server: Implement compaction hash checking

Signed-off-by: Marek Siarkowicz <siarkowicz@google.com>

server/etcdserver/server.go

@@ -108,7 +108,8 @@ var (
 	// monitorVersionInterval should be smaller than the timeout
 	// on the connection. Or we will not be able to reuse the connection
 	// (since it will timeout).
-	monitorVersionInterval = rafthttp.ConnWriteTimeout - time.Second
+	monitorVersionInterval   = rafthttp.ConnWriteTimeout - time.Second
+	CompactHashCheckInterval = 15 * time.Second
 
 	recommendedMaxRequestBytesString = humanize.Bytes(uint64(recommendedMaxRequestBytes))
 	storeMemberAttributeRegexp       = regexp.MustCompile(path.Join(membership.StoreMembersPrefix, "[[:xdigit:]]{1,16}", "attributes"))
@@ -630,7 +631,7 @@ func NewServer(cfg config.ServerConfig) (srv *EtcdServer, err error) {
 			)
 		}
 	}
-	srv.corruptionChecker = NewCorruptionChecker(cfg.Logger, srv)
+	srv.corruptionChecker = newCorruptionChecker(cfg.Logger, srv, srv.kv.HashStorage())
 
 	srv.authStore = auth.NewAuthStore(srv.Logger(), srv.be, tp, int(cfg.BcryptCost))
 
@@ -805,6 +806,7 @@ func (s *EtcdServer) Start() {
 	s.GoAttach(s.monitorVersions)
 	s.GoAttach(s.linearizableReadLoop)
 	s.GoAttach(s.monitorKVHash)
+	s.GoAttach(s.monitorCompactHash)
 	s.GoAttach(s.monitorDowngrade)
 }
 
@@ -2537,6 +2539,20 @@ func (s *EtcdServer) monitorKVHash() {
 	}
 }
 
+func (s *EtcdServer) monitorCompactHash() {
+	for {
+		select {
+		case <-time.After(CompactHashCheckInterval):
+		case <-s.stopping:
+			return
+		}
+		if !s.isLeader() {
+			continue
+		}
+		s.corruptionChecker.CompactHashCheck()
+	}
+}
+
 func (s *EtcdServer) updateClusterVersionV2(ver string) {
 	lg := s.Logger()