Add subsystems package and make modules able to be turned off and on

modules/start.go

@@ -1,34 +1,38 @@
 package modules
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"runtime"
-	"time"
+
+	"github.com/tevino/abool"
 
 	"github.com/safing/portbase/log"
-	"github.com/tevino/abool"
 )
 
 var (
-	startComplete       = abool.NewBool(false)
-	startCompleteSignal = make(chan struct{})
+	initialStartCompleted = abool.NewBool(false)
+	globalPrepFn          func() error
 )
 
-// StartCompleted returns whether starting has completed.
-func StartCompleted() bool {
-	return startComplete.IsSet()
-}
-
-// WaitForStartCompletion returns as soon as starting has completed.
-func WaitForStartCompletion() <-chan struct{} {
-	return startCompleteSignal
+// SetGlobalPrepFn sets a global prep function that is run before all modules. This can be used to pre-initialize modules, such as setting the data root or database path.
+// SetGlobalPrepFn sets a global prep function that is run before all modules.
+func SetGlobalPrepFn(fn func() error) {
+	if globalPrepFn == nil {
+		globalPrepFn = fn
+	}
 }
 
 // Start starts all modules in the correct order. In case of an error, it will automatically shutdown again.
 func Start() error {
-	modulesLock.RLock()
-	defer modulesLock.RUnlock()
+	if !modulesLocked.SetToIf(false, true) {
+		return errors.New("module system already started")
+	}
+
+	// lock mgmt
+	mgmtLock.Lock()
+	defer mgmtLock.Unlock()
 
 	// start microtask scheduler
 	go microTaskScheduler()
@@ -48,6 +52,17 @@ func Start() error {
 		return err
 	}
 
+	// execute global prep fn
+	if globalPrepFn != nil {
+		err = globalPrepFn()
+		if err != nil {
+			if err != ErrCleanExit {
+				fmt.Fprintf(os.Stderr, "CRITICAL ERROR: %s\n", err)
+			}
+			return err
+		}
+	}
+
 	// prep modules
 	err = prepareModules()
 	if err != nil {
@@ -65,6 +80,9 @@ func Start() error {
 		return err
 	}
 
+	// build dependency tree
+	buildEnabledTree()
+
 	// start modules
 	log.Info("modules: initiating...")
 	err = startModules()
@@ -75,13 +93,11 @@ func Start() error {
 
 	// complete startup
 	log.Infof("modules: started %d modules", len(modules))
-	if startComplete.SetToIf(false, true) {
-		close(startCompleteSignal)
-	}
 
 	go taskQueueHandler()
 	go taskScheduleHandler()
 
+	initialStartCompleted.Set()
 	return nil
 }
 
@@ -97,45 +113,36 @@ func prepareModules() error {
 	reportCnt := 0
 
 	for {
+		waiting := 0
+
 		// find modules to exec
 		for _, m := range modules {
-			if m.ReadyToPrep() {
+			switch m.readyToPrep() {
+			case statusNothingToDo:
+			case statusWaiting:
+				waiting++
+			case statusReady:
 				execCnt++
-				m.inTransition.Set()
-
-				execM := m
-				go func() {
-					reports <- &report{
-						module: execM,
-						err: execM.runCtrlFnWithTimeout(
-							"prep module",
-							10*time.Second,
-							execM.prep,
-						),
-					}
-				}()
+				m.prep(reports)
 			}
 		}
 
-		// check for dep loop
-		if execCnt == reportCnt {
-			return fmt.Errorf("modules: dependency loop detected, cannot continue")
-		}
-
-		// wait for reports
-		rep = <-reports
-		rep.module.inTransition.UnSet()
-		if rep.err != nil {
-			if rep.err == ErrCleanExit {
-				return rep.err
+		if reportCnt < execCnt {
+			// wait for reports
+			rep = <-reports
+			if rep.err != nil {
+				if rep.err == ErrCleanExit {
+					return rep.err
+				}
+				return fmt.Errorf("failed to prep module %s: %s", rep.module.Name, rep.err)
+			}
+			reportCnt++
+		} else {
+			// finished
+			if waiting > 0 {
+				// check for dep loop
+				return fmt.Errorf("modules: dependency loop detected, cannot continue")
 			}
-			return fmt.Errorf("failed to prep module %s: %s", rep.module.Name, rep.err)
-		}
-		reportCnt++
-		rep.module.Prepped.Set()
-
-		// exit if done
-		if reportCnt == len(modules) {
 			return nil
 		}
 
@@ -149,45 +156,36 @@ func startModules() error {
 	reportCnt := 0
 
 	for {
+		waiting := 0
+
 		// find modules to exec
 		for _, m := range modules {
-			if m.ReadyToStart() {
+			switch m.readyToStart() {
+			case statusNothingToDo:
+			case statusWaiting:
+				waiting++
+			case statusReady:
 				execCnt++
-				m.inTransition.Set()
-
-				execM := m
-				go func() {
-					reports <- &report{
-						module: execM,
-						err: execM.runCtrlFnWithTimeout(
-							"start module",
-							60*time.Second,
-							execM.start,
-						),
-					}
-				}()
+				m.start(reports)
 			}
 		}
 
-		// check for dep loop
-		if execCnt == reportCnt {
-			return fmt.Errorf("modules: dependency loop detected, cannot continue")
-		}
-
-		// wait for reports
-		rep = <-reports
-		rep.module.inTransition.UnSet()
-		if rep.err != nil {
-			return fmt.Errorf("modules: could not start module %s: %s", rep.module.Name, rep.err)
-		}
-		reportCnt++
-		rep.module.Started.Set()
-		log.Infof("modules: started %s", rep.module.Name)
-
-		// exit if done
-		if reportCnt == len(modules) {
+		if reportCnt < execCnt {
+			// wait for reports
+			rep = <-reports
+			if rep.err != nil {
+				return fmt.Errorf("modules: could not start module %s: %s", rep.module.Name, rep.err)
+			}
+			reportCnt++
+			log.Infof("modules: started %s", rep.module.Name)
+		} else {
+			// finished
+			if waiting > 0 {
+				// check for dep loop
+				return fmt.Errorf("modules: dependency loop detected, cannot continue")
+			}
+			// return last error
 			return nil
 		}
-
 	}
 }