LogDog: Implement RegisterPrefix RPC.

appengine/logdog/coordinator/hierarchy/hierarchy.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package hierarchy
 
 import (
         "crypto/sha256"
         "encoding/base64"
         "encoding/hex"
@@ skipping 22 matching lines @@
 //
 // Storing the component's name in its key ensures that a keys query will pull
 // the set of elements in the correct order, requiring no non-default indexes.
 //
 // Writing path components is inherently idempotent, since each one is defined
 // solely by its identity. Consequently, transactions are not necessary when
 // writing path components.
 //
 // All componentEntity share a common implicit ancestor, "/".
 //
-// This entity is created at stream registration, and is entirely centered
-// around being queried for log stream "directory" listings. For example:
+// This entity is created at stream and prefix registration, and is entirely
+// centered around being queried for log stream "directory" listings. For
+// example:
 //
 //      foo/bar/+/baz/qux
 //
 // This stream would add the following name components to the datastore, keyed
 // (parent-key, id) as:
 //      ("/", "foo")
 //      ("/foo", "bar")
 //      ("/foo/bar", "+")
 //      ("/foo/bar/+", "baz")
 //      ("/foo/bar/+/baz", "qux")
@@ skipping 211 matching lines @@
 
         return di.NewKey("_StreamNameComponent", string(d), 0, nil), nil
 }
 
 // cursorForKey returns a cursor for the supplied componentID. This cursor will
 // start new queries at the component immediately following this ID.
 func cursorForKey(di ds.Interface, e *componentEntity) string {
         key := di.KeyForObj(e)
         return base64.URLEncoding.EncodeToString([]byte(key.StringID()))
 }