feat: drop item returns bool, whether item existed

cuckoo_fuzz_test.go

@@ -68,12 +68,13 @@ func FuzzInsertLookup(f *testing.F) {
 
 		for _, step := range scenario.steps {
 			if step.drop {
-				err := actual.Drop(step.key)
-				assert.NoError(err)
+				ok := actual.Drop(step.key)
+				_, has := expected[step.key]
+				assert.Equal(ok, has)
 
 				delete(expected, step.key)
 
-				_, err = actual.Get(step.key)
+				_, err := actual.Get(step.key)
 				assert.Error(err)
 			} else {
 				_, err := actual.Put(step.key, step.value)

cuckoo_test.go

@@ -124,9 +124,9 @@ func TestDropExistingItem(t *testing.T) {
 	table := cuckoo.NewTable[int, bool]()
 	(table.Put(key, value))
 
-	err := table.Drop(key)
+	had := table.Drop(key)
 
-	assert.NoError(err)
+	assert.True(had)
 	assert.Equal(0, table.Size())
 	assert.False(table.Has(key))
 }
@@ -136,9 +136,9 @@ func TestDropNoItem(t *testing.T) {
 	key := 0
 	table := cuckoo.NewTable[int, bool]()
 
-	err := table.Drop(key)
+	had := table.Drop(key)
 
-	assert.NoError(err)
+	assert.False(had)
 	assert.Equal(0, table.Size())
 	assert.False(table.Has(key))
 }
@@ -152,10 +152,9 @@ func TestDropItemCapacity(t *testing.T) {
 	)
 
 	startingCapacity := table.TotalCapacity()
-	err := table.Drop(key)
+	table.Drop(key)
 	endingCapacity := table.TotalCapacity()
 
-	assert.NoError(err)
 	assert.Equal(0, table.Size())
 	assert.Equal(uint64(128), startingCapacity)
 	assert.Equal(uint64(64), endingCapacity)
@@ -203,9 +202,9 @@ func TestDropResizeCapacity(t *testing.T) {
 
 	_, err1 := table.Put(0, true)
 	_, err2 := table.Put(1, true)
-	err3 := table.Drop(1)
+	table.Drop(1)
 
-	assert.NoError(errors.Join(err1, err2, err3))
+	assert.NoError(errors.Join(err1, err2))
 	assert.Equal(uint64(20), table.TotalCapacity())
 }
 

table.go

@@ -171,11 +171,10 @@ func (t *Table[K, V]) Put(key K, value V) (displaced Entry[K, V], err error) {
 	return entry, fmt.Errorf("bad hash: could not place entry after %d resizes", defaultGrowthLimit)
 }
 
-// Drop removes a value for a key in the table. Returns an error if its value
-// cannot be removed.
-func (t *Table[K, V]) Drop(key K) (err error) {
-	t.bucketA.drop(key)
-	t.bucketB.drop(key)
+// Drop removes a value for a key in the table. Returns whether the key had
+// existed.
+func (t *Table[K, V]) Drop(key K) bool {
+	occupied := t.bucketA.drop(key) || t.bucketB.drop(key)
 
 	if t.load() < t.minLoadFactor {
 		// The error is not handled here, because table-shrinking is an internal
@@ -183,7 +182,7 @@ func (t *Table[K, V]) Drop(key K) (err error) {
 		t.shrink()
 	}
 
-	return nil
+	return occupied
 }
 
 // Entries returns an unordered sequence of all key-value pairs in the table.