "--random":
         # Use all errnos, minus any specified in trailing arguments.
         errnos_selected = {code: name for code, name in