Refactor/fix ph.

Refactor ph to support configurable comparison functions.  Use a cpp
macro code generation form equivalent to the rb macros so that pairing
heaps can be used for both run heaps and chunk heaps.

Remove per node parent pointers, and instead use leftmost siblings' prev
pointers to track parents.

Fix multi-pass sibling merging to iterate over intermediate results
using a FIFO, rather than a LIFO.  Use this fixed sibling merging
implementation for both merge phases of the auxiliary twopass algorithm
(first merging the aux list, then replacing the root with its merged
children).  This fixes both degenerate merge behavior and the potential
for deep recursion.

This regression was introduced by
6bafa6678f (Pairing heap).

This resolves #371.
This commit is contained in:
Jason Evans
2016-03-26 17:30:37 -07:00
parent 2ee2f1ec57
commit c6a2c39404
8 changed files with 613 additions and 335 deletions

View File

@@ -3,58 +3,275 @@
typedef struct node_s node_t;
struct node_s {
ph_node_t link;
#define NODE_MAGIC 0x9823af7e
uint32_t magic;
phn(node_t) link;
uint64_t key;
};
static int
node_cmp(const node_t *a, const node_t *b)
{
int ret;
ret = (a->key > b->key) - (a->key < b->key);
if (ret == 0) {
/*
* Duplicates are not allowed in the heap, so force an
* arbitrary ordering for non-identical items with equal keys.
*/
ret = (((uintptr_t)a) > ((uintptr_t)b))
- (((uintptr_t)a) < ((uintptr_t)b));
}
return (ret);
}
static int
node_cmp_magic(const node_t *a, const node_t *b) {
assert_u32_eq(a->magic, NODE_MAGIC, "Bad magic");
assert_u32_eq(b->magic, NODE_MAGIC, "Bad magic");
return (node_cmp(a, b));
}
typedef ph(node_t) heap_t;
ph_gen(static, heap_, heap_t, node_t, link, node_cmp_magic);
static void
node_print(const node_t *node, unsigned depth)
{
unsigned i;
node_t *leftmost_child, *sibling;
for (i = 0; i < depth; i++)
malloc_printf("\t");
malloc_printf("%2"FMTu64"\n", node->key);
leftmost_child = phn_lchild_get(node_t, link, node);
if (leftmost_child == NULL)
return;
node_print(leftmost_child, depth + 1);
for (sibling = phn_next_get(node_t, link, leftmost_child); sibling !=
NULL; sibling = phn_next_get(node_t, link, sibling)) {
node_print(sibling, depth + 1);
}
}
static void
heap_print(const heap_t *heap)
{
node_t *auxelm;
malloc_printf("vvv heap %p vvv\n", heap);
if (heap->ph_root == NULL)
goto label_return;
node_print(heap->ph_root, 0);
for (auxelm = phn_next_get(node_t, link, heap->ph_root); auxelm != NULL;
auxelm = phn_next_get(node_t, link, auxelm)) {
assert_ptr_eq(phn_next_get(node_t, link, phn_prev_get(node_t,
link, auxelm)), auxelm,
"auxelm's prev doesn't link to auxelm");
node_print(auxelm, 0);
}
label_return:
malloc_printf("^^^ heap %p ^^^\n", heap);
}
static unsigned
node_validate(const node_t *node, const node_t *parent)
{
unsigned nnodes = 1;
node_t *leftmost_child, *sibling;
if (parent != NULL) {
assert_d_ge(node_cmp_magic(node, parent), 0,
"Child is less than parent");
}
leftmost_child = phn_lchild_get(node_t, link, node);
if (leftmost_child == NULL)
return (nnodes);
assert_ptr_eq((void *)phn_prev_get(node_t, link, leftmost_child),
(void *)node, "Leftmost child does not link to node");
nnodes += node_validate(leftmost_child, node);
for (sibling = phn_next_get(node_t, link, leftmost_child); sibling !=
NULL; sibling = phn_next_get(node_t, link, sibling)) {
assert_ptr_eq(phn_next_get(node_t, link, phn_prev_get(node_t,
link, sibling)), sibling,
"sibling's prev doesn't link to sibling");
nnodes += node_validate(sibling, node);
}
return (nnodes);
}
static unsigned
heap_validate(const heap_t *heap)
