wip: slot height tracking

pkg/monitoring/chain_reader.go

@@ -17,6 +17,7 @@ type ChainReader interface {
 	GetBalance(ctx context.Context, account solana.PublicKey, commitment rpc.CommitmentType) (out *rpc.GetBalanceResult, err error)
 	GetSignaturesForAddressWithOpts(ctx context.Context, account solana.PublicKey, opts *rpc.GetSignaturesForAddressOpts) (out []*rpc.TransactionSignature, err error)
 	GetTransaction(ctx context.Context, txSig solana.Signature, opts *rpc.GetTransactionOpts) (out *rpc.GetTransactionResult, err error)
+	GetSlot(ctx context.Context) (slot uint64, err error)
 }
 
 func NewChainReader(client *rpc.Client) ChainReader {
@@ -50,3 +51,7 @@ func (c *chainReader) GetSignaturesForAddressWithOpts(ctx context.Context, accou
 func (c *chainReader) GetTransaction(ctx context.Context, txSig solana.Signature, opts *rpc.GetTransactionOpts) (out *rpc.GetTransactionResult, err error) {
 	return c.client.GetTransaction(ctx, txSig, opts)
 }
+
+func (c *chainReader) GetSlot(ctx context.Context) (uint64, error) {
+	return c.client.GetSlot(ctx, rpc.CommitmentProcessed) // get latest height
+}

pkg/monitoring/source_slotheight.go

@@ -0,0 +1,43 @@
+package monitoring
+
+import (
+	"context"
+
+	commonMonitoring "github.com/smartcontractkit/chainlink-common/pkg/monitoring"
+
+	"github.com/smartcontractkit/chainlink-solana/pkg/monitoring/types"
+)
+
+func NewSlotHeightSourceFactory(
+	client ChainReader,
+	log commonMonitoring.Logger,
+) commonMonitoring.NetworkSourceFactory {
+	return &slotHeightSourceFactory{
+		client,
+		log,
+	}
+}
+
+type slotHeightSourceFactory struct {
+	client ChainReader
+	log    commonMonitoring.Logger
+}
+
+func (s *slotHeightSourceFactory) NewSource(
+	_ commonMonitoring.ChainConfig,
+	_ []commonMonitoring.NodeConfig,
+) (commonMonitoring.Source, error) {
+	return &slotHeightSource{s.client}, nil
+}
+
+func (s *slotHeightSourceFactory) GetType() string {
+	return types.SlotHeightType
+}
+
+type slotHeightSource struct {
+	client ChainReader
+}
+
+func (t *slotHeightSource) Fetch(ctx context.Context) (interface{}, error) {
+	return t.client.GetSlot(ctx) // TODO: wrap the type to make it clear which type it is?
+}

pkg/monitoring/types/types.go

@@ -0,0 +1,5 @@
+package types
+
+const (
+	SlotHeightType = "slot_height"
+)