Add Exporter interface

exporters/exporter.go

@@ -0,0 +1,27 @@
+package exporters
+
+import "github.com/algorand/go-algorand/rpcs"
+
+// ExporterConfig is a generic type providing serialization/deserialization for exporter config files
+type ExporterConfig interface{}
+
+// Exporter defines the interface for plugins
+type Exporter interface {
+	// Connect will be called during initialization, before block data starts going through the pipeline.
+	// Typically used for things like initializing network connections.
+	// The ExporterConfig passed to Connect will contain the Unmarhsalled config file specific to this plugin.
+	// Should return an error if it fails--this will result in the Indexer process terminating.
+	Connect(cfg ExporterConfig) error
+
+	// Shutdown will be called during termination of the Indexer process.
+	// There is no guarantee that plugin lifecycle hooks will be invoked in any specific order in relation to one another.
+	// Returns an error if it fails which will be surfaced in the logs, but the process is already terminating.
+	Shutdown() error
+
+	// Receive is called for each block to be processed by the exporter.
+	// Should return an error on failure--retries are configurable.
+	Receive(blockData *rpcs.EncodedBlockCert) error
+
+	// Round returns the next round not yet processed by the Exporter. Atomically updated when Receive successfully completes.
+	Round() uint64
+}