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radix-tree: More debugging of remove

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There's now a pretty printer called radix_tree_dump()

n4, n16, and n48 weren't UNSETting the last entry after
sliding values down.
This commit is contained in:
Joe Thornber 2018-06-20 10:04:59 +01:00
parent c8cfbfa605
commit 40c1f7889f
3 changed files with 174 additions and 17 deletions
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151
base/data-struct/radix-tree.c
View File

@ -251,7 +251,11 @@ static bool _insert_prefix_chain(struct radix_tree *rt, struct value *v, uint8_t
{
struct prefix_chain *pc = v->value.ptr;
if (*kb == pc->prefix[0]) {
if (!pc->len) {
v->type = VALUE;
v->value = rv;
} else if (*kb == pc->prefix[0]) {
// There's a common prefix let's split the chain into two and
// recurse.
struct prefix_chain *pc2;
@ -282,25 +286,23 @@ static bool _insert_prefix_chain(struct radix_tree *rt, struct value *v, uint8_t
if (!n4)
return false;
n4->keys[0] = *kb;
if (!_insert(rt, n4->values, kb + 1, ke, rv)) {
free(n4);
return false;
}
if (pc->len) {
n4->keys[1] = pc->prefix[0];
n4->keys[0] = pc->prefix[0];
if (pc->len == 1) {
n4->values[1] = pc->child;
n4->values[0] = pc->child;
free(pc);
} else {
memmove(pc->prefix, pc->prefix + 1, pc->len - 1);
pc->len--;
n4->values[1] = *v;
n4->values[0] = *v;
}
n4->keys[1] = *kb;
if (!_insert(rt, n4->values + 1, kb + 1, ke, rv)) {
free(n4);
return false;
}
n4->nr_entries = 2;
} else
n4->nr_entries = 1;
v->type = NODE4;
v->value.ptr = n4;
@ -330,7 +332,6 @@ static bool _insert_node4(struct radix_tree *rt, struct value *v, uint8_t *kb, u
v->type = NODE16;
v->value.ptr = n16;
} else {
n4 = v->value.ptr;
if (!_insert(rt, n4->values + n4->nr_entries, kb + 1, ke, rv))
return false;
@ -699,6 +700,7 @@ static bool _remove(struct radix_tree *rt, struct value *root, uint8_t *kb, uint
}
n4->nr_entries--;
n4->values[n4->nr_entries].type = UNSET;
if (!n4->nr_entries) {
free(n4);
root->type = UNSET;
@ -721,6 +723,7 @@ static bool _remove(struct radix_tree *rt, struct value *root, uint8_t *kb, uint
}
n16->nr_entries--;
n16->values[n16->nr_entries].type = UNSET;
if (n16->nr_entries <= 4) {
_degrade_to_n4(n16, root);
}
@ -742,6 +745,7 @@ static bool _remove(struct radix_tree *rt, struct value *root, uint8_t *kb, uint
n48->keys[j]--;
_erase_elt(n48->values, sizeof(*n48->values), n48->nr_entries, i);
n48->nr_entries--;
n48->values[n48->nr_entries].type = UNSET;
if (n48->nr_entries <= 16)
_degrade_to_n16(n48, root);
}
@ -1024,6 +1028,8 @@ void radix_tree_iterate(struct radix_tree *rt, uint8_t *kb, uint8_t *ke,
// Checks:
// 1) The number of entries matches rt->nr_entries
// 2) The number of entries is correct in each node
// 3) prefix chain len > 0
// 4) all unused values are UNSET
static bool _check_nodes(struct value *v, unsigned *count)
{
@ -1057,6 +1063,13 @@ static bool _check_nodes(struct value *v, unsigned *count)
for (i = 0; i < n4->nr_entries; i++)
if (!_check_nodes(n4->values + i, count))
return false;
for (i = n4->nr_entries; i < 4; i++)
if (n4->values[i].type != UNSET) {
fprintf(stderr, "unused value is not UNSET\n");
return false;
}
return true;
case NODE16:
@ -1064,6 +1077,13 @@ static bool _check_nodes(struct value *v, unsigned *count)
for (i = 0; i < n16->nr_entries; i++)
if (!_check_nodes(n16->values + i, count))
return false;
for (i = n16->nr_entries; i < 16; i++)
if (n16->values[i].type != UNSET) {
fprintf(stderr, "unused value is not UNSET\n");
return false;
}
return true;
case NODE48:
@ -1083,6 +1103,12 @@ static bool _check_nodes(struct value *v, unsigned *count)
return false;
}
for (i = n48->nr_entries; i < 48; i++)
if (n48->values[i].type != UNSET) {
fprintf(stderr, "unused value is not UNSET\n");
return false;
}
return true;
case NODE256:
@ -1134,3 +1160,100 @@ bool radix_tree_is_well_formed(struct radix_tree *rt)
}
//----------------------------------------------------------------
static void _dump(FILE *out, struct value v, unsigned indent)
{
unsigned i;
struct value_chain *vc;
struct prefix_chain *pc;
struct node4 *n4;
struct node16 *n16;
struct node48 *n48;
struct node256 *n256;
if (v.type == UNSET)
return;
for (i = 0; i < 2 * indent; i++)
fprintf(out, " ");
switch (v.type) {
case UNSET:
// can't happen
break;
case VALUE:
fprintf(out, "<val: %llu>\n", (unsigned long long) v.value.n);
break;
case VALUE_CHAIN:
vc = v.value.ptr;
fprintf(out, "<val_chain: %llu>\n", (unsigned long long) vc->value.n);
_dump(out, vc->child, indent + 1);
break;
case PREFIX_CHAIN:
pc = v.value.ptr;
fprintf(out, "<prefix: ");
for (i = 0; i < pc->len; i++)
fprintf(out, "%x.", (unsigned) *(pc->prefix + i));
fprintf(out, ">\n");
_dump(out, pc->child, indent + 1);
break;
case NODE4:
n4 = v.value.ptr;
fprintf(out, "<n4: ");
for (i = 0; i < n4->nr_entries; i++)
fprintf(out, "%x ", (unsigned) n4->keys[i]);
fprintf(out, ">\n");
for (i = 0; i < n4->nr_entries; i++)
_dump(out, n4->values[i], indent + 1);
break;
case NODE16:
n16 = v.value.ptr;
fprintf(out, "<n16: ");
for (i = 0; i < n16->nr_entries; i++)
fprintf(out, "%x ", (unsigned) n16->keys[i]);
fprintf(out, ">\n");
for (i = 0; i < n16->nr_entries; i++)
_dump(out, n16->values[i], indent + 1);
break;
case NODE48:
n48 = v.value.ptr;
fprintf(out, "<n48: ");
for (i = 0; i < 256; i++)
if (n48->keys[i] < 48)
fprintf(out, "%x ", i);
fprintf(out, ">\n");
for (i = 0; i < 256; i++)
if (n48->keys[i] < 48)
_dump(out, n48->values[i], indent + 1);
break;
case NODE256:
n256 = v.value.ptr;
fprintf(out, "<n256: ");
for (i = 0; i < 256; i++)
if (n256->values[i].type != UNSET)
fprintf(out, "%x ", i);
fprintf(out, ">\n");
for (i = 0; i < 256; i++)
if (n256->values[i].type != UNSET)
_dump(out, n256->values[i], indent + 1);
break;
}
}
void radix_tree_dump(struct radix_tree *rt, FILE *out)
{
_dump(out, rt->root, 0);
}
//----------------------------------------------------------------

