[split] com.twitter.finagle.Path: don't support empty path elements

These complicate the grammar and makes it difficult to represent the
path "/" accurately. The only place I could these in use was for inet
address like

	/$/inet//8080

this is equivalent to

	/$/inet/0/8080

since Java's InetSocketAddress interpretes an empty host argument as
the Internet address 0.

RB_ID=381909

finagle-core/src/main/scala/com/twitter/finagle/NameTree.scala

@@ -323,15 +323,15 @@ private trait NameTreePathParsers extends NameTreeParsers {
 
   val byte: Parser[Byte] = escapedByte | showableChar ^^ (_.toByte)
 
-  val label: Parser[Buf] = (
+  val label: Parser[Buf] =
       rep1(byte)  ^^ {
         case bytes => Buf.ByteArray(bytes:_*)
       }
-    | "" ^^^ Buf.Empty
-  )
 
-  val path: Parser[Path] = 
-    rep1("/" ~> label) ^^ { labels => Path(labels:_*) }
+  val path: Parser[Path] = (
+      rep1("/" ~> label) ^^ { labels => Path(labels:_*) }
+    | "/" ^^^ Path.empty
+  )
 
   val leaf = path
 }

finagle-core/src/main/scala/com/twitter/finagle/Path.scala

@@ -10,6 +10,8 @@ import java.util.BitSet
  * hierarchically-addressed object.
  */
 case class Path(elems: Buf*) {
+  require(elems.forall(Path.nonemptyBuf))
+
   def startsWith(other: Path) = elems startsWith other.elems
 
   def take(n: Int) = Path((elems take n):_*)
@@ -48,16 +50,19 @@ case class Path(elems: Buf*) {
     }
   }
 
-  lazy val show = showElems map ("/"+_) mkString ""
+  lazy val show = "/"+(showElems mkString "/")
 
   override def toString = "Path("+(showElems mkString ",")+")"
 }
 
 object Path {
+  private val nonemptyBuf: Buf => Boolean = !_.isEmpty
 
   implicit val showable: Showable[Path] = new Showable[Path] {
     def show(path: Path) = path.show
   }
+
+  val empty = Path()
 
   private val Utf8Charset = Charset.forName("UTF-8")
 
@@ -107,12 +112,14 @@ object Path {
    *
    * {{{
    * /foo/bar/baz
+   * /
    * }}}
    *
    * parses into the path 
    *
    * {{{
    * Path(foo,bar,baz)
+   * Path()
    * }}}
    *
    * @throws IllegalArgumentException when `s` is not a syntactically valid path.

finagle-core/src/main/scala/com/twitter/finagle/dispatch/ClientDispatcher.scala

@@ -91,7 +91,6 @@ class SerialClientDispatcher[Req, Rep](trans: Transport[Req, Rep])
     }
   }.unit
 
-
   protected def write(req: Req) = trans.write(req)
   protected def read(permit: Permit) = trans.read() ensure { permit.release() }
 }

finagle-core/src/test/scala/com/twitter/finagle/DtabTest.scala

@@ -35,13 +35,13 @@ class DtabTest extends FunSuite {
 
   test("d1 ++ d2") {
     val d1 = Dtab.read("/foo => /bar")
-    val d2 = Dtab.read("/foo=>/biz;/biz=>/$/inet//8080;/bar=>/$/inet//9090")
+    val d2 = Dtab.read("/foo=>/biz;/biz=>/$/inet/0/8080;/bar=>/$/inet/0/9090")
 
     assert(d1++d2 === Dtab.read("""
       /foo=>/bar;
       /foo=>/biz;
-      /biz=>/$/inet//8080;
-      /bar=>/$/inet//9090
+      /biz=>/$/inet/0/8080;
+      /bar=>/$/inet/0/9090
     """))
 
     def assertEval(dtab: Dtab, path: Path, expect: Name*) {

finagle-core/src/test/scala/com/twitter/finagle/NameTreeTest.scala

@@ -17,7 +17,7 @@ class NameTreeTest extends FunSuite {
     "aute", "irure", "dolor", "in", "reprehenderit", "in", "voluptate", "velit", "esse", "cillum", 
     "dolore", "eu", "fugiat", "nulla", "pariatur", "Excepteur", "sint", "occaecat", "cupidatat", 
     "non", "proident", "sunt", "in", "culpa", "qui", "officia", "deserunt", "mollit", "anim", 
-    "id", "est", "laborum", "")
+    "id", "est", "laborum")
 
   def pick[T](xs: Seq[T]): T = xs(rng.nextInt(xs.length))
 
