lib: Introduce generic min-heap
Supports push, pop and converting an array into a heap. If the sense of
the compare function is inverted then it can provide a max-heap.
Based-on-work-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200214075133.181299-3-irogers@google.com
diff --git a/lib/test_min_heap.c b/lib/test_min_heap.c
new file mode 100644
index 0000000..d19c808
--- /dev/null
+++ b/lib/test_min_heap.c
@@ -0,0 +1,194 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#define pr_fmt(fmt) "min_heap_test: " fmt
+
+/*
+ * Test cases for the min max heap.
+ */
+
+#include <linux/log2.h>
+#include <linux/min_heap.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/random.h>
+
+static __init bool less_than(const void *lhs, const void *rhs)
+{
+ return *(int *)lhs < *(int *)rhs;
+}
+
+static __init bool greater_than(const void *lhs, const void *rhs)
+{
+ return *(int *)lhs > *(int *)rhs;
+}
+
+static __init void swap_ints(void *lhs, void *rhs)
+{
+ int temp = *(int *)lhs;
+
+ *(int *)lhs = *(int *)rhs;
+ *(int *)rhs = temp;
+}
+
+static __init int pop_verify_heap(bool min_heap,
+ struct min_heap *heap,
+ const struct min_heap_callbacks *funcs)
+{
+ int *values = heap->data;
+ int err = 0;
+ int last;
+
+ last = values[0];
+ min_heap_pop(heap, funcs);
+ while (heap->nr > 0) {
+ if (min_heap) {
+ if (last > values[0]) {
+ pr_err("error: expected %d <= %d\n", last,
+ values[0]);
+ err++;
+ }
+ } else {
+ if (last < values[0]) {
+ pr_err("error: expected %d >= %d\n", last,
+ values[0]);
+ err++;
+ }
+ }
+ last = values[0];
+ min_heap_pop(heap, funcs);
+ }
+ return err;
+}
+
+static __init int test_heapify_all(bool min_heap)
+{
+ int values[] = { 3, 1, 2, 4, 0x8000000, 0x7FFFFFF, 0,
+ -3, -1, -2, -4, 0x8000000, 0x7FFFFFF };
+ struct min_heap heap = {
+ .data = values,
+ .nr = ARRAY_SIZE(values),
+ .size = ARRAY_SIZE(values),
+ };
+ struct min_heap_callbacks funcs = {
+ .elem_size = sizeof(int),
+ .less = min_heap ? less_than : greater_than,
+ .swp = swap_ints,
+ };
+ int i, err;
+
+ /* Test with known set of values. */
+ min_heapify_all(&heap, &funcs);
+ err = pop_verify_heap(min_heap, &heap, &funcs);
+
+
+ /* Test with randomly generated values. */
+ heap.nr = ARRAY_SIZE(values);
+ for (i = 0; i < heap.nr; i++)
+ values[i] = get_random_int();
+
+ min_heapify_all(&heap, &funcs);
+ err += pop_verify_heap(min_heap, &heap, &funcs);
+
+ return err;
+}
+
+static __init int test_heap_push(bool min_heap)
+{
+ const int data[] = { 3, 1, 2, 4, 0x80000000, 0x7FFFFFFF, 0,
+ -3, -1, -2, -4, 0x80000000, 0x7FFFFFFF };
+ int values[ARRAY_SIZE(data)];
+ struct min_heap heap = {
+ .data = values,
+ .nr = 0,
+ .size = ARRAY_SIZE(values),
+ };
+ struct min_heap_callbacks funcs = {
+ .elem_size = sizeof(int),
+ .less = min_heap ? less_than : greater_than,
+ .swp = swap_ints,
+ };
+ int i, temp, err;
+
+ /* Test with known set of values copied from data. */
+ for (i = 0; i < ARRAY_SIZE(data); i++)
+ min_heap_push(&heap, &data[i], &funcs);
+
+ err = pop_verify_heap(min_heap, &heap, &funcs);
+
+ /* Test with randomly generated values. */
+ while (heap.nr < heap.size) {
+ temp = get_random_int();
+ min_heap_push(&heap, &temp, &funcs);
+ }
+ err += pop_verify_heap(min_heap, &heap, &funcs);
+
+ return err;
+}
+
+static __init int test_heap_pop_push(bool min_heap)
+{
+ const int data[] = { 3, 1, 2, 4, 0x80000000, 0x7FFFFFFF, 0,
+ -3, -1, -2, -4, 0x80000000, 0x7FFFFFFF };
+ int values[ARRAY_SIZE(data)];
+ struct min_heap heap = {
+ .data = values,
+ .nr = 0,
+ .size = ARRAY_SIZE(values),
+ };
+ struct min_heap_callbacks funcs = {
+ .elem_size = sizeof(int),
+ .less = min_heap ? less_than : greater_than,
+ .swp = swap_ints,
+ };
+ int i, temp, err;
+
+ /* Fill values with data to pop and replace. */
+ temp = min_heap ? 0x80000000 : 0x7FFFFFFF;
+ for (i = 0; i < ARRAY_SIZE(data); i++)
+ min_heap_push(&heap, &temp, &funcs);
+
+ /* Test with known set of values copied from data. */
+ for (i = 0; i < ARRAY_SIZE(data); i++)
+ min_heap_pop_push(&heap, &data[i], &funcs);
+
+ err = pop_verify_heap(min_heap, &heap, &funcs);
+
+ heap.nr = 0;
+ for (i = 0; i < ARRAY_SIZE(data); i++)
+ min_heap_push(&heap, &temp, &funcs);
+
+ /* Test with randomly generated values. */
+ for (i = 0; i < ARRAY_SIZE(data); i++) {
+ temp = get_random_int();
+ min_heap_pop_push(&heap, &temp, &funcs);
+ }
+ err += pop_verify_heap(min_heap, &heap, &funcs);
+
+ return err;
+}
+
+static int __init test_min_heap_init(void)
+{
+ int err = 0;
+
+ err += test_heapify_all(true);
+ err += test_heapify_all(false);
+ err += test_heap_push(true);
+ err += test_heap_push(false);
+ err += test_heap_pop_push(true);
+ err += test_heap_pop_push(false);
+ if (err) {
+ pr_err("test failed with %d errors\n", err);
+ return -EINVAL;
+ }
+ pr_info("test passed\n");
+ return 0;
+}
+module_init(test_min_heap_init);
+
+static void __exit test_min_heap_exit(void)
+{
+ /* do nothing */
+}
+module_exit(test_min_heap_exit);
+
+MODULE_LICENSE("GPL");