[3/5] git commit: Made ZooKeeperMasterContenderProcess::master an option to codify the fact that it can be unset after construction.

[vi...@apache.org]

Made ZooKeeperMasterContenderProcess::master an option to codify the
fact that it can be unset after construction.

From: Jiang Yan Xu <ya...@jxu.me>
Review: https://reviews.apache.org/r/16588


Project: http://git-wip-us.apache.org/repos/asf/mesos/repo
Commit: http://git-wip-us.apache.org/repos/asf/mesos/commit/e03700a9
Tree: http://git-wip-us.apache.org/repos/asf/mesos/tree/e03700a9
Diff: http://git-wip-us.apache.org/repos/asf/mesos/diff/e03700a9

Branch: refs/heads/master
Commit: e03700a92a1c7945da1dbbffa45733f92d5ed65b
Parents: fe86c8b
Author: Vinod Kone <vi...@twitter.com>
Authored: Wed Jan 15 12:50:44 2014 -0800
Committer: Vinod Kone <vi...@twitter.com>
Committed: Wed Jan 15 12:54:57 2014 -0800

----------------------------------------------------------------------
 src/master/contender.cpp | 15 +++++++++++----
 src/master/contender.hpp |  2 ++
 2 files changed, 13 insertions(+), 4 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/mesos/blob/e03700a9/src/master/contender.cpp
----------------------------------------------------------------------
diff --git a/src/master/contender.cpp b/src/master/contender.cpp
index 72a7796..7bd25b5 100644
--- a/src/master/contender.cpp
+++ b/src/master/contender.cpp
@@ -62,7 +62,9 @@ public:
 private:
   Owned<zookeeper::Group> group;
   LeaderContender* contender;
-  PID<Master> master;
+
+  // The master this contender contends on behalf of.
+  Option<PID<Master> > master;
 };
 
 
@@ -115,9 +117,12 @@ void StandaloneMasterContender::initialize(
   initialized = true;
 }
 
+
 Future<Future<Nothing> > StandaloneMasterContender::contend()
 {
-  CHECK(initialized) << "Initialize the contender first";
+  if (!initialized) {
+    return Failure("Initialize the contender first");
+  }
 
   if (promise != NULL) {
     LOG(INFO) << "Withdrawing the previous membership before recontending";
@@ -194,14 +199,16 @@ void ZooKeeperMasterContenderProcess::initialize(
 
 Future<Future<Nothing> > ZooKeeperMasterContenderProcess::contend()
 {
-  CHECK(master) << "Initialize the contender first";
+  if (master.isNone()) {
+    return Failure("Initialize the contender first");
+  }
 
   if (contender != NULL) {
     LOG(INFO) << "Withdrawing the previous membership before recontending";
     delete contender;
   }
 
-  contender = new LeaderContender(group.get(), master);
+  contender = new LeaderContender(group.get(), master.get());
   return contender->contend();
 }
 

http://git-wip-us.apache.org/repos/asf/mesos/blob/e03700a9/src/master/contender.hpp
----------------------------------------------------------------------
diff --git a/src/master/contender.hpp b/src/master/contender.hpp
index 7764edd..0156369 100644
--- a/src/master/contender.hpp
+++ b/src/master/contender.hpp
@@ -69,6 +69,8 @@ public:
 
   // Returns a Future<Nothing> once the contender has entered the
   // contest (by obtaining a membership) and an error otherwise.
+  // A failed future is returned if this method is called before
+  // initialize().
   // The inner Future returns Nothing when the contender is out of
   // the contest (i.e. its membership is lost).
   //