Php/docs/mysqlnd-qc.set-user-handlers

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Beyond TTL: user-defined storage

The query cache plugin supports the use of user-defined storage handler. User-defined storage handler can use arbitrarily complex invalidation algorithms and support arbitrary storage media.

All user-defined storage handlers have to provide a certain interface. The functions of the user-defined storage handler will be called by the core of the cache plugin. The necessary interface consists of seven public functions. Both procedural and object oriented user-defined storage handler must implement the same set of functions.

Example #1 Using a user-defined storage handler

<?php/* Enable default caching of all statements */ini_set("mysqlnd_qc.cache_by_default", 1);/* Procedural user defined storage handler functions */$__cache = array();function get_hash($host_info, $port, $user, $db, $query) {    global $__cache;    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());    return md5(sprintf("%s%s%s%s%s", $host_info, $port, $user, $db, $query));}function find_query_in_cache($key) {    global $__cache;    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());    if (isset($__cache[$key])) {        $tmp = $__cache[$key];        if ($tmp["valid_until"] < time()) {            unset($__cache[$key]);            $ret = NULL;        } else {            $ret = $__cache[$key]["data"];        }    } else {        $ret = NULL;    }    return $ret;}function return_to_cache($key) {    /*     Called on cache hit after cached data has been processed,     may be used for reference counting    */    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());}function add_query_to_cache_if_not_exists($key, $data, $ttl, $run_time, $store_time, $row_count) {    global $__cache;    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());    $__cache[$key] = array(        "data"               => $data,        "row_count"          => $row_count,        "valid_until"        => time() + $ttl,        "hits"               => 0,        "run_time"           => $run_time,        "store_time"         => $store_time,        "cached_run_times"   => array(),        "cached_store_times" => array(),    );    return TRUE;}function query_is_select($query) {    printf("\t%s('%s'): ", __FUNCTION__, $query);    $ret = FALSE;    if (stristr($query, "SELECT") !== FALSE) {        /* cache for 5 seconds */        $ret = 5;    }    printf("%s\n", (FALSE === $ret) ? "FALSE" : $ret);    return $ret;}function update_query_run_time_stats($key, $run_time, $store_time) {    global $__cache;    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());    if (isset($__cache[$key])) {        $__cache[$key]['hits']++;        $__cache[$key]["cached_run_times"][] = $run_time;        $__cache[$key]["cached_store_times"][] = $store_time;    }}function get_stats($key = NULL) {    global $__cache;    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());    if ($key && isset($__cache[$key])) {        $stats = $__cache[$key];    } else {        $stats = array();        foreach ($__cache as $key => $details) {            $stats[$key] = array(               'hits'              => $details['hits'],               'bytes'             => strlen($details['data']),               'uncached_run_time' => $details['run_time'],               'cached_run_time'   => (count($details['cached_run_times']))                                      ? array_sum($details['cached_run_times']) / count($details['cached_run_times'])                                      : 0,            );        }    }    return $stats;}function clear_cache() {    global $__cache;    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());    $__cache = array();    return TRUE;}/* Install procedural user-defined storage handler */if (!mysqlnd_qc_set_user_handlers("get_hash", "find_query_in_cache",    "return_to_cache", "add_query_to_cache_if_not_exists",    "query_is_select", "update_query_run_time_stats", "get_stats", "clear_cache")) {          printf("Failed to install user-defined storage handler\n");}/* Connect, create and populate test table */$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");$mysqli->query("DROP TABLE IF EXISTS test");$mysqli->query("CREATE TABLE test(id INT)");$mysqli->query("INSERT INTO test(id) VALUES (1), (2)");printf("\nCache put/cache miss\n");$res = $mysqli->query("SELECT id FROM test WHERE id = 1");var_dump($res->fetch_assoc());$res->free();/* Delete record to verify we get our data from the cache */$mysqli->query("DELETE FROM test WHERE id = 1");printf("\nCache hit\n");$res = $mysqli->query("SELECT id FROM test WHERE id = 1");var_dump($res->fetch_assoc());$res->free();printf("\nDisplay cache statistics\n");var_dump(mysqlnd_qc_get_cache_info());printf("\nFlushing cache, cache put/cache miss");var_dump(mysqlnd_qc_clear_cache());$res = $mysqli->query("SELECT id FROM test WHERE id = 1");var_dump($res->fetch_assoc());$res->free();?>

以上例程的输出类似于:


        query_is_select('DROP TABLE IF EXISTS test'): FALSE
        query_is_select('CREATE TABLE test(id INT)'): FALSE
        query_is_select('INSERT INTO test(id) VALUES (1), (2)'): FALSE

Cache put/cache miss
        query_is_select('SELECT id FROM test WHERE id = 1'): 5
        get_hash(5)
        find_query_in_cache(1)
        add_query_to_cache_if_not_exists(6)
array(1) {
  ["id"]=>
  string(1) "1"
}
        query_is_select('DELETE FROM test WHERE id = 1'): FALSE

Cache hit
        query_is_select('SELECT id FROM test WHERE id = 1'): 5
        get_hash(5)
        find_query_in_cache(1)
        return_to_cache(1)
        update_query_run_time_stats(3)
array(1) {
  ["id"]=>
  string(1) "1"
}

Display cache statistics
        get_stats(0)
array(4) {
  ["num_entries"]=>
  int(1)
  ["handler"]=>
  string(4) "user"
  ["handler_version"]=>
  string(5) "1.0.0"
  ["data"]=>
  array(1) {
    ["18683c177dc89bb352b29965d112fdaa"]=>
    array(4) {
      ["hits"]=>
      int(1)
      ["bytes"]=>
      int(71)
      ["uncached_run_time"]=>
      int(398)
      ["cached_run_time"]=>
      int(4)
    }
  }
}

Flushing cache, cache put/cache miss    clear_cache(0)
bool(true)
        query_is_select('SELECT id FROM test WHERE id = 1'): 5
        get_hash(5)
        find_query_in_cache(1)
        add_query_to_cache_if_not_exists(6)
NULL