Move userspace code to sub-package in proxy.

Moves the userspace code in proxy to a sub-package and adds the
ProxyProvider interface.

This is in preparation for landing an implementation of
https://github.com/GoogleCloudPlatform/kubernetes/issues/3760, which
will mostly be in another sub package for iptables.

pkg/proxy/userspace/port_allocator_test.go

@@ -0,0 +1,101 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package userspace
+
+import (
+	"reflect"
+	"testing"
+
+	"k8s.io/kubernetes/pkg/util"
+)
+
+func TestRangeAllocatorEmpty(t *testing.T) {
+	r := &util.PortRange{}
+	r.Set("0-0")
+	defer func() {
+		if rv := recover(); rv == nil {
+			t.Fatalf("expected panic because of empty port range: %+v", r)
+		}
+	}()
+	_ = newPortRangeAllocator(*r)
+}
+
+func TestRangeAllocatorFullyAllocated(t *testing.T) {
+	r := &util.PortRange{}
+	r.Set("1-1")
+	a := newPortRangeAllocator(*r)
+	p, err := a.AllocateNext()
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if p != 1 {
+		t.Fatalf("unexpected allocated port: %d", p)
+	}
+
+	_, err = a.AllocateNext()
+	if err == nil {
+		t.Fatalf("expected error because of fully-allocated range")
+	}
+
+	a.Release(p)
+	p, err = a.AllocateNext()
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if p != 1 {
+		t.Fatalf("unexpected allocated port: %d", p)
+	}
+
+	_, err = a.AllocateNext()
+	if err == nil {
+		t.Fatalf("expected error because of fully-allocated range")
+	}
+}
+
+func TestRangeAllocator_RandomishAllocation(t *testing.T) {
+	r := &util.PortRange{}
+	r.Set("1-100")
+	a := newPortRangeAllocator(*r)
+
+	// allocate all the ports
+	var err error
+	ports := make([]int, 100, 100)
+	for i := 0; i < 100; i++ {
+		ports[i], err = a.AllocateNext()
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+	}
+
+	// release them all
+	for i := 0; i < 100; i++ {
+		a.Release(ports[i])
+	}
+
+	// allocate the ports again
+	rports := make([]int, 100, 100)
+	for i := 0; i < 100; i++ {
+		rports[i], err = a.AllocateNext()
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+	}
+
+	if reflect.DeepEqual(ports, rports) {
+		t.Fatalf("expected re-allocated ports to be in a somewhat random order")
+	}
+}