refactor zen command return value handling (#487)

- Improvement: Use consistent language for command line argument parsing errors
- Improvement: Changed zen command parsing errors to output help first and error last to make it easier to spot the error
- Improvement: Refactor zen command return codes to conform to valid Linux range (0-255)

        kSuccess     = 0,
        kOtherError  = 1,
        kBadInput    = 2,

        kOutOfMemory = 16,
        kOutOfDisk   = 17,

        kAssertError = 70,
        
        kHttpOtherClientError = 80,
        kHttpCantConnectError = 81,
        kHttpNotFound         = 66,  // NotFound(404)
        kHttpUnauthorized     = 77,  // Unauthorized(401),
        kHttpSLLError         = 82,
        kHttpForbidden        = 83,  // Forbidden(403)
        kHttpTimeout          = 84,  // RequestTimeout(408)
        kHttpConflict         = 85,  // Conflict(409)
        kHttpNoHost           = 86,
        
        kHttpOtherServerError	   = 90,
        kHttpInternalServerError = 91,  // InternalServerError(500)
        kHttpServiceUnavailable  = 69,  // ServiceUnavailable(503)
        kHttpBadGateway          = 92,  // BadGateway(502)
        kHttpGatewayTimeout      = 93,  // GatewayTimeout(504)

1 files changed, 4 insertions, 8 deletions

diff --git a/src/zen/cmds/top_cmd.cpp b/src/zen/cmds/top_cmd.cpp
index 9794dc1c0..0e44dbbec 100644
--- a/src/zen/cmds/top_cmd.cpp
+++ b/src/zen/cmds/top_cmd.cpp
@@ -19,7 +19,7 @@ TopCommand::TopCommand()
 
 TopCommand::~TopCommand() = default;
 
-int
+void
 TopCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 {
 	ZEN_UNUSED(GlobalOptions, argc, argv);
@@ -29,7 +29,7 @@ TopCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 	{
 		ZEN_CONSOLE("No Zen state found");
 
-		return 0;
+		return;
 	}
 
 	int		  n			   = 0;
@@ -55,8 +55,6 @@ TopCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 			State.Sweep();
 		}
 	}
-
-	return 0;
 }
 
 //////////////////////////////////////////////////////////////////////////
@@ -67,7 +65,7 @@ PsCommand::PsCommand()
 
 PsCommand::~PsCommand() = default;
 
-int
+void
 PsCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 {
 	ZEN_UNUSED(GlobalOptions, argc, argv);
@@ -77,14 +75,12 @@ PsCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 	{
 		ZEN_CONSOLE("No Zen state found");
 
-		return 0;
+		return;
 	}
 
 	State.Snapshot([&](const ZenServerState::ZenServerEntry& Entry) {
 		ZEN_CONSOLE("Port {} : pid {}", Entry.EffectiveListenPort.load(), Entry.Pid.load());
 	});
-
-	return 0;
 }
 
 }  // namespace zen