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astdb: Improve prefix searches in astdb 

Using the LIKE operator requires a full table scan of 'astdb', whereas a
comparison operation is able to use the primary key index.

This patch adds a new function to the AstDB API for quick prefix matches
and updates res_sorcery_astdb to utilize it. This showed substantial
performance improvement in my test environment.

Related to ASTERISK~26806, but does not completely resolve it.

Change-Id: I7d37f9ba2aea139dabf2ca72d31fbe34bd9b2fa1
This commit is contained in:
Sean Bright 2017-12-07 15:19:40 -05:00
parent b0b28446c1
commit 9a9edc6c9e
3 changed files with 107 additions and 30 deletions
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10
include/asterisk/astdb.h
View File

@ -83,6 +83,16 @@ int ast_db_deltree(const char *family, const char *keytree);
*/
struct ast_db_entry *ast_db_gettree(const char *family, const char *keytree);
/*!
* \brief Get a list of values with the given key prefix
*
* \param family The family to search under
* \param key_prefix The key prefix to search under
*
* \retval NULL An error occurred
*/
struct ast_db_entry *ast_db_gettree_by_prefix(const char *family, const char *key_prefix);
/*! \brief Free structure created by ast_db_gettree() */
void ast_db_freetree(struct ast_db_entry *entry);

