pd-server v3.0.0-rc.1

• Upgrade ETCD #1452
  • Unify the log format of etcd and PD server
  • Fix the issue of failing to elect Leader by PreVote
  • Support fast dropping the “propose” and “read” requests that are to fail to avoid blocking the subsequent requests
  • Fix the deadlock issue of Lease

• Fix the issue that a hot store makes incorrect statistics of keys #1487
• Support forcibly rebuilding a PD cluster from a single PD node
• #1485
• Fix the issue that regionScatterer might generate an invalid OperatorStep
• #1482
• Fix the too short timeout issue of the MergeRegion operator #1495
• Support giving high priority to hot region scheduling #1492
• Add the metrics for recording the time of handling TSO requests on the PD server side #1502
• Add the corresponding Store ID and Address to the metrics related to the store #1507
• Support the GetOperator service #1477
• Fix the issue that the error cannot be sent in the Heartbeat stream because the store cannot be found #1522