Add Unique Queue infrastructure and move TestPullRequests to this (#9856)

* Upgrade levelqueue to version 0.2.0

This adds functionality for Unique Queues

* Add UniqueQueue interface and functions to create them

* Add UniqueQueue implementations

* Move TestPullRequests over to use UniqueQueue

* Reduce code duplication

* Add bytefifos

* Ensure invalid types are logged

* Fix close race in PersistableChannelQueue Shutdown

1 files changed, 61 insertions, 0 deletions

diff --git a/modules/queue/bytefifo.go b/modules/queue/bytefifo.go
new file mode 100644
index 0000000000..2cd0ba0b95
--- /dev/null
+++ b/modules/queue/bytefifo.go
@@ -0,0 +1,61 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package queue
+
+// ByteFIFO defines a FIFO that takes a byte array
+type ByteFIFO interface {
+	// Len returns the length of the fifo
+	Len() int64
+	// PushFunc pushes data to the end of the fifo and calls the callback if it is added
+	PushFunc(data []byte, fn func() error) error
+	// Pop pops data from the start of the fifo
+	Pop() ([]byte, error)
+	// Close this fifo
+	Close() error
+}
+
+// UniqueByteFIFO defines a FIFO that Uniques its contents
+type UniqueByteFIFO interface {
+	ByteFIFO
+	// Has returns whether the fifo contains this data
+	Has(data []byte) (bool, error)
+}
+
+var _ (ByteFIFO) = &DummyByteFIFO{}
+
+// DummyByteFIFO represents a dummy fifo
+type DummyByteFIFO struct{}
+
+// PushFunc returns nil
+func (*DummyByteFIFO) PushFunc(data []byte, fn func() error) error {
+	return nil
+}
+
+// Pop returns nil
+func (*DummyByteFIFO) Pop() ([]byte, error) {
+	return []byte{}, nil
+}
+
+// Close returns nil
+func (*DummyByteFIFO) Close() error {
+	return nil
+}
+
+// Len is always 0
+func (*DummyByteFIFO) Len() int64 {
+	return 0
+}
+
+var _ (UniqueByteFIFO) = &DummyUniqueByteFIFO{}
+
+// DummyUniqueByteFIFO represents a dummy unique fifo
+type DummyUniqueByteFIFO struct {
+	DummyByteFIFO
+}
+
+// Has always returns false
+func (*DummyUniqueByteFIFO) Has([]byte) (bool, error) {
+	return false, nil
+}