121
main/db.c
View File

@ -127,6 +127,20 @@ DEFINE_SQL_STATEMENT(gettree_all_stmt, "SELECT key, value FROM astdb ORDER BY ke
DEFINE_SQL_STATEMENT(showkey_stmt, "SELECT key, value FROM astdb WHERE key LIKE '%' || '/' || ? ORDER BY key")
DEFINE_SQL_STATEMENT(create_astdb_stmt, "CREATE TABLE IF NOT EXISTS astdb(key VARCHAR(256), value VARCHAR(256), PRIMARY KEY(key))")
/* This query begs an explanation:
*
* First, the parameter binding syntax used here is slightly different then the other
* queries in that we use a numbered parameter so that we can bind once and get the same
* value substituted multiple times within the executed query.
*
* Second, the key comparison is being used to find all keys that are lexicographically
* greater than the provided key, but less than the provided key with a high (but
* invalid) Unicode codepoint appended to it. This will give us all keys in the database
* that have 'key' as a prefix and performs much better than the equivalent "LIKE key ||
* '%'" operation.
*/
DEFINE_SQL_STATEMENT(gettree_prefix_stmt, "SELECT key, value FROM astdb WHERE key > ?1 AND key <= ?1 || X'ffff'")
static int init_stmt(sqlite3_stmt **stmt, const char *sql, size_t len)
{
ast_mutex_lock(&dblock);
@ -167,6 +181,7 @@ static void clean_statements(void)
clean_stmt(&deltree_all_stmt, deltree_all_stmt_sql);
clean_stmt(&gettree_stmt, gettree_stmt_sql);
clean_stmt(&gettree_all_stmt, gettree_all_stmt_sql);
clean_stmt(&gettree_prefix_stmt, gettree_prefix_stmt_sql);
clean_stmt(&showkey_stmt, showkey_stmt_sql);
clean_stmt(&put_stmt, put_stmt_sql);
clean_stmt(&create_astdb_stmt, create_astdb_stmt_sql);
@ -182,6 +197,7 @@ static int init_statements(void)
|| init_stmt(&deltree_all_stmt, deltree_all_stmt_sql, sizeof(deltree_all_stmt_sql))
|| init_stmt(&gettree_stmt, gettree_stmt_sql, sizeof(gettree_stmt_sql))
|| init_stmt(&gettree_all_stmt, gettree_all_stmt_sql, sizeof(gettree_all_stmt_sql))
|| init_stmt(&gettree_prefix_stmt, gettree_prefix_stmt_sql, sizeof(gettree_prefix_stmt_sql))
|| init_stmt(&showkey_stmt, showkey_stmt_sql, sizeof(showkey_stmt_sql))
|| init_stmt(&put_stmt, put_stmt_sql, sizeof(put_stmt_sql));
}
@ -473,19 +489,64 @@ int ast_db_deltree(const char *family, const char *keytree)
return res;
}
static struct ast_db_entry *db_gettree_common(sqlite3_stmt *stmt)
{
struct ast_db_entry *head = NULL, *prev = NULL, *cur;
while (sqlite3_step(stmt) == SQLITE_ROW) {
const char *key, *value;
size_t key_len, value_len;
key = (const char *) sqlite3_column_text(stmt, 0);
value = (const char *) sqlite3_column_text(stmt, 1);
if (!key || !value) {
break;
}
key_len = strlen(key);
value_len = strlen(value);
cur = ast_malloc(sizeof(*cur) + key_len + value_len + 2);
if (!cur) {
break;
}
cur->next = NULL;
cur->key = cur->data + value_len + 1;
memcpy(cur->data, value, value_len + 1);
memcpy(cur->key, key, key_len + 1);
if (prev) {
prev->next = cur;
} else {
head = cur;
}
prev = cur;
}
return head;
}
struct ast_db_entry *ast_db_gettree(const char *family, const char *keytree)
{
char prefix[MAX_DB_FIELD];
sqlite3_stmt *stmt = gettree_stmt;
struct ast_db_entry *cur, *last = NULL, *ret = NULL;
size_t res = 0;
struct ast_db_entry *ret;
if (!ast_strlen_zero(family)) {
if (!ast_strlen_zero(keytree)) {
/* Family and key tree */
snprintf(prefix, sizeof(prefix), "/%s/%s", family, keytree);
res = snprintf(prefix, sizeof(prefix), "/%s/%s", family, keytree);
} else {
/* Family only */
snprintf(prefix, sizeof(prefix), "/%s", family);
res = snprintf(prefix, sizeof(prefix), "/%s", family);
}
if (res >= sizeof(prefix)) {
ast_log(LOG_WARNING, "Requested prefix is too long: %s\n", keytree);
return NULL;
}
} else {
prefix[0] = '\0';
@ -493,41 +554,47 @@ struct ast_db_entry *ast_db_gettree(const char *family, const char *keytree)
}
ast_mutex_lock(&dblock);
if (!ast_strlen_zero(prefix) && (sqlite3_bind_text(stmt, 1, prefix, -1, SQLITE_STATIC) != SQLITE_OK)) {
ast_log(LOG_WARNING, "Could bind %s to stmt: %s\n", prefix, sqlite3_errmsg(astdb));
if (res && (sqlite3_bind_text(stmt, 1, prefix, res, SQLITE_STATIC) != SQLITE_OK)) {
ast_log(LOG_WARNING, "Could not bind %s to stmt: %s\n", prefix, sqlite3_errmsg(astdb));
sqlite3_reset(stmt);
ast_mutex_unlock(&dblock);
return NULL;
}
while (sqlite3_step(stmt) == SQLITE_ROW) {
const char *key_s, *value_s;
if (!(key_s = (const char *) sqlite3_column_text(stmt, 0))) {
break;
}
if (!(value_s = (const char *) sqlite3_column_text(stmt, 1))) {
break;
}
if (!(cur = ast_malloc(sizeof(*cur) + strlen(key_s) + strlen(value_s) + 2))) {
break;
}
cur->next = NULL;
cur->key = cur->data + strlen(value_s) + 1;
strcpy(cur->data, value_s);
strcpy(cur->key, key_s);
if (last) {
last->next = cur;
} else {
ret = cur;
}
last = cur;
}
ret = db_gettree_common(stmt);
sqlite3_reset(stmt);
ast_mutex_unlock(&dblock);
return ret;
}
struct ast_db_entry *ast_db_gettree_by_prefix(const char *family, const char *key_prefix)
{
char prefix[MAX_DB_FIELD];
size_t res;
struct ast_db_entry *ret;
res = snprintf(prefix, sizeof(prefix), "/%s/%s", family, key_prefix);
if (res >= sizeof(prefix)) {
ast_log(LOG_WARNING, "Requested key prefix is too long: %s\n", key_prefix);
return NULL;
}
ast_mutex_lock(&dblock);
if (sqlite3_bind_text(gettree_prefix_stmt, 1, prefix, res, SQLITE_STATIC) != SQLITE_OK) {
ast_log(LOG_WARNING, "Could not bind %s to stmt: %s\n", prefix, sqlite3_errmsg(astdb));
sqlite3_reset(gettree_prefix_stmt);
ast_mutex_unlock(&dblock);
return NULL;
}
ret = db_gettree_common(gettree_prefix_stmt);
sqlite3_reset(gettree_prefix_stmt);
ast_mutex_unlock(&dblock);
return ret;
}
void ast_db_freetree(struct ast_db_entry *dbe)
{
struct ast_db_entry *last;

6
res/res_sorcery_astdb.c
View File

@ -334,14 +334,14 @@ static void sorcery_astdb_retrieve_prefix(const struct ast_sorcery *sorcery, voi
const char *family_prefix = data;
size_t family_len = strlen(family_prefix) + strlen(type) + 1; /* +1 for slash delimiter */
char family[family_len + 1];
char tree[prefix_len + sizeof("%")];
char tree[prefix_len + 1];
RAII_VAR(struct ast_db_entry *, entries, NULL, ast_db_freetree);
struct ast_db_entry *entry;
snprintf(tree, sizeof(tree), "%.*s%%", (int) prefix_len, prefix);
snprintf(tree, sizeof(tree), "%.*s", (int) prefix_len, prefix);
snprintf(family, sizeof(family), "%s/%s", family_prefix, type);
if (!(entries = ast_db_gettree(family, tree))) {
if (!(entries = ast_db_gettree_by_prefix(family, tree))) {
return;
}