Merge pull request #1392 from cfromknecht/signal-package

Signal/Interrupt package

lnd.go

@@ -35,7 +35,6 @@ import (
 
 	proxy "github.com/grpc-ecosystem/grpc-gateway/runtime"
 	flags "github.com/jessevdk/go-flags"
-	"github.com/lightningnetwork/lnd/autopilot"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lncfg"
@@ -44,6 +43,7 @@ import (
 	"github.com/lightningnetwork/lnd/lnwallet/btcwallet"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/macaroons"
+	"github.com/lightningnetwork/lnd/signal"
 	"github.com/lightningnetwork/lnd/walletunlocker"
 	"github.com/roasbeef/btcd/btcec"
 	"github.com/roasbeef/btcd/wire"
@@ -62,7 +62,6 @@ var (
 	Commit string
 
 	cfg              *config
-	shutdownChannel  = make(chan struct{})
 	registeredChains = newChainRegistry()
 
 	macaroonDatabaseDir string
@@ -94,6 +93,8 @@ var (
 // defers created in the top-level scope of a main method aren't executed if
 // os.Exit() is called.
 func lndMain() error {
+	defer ltndLog.Info("Shutdown complete")
+
 	// Load the configuration, and parse any command line options. This
 	// function will also set up logging properly.
 	loadedConfig, err := loadConfig()
@@ -500,6 +501,7 @@ func lndMain() error {
 		return err
 	}
 	server.fundingMgr = fundingMgr
+	defer fundingMgr.Stop()
 
 	// Check macaroon authentication if macaroons aren't disabled.
 	if macaroonService != nil {
@@ -517,6 +519,7 @@ func lndMain() error {
 	if err := rpcServer.Start(); err != nil {
 		return err
 	}
+	defer rpcServer.Stop()
 
 	grpcServer := grpc.NewServer(serverOpts...)
 	lnrpc.RegisterLightningServer(grpcServer, rpcServer)
@@ -574,18 +577,9 @@ func lndMain() error {
 		ltndLog.Infof("Waiting for chain backend to finish sync, "+
 			"start_height=%v", bestHeight)
 
-		// We'll add an interrupt handler in order to process shutdown
-		// requests while the chain backend syncs.
-		addInterruptHandler(func() {
-			rpcServer.Stop()
-			fundingMgr.Stop()
-		})
-
 		for {
-			select {
-			case <-shutdownChannel:
+			if !signal.Alive() {
 				return nil
-			default:
 			}
 
 			synced, _, err := activeChainControl.wallet.IsSynced()
@@ -615,10 +609,10 @@ func lndMain() error {
 		srvrLog.Errorf("unable to start server: %v\n", err)
 		return err
 	}
+	defer server.Stop()
 
 	// Now that the server has started, if the autopilot mode is currently
 	// active, then we'll initialize a fresh instance of it and start it.
-	var pilot *autopilot.Agent
 	if cfg.Autopilot.Active {
 		pilot, err := initAutoPilot(server, cfg.Autopilot)
 		if err != nil {
@@ -631,21 +625,12 @@ func lndMain() error {
 				err)
 			return err
 		}
+		defer pilot.Stop()
 	}
 
-	addInterruptHandler(func() {
-		rpcServer.Stop()
-		fundingMgr.Stop()
-		if pilot != nil {
-			pilot.Stop()
-		}
-		server.Stop()
-	})
-
 	// Wait for shutdown signal from either a graceful server stop or from
 	// the interrupt handler.
-	<-shutdownChannel
-	ltndLog.Info("Shutdown complete")
+	<-signal.ShutdownChannel()
 	return nil
 }
 
@@ -1036,7 +1021,7 @@ func waitForWalletPassword(grpcEndpoints, restEndpoints []net.Addr,
 			// Don't leave the file open in case the new wallet
 			// could not be created for whatever reason.
 			if err := loader.UnloadWallet(); err != nil {
-				ltndLog.Errorf("Could not unload new " +
+				ltndLog.Errorf("Could not unload new "+
 					"wallet: %v", err)
 			}
 			return nil, err
@@ -1061,7 +1046,7 @@ func waitForWalletPassword(grpcEndpoints, restEndpoints []net.Addr,
 		}
 		return walletInitParams, nil
 
