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issue: #46540 Empty timetick is just used to sync up the time clock between different component in milvus. So empty timetick can be ignored if we achieve the lsn/mvcc semantic for timetick. Currently, some components need the empty timetick to trigger some operation, such as flush/tsafe. So we only slow down the empty time tick for 5 seconds. <!-- This is an auto-generated comment: release notes by coderabbit.ai --> - Core invariant: with LSN/MVCC semantics consumers only need (a) the first timetick that advances the latest-required-MVCC to unblock MVCC-dependent waits and (b) occasional periodic timeticks (~≤5s) for clock synchronization—therefore frequent non-persisted empty timeticks can be suppressed without breaking MVCC correctness. - Logic removed/simplified: per-message dispatch/consumption of frequent non-persisted empty timeticks is suppressed — an MVCC-aware filter emptyTimeTickSlowdowner (internal/util/pipeline/consuming_slowdown.go) short-circuits frequent empty timeticks in the stream pipeline (internal/util/pipeline/stream_pipeline.go), and the WAL flusher rate-limits non-persisted timetick dispatch to one emission per ~5s (internal/streamingnode/server/flusher/flusherimpl/wal_flusher.go); the delegator exposes GetLatestRequiredMVCCTimeTick to drive the filter (internal/querynodev2/delegator/delegator.go). - Why this does NOT introduce data loss or regressions: the slowdowner always refreshes latestRequiredMVCCTimeTick via GetLatestRequiredMVCCTimeTick and (1) never filters timeticks < latestRequiredMVCCTimeTick (so existing tsafe/flush waits stay unblocked) and (2) always lets the first timetick ≥ latestRequiredMVCCTimeTick pass to notify pending MVCC waits; separately, WAL flusher suppression applies only to non-persisted timeticks and still emits when the 5s threshold elapses, preserving periodic clock-sync messages used by flush/tsafe. - Enhancement summary (where it takes effect): adds GetLatestRequiredMVCCTimeTick on ShardDelegator and LastestMVCCTimeTickGetter, wires emptyTimeTickSlowdowner into NewPipelineWithStream (internal/util/pipeline), and adds WAL flusher rate-limiting + metrics (internal/streamingnode/server/flusher/flusherimpl/wal_flusher.go, pkg/metrics) to reduce CPU/dispatch overhead while keeping MVCC correctness and periodic synchronization. <!-- end of auto-generated comment: release notes by coderabbit.ai --> --------- Signed-off-by: chyezh <chyezh@outlook.com>
WAL
wal package is the basic defination of wal interface of milvus streamingnode.
wal use github.com/milvus-io/milvus/pkg/streaming/walimpls to implement the final wal service.
Project arrangement
wal/: only define exposed interfaces./adaptor/: adaptors to implementwalinterface fromwalimplsinterface/utility/: A utility code for common logic or data structure.
github.com/milvus-io/milvus/pkg/streaming/walimpls/: define the underlying message system interfaces need to be implemented./registry/: A static lifetime registry to regsiter new implementation for inverting dependency./helper/: A utility used to help developer to implementwalimplsconveniently./impls/: A official implemented walimpls sets.
Lifetime Of Interfaces
OpenerBuilderhas a static lifetime in a programs:Openerkeep same lifetime with underlying resources (such as mq client).WALkeep same lifetime with underlying writer of wal, and it's lifetime is always included in relatedOpener.Scannerkeep same lifetime with underlying reader of wal, and it's lifetime is always included in relatedWAL.
Add New Implemetation Of WAL
developper who want to add a new implementation of wal should implements the github.com/milvus-io/milvus/pkg/streaming/walimpls package interfaces. following interfaces is required:
walimpls.OpenerBuilderImplswalimpls.OpenerImplswalimpls.ScannerImplswalimpls.WALImpls
OpenerBuilderImpls create OpenerImpls; OpenerImpls creates WALImpls; WALImpls create ScannerImpls.
Then register the implmentation of walimpls.OpenerBuilderImpls into github.com/milvus-io/milvus/pkg/streaming/walimpls/registry package.
import "github.com/milvus-io/milvus/pkg/streaming/walimpls/registry"
var _ OpenerBuilderImpls = b{};
registry.RegisterBuilder(b{})
All things have been done.
Use WAL
import "github.com/milvus-io/milvus/internal/streamingnode/server/wal/registry"
name := "your builder name"
var yourCh *options.PChannelInfo
opener, err := registry.MustGetBuilder(name).Build()
if err != nil {
panic(err)
}
ctx := context.Background()
logger, err := opener.Open(ctx, wal.OpenOption{
Channel: yourCh
})
if err != nil {
panic(err)
}
Adaptor
package adaptor is used to adapt walimpls and wal together.
common wal function should be implement by it. Such as:
- lifetime management
- interceptor implementation
- scanner wrapped up
- write ahead cache implementation