milvus/docs/developer_guides/chap05_proxy.md

6. Proxy

6.0 Proxy Service Interface

type ProxyService interface {
  Service
  RegisterLink() (RegisterLinkResponse, error)
  RegisterNode(req RegisterNodeRequest) (RegisterNodeResponse, error)
  InvalidateCollectionMetaCache(req InvalidateCollMetaCacheRequest) (Status, error)
}

• MsgBase

type MsgBase struct {
  MsgType MsgType
  MsgID	UniqueID
  Timestamp Timestamp
  SourceID UniqueID
}

• RegisterLink

type RegisterLinkResponse struct {
  Address string
  Port int32
}

• RegisterNode

type RegisterNodeRequest struct {
  MsgBase
  Address string
  Port int64
}

type RegisterNodeResponse struct {
  //InitParams
}

• InvalidateCollectionMetaCache

type InvalidateCollMetaCacheRequest struct {
  MsgBase
  DbName string
  CollectionName string
}

6.0 Proxy Node Interface

type ProxyNode interface {
  Service
  //SetTimeTickChannel(channelName string) error
  //SetStatsChannel(channelName string) error

  InvalidateCollectionMetaCache(request InvalidateCollMetaCacheRequest) (Status, error)
  
  CreateCollection(req CreateCollectionRequest) error
  DropCollection(req DropCollectionRequest) error
  HasCollection(req HasCollectionRequest) (bool, error)
  LoadCollection(req LoadCollectionRequest) error
  ReleaseCollection(req ReleaseCollectionRequest) error
  DescribeCollection(req DescribeCollectionRequest) (DescribeCollectionResponse, error)
  GetCollectionStatistics(req CollectionStatsRequest) (CollectionStatsResponse, error)
  ShowCollections(req ShowCollectionRequest) (ShowCollectionResponse, error)
  
  CreatePartition(req CreatePartitionRequest) error
  DropPartition(req DropPartitionRequest) error
  HasPartition(req HasPartitionRequest) (bool, error)
  LoadPartitions(req LoadPartitonRequest) error
  ReleasePartitions(req ReleasePartitionRequest) error
  GetPartitionStatistics(req PartitionStatsRequest) (PartitionStatsResponse, error)
  ShowPartitions(req ShowPartitionRequest) (ShowPartitionResponse)
  
  CreateIndex(req CreateIndexRequest) error
  DescribeIndex(DescribeIndexRequest) (DescribeIndexResponse, error)
  GetIndexState(IndexStateRequest) (IndexStateResponse, error)

  Insert(req InsertRequest) (InsertResponse, error)
  Search(req SearchRequest) (SearchResults, error)
  Flush(req FlushRequest) error

  GetDdChannel(Empty) (StringResponse, error)

  GetQuerySegmentInfo(QuerySegmentInfoRequest) (QuerySegmentInfoResponse, error)
  GetPersistentSegmentInfo(PersistentSegmentInfoRequest) (PersistentSegmentInfoResponse, error)
}

• CreateCollection

See Master API for detailed definitions.

• DropCollection

See Master API for detailed definitions.

• HasCollection

See Master API for detailed definitions.

• LoadCollection

type LoadCollectionRequest struct {
  MsgBase
  DbName string
  CollectionName string
}

• ReleaseCollection

type ReleaseCollectionRequest struct {
  MsgBase
  DbName string
  CollectionName string
}

• DescribeCollection

See Master API for detailed definitions.

• GetCollectionStatistics

See Master API for detailed definitions.

• ShowCollections

See Master API for detailed definitions.

• CreatePartition

See Master API for detailed definitions.

• DropPartition

See Master API for detailed definitions.

• HasPartition

See Master API for detailed definitions.

• LoadPartitions

type LoadPartitonRequest struct {
  MsgBase
  DbName string
  CollectionName string
  PartitionNames []string
}

• ReleasePartitions

type ReleasePartitionRequest struct {
  MsgBase
  DbName string
  CollectionName string
  PartitionNames []string
}

• GetPartitionStatistics

See Master API for detailed definitions.

• ShowPartitions

See Master API for detailed definitions.

• CreateIndex

See Master API for detailed definitions.

• DescribeIndex

See Master API for detailed definitions.