@@ -48,8 +48,6 @@ class NameTreeTest extends FunSuite {
     }
 
     val leaves = Seq[() => NameTree[Path]](
-      // Note: atoms don't have a syntactic component yet.
-      //      () => NameTree.Atom(new SocketAddress{}),
       () => NameTree.Empty,
       () => NameTree.Neg,
       () => newPath())
@@ -72,13 +70,7 @@ class NameTreeTest extends FunSuite {
 
     val trees = Seq.fill(100) { newTree(2) }
     for (tree <- trees)
-      try { 
-        assert(splice(NameTree.read(tree.show)) == splice(tree))
-      } catch {
-        case NonFatal(exc) =>
-          fail("Exception %s while parsing %s: %s; spliced: %s".format(
-            exc, tree.show, tree, splice(tree)))
-      }
+      assert(splice(NameTree.read(tree.show)) === splice(tree))
   }
 
   test("NameTree.bind: infinite loop") {

finagle-core/src/test/scala/com/twitter/finagle/NamerTest.scala

@@ -57,10 +57,10 @@ class NamerTest extends FunSuite {
     namer("/test/0").notify(Return(NameTree.read("/test/2")))
     assert(res.run.sample() === Activity.Pending)
 
-    namer("/test/1").notify(Return(NameTree.read("/$/inet//1")))
+    namer("/test/1").notify(Return(NameTree.read("/$/inet/0/1")))
     assert(res.run.sample() === Activity.Pending)
 
-    namer("/test/2").notify(Return(NameTree.read("/$/inet//2")))
+    namer("/test/2").notify(Return(NameTree.read("/$/inet/0/2")))
 
     assertEval(res, ia(1), ia(2))
 
@@ -88,16 +88,16 @@ class NamerTest extends FunSuite {
 
     assert(res.sample().eval === Some(Set.empty))
 
-    namer("/test/0").notify(Return(NameTree.read("/$/inet//1")))
+    namer("/test/0").notify(Return(NameTree.read("/$/inet/0/1")))
     assertEval(res, ia(1))
 
     namer("/test/0").notify(Return(NameTree.Neg))
     assert(res.sample().eval === None)
 
-    namer("/test/2").notify(Return(NameTree.read("/$/inet//2")))
+    namer("/test/2").notify(Return(NameTree.read("/$/inet/0/2")))
     assertEval(res, ia(2))
 
-    namer("/test/0").notify(Return(NameTree.read("/$/inet//3")))
+    namer("/test/0").notify(Return(NameTree.read("/$/inet/0/3")))
     assertEval(res, ia(3)) 
   })
 

finagle-core/src/test/scala/com/twitter/finagle/factory/BindingFactoryTest.scala

@@ -20,7 +20,7 @@ class BindingFactoryTest extends FunSuite with MockitoSugar with BeforeAndAfter
   before {
     saveBase = Dtab.base
     Dtab.base = Dtab.read("""
-      /test1010=>/$/inet//1010
+      /test1010=>/$/inet/0/1010
     """)
   }
 
@@ -79,10 +79,10 @@ class BindingFactoryTest extends FunSuite with MockitoSugar with BeforeAndAfter
 
   test("Caches namers") (new Ctx {
 
-    val n1 = Dtab.read("/foo/bar=>/$/inet//1")
-    val n2 = Dtab.read("/foo/bar=>/$/inet//2")
-    val n3 = Dtab.read("/foo/bar=>/$/inet//3")
-    val n4 = Dtab.read("/foo/bar=>/$/inet//4")
+    val n1 = Dtab.read("/foo/bar=>/$/inet/0/1")
+    val n2 = Dtab.read("/foo/bar=>/$/inet/0/2")
+    val n3 = Dtab.read("/foo/bar=>/$/inet/0/3")
+    val n4 = Dtab.read("/foo/bar=>/$/inet/0/4")
 
     assert(news === 0)
     Await.result(newWith(n1).close() before newWith(n1).close())
@@ -113,10 +113,10 @@ class BindingFactoryTest extends FunSuite with MockitoSugar with BeforeAndAfter
   })
 
   test("Caches names") (new Ctx {
-    val n1 = Dtab.read("/foo/bar=>/$/inet//1; /bar/baz=>/$/nil")
-    val n2 = Dtab.read("/foo/bar=>/$/inet//1")
-    val n3 = Dtab.read("/foo/bar=>/$/inet//2")
-    val n4 = Dtab.read("/foo/bar=>/$/inet//3")
+    val n1 = Dtab.read("/foo/bar=>/$/inet/0/1; /bar/baz=>/$/nil")
+    val n2 = Dtab.read("/foo/bar=>/$/inet/0/1")
+    val n3 = Dtab.read("/foo/bar=>/$/inet/0/2")
+    val n4 = Dtab.read("/foo/bar=>/$/inet/0/3")
 
     assert(news === 0)
     Await.result(newWith(n1).close() before newWith(n1).close())