Adding current project state

process.go

@@ -0,0 +1,116 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"sync"
+)
+
+type ProcessManager struct {
+	sync.RWMutex
+	ActiveInstances map[string]*exec.Cmd
+	StdinPipes      map[string]io.WriteCloser
+}
+
+func NewProcessManager() *ProcessManager {
+	return &ProcessManager{
+		ActiveInstances: make(map[string]*exec.Cmd),
+		StdinPipes:      make(map[string]io.WriteCloser),
+	}
+}
+
+func (pm *ProcessManager) StartInstance(name string, version string, options VsServerConfigOptions, config *AppConfig) error {
+	pm.Lock()
+	defer pm.Unlock()
+
+	if _, running := pm.ActiveInstances[name]; running {
+		return fmt.Errorf("Instance '%s' is already running", name)
+	}
+
+	binaryPath := filepath.Join(config.Storage.InstallDir, version, "VintagestoryServer")
+	instanceDataPath := filepath.Join(config.Storage.InstancesDir, name)
+
+	if _, err := os.Stat(binaryPath); os.IsNotExist(err) {
+		fmt.Printf("Server version '%s' not installed, attempting to install\n", version)
+		install_err := DownloadAndExtractServer(version, config.Storage.InstallDir)
+		if install_err != nil {
+			return fmt.Errorf("Could not locate or download a server binary for version '%s'", version)
+		}
+	}
+
+	cmd := exec.Command(binaryPath, "--dataPath", instanceDataPath)
+	cmd.Env = os.Environ()
+	cmd.Stderr = os.Stderr
+
+	stdinPipe, err := cmd.StdinPipe()
+	if err != nil {
+		return fmt.Errorf("Failed to open stdin pipe: %w", err)
+	}
+
+	stdoutPipe, err := cmd.StdoutPipe()
+	if err != nil {
+		stdinPipe.Close()
+		return fmt.Errorf("failed to open stdout conduit: %w", err)
+	}
+
+	if err := cmd.Start(); err != nil {
+		stdinPipe.Close()
+		stdoutPipe.Close()
+		return fmt.Errorf("Failed to start process thread: %w", err)
+	}
+
+	pm.ActiveInstances[name] = cmd
+	pm.StdinPipes[name] = stdinPipe
+
+	go pm.streamLogs(name, stdoutPipe)
+	go pm.watchProcessExit(name, cmd)
+
+	fmt.Printf("Server instance '%s' successfully spawned under PID %d\n", name, cmd.Process.Pid)
+	return nil
+}
+
+func (pm *ProcessManager) streamLogs(name string, stdout io.ReadCloser) {
+	defer stdout.Close()
+	scanner := bufio.NewScanner(stdout)
+
+	for scanner.Scan() {
+		//stream straight to the manager console terminal,
+		// but later dispatch payloads to our web UI or a log file
+		fmt.Printf("[%s]: %s\n", name, scanner.Text())
+	}
+}
+
+func (pm *ProcessManager) watchProcessExit(name string, cmd *exec.Cmd) {
+	_ = cmd.Wait()
+
+	pm.Lock()
+	defer pm.Unlock()
+
+	delete(pm.ActiveInstances, name)
+	if pipe, exists := pm.StdinPipes[name]; exists {
+		pipe.Close()
+		delete(pm.StdinPipes, name)
+	}
+	fmt.Printf("Server instance '%s' has shut down or terminated.\n", name)
+}
+
+func (pm *ProcessManager) SendCommand(name string, command string) error {
+	pm.RLock()
+	pipe, exists := pm.StdinPipes[name]
+	pm.RUnlock()
+
+	if !exists {
+		return fmt.Errorf("Cannot send command, instance with name '%s' is not running", name)
+	}
+
+	_, err := io.WriteString(pipe, command+"\n")
+	if err != nil {
+		return fmt.Errorf("failed writing to server process stdin conduit: %w", err)
+	}
+
+	return nil
+}