Update service and syslog code to use variable instead of constant

for the process name and service name. This allows the reuse of this
code in NATS Streaming Server by invoking the new setters to
change the service and process names.

Signed-off-by: Ivan Kozlovic <ivan@synadia.com>

server/const.go

@@ -35,7 +35,7 @@ var (
 
 const (
 	// VERSION is the current version for the server.
-	VERSION = "1.2.0"
+	VERSION = "1.3.0"
 
 	// PROTO is the currently supported protocol.
 	// 0 was the original

server/service_windows.go

@@ -22,12 +22,18 @@ import (
 )
 
 const (
-	serviceName     = "gnatsd"
 	reopenLogCode   = 128
 	reopenLogCmd    = svc.Cmd(reopenLogCode)
 	acceptReopenLog = svc.Accepted(reopenLogCode)
 )
 
+var serviceName = "gnatsd"
+
+// SetServiceName allows setting a different service name
+func SetServiceName(name string) {
+	serviceName = name
+}
+
 // winServiceWrapper implements the svc.Handler interface for implementing
 // gnatsd as a Windows service.
 type winServiceWrapper struct {

server/signal.go

@@ -26,7 +26,12 @@ import (
 	"syscall"
 )
 
-const processName = "gnatsd"
+var processName = "gnatsd"
+
+// SetProcessName allows to change the expected name of the process.
+func SetProcessName(name string) {
+	processName = name
+}
 
 // Signal Handling
 func (s *Server) handleSignals() {
@@ -76,10 +81,10 @@ func ProcessSignal(command Command, pidStr string) error {
 			return err
 		}
 		if len(pids) == 0 {
-			return errors.New("no gnatsd processes running")
+			return fmt.Errorf("no %s processes running", processName)
 		}
 		if len(pids) > 1 {
-			errStr := "multiple gnatsd processes running:\n"
+			errStr := fmt.Sprintf("multiple %s processes running:\n", processName)
 			prefix := ""
 			for _, p := range pids {
 				errStr += fmt.Sprintf("%s%d", prefix, p)