Merge pull request #43 from blinklabs-io/feat/output-embedded

feat: embedded output plugin

filter/filter.go

@@ -14,6 +14,7 @@
 
 package filter
 
+// We import the various plugins that we want to be auto-registered
 import (
 	_ "github.com/blinklabs-io/snek/filter/chainsync"
 	_ "github.com/blinklabs-io/snek/filter/event"

input/input.go

@@ -14,6 +14,7 @@
 
 package input
 
+// We import the various plugins that we want to be auto-registered
 import (
 	_ "github.com/blinklabs-io/snek/input/chainsync"
 )

output/embedded/embedded.go

@@ -0,0 +1,89 @@
+// Copyright 2023 Blink Labs, LLC.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package embedded
+
+import (
+	"fmt"
+
+	"github.com/blinklabs-io/snek/event"
+)
+
+type CallbackFunc func(event.Event) error
+
+type EmbeddedOutput struct {
+	errorChan    chan error
+	eventChan    chan event.Event
+	callbackFunc CallbackFunc
+	outputChan   chan event.Event
+}
+
+func New(options ...EmbeddedOptionFunc) *EmbeddedOutput {
+	e := &EmbeddedOutput{
+		errorChan: make(chan error),
+		eventChan: make(chan event.Event, 10),
+	}
+	for _, option := range options {
+		option(e)
+	}
+	return e
+}
+
+// Start the embedded output
+func (e *EmbeddedOutput) Start() error {
+	go func() {
+		for {
+			evt, ok := <-e.eventChan
+			// Channel has been closed, which means we're shutting down
+			if !ok {
+				return
+			}
+			if e.callbackFunc != nil {
+				if err := e.callbackFunc(evt); err != nil {
+					e.errorChan <- fmt.Errorf("callback function error: %s", err)
+					return
+				}
+			}
+			if e.outputChan != nil {
+				e.outputChan <- evt
+			}
+		}
+	}()
+	return nil
+}
+
+// Stop the embedded output
+func (e *EmbeddedOutput) Stop() error {
+	close(e.eventChan)
+	close(e.errorChan)
+	if e.outputChan != nil {
+		close(e.outputChan)
+	}
+	return nil
+}
+
+// ErrorChan returns the input error channel
+func (e *EmbeddedOutput) ErrorChan() chan error {
+	return e.errorChan
+}
+
+// InputChan returns the input event channel
+func (e *EmbeddedOutput) InputChan() chan<- event.Event {
+	return e.eventChan
+}
+
+// OutputChan always returns nil
+func (e *EmbeddedOutput) OutputChan() <-chan event.Event {
+	return nil
+}

output/embedded/options.go

@@ -0,0 +1,33 @@
+// Copyright 2023 Blink Labs, LLC.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package embedded
+
+import "github.com/blinklabs-io/snek/event"
+
+type EmbeddedOptionFunc func(*EmbeddedOutput)
+
+// WithCallbackFunc specifies a callback function for events
+func WithCallbackFunc(callbackFunc CallbackFunc) EmbeddedOptionFunc {
+	return func(o *EmbeddedOutput) {
+		o.callbackFunc = callbackFunc
+	}
+}
+
+// WithOutputChan specifies an event.Event channel to use for events
+func WithOutputChan(outputChan chan event.Event) EmbeddedOptionFunc {
+	return func(o *EmbeddedOutput) {
+		o.outputChan = outputChan
+	}
+}

output/output.go

@@ -14,6 +14,7 @@
 
 package output
 
+// We import the various plugins that we want to be auto-registered
 import (
 	_ "github.com/blinklabs-io/snek/output/log"
 )