writecoordinator

Documentation

Overview

Package writecoordinator serialises all SQLite write operations through a single goroutine, eliminating concurrent write contention on the primary instance and providing a natural chokepoint for metrics and backpressure.

Index

• type Coordinator
  • func New(ctx context.Context, q db.Querier, queueSize int) *Coordinator
  • func (c *Coordinator) Metrics() CoordinatorMetrics
  • func (c *Coordinator) SetPublisher(pub changepub.Publisher)
  • func (c *Coordinator) Shutdown()
  • func (c *Coordinator) Submit(ctx context.Context, req dbproxy.WriteRequest) (json.RawMessage, error)
• type CoordinatorMetrics
• type WriteJob
• type WriteResult

Types

type Coordinator

type Coordinator struct {
	// contains filtered or unexported fields
}

Coordinator serialises all write operations through a single background goroutine, satisfying the dbproxy.WriteSubmitter interface.

func New

func New(ctx context.Context, q db.Querier, queueSize int) *Coordinator

New creates a Coordinator and starts the serialisation goroutine. queueSize specifies the job-channel buffer; values <= 0 default to 256.

func (*Coordinator) Metrics

func (c *Coordinator) Metrics() CoordinatorMetrics

Metrics returns a consistent snapshot of coordinator statistics.

func (*Coordinator) SetPublisher

func (c *Coordinator) SetPublisher(pub changepub.Publisher)

SetPublisher attaches a change-event publisher to the coordinator. Must be called before the first Submit; not safe for concurrent use.

func (*Coordinator) Shutdown

func (c *Coordinator) Shutdown()

Shutdown stops the coordinator gracefully. In-flight jobs that have already been dequeued will still complete; pending jobs that are still in the channel will have their callers unblocked via the done signal.

func (*Coordinator) Submit

func (c *Coordinator) Submit(ctx context.Context, req dbproxy.WriteRequest) (json.RawMessage, error)

Submit enqueues a write job and blocks until the result is available or the caller's context is cancelled. It satisfies dbproxy.WriteSubmitter.

type CoordinatorMetrics

type CoordinatorMetrics struct {
	Accepted   uint64
	Completed  uint64
	Failed     uint64
	QueueDepth int
	MaxQueue   int
}

CoordinatorMetrics holds a consistent snapshot of coordinator statistics.

type WriteJob

type WriteJob struct {
	// contains filtered or unexported fields
}

WriteJob is a single write request queued for serialised execution.

type WriteResult

type WriteResult struct {
	Result json.RawMessage
	Error  error
}

WriteResult is the outcome of a serialised write operation.