LogDog: Implement prefix expiration.

appengine/logdog/coordinator/endpoints/services/registerStream.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 services
 
 import (
         "crypto/subtle"
         "time"
 
@@ skipping 91 matching lines @@
                         log.ErrorKey: err,
                         "id":         pfx.ID,
                         "prefix":     prefix,
                 }.Errorf(c, "Failed to load log stream prefix.")
                 if err == ds.ErrNoSuchEntity {
                         return nil, grpcutil.Errf(codes.FailedPrecondition, "prefix is not registered")
                 }
                 return nil, grpcutil.Internal
         }
 
+        // If we're past prefix's expiration, reject this stream.
+        //
+        // If the prefix doesn't have an expiration, use its creation time and apply
+        // the maximum expiration.
+        expirationTime := pfx.Expiration
+        if expirationTime.IsZero() {
+                expiration := endpoints.MinDuration(cfg.Coordinator.PrefixExpiration, pcfg.PrefixExpiration)
+                if expiration > 0 {
+                        expirationTime = pfx.Created.Add(expiration)
+                }
+        }
+        if now := clock.Now(c); expirationTime.IsZero() || !now.Before(expirationTime) {
+                log.Fields{
+                        "prefix":     pfx.Prefix,
+                        "expiration": expirationTime,
+                }.Errorf(c, "The log stream Prefix has expired.")
+                return nil, grpcutil.Errf(codes.FailedPrecondition, "prefix has expired")
+        }
+
         // The prefix secret must match the request secret. If it does, we know this
         // is a legitimate registration attempt.
         if subtle.ConstantTimeCompare(pfx.Secret, req.Secret) != 1 {
                 log.Errorf(c, "Request secret does not match prefix secret.")
                 return nil, grpcutil.Errf(codes.InvalidArgument, "invalid secret")
         }
 
         // Check for registration, and that the prefix did not expire
         // (non-transactional).
         ls := &coordinator.LogStream{ID: coordinator.LogStreamID(path)}
@@ skipping 114 matching lines @@
                         return nil, grpcutil.Internal
                 }
         }
 
         return nil, nil
 }
 
 func (m *registerStreamMutation) Root(c context.Context) *ds.Key {
         return ds.Get(c).KeyForObj(m.ls)
 }