EventStore/snapshot.go at main · BrobridgeOrg/EventStore · GitHub

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package eventstore

import (
	"sync"
	"sync/atomic"

	"github.com/cockroachdb/pebble"
)

type SnapshotRequest struct {
	Sequence uint64
	Store    *Store
	Data     []byte
	Batch    *pebble.Batch
}

var snapshotRequestPool = sync.Pool{
	New: func() interface{} {
		return NewSnapshotRequest()
	},
}

func NewSnapshotRequest() *SnapshotRequest {
	return &SnapshotRequest{}
}

func (request *SnapshotRequest) Get(collection []byte, key []byte) ([]byte, error) {

	snapshotKey := genSnapshotKey(
		collection,
		key,
	)

	value, closer, err := request.Store.cfSnapshot.Get(request.Batch, snapshotKey)
	if err != nil {
		if err == pebble.ErrNotFound {
			return nil, ErrRecordNotFound
		}

		return nil, err
	}

	data := make([]byte, len(value))
	copy(data, value)

	closer.Close()

	return data, nil
}

func (request *SnapshotRequest) Upsert(collection []byte, key []byte, value []byte, fn func([]byte, []byte) []byte) error {

	snapshotKey := genSnapshotKey(
		collection,
		key,
	)

	oldValue, closer, err := request.Store.cfSnapshot.Get(request.Batch, snapshotKey)
	if err != nil {
		if err != pebble.ErrNotFound {
			return err
		}

		// New record, it should update snapshot states
		request.Store.state.snapshotCount.Increase(1)
		err = request.Store.state.syncSnapshotCount(request.Store, request.Batch)
		if err != nil {
			return err
		}
	}

	if closer != nil {
		defer closer.Close()
	}

	err = request.Store.cfSnapshot.Write(request.Batch, snapshotKey, fn(oldValue, value))
	if err != nil {
		return err
	}

	// Update snapshot state
	err = request.updateDurableState(request.Batch, collection)
	if err != nil {
		return err
	}

	return nil
}

func (request *SnapshotRequest) updateDurableState(b *pebble.Batch, collection []byte) error {

	// Update snapshot state
	return request.Store.SetStateUint64(b, []byte("snapshot"), collection, []byte("lastSeq"), request.Sequence)
}

func (request *SnapshotRequest) UpdateDurableState(b *pebble.Batch, collection []byte) error {
	return request.updateDurableState(b, collection)
}

func (request *SnapshotRequest) Delete(collection []byte, key []byte) error {

	snapshotKey := genSnapshotKey(
		collection,
		key,
	)

	err := request.Store.cfSnapshot.Delete(request.Batch, snapshotKey)
	if err != nil {
		return err
	}

	// Update snapshot states
	atomic.AddUint64((*uint64)(&request.Store.state.snapshotCount), ^uint64(0))
	err = request.Store.state.syncSnapshotCount(request.Store, request.Batch)
	if err != nil {
		return err
	}

	return nil
}