• Insert

type InsertRequest struct {
  MsgBase
  DbName string
  CollectionName string
  PartitionName string
  RowData []Blob
  HashKeys []uint32
}

type InsertResponse struct {
  RowIDBegin UniqueID
  RowIDEnd UniqueID
}

• Search

type SearchRequest struct {
  MsgBase
  DbName string
  CollectionName string
  PartitionNames []string
  Dsl string
  PlaceholderGroup []byte
}

• Flush

type FlushRequest struct {
  MsgBase
  DbName string
  CollectionName string
}

• GetPersistentSegmentInfo

type PersistentSegmentInfoRequest  struct{
  MsgBase
  DbName string
  CollectionName string
}

type PersistentSegmentInfo struct {
	SegmentID            UniqueID
	CollectionID         UniqueID
	PartitionID          UniqueID
	OpenTime             Timestamp
	SealedTime           Timestamp
	FlushedTime          Timestamp
	NumRows              int64
	MemSize              int64
	State                SegmentState
}

type PersistentSegmentInfoResponse  struct{
  infos []SegmentInfo
}

6.1 Proxy Instance

type Proxy struct {
  servicepb.UnimplementedMilvusServiceServer
  masterClient mpb.MasterClient
  
  timeTick *timeTick
  ttStream *MessageStream
  scheduler *taskScheduler
  tsAllocator *TimestampAllocator
  ReqIdAllocator *IdAllocator
  RowIdAllocator *IdAllocator
  SegIdAssigner *segIdAssigner
}

func (proxy *Proxy) Start() error
func NewProxy(ctx context.Context) *Proxy

Global Parameter Table

type GlobalParamsTable struct {
}
func (*paramTable GlobalParamsTable) ProxyId() int64
func (*paramTable GlobalParamsTable) ProxyAddress() string
func (*paramTable GlobalParamsTable) MasterAddress() string
func (*paramTable GlobalParamsTable) PulsarAddress() string
func (*paramTable GlobalParamsTable) TimeTickTopic() string
func (*paramTable GlobalParamsTable) InsertTopics() []string
func (*paramTable GlobalParamsTable) QueryTopic() string
func (*paramTable GlobalParamsTable) QueryResultTopics() []string
func (*paramTable GlobalParamsTable) Init() error

var ProxyParamTable GlobalParamsTable

6.2 Task

type task interface {
  Id() int64	// return ReqId
  PreExecute() error
  Execute() error
  PostExecute() error
  WaitToFinish() error
  Notify() error
}

• Base Task

type baseTask struct {
  Type ReqType
  ReqId int64
  Ts Timestamp
  ProxyId int64
}

func (task *baseTask) PreExecute() error
func (task *baseTask) Execute() error
func (task *baseTask) PostExecute() error
func (task *baseTask) WaitToFinish() error
func (task *baseTask) Notify() error

• Insert Task

  Take insertTask as an example:

type insertTask struct {
  baseTask
  SegIdAssigner *segIdAssigner
  RowIdAllocator *IdAllocator
  rowBatch *RowBatch
}

func (task *InsertTask) Execute() error
func (task *InsertTask) WaitToFinish() error
func (task *InsertTask) Notify() error

6.2 Task Scheduler

• Base Task Queue

type baseTaskQueue struct {
  unissuedTasks *List
  activeTasks map[int64]*task
  utLock sync.Mutex	// lock for UnissuedTasks
  atLock sync.Mutex	// lock for ActiveTasks
}
func (queue *baseTaskQueue) AddUnissuedTask(task *task)
func (queue *baseTaskQueue) FrontUnissuedTask() *task
func (queue *baseTaskQueue) PopUnissuedTask(id int64) *task
func (queue *baseTaskQueue) AddActiveTask(task *task)
func (queue *baseTaskQueue) PopActiveTask(id int64) *task
func (queue *baseTaskQueue) TaskDoneTest(ts Timestamp) bool

AddUnissuedTask(task *task) will put a new task into unissuedTasks, while maintaining the list by timestamp order.

TaskDoneTest(ts Timestamp) will check both unissuedTasks and unissuedTasks. If no task found before ts, then the function returns true, indicates that all the tasks before ts are completed.

