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zset.cpp
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zset.cpp
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#include <assert.h>
#include <string.h>
#include <stdlib.h>
// proj
#include "zset.h"
#include "common.h"
static ZNode *znode_new(const char *name, size_t len, double score) {
ZNode *node = (ZNode *)malloc(sizeof(ZNode) + len);
assert(node); // not a good idea in real projects
avl_init(&node->tree);
node->hmap.next = NULL;
node->hmap.hcode = str_hash((uint8_t *)name, len);
node->score = score;
node->len = len;
memcpy(&node->name[0], name, len);
return node;
}
static uint32_t min(size_t lhs, size_t rhs) {
return lhs < rhs ? lhs : rhs;
}
// compare by the (score, name) tuple
static bool zless(
AVLNode *lhs, double score, const char *name, size_t len)
{
ZNode *zl = container_of(lhs, ZNode, tree);
if (zl->score != score) {
return zl->score < score;
}
int rv = memcmp(zl->name, name, min(zl->len, len));
if (rv != 0) {
return rv < 0;
}
return zl->len < len;
}
static bool zless(AVLNode *lhs, AVLNode *rhs) {
ZNode *zr = container_of(rhs, ZNode, tree);
return zless(lhs, zr->score, zr->name, zr->len);
}
// insert into the AVL tree
static void tree_add(ZSet *zset, ZNode *node) {
if (!zset->tree) {
zset->tree = &node->tree;
return;
}
AVLNode *cur = zset->tree;
while (true) {
AVLNode **from = zless(&node->tree, cur) ? &cur->left : &cur->right;
if (!*from) {
*from = &node->tree;
node->tree.parent = cur;
zset->tree = avl_fix(&node->tree);
break;
}
cur = *from;
}
}
// update the score of an existing node (AVL tree reinsertion)
static void zset_update(ZSet *zset, ZNode *node, double score) {
if (node->score == score) {
return;
}
zset->tree = avl_del(&node->tree);
node->score = score;
avl_init(&node->tree);
tree_add(zset, node);
}
// add a new (score, name) tuple, or update the score of the existing tuple
bool zset_add(ZSet *zset, const char *name, size_t len, double score) {
ZNode *node = zset_lookup(zset, name, len);
if (node) {
zset_update(zset, node, score);
return false;
} else {
node = znode_new(name, len, score);
hm_insert(&zset->hmap, &node->hmap);
tree_add(zset, node);
return true;
}
}
// a helper structure for the hashtable lookup
struct HKey {
HNode node;
const char *name = NULL;
size_t len = 0;
};
static bool hcmp(HNode *node, HNode *key) {
if (node->hcode != key->hcode) {
return false;
}
ZNode *znode = container_of(node, ZNode, hmap);
HKey *hkey = container_of(key, HKey, node);
if (znode->len != hkey->len) {
return false;
}
return 0 == memcmp(znode->name, hkey->name, znode->len);
}
// lookup by name
ZNode *zset_lookup(ZSet *zset, const char *name, size_t len) {
if (!zset->tree) {
return NULL;
}
HKey key;
key.node.hcode = str_hash((uint8_t *)name, len);
key.name = name;
key.len = len;
HNode *found = hm_lookup(&zset->hmap, &key.node, &hcmp);
if (!found) {
return NULL;
}
return container_of(found, ZNode, hmap);
}
// deletion by name
ZNode *zset_pop(ZSet *zset, const char *name, size_t len) {
if (!zset->tree) {
return NULL;
}
HKey key;
key.node.hcode = str_hash((uint8_t *)name, len);
key.name = name;
key.len = len;
HNode *found = hm_pop(&zset->hmap, &key.node, &hcmp);
if (!found) {
return NULL;
}
ZNode *node = container_of(found, ZNode, hmap);
zset->tree = avl_del(&node->tree);
return node;
}
// find the (score, name) tuple that is greater or equal to the argument,
// then offset relative to it.
ZNode *zset_query(
ZSet *zset, double score, const char *name, size_t len, int64_t offset)
{
AVLNode *found = NULL;
AVLNode *cur = zset->tree;
while (cur) {
if (zless(cur, score, name, len)) {
cur = cur->right;
} else {
found = cur; // candidate
cur = cur->left;
}
}
if (found) {
found = avl_offset(found, offset);
}
return found ? container_of(found, ZNode, tree) : NULL;
}
void znode_del(ZNode *node) {
free(node);
}
static void tree_dispose(AVLNode *node) {
if (!node) {
return;
}
tree_dispose(node->left);
tree_dispose(node->right);
znode_del(container_of(node, ZNode, tree));
}
// destroy the zset
void zset_dispose(ZSet *zset) {
tree_dispose(zset->tree);
hm_destroy(&zset->hmap);
}