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package meta_cache
import (
"context"
"strings"
"github.com/seaweedfs/seaweedfs/weed/glog"
"github.com/seaweedfs/seaweedfs/weed/pb"
"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
"github.com/seaweedfs/seaweedfs/weed/util"
)
type MetadataFollower struct {
PathPrefixToWatch string
ProcessEventFn func(resp *filer_pb.SubscribeMetadataResponse) error
}
func mergeProcessors(mainProcessor func(resp *filer_pb.SubscribeMetadataResponse) error, followers ...*MetadataFollower) func(resp *filer_pb.SubscribeMetadataResponse) error {
return func(resp *filer_pb.SubscribeMetadataResponse) error {
// build the full path
entry := resp.EventNotification.NewEntry
if entry == nil {
entry = resp.EventNotification.OldEntry
}
if entry != nil {
dir := resp.Directory
if resp.EventNotification.NewParentPath != "" {
dir = resp.EventNotification.NewParentPath
}
fp := util.NewFullPath(dir, entry.Name)
for _, follower := range followers {
if strings.HasPrefix(string(fp), follower.PathPrefixToWatch) {
if err := follower.ProcessEventFn(resp); err != nil {
return err
}
}
}
}
return mainProcessor(resp)
}
}
func SubscribeMetaEvents(mc *MetaCache, selfSignature int32, client filer_pb.FilerClient, dir string, lastTsNs int64, onRetry func(lastTsNs int64, err error), followers ...*MetadataFollower) error {
var prefixes []string
for _, follower := range followers {
prefixes = append(prefixes, follower.PathPrefixToWatch)
}
processEventFn := func(resp *filer_pb.SubscribeMetadataResponse) error {
// Let all events (including self-originated ones) flow through the
// applier so that the directory-build buffering and dedup logic
// can handle them consistently. The dedupRing in
// applyMetadataResponseNow catches duplicates that were already
// applied locally via applyLocalMetadataEvent.
return mc.ApplyMetadataResponse(context.Background(), resp, SubscriberMetadataResponseApplyOptions)
}
prefix := dir
if !strings.HasSuffix(prefix, "/") {
prefix = prefix + "/"
}
metadataFollowOption := &pb.MetadataFollowOption{
ClientName: "mount",
ClientId: selfSignature,
ClientEpoch: 1,
SelfSignature: selfSignature,
PathPrefix: prefix,
AdditionalPathPrefixes: prefixes,
DirectoriesToWatch: nil,
StartTsNs: lastTsNs,
StopTsNs: 0,
EventErrorType: pb.FatalOnError,
}
util.RetryUntil("followMetaUpdates", func() error {
metadataFollowOption.ClientEpoch++
return pb.WithFilerClientFollowMetadata(client, metadataFollowOption, mergeProcessors(processEventFn, followers...))
}, func(err error) bool {
if onRetry != nil {
onRetry(metadataFollowOption.StartTsNs, err)
}
glog.Errorf("follow metadata updates: %v", err)
return true
})
return nil
}