fix the discrepant usage description (#1176)

The correct command is
nighthark-client --failure-predicate benchmark.http_4xx10:10 instead of benchmark.http_4xx,10


Signed-off-by: Zhang Bo <bozhang@ebay.com>

README.md

@@ -173,8 +173,8 @@ bazel-bin/nighthawk_client  [--user-defined-plugin-config <string>] ...
 [--jitter-uniform <duration>] [--open-loop]
 [--experimental-h1-connection-reuse-strategy
 <mru|lru>] [--no-default-failure-predicates]
-[--failure-predicate <string, uint64_t>] ...
-[--termination-predicate <string, uint64_t>]
+[--failure-predicate <string:uint64_t>] ...
+[--termination-predicate <string:uint64_t>]
 ... [--trace <uri format>]
 [--sequencer-idle-strategy <spin|poll
 |sleep>] [--max-concurrent-streams
@@ -305,12 +305,12 @@ Disables the default failure predicates, indicating that Nighthawk
 should continue sending load after observing error status codes and
 connection errors.
 
---failure-predicate <string, uint64_t>  (accepted multiple times)
+--failure-predicate <string:uint64_t>  (accepted multiple times)
 Failure predicate. Allows specifying a counter name plus threshold
 value for failing execution. Defaults to not tolerating error status
 codes and connection errors. Example: benchmark.http_5xx:4294967295.
 
---termination-predicate <string, uint64_t>  (accepted multiple times)
+--termination-predicate <string:uint64_t>  (accepted multiple times)
 Termination predicate. Allows specifying a counter name plus threshold
 value for terminating execution.
 

source/client/options_impl.cc

@@ -229,13 +229,13 @@ OptionsImpl::OptionsImpl(int argc, const char* const* argv) {
       "", "termination-predicate",
       "Termination predicate. Allows specifying a counter name plus threshold value for "
       "terminating execution.",
-      false, "string, uint64_t", cmd);
+      false, "string:uint64_t", cmd);
   TCLAP::MultiArg<std::string> failure_predicates(
       "", "failure-predicate",
       "Failure predicate. Allows specifying a counter name plus threshold value for "
       "failing execution. Defaults to not tolerating error status codes and connection errors. "
       "Example: benchmark.http_5xx:4294967295.",
-      false, "string, uint64_t", cmd);
+      false, "string:uint64_t", cmd);
   TCLAP::SwitchArg no_default_failure_predicates(
       "", "no-default-failure-predicates",
       "Disables the default failure predicates, indicating that Nighthawk should continue sending "