pkg/fuzzer: use queue layers

Instead of relying on a fuzzer-internal priority queue, utilize
stackable layers of request-generating steps.

Move the functionality to a separate pkg/fuzzer/queue package.

The pkg/fuzzer/queue package can be reused to add extra processing
layers on top of the fuzzing and to combine machine checking and fuzzing
execution pipelines.

1 files changed, 54 insertions, 0 deletions

diff --git a/pkg/fuzzer/queue/queue_test.go b/pkg/fuzzer/queue/queue_test.go
new file mode 100644
index 000000000..34a34ccbe
--- /dev/null
+++ b/pkg/fuzzer/queue/queue_test.go
@@ -0,0 +1,54 @@
+// Copyright 2024 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package queue
+
+import (
+	"testing"
+
+	"github.com/google/syzkaller/pkg/stats"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPlainQueue(t *testing.T) {
+	val := stats.Create("v0", "desc0")
+	pq := PlainWithStat(val)
+
+	req1, req2, req3 := &Request{}, &Request{}, &Request{}
+
+	pq.Submit(req1)
+	assert.Equal(t, 1, val.Val())
+	pq.Submit(req2)
+	assert.Equal(t, 2, val.Val())
+
+	assert.Equal(t, req1, pq.Next())
+	assert.Equal(t, 1, val.Val())
+
+	assert.Equal(t, req2, pq.Next())
+	assert.Equal(t, 0, val.Val())
+
+	pq.Submit(req3)
+	assert.Equal(t, 1, val.Val())
+	assert.Equal(t, req3, pq.Next())
+	assert.Nil(t, pq.Next())
+}
+
+func TestPrioQueue(t *testing.T) {
+	req1, req2, req3, req4 :=
+		&Request{}, &Request{}, &Request{}, &Request{}
+	pq := Priority()
+
+	pq1 := pq.AppendQueue()
+	pq2 := pq.AppendQueue()
+	pq3 := pq.AppendQueue()
+
+	pq2.Submit(req2)
+	pq3.Submit(req3)
+	pq3.Submit(req4)
+	pq1.Submit(req1)
+
+	assert.Equal(t, req1, pq.Next())
+	assert.Equal(t, req2, pq.Next())
+	assert.Equal(t, req3, pq.Next())
+	assert.Equal(t, req4, pq.Next())
+}