servctrl: added StopServerAllowKill

if StopServerAllowKill is more than 0, then the specified number is the amount of seconds given to the minecraft server to go offline, after which it is killed

README.md

@@ -42,6 +42,7 @@ How to use:
     - FileName
     - StartServer
     - StopServer
+    - \* StopServerAllowKill
     - \* HibernationInfo and StartingInfo
     - \* TimeBeforeStoppingEmptyServer
     - \* CheckForUpdates
@@ -69,10 +70,12 @@ Location of server folder and executable:
 Commands to start and stop minecraft server:
 ```yaml
 "Commands":{
-  "StartServer": "java {-Xmx1024M} {-Xms1024M} -jar serverFileName nogui",
-  "StopServer": "{stop}"
+    "StartServer": "java {-Xmx1024M} {-Xms1024M} -jar serverFileName nogui",
+    "StopServer": "{stop}",
+    "StopServerAllowKill": 10
 }
-
+# if StopServerAllowKill is more than 0, then the specified number is the amount of seconds
+# given to the minecraft server to go offline, after which it is killed
 ```
 Hibernation and warming up server description
 ```yaml

config.json

@@ -7,7 +7,8 @@
   },
   "Commands":{
     "StartServer": "java {-Xmx1024M} {-Xms1024M} -jar serverFileName nogui",
-    "StopServer": "{stop}"
+    "StopServer": "{stop}",
+    "StopServerAllowKill": 10
   },
   "Msh":{
     "Port": "25555",

info.txt

@@ -3,6 +3,7 @@
         - functions containing "[goroutine]" in their comment are meant to be launched as goroutine
         - functions containing "[goroutine]" in their comment will return without any parameter
         - functions containing "[blocking]" in their comment should not be launched as goroutine
+        - functions containing "[non-blocking]" in their comment execute commands in a non-blocking manner
     + error management
         - every function should return the error parameter
             exception for: 

lib/confctrl/confctrl.go

@@ -29,8 +29,9 @@ type configuration struct {
 		Version  string `json:"Version"`
 	} `json:"Server"`
 	Commands struct {
-		StartServer string `json:"StartServer"`
-		StopServer  string `json:"StopServer"`
+		StartServer           string `json:"StartServer"`
+		StopServer            string `json:"StopServer"`
+		StopServerAllowSIGINT int    `json:"StopServerAllowSIGINT"`
 	} `json:"Commands"`
 	Msh struct {
 		CheckForUpdates               bool   `json:"CheckForUpdates"`

lib/servctrl/cmd.go

@@ -60,6 +60,7 @@ func CmdStart(dir, command string) error {
 }
 
 // Execute executes a command on the specified term
+// [non-blocking]
 func (term *ServTerm) Execute(command, origin string) (string, error) {
 	if !term.IsActive {
 		return "", fmt.Errorf("Execute: terminal not active")

lib/servctrl/servctrl.go

@@ -64,20 +64,27 @@ func StopMinecraftServer(playersCheck bool) error {
 		return fmt.Errorf("stopEmptyMinecraftServer: error executing minecraft server stop command: %v", errExec)
 	}
 
+	// if sigint is allowed, launch a function to check the shutdown of minecraft server
+	if confctrl.Config.Commands.StopServerAllowSIGINT > 0 {
+		go sigintMinecraftServerIfOnlineAfterTimeout()
+	}
+
+	// if a player check was not executed and the server is stopping make this function blocking until server is down
 	if !playersCheck {
 		if ServStats.Status == "stopping" {
-			// wait for the terminal to exit
+			// wait for the terminal to exit then return
 			debugctrl.Logln("waiting for server terminal to exit")
 			ServTerminal.Wg.Wait()
 		} else {
-			debugctrl.Logln("server was not stopped by stop command, world save might be compromised")
+			return fmt.Errorf("stopEmptyMinecraftServer: stop command does not seem to be stopping server (no playersCheck)")
 		}
 	}
 
 	return nil
 }
 
 // RequestStopMinecraftServer increases stopInstances by one and starts the timer to execute stopEmptyMinecraftServer(false)
+// [goroutine]
 func RequestStopMinecraftServer() {
 	asyncctrl.WithLock(func() { ServStats.StopInstances++ })
 
@@ -93,3 +100,32 @@ func RequestStopMinecraftServer() {
 		}
 	})
 }
+
+// sigintMinecraftServerIfOnlineAfterTimeout waits for the specified time and then if the server is still online sends SIGINT to the process
+func sigintMinecraftServerIfOnlineAfterTimeout() {
+	countdown := confctrl.Config.Commands.StopServerAllowSIGINT
+
+	for countdown > 0 {
+		// if server goes offline it's the correct behaviour -> return
+		if ServStats.Status == "offline" {
+			return
+		}
+
+		countdown--
+		time.Sleep(time.Second)
+	}
+
+	// save world before killing the server, do not check for errors
+	debugctrl.Logln("saving word before killing the minecraft server process")
+	_, _ = ServTerminal.Execute("/save-all", "sigintMinecraftServerIfOnlineAfterTimeout")
+
+	// give time to save word
+	time.Sleep(time.Duration(10) * time.Second)
+
+	// send kill signal to server
+	debugctrl.Logln("send kill signal to minecraft server process since it won't stop normally")
+	err := ServTerminal.cmd.Process.Kill()
+	if err != nil {
+		debugctrl.Logln("sigintMinecraftServerIfOnlineAfterTimeout: %v", err)
+	}
+}