cmd/utils, rpc/comms: stop XEth when IPC connection ends

There are a bunch of changes required to make this work:

- in miner: allow unregistering agents, fix RemoteAgent.Stop
- in eth/filters: make FilterSystem.Stop not crash
- in rpc/comms: move listen loop to platform-independent code

Fixes #1930. I ran the shell loop there for a few minutes and didn't see
any changes in the memory profile.

3 files changed, 49 insertions, 70 deletions

diff --git a/rpc/comms/ipc.go b/rpc/comms/ipc.go
index 3de659b65..882d62ab4 100644
--- a/rpc/comms/ipc.go
+++ b/rpc/comms/ipc.go
@@ -20,13 +20,22 @@ import (
 	"fmt"
 	"math/rand"
 	"net"
+	"os"
 
 	"encoding/json"
 
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/rpc/codec"
 	"github.com/ethereum/go-ethereum/rpc/shared"
 )
 
+type Stopper interface {
+	Stop()
+}
+
+type InitFunc func(conn net.Conn) (Stopper, shared.EthereumApi, error)
+
 type IpcConfig struct {
 	Endpoint string
 }
@@ -90,8 +99,38 @@ func NewIpcClient(cfg IpcConfig, codec codec.Codec) (*ipcClient, error) {
 }
 
 // Start IPC server
-func StartIpc(cfg IpcConfig, codec codec.Codec, initializer func(conn net.Conn) (shared.EthereumApi, error)) error {
-	return startIpc(cfg, codec, initializer)
+func StartIpc(cfg IpcConfig, codec codec.Codec, initializer InitFunc) error {
+	l, err := ipcListen(cfg)
+	if err != nil {
+		return err
+	}
+	go ipcLoop(cfg, codec, initializer, l)
+	return nil
+}
+
+func ipcLoop(cfg IpcConfig, codec codec.Codec, initializer InitFunc, l net.Listener) {
+	glog.V(logger.Info).Infof("IPC service started (%s)\n", cfg.Endpoint)
+	defer os.Remove(cfg.Endpoint)
+	defer l.Close()
+	for {
+		conn, err := l.Accept()
+		if err != nil {
+			glog.V(logger.Debug).Infof("accept: %v", err)
+			return
+		}
+		id := newIpcConnId()
+		go func() {
+			defer conn.Close()
+			glog.V(logger.Debug).Infof("new connection with id %06d started", id)
+			stopper, api, err := initializer(conn)
+			if err != nil {
+				glog.V(logger.Error).Infof("Unable to initialize IPC connection: %v", err)
+				return
+			}
+			defer stopper.Stop()
+			handle(id, conn, api, codec)
+		}()
+	}
 }
 
 func newIpcConnId() int {
diff --git a/rpc/comms/ipc_unix.go b/rpc/comms/ipc_unix.go
index d68363a45..4b839572a 100644
--- a/rpc/comms/ipc_unix.go
+++ b/rpc/comms/ipc_unix.go
@@ -23,8 +23,6 @@ import (
 	"os"
 	"path/filepath"
 
-	"github.com/ethereum/go-ethereum/logger"
-	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/rpc/codec"
 	"github.com/ethereum/go-ethereum/rpc/shared"
 	"github.com/ethereum/go-ethereum/rpc/useragent"
@@ -69,44 +67,16 @@ func (self *ipcClient) reconnect() error {
 	return err
 }
 
-func startIpc(cfg IpcConfig, codec codec.Codec, initializer func(conn net.Conn) (shared.EthereumApi, error)) error {
+func ipcListen(cfg IpcConfig) (net.Listener, error) {
 	// Ensure the IPC path exists and remove any previous leftover
 	if err := os.MkdirAll(filepath.Dir(cfg.Endpoint), 0751); err != nil {
-		return err
+		return nil, err
 	}
 	os.Remove(cfg.Endpoint)
-
-	l, err := net.ListenUnix("unix", &net.UnixAddr{Name: cfg.Endpoint, Net: "unix"})
+	l, err := net.Listen("unix", cfg.Endpoint)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	os.Chmod(cfg.Endpoint, 0600)
-
-	go func() {
-		for {
-			conn, err := l.AcceptUnix()
-			if err != nil {
-				glog.V(logger.Error).Infof("Error accepting ipc connection - %v\n", err)
-				continue
-			}
-
-			id := newIpcConnId()
-			glog.V(logger.Debug).Infof("New IPC connection with id %06d started\n", id)
-
-			api, err := initializer(conn)
-			if err != nil {
-				glog.V(logger.Error).Infof("Unable to initialize IPC connection - %v\n", err)
-				conn.Close()
-				continue
-			}
-
-			go handle(id, conn, api, codec)
-		}
-
-		os.Remove(cfg.Endpoint)
-	}()
-
-	glog.V(logger.Info).Infof("IPC service started (%s)\n", cfg.Endpoint)
-
-	return nil
+	return l, nil
 }
diff --git a/rpc/comms/ipc_windows.go b/rpc/comms/ipc_windows.go
index 47edd9e5b..e25fba253 100644
--- a/rpc/comms/ipc_windows.go
+++ b/rpc/comms/ipc_windows.go
@@ -28,8 +28,6 @@ import (
 	"time"
 	"unsafe"
 
-	"github.com/ethereum/go-ethereum/logger"
-	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/rpc/codec"
 	"github.com/ethereum/go-ethereum/rpc/shared"
 	"github.com/ethereum/go-ethereum/rpc/useragent"
@@ -688,40 +686,12 @@ func (self *ipcClient) reconnect() error {
 	return err
 }
 
-func startIpc(cfg IpcConfig, codec codec.Codec, initializer func(conn net.Conn) (shared.EthereumApi, error)) error {
+func ipcListen(cfg IpcConfig) (net.Listener, error) {
 	os.Remove(cfg.Endpoint) // in case it still exists from a previous run
-
 	l, err := Listen(cfg.Endpoint)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	os.Chmod(cfg.Endpoint, 0600)
-
-	go func() {
-		for {
-			conn, err := l.Accept()
-			if err != nil {
-				glog.V(logger.Error).Infof("Error accepting ipc connection - %v\n", err)
-				continue
-			}
-
-			id := newIpcConnId()
-			glog.V(logger.Debug).Infof("New IPC connection with id %06d started\n", id)
-
-			api, err := initializer(conn)
-			if err != nil {
-				glog.V(logger.Error).Infof("Unable to initialize IPC connection - %v\n", err)
-				conn.Close()
-				continue
-			}
-
-			go handle(id, conn, api, codec)
-		}
-
-		os.Remove(cfg.Endpoint)
-	}()
-
-	glog.V(logger.Info).Infof("IPC service started (%s)\n", cfg.Endpoint)
-
-	return nil
+	return l, nil
 }