all: Support multiple device connections (fixes #141) (#8918)

This adds the ability to have multiple concurrent connections to a single device. This is primarily useful when the network has multiple physical links for aggregated bandwidth. A single connection will never see a higher rate than a single link can give, but multiple connections are load-balanced over multiple links.

It is also incidentally useful for older multi-core CPUs, where bandwidth could be limited by the TLS performance of a single CPU core -- using multiple connections achieves concurrency in the required crypto calculations...

Co-authored-by: Simon Frei <freisim93@gmail.com>
Co-authored-by: tomasz1986 <twilczynski@naver.com>
Co-authored-by: bt90 <btom1990@googlemail.com>

lib/protocol/mocks/connection.go

@@ -31,6 +31,16 @@ type Connection struct {
 	clusterConfigArgsForCall []struct {
 		arg1 protocol.ClusterConfig
 	}
+	ConnectionIDStub        func() string
+	connectionIDMutex       sync.RWMutex
+	connectionIDArgsForCall []struct {
+	}
+	connectionIDReturns struct {
+		result1 string
+	}
+	connectionIDReturnsOnCall map[int]struct {
+		result1 string
+	}
 	CryptoStub        func() string
 	cryptoMutex       sync.RWMutex
 	cryptoArgsForCall []struct {
@@ -315,6 +325,59 @@ func (fake *Connection) ClusterConfigArgsForCall(i int) protocol.ClusterConfig {
 	return argsForCall.arg1
 }
 
+func (fake *Connection) ConnectionID() string {
+	fake.connectionIDMutex.Lock()
+	ret, specificReturn := fake.connectionIDReturnsOnCall[len(fake.connectionIDArgsForCall)]
+	fake.connectionIDArgsForCall = append(fake.connectionIDArgsForCall, struct {
+	}{})
+	stub := fake.ConnectionIDStub
+	fakeReturns := fake.connectionIDReturns
+	fake.recordInvocation("ConnectionID", []interface{}{})
+	fake.connectionIDMutex.Unlock()
+	if stub != nil {
+		return stub()
+	}
+	if specificReturn {
+		return ret.result1
+	}
+	return fakeReturns.result1
+}
+
+func (fake *Connection) ConnectionIDCallCount() int {
+	fake.connectionIDMutex.RLock()
+	defer fake.connectionIDMutex.RUnlock()
+	return len(fake.connectionIDArgsForCall)
+}
+
+func (fake *Connection) ConnectionIDCalls(stub func() string) {
+	fake.connectionIDMutex.Lock()
+	defer fake.connectionIDMutex.Unlock()
+	fake.ConnectionIDStub = stub
+}
+
+func (fake *Connection) ConnectionIDReturns(result1 string) {
+	fake.connectionIDMutex.Lock()
+	defer fake.connectionIDMutex.Unlock()
+	fake.ConnectionIDStub = nil
+	fake.connectionIDReturns = struct {
+		result1 string
+	}{result1}
+}
+
+func (fake *Connection) ConnectionIDReturnsOnCall(i int, result1 string) {
+	fake.connectionIDMutex.Lock()
+	defer fake.connectionIDMutex.Unlock()
+	fake.ConnectionIDStub = nil
+	if fake.connectionIDReturnsOnCall == nil {
+		fake.connectionIDReturnsOnCall = make(map[int]struct {
+			result1 string
+		})
+	}
+	fake.connectionIDReturnsOnCall[i] = struct {
+		result1 string
+	}{result1}
+}
+
 func (fake *Connection) Crypto() string {
 	fake.cryptoMutex.Lock()
 	ret, specificReturn := fake.cryptoReturnsOnCall[len(fake.cryptoArgsForCall)]
@@ -1162,6 +1225,8 @@ func (fake *Connection) Invocations() map[string][][]interface{} {
 	defer fake.closedMutex.RUnlock()
 	fake.clusterConfigMutex.RLock()
 	defer fake.clusterConfigMutex.RUnlock()
+	fake.connectionIDMutex.RLock()
+	defer fake.connectionIDMutex.RUnlock()
 	fake.cryptoMutex.RLock()
 	defer fake.cryptoMutex.RUnlock()
 	fake.deviceIDMutex.RLock()

