Handle container links

Ensures that linked containers are restarted if any of their
dependencies are restarted -- and makes sure that everything happens in
the correct order.

docker/util.go

@@ -0,0 +1,64 @@
+package docker
+
+func sliceEqual(s1, s2 []string) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+
+	for i := range s1 {
+		if s1[i] != s2[i] {
+			return false
+		}
+	}
+
+	return true
+}
+
+func sliceSubtract(a1, a2 []string) []string {
+	a := []string{}
+
+	for _, e1 := range a1 {
+		found := false
+
+		for _, e2 := range a2 {
+			if e1 == e2 {
+				found = true
+				break
+			}
+		}
+
+		if !found {
+			a = append(a, e1)
+		}
+	}
+
+	return a
+}
+
+func stringMapSubtract(m1, m2 map[string]string) map[string]string {
+	m := map[string]string{}
+
+	for k1, v1 := range m1 {
+		if v2, ok := m2[k1]; ok {
+			if v2 != v1 {
+				m[k1] = v1
+			}
+		} else {
+			m[k1] = v1
+		}
+	}
+
+	return m
+}
+
+func structMapSubtract(m1, m2 map[string]struct{}) map[string]struct{} {
+	m := map[string]struct{}{}
+
+	for k1, v1 := range m1 {
+		if _, ok := m2[k1]; !ok {
+			m[k1] = v1
+		}
+	}
+
+	return m
+}