Plugin lifecycle optimization

- Added term flow before plugin is killed
- Updated example implementations
- Added SIGINT to Zoraxy for shutdown sequence (Fixes #561 ?)

src/mod/plugins/lifecycle.go

@@ -4,12 +4,14 @@ import (
 	"encoding/json"
 	"errors"
 	"io"
+	"net/http"
 	"net/url"
-	"os"
 	"os/exec"
 	"path/filepath"
+	"runtime"
 	"strconv"
 	"strings"
+	"syscall"
 	"time"
 
 	"imuslab.com/zoraxy/mod/dynamicproxy/dpcore"
@@ -146,20 +148,55 @@ func (m *Manager) StopPlugin(pluginID string) error {
 	}
 
 	thisPlugin := plugin.(*Plugin)
-	thisPlugin.process.Process.Signal(os.Interrupt)
-	go func() {
-		//Wait for 10 seconds for the plugin to stop gracefully
-		time.Sleep(10 * time.Second)
+	var err error
+
+	//Make a GET request to plugin ui path /term to gracefully stop the plugin
+	if thisPlugin.uiProxy != nil {
+		requestURI := "http://127.0.0.1:" + strconv.Itoa(thisPlugin.AssignedPort) + "/" + thisPlugin.Spec.UIPath + "/term"
+		resp, err := http.Get(requestURI)
+		if err != nil {
+			//Plugin do not support termination request, do it the hard way
+			m.Log("Plugin "+thisPlugin.Spec.ID+" termination request failed. Force shutting down", nil)
+		} else {
+			defer resp.Body.Close()
+			if resp.StatusCode != http.StatusOK {
+				if resp.StatusCode == http.StatusNotFound {
+					m.Log("Plugin "+thisPlugin.Spec.ID+" does not support termination request", nil)
+				} else {
+					m.Log("Plugin "+thisPlugin.Spec.ID+" termination request returned status: "+resp.Status, nil)
+				}
+
+			}
+		}
+	}
+
+	if runtime.GOOS == "windows" && thisPlugin.process != nil {
+		//There is no SIGTERM in windows, kill the process directly
+		time.Sleep(300 * time.Millisecond)
+		thisPlugin.process.Process.Kill()
+	} else {
+		//Send SIGTERM to the plugin process, if it is still running
+		err = thisPlugin.process.Process.Signal(syscall.SIGTERM)
+		if err != nil {
+			m.Log("Failed to send Interrupt signal to plugin "+thisPlugin.Spec.Name+": "+err.Error(), nil)
+		}
+
+		//Wait for the plugin to stop
+		for range 5 {
+			time.Sleep(1 * time.Second)
+			if thisPlugin.process.ProcessState != nil && thisPlugin.process.ProcessState.Exited() {
+				m.Log("Plugin "+thisPlugin.Spec.Name+" background process stopped", nil)
+				break
+			}
+		}
 		if thisPlugin.process.ProcessState == nil || !thisPlugin.process.ProcessState.Exited() {
 			m.Log("Plugin "+thisPlugin.Spec.Name+" failed to stop gracefully, killing it", nil)
 			thisPlugin.process.Process.Kill()
-		} else {
-			m.Log("Plugin "+thisPlugin.Spec.Name+" background process stopped", nil)
 		}
+	}
 
-		//Remove the UI proxy
-		thisPlugin.uiProxy = nil
-	}()
+	//Remove the UI proxy
+	thisPlugin.uiProxy = nil
 	plugin.(*Plugin).Enabled = false
 	return nil
 }

src/mod/plugins/plugins.go

@@ -112,7 +112,7 @@ func (m *Manager) GetPluginPreviousEnableState(pluginID string) bool {
 
 // ListLoadedPlugins returns a list of loaded plugins
 func (m *Manager) ListLoadedPlugins() ([]*Plugin, error) {
-	var plugins []*Plugin
+	var plugins []*Plugin = []*Plugin{}
 	m.LoadedPlugins.Range(func(key, value interface{}) bool {
 		plugin := value.(*Plugin)
 		plugins = append(plugins, plugin)

src/mod/plugins/zoraxy_plugin/embed_webserver.go

@@ -6,6 +6,7 @@ import (
 	"io/fs"
 	"net/http"
 	"net/url"
+	"os"
 	"strings"
 	"time"
 )
@@ -15,6 +16,8 @@ type PluginUiRouter struct {
 	TargetFs       *embed.FS //The embed.FS where the UI files are stored
 	TargetFsPrefix string    //The prefix of the embed.FS where the UI files are stored, e.g. /web
 	HandlerPrefix  string    //The prefix of the handler used to route this router, e.g. /ui
+
+	terminateHandler func() //The handler to be called when the plugin is terminated
 }
 
 // NewPluginEmbedUIRouter creates a new PluginUiRouter with embed.FS
@@ -104,3 +107,22 @@ func (p *PluginUiRouter) Handler() http.Handler {
 		p.populateCSRFToken(r, http.FileServer(http.FS(subFS))).ServeHTTP(w, r)
 	})
 }
+
+// RegisterTerminateHandler registers the terminate handler for the PluginUiRouter
+// The terminate handler will be called when the plugin is terminated from Zoraxy plugin manager
+// if mux is nil, the handler will be registered to http.DefaultServeMux
+func (p *PluginUiRouter) RegisterTerminateHandler(termFunc func(), mux *http.ServeMux) {
+	p.terminateHandler = termFunc
+	if mux == nil {
+		mux = http.DefaultServeMux
+	}
+	mux.HandleFunc(p.HandlerPrefix+"/term", func(w http.ResponseWriter, r *http.Request) {
+		p.terminateHandler()
+		w.WriteHeader(http.StatusOK)
+		go func() {
+			//Make sure the response is sent before the plugin is terminated
+			time.Sleep(100 * time.Millisecond)
+			os.Exit(0)
+		}()
+	})
+}

src/mod/plugins/zoraxy_plugin/zoraxy_plugin.go

@@ -4,9 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
-	"os/signal"
 	"strings"
-	"syscall"
 )
 
 /*
@@ -174,25 +172,3 @@ func ServeAndRecvSpec(pluginSpect *IntroSpect) (*ConfigureSpec, error) {
 	ServeIntroSpect(pluginSpect)
 	return RecvConfigureSpec()
 }
-
-/*
-
-Shutdown handler
-
-This function will register a shutdown handler for the plugin
-The shutdown callback will be called when the plugin is shutting down
-You can use this to clean up resources like closing database connections
-*/
-
-func RegisterShutdownHandler(shutdownCallback func()) {
-	// Set up a channel to receive OS signals
-	sigChan := make(chan os.Signal, 1)
-	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
-
-	// Start a goroutine to listen for signals
-	go func() {
-		<-sigChan
-		shutdownCallback()
-		os.Exit(0)
-	}()
-}