ProxyACN and ErrorACN for nicer ACN Management

acn.go

@@ -58,5 +58,7 @@ type ACN interface {
 	// GetVersion returns a string of what the ACN returns when asked for a version
 	GetVersion() string
 
+	Callback() func(int, string)
+
 	Close()
 }

error_acn.go

@@ -0,0 +1,49 @@
+package connectivity
+
+import (
+	"fmt"
+	"net"
+)
+
+// ErrorACN - a status-callback safe errored ACN. Use this when ACN construction goes wrong
+// and you need a safe substitute that can later be replaced with a working ACN without impacting calling clients.
+type ErrorACN struct {
+	statusCallbackCache func(int, string)
+}
+
+func (e ErrorACN) Callback() func(int, string) {
+	return e.statusCallbackCache
+}
+
+func (e ErrorACN) GetBootstrapStatus() (int, string) {
+	return -1, "error initializing tor"
+}
+
+func (e ErrorACN) WaitTillBootstrapped() {
+}
+
+func (e *ErrorACN) SetStatusCallback(callback func(int, string)) {
+	e.statusCallbackCache = callback
+}
+
+func (e ErrorACN) Restart() {
+}
+
+func (e ErrorACN) Open(hostname string) (net.Conn, string, error) {
+	return nil, "", fmt.Errorf("error initializing tor")
+}
+
+func (e ErrorACN) Listen(identity PrivateKey, port int) (ListenService, error) {
+	return nil, fmt.Errorf("error initializing tor")
+}
+
+func (e ErrorACN) GetPID() (int, error) {
+	return -1, fmt.Errorf("error initializing tor")
+}
+
+func (e ErrorACN) GetVersion() string {
+	return "Error Initializing Tor"
+}
+
+func (e ErrorACN) Close() {
+}

localProvider.go

@@ -18,6 +18,10 @@ func NewLocalACN() ACN {
 	return &localProvider{}
 }
 
+func (lp *localProvider) Callback() func(int, string) {
+	return func(int, string) {}
+}
+
 func (ls *localListenService) AddressFull() string {
 	return ls.l.Addr().String()
 }

proxy_acn.go

@@ -0,0 +1,67 @@
+package connectivity
+
+import (
+	"net"
+)
+
+// ProxyACN because there is rarely a problem that can't be solved by another layer of indirection.
+// ACN is a core resource that many parts of a system may need access too e.g. all clients and servers need an instance
+// and a UI may also need status information and a configuration interface.
+// We want to allow configuration and replacement of an ACN without impacting the API of all downstream systems - introducing
+// ProxyACN - a wrapper around an ACN that allows safe replacement of a running ACN that is transparent to callers.
+type ProxyACN struct {
+	acn ACN
+}
+
+func NewProxyACN(acn ACN) ProxyACN {
+	return ProxyACN{
+		acn: acn,
+	}
+}
+
+// ReplaceACN closes down the current ACN and replaces it with a new ACN.
+func (p *ProxyACN) ReplaceACN(acn ACN) {
+	p.acn.Close()
+	acn.SetStatusCallback(p.acn.Callback())
+	p.acn = acn
+}
+
+func (p *ProxyACN) GetBootstrapStatus() (int, string) {
+	return p.acn.GetBootstrapStatus()
+}
+
+func (p *ProxyACN) WaitTillBootstrapped() {
+	p.acn.WaitTillBootstrapped()
+}
+
+func (p *ProxyACN) SetStatusCallback(callback func(int, string)) {
+	p.acn.SetStatusCallback(callback)
+}
+
+func (p *ProxyACN) Restart() {
+	p.acn.Restart()
+}
+
+func (p *ProxyACN) Open(hostname string) (net.Conn, string, error) {
+	return p.acn.Open(hostname)
+}
+
+func (p *ProxyACN) Listen(identity PrivateKey, port int) (ListenService, error) {
+	return p.acn.Listen(identity, port)
+}
+
+func (p *ProxyACN) GetPID() (int, error) {
+	return p.acn.GetPID()
+}
+
+func (p *ProxyACN) GetVersion() string {
+	return p.acn.GetVersion()
+}
+
+func (p *ProxyACN) Close() {
+	p.acn.Close()
+}
+
+func (p *ProxyACN) Callback() func(int, string) {
+	return p.acn.Callback()
+}

tor/torProvider.go

@@ -303,6 +303,12 @@ func (tp *torProvider) SetStatusCallback(callback func(int, string)) {
 	tp.statusCallback = callback
 }
 
+func (tp *torProvider) Callback() func(int, string) {
+	tp.lock.Lock()
+	defer tp.lock.Unlock()
+	return tp.statusCallback
+}
+
 func (tp *torProvider) callStatusCallback(prog int, status string) {
 	tp.lock.Lock()
 	if tp.statusCallback != nil {