-	case <-shutdownChannel:
+	case <-signal.ShutdownChannel():
 		return nil, fmt.Errorf("shutting down")
 	}
 }

log.go

@@ -20,6 +20,7 @@ import (
 	"github.com/lightningnetwork/lnd/htlcswitch"
 	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/routing"
+	"github.com/lightningnetwork/lnd/signal"
 	"github.com/roasbeef/btcd/connmgr"
 )
 
@@ -89,6 +90,7 @@ func init() {
 	autopilot.UseLogger(atplLog)
 	contractcourt.UseLogger(cnctLog)
 	sphinx.UseLogger(sphxLog)
+	signal.UseLogger(ltndLog)
 }
 
 // subsystemLoggers maps each subsystem identifier to its associated logger.

rpcserver.go

@@ -26,6 +26,7 @@ import (
 	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/routing"
+	"github.com/lightningnetwork/lnd/signal"
 	"github.com/lightningnetwork/lnd/zpay32"
 	"github.com/roasbeef/btcd/blockchain"
 	"github.com/roasbeef/btcd/btcec"
@@ -3416,7 +3417,7 @@ func (r *rpcServer) GetNetworkInfo(ctx context.Context,
 func (r *rpcServer) StopDaemon(ctx context.Context,
 	_ *lnrpc.StopRequest) (*lnrpc.StopResponse, error) {
 
-	shutdownRequestChannel <- struct{}{}
+	signal.RequestShutdown()
 	return &lnrpc.StopResponse{}, nil
 }
 

signal.go

@@ -1,96 +0,0 @@
-// Copyright (c) 2013-2017 The btcsuite developers
-// Copyright (c) 2015-2016 The Decred developers
-// Heavily inspired by https://github.com/btcsuite/btcd/blob/master/signal.go
-// Copyright (C) 2015-2017 The Lightning Network Developers
-
-package main
-
-import (
-	"os"
-	"os/signal"
-)
-
-// interruptChannel is used to receive SIGINT (Ctrl+C) signals.
-var interruptChannel chan os.Signal
-
-// shutdownRequestChannel is used to request the daemon to shutdown gracefully,
-// similar to when receiving SIGINT.
-var shutdownRequestChannel = make(chan struct{})
-
-// addHandlerChannel is used to add an interrupt handler to the list of handlers
-// to be invoked on SIGINT (Ctrl+C) signals and shutdown.
-var addHandlerChannel = make(chan func())
-
-// mainInterruptHandler listens for SIGINT (Ctrl+C) signals on the
-// interruptChannel and shutdown requests on the shutdownRequestChannel, and
-// invokes the registered interruptCallbacks accordingly. It also listens for
-// callback registration.
-// It must be run as a goroutine.
-func mainInterruptHandler() {
-	// interruptCallbacks is a list of callbacks to invoke when a
-	// SIGINT (Ctrl+C) or a shutdown request is received.
-	var interruptCallbacks []func()
-
-	// isShutdown is a flag which is used to indicate whether or not
-	// the shutdown signal has already been received and hence any future
-	// attempts to add a new interrupt handler should invoke them
-	// immediately.
-	var isShutdown bool
-
-	// shutdown invokes the registered interrupt handlers, then signals the
-	// shutdownChannel.
-	shutdown := func() {
-		// Ignore more than one shutdown signal.
-		if isShutdown {
-			ltndLog.Infof("Already shutting down...")
-			return
-		}
-		isShutdown = true
-		ltndLog.Infof("Shutting down...")
-
-		// Execute the interrupt callbacks in FIFO order.
-		for _, callback := range interruptCallbacks {
-			callback()
-		}
-
-		// Signal the main goroutine to shutdown.
-		go func() {
-			shutdownChannel <- struct{}{}
-		}()
-	}
-
-	for {
-		select {
-		case <-interruptChannel:
-			ltndLog.Infof("Received SIGINT (Ctrl+C).")
-			shutdown()
-
-		case <-shutdownRequestChannel:
-			ltndLog.Infof("Received shutdown request.")
-			shutdown()
-
-		case handler := <-addHandlerChannel:
-			// The shutdown signal has already been received, so
-			// just invoke any new handlers immediately.
-			if isShutdown {
-				handler()
-			}
-
-			interruptCallbacks = append(interruptCallbacks, handler)
-		}
-	}
-}
-
-// addInterruptHandler adds a handler to call when a SIGINT (Ctrl+C) or a
-// shutdown request is received.
-func addInterruptHandler(handler func()) {
-	// Create the channel and start the main interrupt handler which invokes
-	// all other callbacks and exits if not already done.
-	if interruptChannel == nil {
-		interruptChannel = make(chan os.Signal, 1)
-		signal.Notify(interruptChannel, os.Interrupt)
-		go mainInterruptHandler()
-	}
-
-	addHandlerChannel <- handler
-}

