refactor: extract outputFormatter collaborator from eventLoop

The printCb and warningCb function fields on eventLoop bundled two
distinct concerns (pair emission and warning delivery) directly on the
event-processing struct. This commit extracts them into a dedicated
outputFormatter type that owns these callbacks plus emit() and
notifyWarning() helper methods.

outputFormatter is embedded (not pointed-to) in eventLoop so that
existing call sites — including tests that write el.printCb = ... and
el.warningCb = ... directly — require no changes beyond the three
struct-literal sites in eventloop_filter_test.go that used field
initialiser syntax.

fdTracker and commResolver were already proper collaborator types; only
the output concern needed extraction.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 5 insertions, 7 deletions

diff --git a/internal/eventloop_exit.go b/internal/eventloop_exit.go
index 5f6442c..e4ae6eb 100644
--- a/internal/eventloop_exit.go
+++ b/internal/eventloop_exit.go
@@ -291,18 +291,16 @@ func (e *eventLoop) registerDup(fdFile *file.FdFile, newFd int32, extraFlags int
 	e.fdState().set(newFd, duppedFdFile)
 }
 
+// recyclePair notifies about the problem described by warning, then returns ep
+// to the pool. It is a convenience helper used throughout the exit handlers to
+// keep the error path concise.
 func (e *eventLoop) recyclePair(ep *event.Pair, warning string) {
 	e.notifyWarning(warning)
 	ep.Recycle()
 }
 
-func (e *eventLoop) notifyWarning(message string) {
-	if e.warningCb == nil || message == "" {
-		return
-	}
-	e.warningCb(message)
-}
-
+// dropMalformedRawEvent records a warning when a raw BPF event cannot be
+// decoded, keeping the error visible without crashing the event loop.
 func (e *eventLoop) dropMalformedRawEvent(evType types.EventType, raw []byte) {
 	e.notifyWarning(fmt.Sprintf("Dropped malformed raw event type %d (len=%d)", evType, len(raw)))
 }