gnu-social/src/Core/Cache.php
2021-09-14 13:06:45 +01:00

211 lines
9.0 KiB
PHP

<?php
// {{{ License
// This file is part of GNU social - https://www.gnu.org/software/social
//
// GNU social is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// GNU social is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with GNU social. If not, see <http://www.gnu.org/licenses/>.
// }}}
namespace App\Core;
use Functional as F;
use Redis;
use RedisCluster;
use SplFixedArray;
use Symfony\Component\Cache\Adapter;
use Symfony\Component\Cache\Adapter\ChainAdapter;
abstract class Cache
{
protected static $pools;
protected static $redis;
private static string $ENV_VAR = 'SOCIAL_CACHE_ADAPTER';
/**
* Configure a cache pool, with adapters taken from `ENV_VAR`.
* We may want multiple of these in the future, but for now it seems
* unnecessary
*/
public static function setupCache()
{
if (!isset($_ENV[self::$ENV_VAR])) {
die("A cache adapter is needed in the environment variable {$ENV_VAR}");
}
self::$pools = [];
self::$redis = [];
$adapters = [];
foreach (explode(';', $_ENV[self::$ENV_VAR]) as $a) {
list($pool, $val) = explode('=', $a);
self::$pools[$pool] = [];
self::$redis[$pool] = [];
foreach (explode(',', $val) as $dsn) {
list($scheme, $rest) = explode('://', $dsn);
$partial_to_dsn = function ($r) use ($scheme) { return $scheme . '://' . $r; };
switch ($scheme) {
case 'redis':
// Redis can have multiple servers, but we want to take proper advantage of
// redis, not just as a key value store, but using it's datastructures
$dsns = explode(',', $rest);
if (count($dsns) === 1) {
$class = Redis::class;
$r = new Redis();
if ($rest[0] != '/' && strstr($rest, ':') != false) {
list($host, $port) = explode(':', $rest);
$r->pconnect($host, $port);
} else {
$r->pconnect($rest);
}
} else {
$class = RedisCluster::class; // true for persistent connection
$r = new RedisCluster(null, $dsns, null, null, true);
// Distribute reads randomly
$r->setOption($class::OPT_SLAVE_FAILOVER, $class::FAILOVER_DISTRIBUTE);
}
// Improved serializer
$r->setOption($class::OPT_SERIALIZER, $class::SERIALIZER_MSGPACK);
// Persistent connection
$r->setOption($class::OPT_TCP_KEEPALIVE, true);
// Use LZ4 for the improved decompression speed (while keeping an okay compression ratio)
$r->setOption($class::OPT_COMPRESSION, $class::COMPRESSION_LZ4);
self::$redis[$pool] = $r;
$adapters[$pool][] = new Adapter\RedisAdapter($r);
break;
case 'memcached':
// memcached can also have multiple servers
$dsns = F\map(explode(',', $rest), $partial_to_dsn);
$adapters[$pool][] = new Adapter\MemcachedAdapter($dsns);
break;
case 'filesystem':
$adapters[$pool][] = new Adapter\FilesystemAdapter($rest);
break;
case 'apcu':
$adapters[$pool][] = new Adapter\ApcuAdapter();
break;
case 'opcache':
$adapters[$pool][] = new Adapter\PhpArrayAdapter($rest, new FilesystemAdapter($rest . '.fallback'));
break;
case 'doctrine':
$adapters[$pool][] = new Adapter\PdoAdapter($dsn);
break;
default:
Log::error("Unknown or discouraged cache scheme '{$scheme}'");
return;
}
}
if (count($adapters[$pool]) === 1) {
self::$pools[$pool] = array_pop($adapters[$pool]);
} else {
self::$pools[$pool] = new ChainAdapter($adapters);
}
}
}
public static function set(string $key, mixed $value, string $pool = 'default')
{
// there's no set method, must be done this way
return self::$pools[$pool]->get($key, function ($i) use ($value) { return $value; }, INF);
}
public static function get(string $key, callable $calculate, string $pool = 'default', float $beta = 1.0)
{
return self::$pools[$pool]->get($key, $calculate, $beta);
}
public static function delete(string $key, string $pool = 'default'): bool
{
return self::$pools[$pool]->delete($key);
}
public static function getList(string $key, callable $calculate, string $pool = 'default', int $max_count = -1, float $beta = 1.0): array
{
if (isset(self::$redis[$pool])) {
if (!($recompute = $beta === INF || !(self::$redis[$pool]->exists($key)))) {
if (!($_ENV['REDIS_CACHE_USE_EXPONENTIAL_UPDATE'] ?? false)) {
$recompute = (mt_rand() / mt_getrandmax() > ((float) ($_ENV['REDIS_CACHE_RANDOM_UPDATE'] ?? 0.95)));
Log::info('Item "{key}" elected for early recomputation', ['key' => $key]);
} else {
if ($recompute = ($idletime = self::$redis[$pool]->object('idletime', $key) ?? false) && ($expiry = self::$redis[$pool]->ttl($key) ?? false) && $expiry <= $idletime / 1000 * $beta * log(random_int(1, PHP_INT_MAX) / PHP_INT_MAX)) {
Log::info('Item "{key}" elected for early recomputation {delta}s before its expiration', [
'key' => $key,
'delta' => sprintf('%.1f', $expiry - microtime(true)),
]);
}
}
}
if ($recompute) {
$save = true;
$res = $calculate(null, $save);
if ($save) {
self::$redis[$pool]->del($key);
self::$redis[$pool]->lPush($key, ...$res);
}
}
return self::$redis[$pool]->lRange($key, 0, $max_count);
} else {
$keys = self::getKeyList($key, $max_count, $beta);
$list = new SplFixedArray($keys->count());
foreach ($keys as $k) {
$list[] = self::get($k, $calculate, $pool, $beta);
}
return $list->toArray();
}
}
public static function pushList(string $key, mixed $value, string $pool = 'default', int $max_count = 64, float $beta = 1.0): void
{
if (isset(self::$redis[$pool])) {
self::$redis[$pool]
// doesn't need to be atomic, adding at one end, deleting at the other
->multi(Redis::PIPELINE)
->lPush($key, $value)
// trim to $max_count, unless it's 0
->lTrim($key, 0, $max_count != 0 ? $max_count : -1)
->exec();
} else {
$keys = self::getKeyList($key, $max_count, $beta);
$vkey = $key . ':' . count($keys);
self::set($vkey, $value);
$keys[] = $vkey;
self::set($key, $keys);
}
}
public static function deleteList(string $key, string $pool = 'default'): bool
{
if (isset(self::$redis[$pool])) {
return self::$redis[$pool]->del($key) == 1;
} else {
$keys = self::getKeyList($key, $max_count, $beta);
if (!F\every($keys, function ($k) use ($pool) { return self::delete($k, $pool); })) {
Log::warning("Some element of the list associated with {$key} was not deleted. There may be some memory leakage in the cache process");
}
return self::delete($key, $pool);
}
}
private static function getKeyList(string $key, int $max_count, string $pool, float $beta): RingBuffer
{
// Get the current keys associated with a list. If the cache
// is not primed, the function is called and returns an empty
// ring buffer
return self::get($key,
function (ItemInterface $i) use ($max_count) {
return new RingBuffer($max_count);
}, $pool, $beta);
}
}