signal/log.go

@@ -0,0 +1,26 @@
+package signal
+
+import "github.com/btcsuite/btclog"
+
+// log is a logger that is initialized with no output filters.  This
+// means the package will not perform any logging by default until the caller
+// requests it.
+var log btclog.Logger
+
+// The default amount of logging is none.
+func init() {
+	DisableLog()
+}
+
+// DisableLog disables all library log output.  Logging output is disabled
+// by default until UseLogger is called.
+func DisableLog() {
+	log = btclog.Disabled
+}
+
+// UseLogger uses a specified Logger to output package logging info.
+// This should be used in preference to SetLogWriter if the caller is also
+// using btclog.
+func UseLogger(logger btclog.Logger) {
+	log = logger
+}

signal/signal.go

@@ -0,0 +1,101 @@
+// Copyright (c) 2013-2017 The btcsuite developers
+// Copyright (c) 2015-2016 The Decred developers
+// Heavily inspired by https://github.com/btcsuite/btcd/blob/master/signal.go
+// Copyright (C) 2015-2017 The Lightning Network Developers
+
+package signal
+
+import (
+	"os"
+	"os/signal"
+)
+
+var (
+	// interruptChannel is used to receive SIGINT (Ctrl+C) signals.
+	interruptChannel = make(chan os.Signal, 1)
+
+	// shutdownRequestChannel is used to request the daemon to shutdown
+	// gracefully, similar to when receiving SIGINT.
+	shutdownRequestChannel = make(chan struct{})
+
+	// quit is closed when instructing the main interrupt handler to exit.
+	quit = make(chan struct{})
+
+	// shutdownChannel is closed once the main interrupt handler exits.
+	shutdownChannel = make(chan struct{})
+)
+
+func init() {
+	signal.Notify(interruptChannel, os.Interrupt)
+	go mainInterruptHandler()
+}
+
+// mainInterruptHandler listens for SIGINT (Ctrl+C) signals on the
+// interruptChannel and shutdown requests on the shutdownRequestChannel, and
+// invokes the registered interruptCallbacks accordingly. It also listens for
+// callback registration.
+// It must be run as a goroutine.
+func mainInterruptHandler() {
+	// isShutdown is a flag which is used to indicate whether or not
+	// the shutdown signal has already been received and hence any future
+	// attempts to add a new interrupt handler should invoke them
+	// immediately.
+	var isShutdown bool
+
+	// shutdown invokes the registered interrupt handlers, then signals the
+	// shutdownChannel.
+	shutdown := func() {
+		// Ignore more than one shutdown signal.
+		if isShutdown {
+			log.Infof("Already shutting down...")
+			return
+		}
+		isShutdown = true
+		log.Infof("Shutting down...")
+
+		// Signal the main interrupt handler to exit, and stop accept
+		// post-facto requests.
+		close(quit)
+	}
+
+	for {
+		select {
+		case <-interruptChannel:
+			log.Infof("Received SIGINT (Ctrl+C).")
+			shutdown()
+
+		case <-shutdownRequestChannel:
+			log.Infof("Received shutdown request.")
+			shutdown()
+
+		case <-quit:
+			log.Infof("Gracefully shutting down.")
+			close(shutdownChannel)
+			return
+		}
+	}
+}
+
+// Alive returns true if the main interrupt handler has not been killed.
+func Alive() bool {
+	select {
+	case <-quit:
+		return false
+	default:
+		return true
+	}
+}
+
+// RequestShutdown initiates a graceful shutdown from the application.
+func RequestShutdown() {
+	select {
+	case shutdownRequestChannel <- struct{}{}:
+	case <-quit:
+	}
+}
+
+// ShutdownChannel returns the channel that will be closed once the main
+// interrupt handler has exited.
+func ShutdownChannel() <-chan struct{} {
+	return shutdownChannel
+}