{
unsigned nnodes = 0;
node_t *auxelm;
if (heap->ph_root == NULL)
goto label_return;
nnodes += node_validate(heap->ph_root, NULL);
for (auxelm = phn_next_get(node_t, link, heap->ph_root); auxelm != NULL;
auxelm = phn_next_get(node_t, link, auxelm)) {
assert_ptr_eq(phn_next_get(node_t, link, phn_prev_get(node_t,
link, auxelm)), auxelm,
"auxelm's prev doesn't link to auxelm");
nnodes += node_validate(auxelm, NULL);
}
label_return:
if (false)
heap_print(heap);
return (nnodes);
}
TEST_BEGIN(test_ph_empty)
{
ph_heap_t heap;
heap_t heap;
ph_new(&heap);
assert_ptr_null(ph_first(&heap), "Unexpected node");
heap_new(&heap);
assert_true(heap_empty(&heap), "Heap should be empty");
assert_ptr_null(heap_first(&heap), "Unexpected node");
}
TEST_END
static void
node_remove(heap_t *heap, node_t *node)
{
heap_remove(heap, node);
node->magic = 0;
}
static node_t *
node_remove_first(heap_t *heap)
{
node_t *node = heap_remove_first(heap);
node->magic = 0;
return (node);
}
TEST_BEGIN(test_ph_random)
{
#define NNODES 25
#define NBAGS 250
#define SEED 42
sfmt_t *sfmt;
ph_heap_t heap;
uint64_t bag[NNODES];
heap_t heap;
node_t nodes[NNODES];
unsigned i, j, k;
sfmt = init_gen_rand(SEED);
for (i = 0; i < 2; i++) {
for (i = 0; i < NBAGS; i++) {
switch (i) {
case 0:
/* Insert in order. */
for (j = 0; j < NNODES; j++)
bag[j] = j;
break;
case 1:
/* Insert in reverse order. */
for (j = 0; j < NNODES; j++)
bag[j] = NNODES - j - 1;
break;
default:
for (j = 0; j < NNODES; j++)
bag[j] = gen_rand64_range(sfmt, NNODES);
}
for (j = 1; j <= NNODES; j++) {
/* Initialize heap and nodes. */
ph_new(&heap);
heap_new(&heap);
assert_u_eq(heap_validate(&heap), 0,
"Incorrect node count");
for (k = 0; k < j; k++) {
nodes[k].magic = NODE_MAGIC;
nodes[k].key = bag[k];
}
/* Insert nodes. */
for (k = 0; k < j; k++) {
ph_insert(&heap, &nodes[k].link);
assert_ptr_not_null(ph_first(&heap),
"Heap should not be empty");
heap_insert(&heap, &nodes[k]);
if (i % 13 == 12) {
/* Trigger merging. */
assert_ptr_not_null(heap_first(&heap),
"Heap should not be empty");
}
assert_u_eq(heap_validate(&heap), k + 1,
"Incorrect node count");
}
assert_false(heap_empty(&heap),
"Heap should not be empty");
/* Remove nodes. */
switch (i % 2) {
switch (i % 4) {
case 0:
for (k = 0; k < j; k++)
ph_remove(&heap, &nodes[k].link);
for (k = 0; k < j; k++) {
assert_u_eq(heap_validate(&heap), j - k,
"Incorrect node count");
node_remove(&heap, &nodes[k]);
assert_u_eq(heap_validate(&heap), j - k
- 1, "Incorrect node count");
}
break;
case 1:
for (k = j; k > 0; k--)
ph_remove(&heap, &nodes[k-1].link);
for (k = j; k > 0; k--) {
node_remove(&heap, &nodes[k-1]);
assert_u_eq(heap_validate(&heap), k - 1,
"Incorrect node count");
}
break;
default:
case 2: {
node_t *prev = NULL;
for (k = 0; k < j; k++) {
node_t *node = node_remove_first(&heap);
assert_u_eq(heap_validate(&heap), j - k
- 1, "Incorrect node count");
if (prev != NULL) {
assert_d_ge(node_cmp(node,
prev), 0,
"Bad removal order");
}
prev = node;
}
break;
} case 3: {
node_t *prev = NULL;
for (k = 0; k < j; k++) {
node_t *node = heap_first(&heap);
assert_u_eq(heap_validate(&heap), j - k,
"Incorrect node count");
if (prev != NULL) {
assert_d_ge(node_cmp(node,
prev), 0,
"Bad removal order");
}
node_remove(&heap, node);
assert_u_eq(heap_validate(&heap), j - k
- 1, "Incorrect node count");
prev = node;
}
break;
} default:
not_reached();
}
assert_ptr_null(ph_first(&heap),
"Heap should not be empty");
assert_ptr_null(heap_first(&heap),
"Heap should be empty");
assert_true(heap_empty(&heap), "Heap should be empty");
}
}
fini_gen_rand(sfmt);