From 53f29dc721f9eca58cc796519698392cd0c56b18 Mon Sep 17 00:00:00 2001
From: Mike Spreitzer <mspreitz@us.ibm.com>
Date: Wed, 8 Jul 2020 01:15:51 -0400
Subject: [PATCH] Replaced repair with returning error, in delta_fifo.go

When dedupDeltas does the impossible and the key is already queued,
return an error rather than maintain the data structure invariants.

Kubernetes-commit: a39481a4f6cf33f9bf4555adcffa28077863e7a9
---
 tools/cache/delta_fifo.go | 33 ++-------------------------------
 1 file changed, 2 insertions(+), 31 deletions(-)

diff --git a/tools/cache/delta_fifo.go b/tools/cache/delta_fifo.go
index 37e17717..148b478d 100644
--- a/tools/cache/delta_fifo.go
+++ b/tools/cache/delta_fifo.go
@@ -395,9 +395,9 @@ func (f *DeltaFIFO) queueActionLocked(actionType DeltaType, obj interface{}) err
 			klog.Errorf("Impossible dedupDeltas for id=%q: oldDeltas=%#+v, obj=%#+v; ignoring", id, oldDeltas, obj)
 			return nil
 		}
-		klog.Errorf("Impossible dedupDeltas for id=%q: oldDeltas=%#+v, obj=%#+v; removing from queue", id, oldDeltas, obj)
+		klog.Errorf("Impossible dedupDeltas for id=%q: oldDeltas=%#+v, obj=%#+v; breaking invariant by storing empty Deltas", id, oldDeltas, obj)
 		f.items[id] = newDeltas
-		f.filterQueueLocked()
+		return fmt.Errorf("Impossible dedupDeltas for id=%q: oldDeltas=%#+v, obj=%#+v; broke DeltaFIFO invariant by storing empty Deltas", id, oldDeltas, obj)
 	}
 	return nil
 }
@@ -656,35 +656,6 @@ func (f *DeltaFIFO) syncKeyLocked(key string) error {
 	return nil
 }
 
-// A partial repair function.  Removes keys from f.queue that
-// correspond to nothing in f.items.  Removes keys from both when the
-// entry in f.items has zero length.  Ensures each key appears at most
-// once in queue.  Must be called with the lock held.
-func (f *DeltaFIFO) filterQueueLocked() {
-	newQueue := make([]string, 0, len(f.queue))
-	newItems := make(map[string]Deltas, len(f.items))
-	for _, key := range f.queue {
-		if _, exists := newItems[key]; exists {
-			klog.Errorf("Removing duplicate key %q", key)
-			continue
-		}
-		deltas, exists := f.items[key]
-		if !exists {
-			klog.Errorf("Removing key %q because it has no Deltas", key)
-			continue
-		}
-		if len(deltas) == 0 {
-			klog.Errorf("Removing key %q because it has zero-length Deltas", key)
-			continue
-		}
-		newQueue = append(newQueue, key)
-		newItems[key] = deltas
-	}
-	klog.Info("Finished repair of queue")
-	f.queue = newQueue
-	f.items = newItems
-}
-
 // A KeyListerGetter is anything that knows how to list its keys and look up by key.
 type KeyListerGetter interface {
 	KeyLister