• Data Definition Task Queue

type ddTaskQueue struct {
  baseTaskQueue
  lock sync.Mutex
}
func (queue *ddTaskQueue) Enqueue(task *task) error

func newDdTaskQueue() *ddTaskQueue

Data definition tasks (i.e. CreateCollectionTask) will be put into DdTaskQueue. If a task is enqueued, Enqueue(task *task) will set Ts, ReqId, ProxyId, then push it into queue. The timestamps of the enqueued tasks should be strictly monotonically increasing. As Enqueue(task *task) will be called in parallel, setting timestamp and queue insertion need to be done atomically.

• Data Manipulation Task Queue

type dmTaskQueue struct {
  baseTaskQueue
}
func (queue *dmTaskQueue) Enqueue(task *task) error

func newDmTaskQueue() *dmTaskQueue

Insert tasks and delete tasks will be put into DmTaskQueue.

If a insertTask is enqueued, Enqueue(task *task) will set Ts, ReqId, ProxyId, SegIdAssigner, RowIdAllocator, then push it into queue. The SegIdAssigner and RowIdAllocator will later be used in the task's execution phase.

• Data Query Task Queue

type dqTaskQueue struct {
  baseTaskQueue
}
func (queue *dqTaskQueue) Enqueue(task *task) error

func newDqTaskQueue() *dqTaskQueue

Queries will be put into DqTaskQueue.

• Task Scheduler

type taskScheduler struct {
  DdQueue *ddTaskQueue
  DmQueue *dmTaskQueue
  DqQueue *dqTaskQueue
  
  tsAllocator *TimestampAllocator
  ReqIdAllocator *IdAllocator
}

func (sched *taskScheduler) scheduleDdTask() *task
func (sched *taskScheduler) scheduleDmTask() *task
func (sched *taskScheduler) scheduleDqTask() *task

func (sched *taskScheduler) Start() error
func (sched *taskScheduler) TaskDoneTest(ts Timestamp) bool

func newTaskScheduler(ctx context.Context, tsAllocator *TimestampAllocator, ReqIdAllocator *IdAllocator) *taskScheduler

scheduleDdTask() selects tasks in a FIFO manner, thus time order is garanteed.

The policy of scheduleDmTask() should target on throughput, not tasks' time order. Note that the time order of the tasks' execution will later be garanteed by the timestamp & time tick mechanism.

The policy of scheduleDqTask() should target on throughput. It should also take visibility into consideration. For example, if an insert task and a query arrive in a same time tick and the query comes after insert, the query should be scheduled in the next tick thus the query can see the insert.

TaskDoneTest(ts Timestamp) will check all the three task queues. If no task found before ts, then the function returns true, indicates that all the tasks before ts are completed.

• Statistics

// ActiveComponent interfaces
func (sched *taskScheduler) Id() String
func (sched *taskScheduler) Status() Status
func (sched *taskScheduler) Clean() Status
func (sched *taskScheduler) Restart() Status
func (sched *taskScheduler) heartbeat()

// protobuf
message taskSchedulerHeartbeat {
  string id
  uint64 dd_queue_length
  uint64 dm_queue_length
  uint64 dq_queue_length
  uint64 num_dd_done
  uint64 num_dm_done
  uint64 num_dq_done
}

6.3 Time Tick

• Time Tick

type timeTick struct {
  lastTick Timestamp
  currentTick Timestamp
  wallTick Timestamp
  tickStep Timestamp
  syncInterval Timestamp
  
  tsAllocator *TimestampAllocator
  scheduler *taskScheduler
  ttStream *MessageStream
  
  ctx context.Context
}

func (tt *timeTick) Start() error
func (tt *timeTick) synchronize() error

func newTimeTick(ctx context.Context, tickStep Timestamp, syncInterval Timestamp, tsAllocator *TimestampAllocator, scheduler *taskScheduler, ttStream *MessageStream) *timeTick

Start() will enter a loop. On each tickStep, it tries to send a TIME_TICK typed TsMsg into ttStream. After each syncInterval, it sychronizes its wallTick with tsAllocator by calling synchronize(). When currentTick + tickStep < wallTick holds, it will update currentTick with wallTick on next tick. Otherwise, it will update currentTick with currentTick + tickStep.

• Statistics

// ActiveComponent interfaces
func (tt *timeTick) ID() String
func (tt *timeTick) Status() Status
func (tt *timeTick) Clean() Status
func (tt *timeTick) Restart() Status
func (tt *timeTick) heartbeat()

// protobuf
message TimeTickHeartbeat {
  string id
  uint64 last_tick
}