1 files changed, 104 insertions, 0 deletions
diff --git a/internal/concurrency/workers.go b/internal/concurrency/workers.go
new file mode 100644
index 000000000..2e344aece
--- /dev/null
+++ b/internal/concurrency/workers.go
@@ -0,0 +1,104 @@
+package concurrency
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"path"
+	"reflect"
+	"runtime"
+
+	"codeberg.org/gruf/go-runners"
+	"github.com/sirupsen/logrus"
+)
+
+// WorkerPool represents a proccessor for MsgType objects, using a worker pool to allocate resources.
+type WorkerPool[MsgType any] struct {
+	workers runners.WorkerPool
+	process func(context.Context, MsgType) error
+	prefix  string // contains type prefix for logging
+}
+
+// New returns a new WorkerPool[MsgType] with given number of workers and queue ratio,
+// where the queue ratio is multiplied by no. workers to get queue size. If args < 1
+// then suitable defaults are determined from the runtime's GOMAXPROCS variable.
+func NewWorkerPool[MsgType any](workers int, queueRatio int) *WorkerPool[MsgType] {
+	var zero MsgType
+
+	if workers < 1 {
+		// ensure sensible workers
+		workers = runtime.GOMAXPROCS(0)
+	}
+	if queueRatio < 1 {
+		// ensure sensible ratio
+		queueRatio = 100
+	}
+
+	// Calculate the short type string for the msg type
+	msgType := reflect.TypeOf(zero).String()
+	_, msgType = path.Split(msgType)
+
+	w := &WorkerPool[MsgType]{
+		workers: runners.NewWorkerPool(workers, workers*queueRatio),
+		process: nil,
+		prefix:  fmt.Sprintf("worker.Worker[%s]", msgType),
+	}
+
+	// Log new worker creation with type prefix
+	logrus.Infof("%s created with workers=%d queue=%d",
+		w.prefix,
+		workers,
+		workers*queueRatio,
+	)
+
+	return w
+}
+
+// Start will attempt to start the underlying worker pool, or return error.
+func (w *WorkerPool[MsgType]) Start() error {
+	logrus.Infof("%s starting", w.prefix)
+
+	// Check processor was set
+	if w.process == nil {
+		return errors.New("nil Worker.process function")
+	}
+
+	// Attempt to start pool
+	if !w.workers.Start() {
+		return errors.New("failed to start Worker pool")
+	}
+
+	return nil
+}
+
+// Stop will attempt to stop the underlying worker pool, or return error.
+func (w *WorkerPool[MsgType]) Stop() error {
+	logrus.Infof("%s stopping", w.prefix)
+
+	// Attempt to stop pool
+	if !w.workers.Stop() {
+		return errors.New("failed to stop Worker pool")
+	}
+
+	return nil
+}
+
+// SetProcessor will set the Worker's processor function, which is called for each queued message.
+func (w *WorkerPool[MsgType]) SetProcessor(fn func(context.Context, MsgType) error) {
+	if w.process != nil {
+		logrus.Panicf("%s Worker.process is already set", w.prefix)
+	}
+	w.process = fn
+}
+
+// Queue will queue provided message to be processed with there's a free worker.
+func (w *WorkerPool[MsgType]) Queue(msg MsgType) {
+	logrus.Tracef("%s queueing message (workers=%d queue=%d): %+v",
+		w.prefix, w.workers.Workers(), w.workers.Queue(), msg,
+	)
+	w.workers.Enqueue(func(ctx context.Context) {
+		if err := w.process(ctx, msg); err != nil {
+			logrus.Errorf("%s %v", w.prefix, err)
+		}
+	})
+}