Improve queue cleanup, batch fairness, and worker CPU efficiency

internal/client/client.go

@@ -29,8 +29,10 @@ type Client struct {
 
 	connMu sync.Mutex
 	conns  map[net.Conn]struct{}
+	workCh chan struct{}
 
 	lastPollUnixMS atomic.Int64
+	batchCursor    atomic.Uint64
 }
 
 func New(cfg config.Config, lg *logger.Logger) *Client {
@@ -43,6 +45,7 @@ func New(cfg config.Config, lg *logger.Logger) *Client {
 		socksConnections: NewSOCKSConnectionStore(),
 		chunkPolicy:      newChunkPolicy(cfg),
 		conns:            make(map[net.Conn]struct{}),
+		workCh:           make(chan struct{}, 1),
 	}
 }
 
@@ -118,6 +121,13 @@ func (c *Client) closeAllConns() {
 	}
 }
 
+func (c *Client) signalSendWork() {
+	select {
+	case c.workCh <- struct{}{}:
+	default:
+	}
+}
+
 func generateClientSessionKey() string {
 	now := time.Now().UTC().Format("20060102T150405.000000000Z")
 	random := make([]byte, 16)