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, 40 insertions, 0 deletions

diff --git a/pkg/fuzzer/queue/prio_queue_test.go b/pkg/fuzzer/queue/prio_queue_test.go
new file mode 100644
index 000000000..a82886bdd
--- /dev/null
+++ b/pkg/fuzzer/queue/prio_queue_test.go
@@ -0,0 +1,40 @@
+// 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/stretchr/testify/assert"
+)
+
+func TestNextPriority(t *testing.T) {
+	first := priority{0}
+	second := first.next()
+	third := second.next()
+	assert.True(t, first.greaterThan(second))
+	assert.True(t, second.greaterThan(third))
+}
+
+func TestPriority(t *testing.T) {
+	assert.True(t, priority{1, 2}.greaterThan(priority{1, 1}))
+	assert.True(t, priority{3, 2}.greaterThan(priority{2, 3}))
+	assert.True(t, priority{1, -5}.greaterThan(priority{1, -10}))
+	assert.True(t, priority{1}.greaterThan(priority{1, -1}))
+	assert.False(t, priority{1}.greaterThan(priority{1, 1}))
+	assert.True(t, priority{1, 0}.greaterThan(priority{1}))
+}
+
+func TestPrioQueueOrder(t *testing.T) {
+	pq := priorityQueueOps[int]{}
+	pq.Push(1, priority{1})
+	pq.Push(3, priority{3})
+	pq.Push(2, priority{2})
+
+	assert.Equal(t, 3, pq.Pop())
+	assert.Equal(t, 2, pq.Pop())
+	assert.Equal(t, 1, pq.Pop())
+	assert.Zero(t, pq.Pop())
+	assert.Zero(t, pq.Len())
+}