2
base/data-struct/radix-tree.h
View File

@ -15,6 +15,7 @@
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
//----------------------------------------------------------------
@ -56,6 +57,7 @@ void radix_tree_iterate(struct radix_tree *rt, uint8_t *kb, uint8_t *ke,
// Checks that some constraints on the shape of the tree are
// being held. For debug only.
bool radix_tree_is_well_formed(struct radix_tree *rt);
void radix_tree_dump(struct radix_tree *rt, FILE *out);
//----------------------------------------------------------------

32
test/unit/radix_tree_t.c
View File

@ -605,6 +605,37 @@ static void test_destroy_calls_dtr(void *fixture)
//----------------------------------------------------------------
static void test_bcache_scenario(void *fixture)
{
struct radix_tree *rt = fixture;
unsigned i;
uint8_t k[6];
union radix_value v;
memset(k, 0, sizeof(k));
for (i = 0; i < 3; i++) {
// it has to be the 4th byte that varies to
// trigger the bug.
k[4] = i;
v.n = i;
T_ASSERT(radix_tree_insert(rt, k, k + sizeof(k), v));
}
T_ASSERT(radix_tree_is_well_formed(rt));
k[4] = 0;
T_ASSERT(radix_tree_remove(rt, k, k + sizeof(k)));
T_ASSERT(radix_tree_is_well_formed(rt));
k[4] = i;
v.n = i;
T_ASSERT(radix_tree_insert(rt, k, k + sizeof(k), v));
T_ASSERT(radix_tree_is_well_formed(rt));
}
//----------------------------------------------------------------
#define T(path, desc, fn) register_test(ts, "/base/data-struct/radix-tree/" path, desc, fn)
void radix_tree_tests(struct dm_list *all_tests)
@ -637,6 +668,7 @@ void radix_tree_tests(struct dm_list *all_tests)
T("iterate-vary-middle", "iterate keys that vary in the middle", test_iterate_vary_middle);
T("remove-calls-dtr", "remove should call the dtr for the value", test_remove_calls_dtr);
T("destroy-calls-dtr", "destroy should call the dtr for all values", test_destroy_calls_dtr);
T("bcache-scenario", "A specific series of keys from a bcache scenario", test_bcache_scenario);
dm_list_add(all_tests, &ts->list);
}