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// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package trace
import (
"fmt"
"strings"
"testing"
"slices"
)
func TestHeap(t *testing.T) {
var heap []*batchCursor
// Insert a bunch of values into the heap.
checkHeap(t, heap)
heap = heapInsert(heap, makeBatchCursor(5))
checkHeap(t, heap)
for i := int64(-20); i < 20; i++ {
heap = heapInsert(heap, makeBatchCursor(i))
checkHeap(t, heap)
}
// Update an element in the middle to be the new minimum.
for i := range heap {
if heap[i].ev.time == 5 {
heap[i].ev.time = -21
heapUpdate(heap, i)
break
}
}
checkHeap(t, heap)
if heap[0].ev.time != -21 {
t.Fatalf("heap update failed, expected %d as heap min: %s", -21, heapDebugString(heap))
}
// Update the minimum element to be smaller. There should be no change.
heap[0].ev.time = -22
heapUpdate(heap, 0)
checkHeap(t, heap)
if heap[0].ev.time != -22 {
t.Fatalf("heap update failed, expected %d as heap min: %s", -22, heapDebugString(heap))
}
// Update the last element to be larger. There should be no change.
heap[len(heap)-1].ev.time = 21
heapUpdate(heap, len(heap)-1)
checkHeap(t, heap)
if heap[len(heap)-1].ev.time != 21 {
t.Fatalf("heap update failed, expected %d as heap min: %s", 21, heapDebugString(heap))
}
// Update the last element to be smaller.
heap[len(heap)-1].ev.time = 7
heapUpdate(heap, len(heap)-1)
checkHeap(t, heap)
if heap[len(heap)-1].ev.time == 21 {
t.Fatalf("heap update failed, unexpected %d as heap min: %s", 21, heapDebugString(heap))
}
// Remove an element in the middle.
for i := range heap {
if heap[i].ev.time == 5 {
heap = heapRemove(heap, i)
break
}
}
checkHeap(t, heap)
for i := range heap {
if heap[i].ev.time == 5 {
t.Fatalf("failed to remove heap elem with time %d: %s", 5, heapDebugString(heap))
}
}
// Remove tail.
heap = heapRemove(heap, len(heap)-1)
checkHeap(t, heap)
// Remove from the head, and make sure the result is sorted.
l := len(heap)
var removed []*batchCursor
for i := 0; i < l; i++ {
removed = append(removed, heap[0])
heap = heapRemove(heap, 0)
checkHeap(t, heap)
}
if !slices.IsSortedFunc(removed, (*batchCursor).compare) {
t.Fatalf("heap elements not removed in sorted order, got: %s", heapDebugString(removed))
}
}
func makeBatchCursor(v int64) *batchCursor {
return &batchCursor{ev: baseEvent{time: Time(v)}}
}
func heapDebugString(heap []*batchCursor) string {
var sb strings.Builder
fmt.Fprintf(&sb, "[")
for i := range heap {
if i != 0 {
fmt.Fprintf(&sb, ", ")
}
fmt.Fprintf(&sb, "%d", heap[i].ev.time)
}
fmt.Fprintf(&sb, "]")
return sb.String()
}
func checkHeap(t *testing.T, heap []*batchCursor) {
t.Helper()
for i := range heap {
if i == 0 {
continue
}
if heap[(i-1)/2].compare(heap[i]) > 0 {
t.Errorf("heap invariant not maintained between index %d and parent %d: %s", i, i/2, heapDebugString(heap))
}
}
if t.Failed() {
t.FailNow()
}
}
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