tcm: add tt tcm stop command

@TarantoolBot document
Title: add the tt tcm stop command.

Add command tt tcm stop to gracefully terminate TCM:
- Works in both modes(watchdog and interactive)
- Stops all subprocesses

Closes #TNTP-1993

Author: AlexandrLitkevich

CHANGELOG.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - `tt tcm start` OR `tt tcm start --path /path/to/tcm`: added the capability to run TCM in interactive mode.
 - `tt tcm start --watchdog`: implemented Watchdog mode for automatic restarting of TCM upon unexpected termination.
 - `tt tcm status`: added command to check TCM runtime status (modes: `watchdog` or `interactive`).
+- `tt tcm stop`: add command for graceful termination of TCM processes (modes: `watchdog` or `interactive`).
 
 ### Changed
 

cli/cmd/tcm.go

@@ -13,10 +13,8 @@ import (
 	"github.com/jedib0t/go-pretty/v6/text"
 	"github.com/spf13/cobra"
 	"github.com/tarantool/tt/cli/cmdcontext"
-	"github.com/tarantool/tt/cli/modules"
 	"github.com/tarantool/tt/cli/process_utils"
 	tcmCmd "github.com/tarantool/tt/cli/tcm"
-	"github.com/tarantool/tt/cli/util"
 	libwatchdog "github.com/tarantool/tt/lib/watchdog"
 )
 
@@ -34,11 +32,7 @@ func newTcmStartCmd() *cobra.Command {
 		Long: `Start to the tcm.
 		tt tcm start --watchdog
 		tt tcm start --path`,
-		Run: func(cmd *cobra.Command, args []string) {
-			cmdCtx.CommandName = cmd.Name()
-			err := modules.RunCmd(&cmdCtx, cmd.CommandPath(), &modulesInfo, internalStartTcm, args)
-			util.HandleCmdErr(cmd, err)
-		},
+		Run: RunModuleFunc(internalStartTcm),
 	}
 	tcmCmd.Flags().StringVar(&tcmCtx.Executable, "path", "", "the path to the tcm binary file")
 	tcmCmd.Flags().BoolVar(&tcmCtx.Watchdog, "watchdog", false, "enables the watchdog")
@@ -52,11 +46,7 @@ func newTcmStatusCmd() *cobra.Command {
 		Short: "Status tcm application",
 		Long: `Status to the tcm.
 		tt tcm status`,
-		Run: func(cmd *cobra.Command, args []string) {
-			cmdCtx.CommandName = cmd.Name()
-			err := modules.RunCmd(&cmdCtx, cmd.CommandPath(), &modulesInfo, internalTcmStatus, args)
-			util.HandleCmdErr(cmd, err)
-		},
+		Run: RunModuleFunc(internalTcmStatus),
 	}
 	return tcmCmd
 }
@@ -66,11 +56,7 @@ func newTcmStopCmd() *cobra.Command {
 		Use:   "stop",
 		Short: "Stop tcm application",
 		Long:  `Stop to the tcm. tt tcm stop`,
-		Run: func(cmd *cobra.Command, args []string) {
-			cmdCtx.CommandName = cmd.Name()
-			err := modules.RunCmd(&cmdCtx, cmd.CommandPath(), &modulesInfo, internalTcmStop, args)
-			util.HandleCmdErr(cmd, err)
-		},
+		Run:   RunModuleFunc(internalTcmStop),
 	}
 	return tcmCmd
 }
@@ -178,13 +164,13 @@ func internalTcmStop(cmdCtx *cmdcontext.CmdCtx, args []string) error {
 		if err != nil {
 			return err
 		}
-		log.Println("Watchdog and TCM stoped")
+		log.Println("Watchdog and TCM stopped")
 	} else {
 		_, err := process_utils.StopProcess(tcmPidFile)
 		if err != nil {
 			return err
 		}
-		log.Println("TCM stoped")
+		log.Println("TCM stopped")
 	}
 
 	return nil

cli/process_utils/process_utils.go

@@ -118,8 +118,8 @@ func ExistsAndRecord(pidFileName string) (bool, error) {
 			return true, nil
 		}
 	} else if !os.IsNotExist(err) {
-		return false, fmt.Errorf(`something went wrong while trying to read the PID file. Error: "%v"`,
-			err)
+		return false, fmt.Errorf(`something went wrong while trying to read the`+
+			`PID file. Error: "%v"`, err)
 	}
 
 	return false, nil

cli/tcm/tcm.go

@@ -1,9 +1,13 @@
 package tcm
 
+// TcmCtx holds parameters and state for managing the TCM process and its watchdog.
 type TcmCtx struct {
+	// Path to the TCM executable file.
 	Executable string
+	// Path to the file storing the TCM process PID.
 	TcmPidFile string
-
-	Watchdog       bool
+	// Flag indicating whether the watchdog is enabled.
+	Watchdog bool
+	// Path to the file storing the watchdog process PID.
 	WathdogPidFile string
 }

cli/tcm/watchdog.go

@@ -16,17 +16,27 @@ import (
 )
 
 type Watchdog struct {
-	cmd            *exec.Cmd
+	// Command for launching and managing the child process.
+	cmd *exec.Cmd
+	// Timeout before restarting a failed process.
 	restartTimeout time.Duration
-	shouldStop     atomic.Bool
-	doneBarrier    sync.WaitGroup
-	pidFile        string
-	wdPidFile      string
-
-	cmdMutex        sync.Mutex
-	pidFileMutex    sync.Mutex
-	signalChan      chan os.Signal
+	// Atomic flag for graceful shutdown.
+	shouldStop atomic.Bool
+	// Waits for all watchdog goroutines to complete.
+	doneBarrier sync.WaitGroup
+	// File to store the child process PID.
+	pidFile string
+	// File to store the watchdog's own PID.
+	wdPidFile string
+	// Protects access to cmd (concurrent Start/Stop operations).
+	cmdMutex sync.Mutex
+	// Protects PID file read/write operations.
+	pidFileMutex sync.Mutex
+	// Channel for receiving system signals (SIGTERM etc.).
+	signalChan chan os.Signal
+	// Process Group ID (PGID) for proper process termination.
 	processGroupPID atomic.Int32
+	// Closed when process successfully starts (synchronization).
 	startupComplete chan struct{}
 }