lib/protocol/mocks/connection_info.go

@@ -10,6 +10,16 @@ import (
 )
 
 type ConnectionInfo struct {
+	ConnectionIDStub        func() string
+	connectionIDMutex       sync.RWMutex
+	connectionIDArgsForCall []struct {
+	}
+	connectionIDReturns struct {
+		result1 string
+	}
+	connectionIDReturnsOnCall map[int]struct {
+		result1 string
+	}
 	CryptoStub        func() string
 	cryptoMutex       sync.RWMutex
 	cryptoArgsForCall []struct {
@@ -94,6 +104,59 @@ type ConnectionInfo struct {
 	invocationsMutex sync.RWMutex
 }
 
+func (fake *ConnectionInfo) ConnectionID() string {
+	fake.connectionIDMutex.Lock()
+	ret, specificReturn := fake.connectionIDReturnsOnCall[len(fake.connectionIDArgsForCall)]
+	fake.connectionIDArgsForCall = append(fake.connectionIDArgsForCall, struct {
+	}{})
+	stub := fake.ConnectionIDStub
+	fakeReturns := fake.connectionIDReturns
+	fake.recordInvocation("ConnectionID", []interface{}{})
+	fake.connectionIDMutex.Unlock()
+	if stub != nil {
+		return stub()
+	}
+	if specificReturn {
+		return ret.result1
+	}
+	return fakeReturns.result1
+}
+
+func (fake *ConnectionInfo) ConnectionIDCallCount() int {
+	fake.connectionIDMutex.RLock()
+	defer fake.connectionIDMutex.RUnlock()
+	return len(fake.connectionIDArgsForCall)
+}
+
+func (fake *ConnectionInfo) ConnectionIDCalls(stub func() string) {
+	fake.connectionIDMutex.Lock()
+	defer fake.connectionIDMutex.Unlock()
+	fake.ConnectionIDStub = stub
+}
+
+func (fake *ConnectionInfo) ConnectionIDReturns(result1 string) {
+	fake.connectionIDMutex.Lock()
+	defer fake.connectionIDMutex.Unlock()
+	fake.ConnectionIDStub = nil
+	fake.connectionIDReturns = struct {
+		result1 string
+	}{result1}
+}
+
+func (fake *ConnectionInfo) ConnectionIDReturnsOnCall(i int, result1 string) {
+	fake.connectionIDMutex.Lock()
+	defer fake.connectionIDMutex.Unlock()
+	fake.ConnectionIDStub = nil
+	if fake.connectionIDReturnsOnCall == nil {
+		fake.connectionIDReturnsOnCall = make(map[int]struct {
+			result1 string
+		})
+	}
+	fake.connectionIDReturnsOnCall[i] = struct {
+		result1 string
+	}{result1}
+}
+
 func (fake *ConnectionInfo) Crypto() string {
 	fake.cryptoMutex.Lock()
 	ret, specificReturn := fake.cryptoReturnsOnCall[len(fake.cryptoArgsForCall)]
@@ -521,6 +584,8 @@ func (fake *ConnectionInfo) TypeReturnsOnCall(i int, result1 string) {
 func (fake *ConnectionInfo) Invocations() map[string][][]interface{} {
 	fake.invocationsMutex.RLock()
 	defer fake.invocationsMutex.RUnlock()
+	fake.connectionIDMutex.RLock()
+	defer fake.connectionIDMutex.RUnlock()
 	fake.cryptoMutex.RLock()
 	defer fake.cryptoMutex.RUnlock()
 	fake.establishedAtMutex.RLock()