Change log:
1. PeerServer
- estimate initial mode from its log through removedInLog variable
- refactor FindCluster to return the estimation
- refactor Start to call FindCluster explicitly
- move raftServer start and cluster init from FindCluster to Start
- remove stopNotify from PeerServer because it is not used anymore
2. Etcd
- refactor Run logic to fit the specification
3. ClusterConfig
- rename promoteDelay to removeDelay for better naming
- add SyncClusterInterval field to ClusterConfig
- commit command to set default cluster config when cluster is created
- store cluster config info into key space for consistency
- reload cluster config when reboot
4. add StandbyServer
5. Error
- remove unused EcodePromoteError
Without this commit etcd returns the following error message when
setting values on directories:
{
"errorCode":102,
"message":"Not a file",
"cause":"/postgres",
"index":2
}
While the above error message is accurate it's not very descriptive.
This commit adds a new error code/message which better describes why the
write operation failed. etcd now returns the following:
{
"errorCode":109,
"message":"Cannot set value on directory",
"cause":"/postgres",
"index":2
}
This commits adds test coverage for all the error and non-error cases
described below, but only the behavior of the 403, 404 and 412 cases
are changing in this commit.
When setting a key results in a new resource, we asset an HTTP status
code of 201 (aka "Created").
When attempting to get a resource that doesn't exist, we assert an
HTTP status code of 404 (aka "Not Found").
When attempting to delete a directory without dir=true, or a non-empty
directory without recursive=true, but the request is otherwise valid,
we assert an HTTP status code of 403 (aka "Forbidden").
When a precondition (e.g. specified by prevIndex, or prevValue) is not
met, but the request is otherwise syntactically valid, we assert an
HTTP status code of 412 (aka "Precondition Failed"). However,
prevExist is handled slightly differently. If prevExist=false fails,
then this is treated like a failed precondition, so it should use
PreconditionFailed. But, if prevExist=true fails, then this is
treated like other requests that require the existence of the
resource, and uses NotFound if the resource doesn't exist.
We continue to assert an HTTP status code of 400 when the request is
syntactically invalid (e.g. when prevIndex=bad_index).
