add experimental-snapshot-catchup-entries flag.

Signed-off-by: Siyuan Zhang <[email protected]>

server/embed/config.go

@@ -151,7 +151,7 @@ type Config struct {
 	// follower to catch up.
 	// WARNING: only change this for tests.
 	// Always use "DefaultSnapshotCatchUpEntries"
-	SnapshotCatchUpEntries uint64
+	SnapshotCatchUpEntries uint64 `json:"experimental-snapshot-catch-up-entries"`
 
 	MaxSnapFiles uint `json:"max-snapshots"`
 	MaxWalFiles  uint `json:"max-wals"`

server/etcdmain/config.go

@@ -302,6 +302,7 @@ func newConfig() *config {
 	fs.BoolVar(&cfg.ec.ExperimentalMemoryMlock, "experimental-memory-mlock", cfg.ec.ExperimentalMemoryMlock, "Enable to enforce etcd pages (in particular bbolt) to stay in RAM.")
 	fs.BoolVar(&cfg.ec.ExperimentalTxnModeWriteWithSharedBuffer, "experimental-txn-mode-write-with-shared-buffer", true, "Enable the write transaction to use a shared buffer in its readonly check operations.")
 	fs.UintVar(&cfg.ec.ExperimentalBootstrapDefragThresholdMegabytes, "experimental-bootstrap-defrag-threshold-megabytes", 0, "Enable the defrag during etcd server bootstrap on condition that it will free at least the provided threshold of disk space. Needs to be set to non-zero value to take effect.")
+	fs.Uint64Var(&cfg.ec.SnapshotCatchUpEntries, "experimental-snapshot-catchup-entries", cfg.ec.SnapshotCatchUpEntries, "Number of entries for a slow follower to catch up after compacting the raft storage entries. (WARNING: only use this flag for tests.)")
 
 	// unsafe
 	fs.BoolVar(&cfg.ec.UnsafeNoFsync, "unsafe-no-fsync", false, "Disables fsync, unsafe, will cause data loss.")

server/etcdmain/config_test.go

@@ -505,7 +505,10 @@ func TestFlagsPresentInHelp(t *testing.T) {
 			// Ignored flags do not need to be in the help
 			return
 		}
-
+		if f.Name == "experimental-snapshot-catchup-entries" {
+			// Ignore because it is supposed to only be used in tests.
+			return
+		}
 		flagText := fmt.Sprintf("--%s", f.Name)
 		if !strings.Contains(flagsline, flagText) && !strings.Contains(usageline, flagText) {
 			t.Errorf("Neither flagsline nor usageline in help.go contains flag named %s", flagText)