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Merge pull request #43297 from nextcloud/fix/db/dirty-read-cool-off

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fix(db): Let dirty writes cool off
This commit is contained in:
Christoph Wurst 2024-02-19 10:53:05 +01:00 committed by GitHub
commit d52ebaa7cd
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1 changed files with 20 additions and 3 deletions
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23
lib/private/DB/Connection.php
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@ -55,7 +55,9 @@ use OCP\Diagnostics\IEventLogger;
use OCP\IRequestId;
use OCP\PreConditionNotMetException;
use OCP\Profiler\IProfiler;
use Psr\Clock\ClockInterface;
use Psr\Log\LoggerInterface;
use function in_array;
class Connection extends PrimaryReadReplicaConnection {
/** @var string */
@ -67,6 +69,8 @@ class Connection extends PrimaryReadReplicaConnection {
/** @var SystemConfig */
private $systemConfig;
private ClockInterface $clock;
private LoggerInterface $logger;
protected $lockedTable = null;
@ -83,6 +87,7 @@ class Connection extends PrimaryReadReplicaConnection {
protected ?float $transactionActiveSince = null;
/** @var array<string, int> */
protected $tableDirtyWrites = [];
/**
@ -110,6 +115,7 @@ class Connection extends PrimaryReadReplicaConnection {
$this->tablePrefix = $params['tablePrefix'];
$this->systemConfig = \OC::$server->getSystemConfig();
$this->clock = \OCP\Server::get(ClockInterface::class);
$this->logger = \OC::$server->get(LoggerInterface::class);
/** @var \OCP\Profiler\IProfiler */
@ -265,10 +271,19 @@ class Connection extends PrimaryReadReplicaConnection {
*/
public function executeQuery(string $sql, array $params = [], $types = [], QueryCacheProfile $qcp = null): Result {
$tables = $this->getQueriedTables($sql);
$now = $this->clock->now()->getTimestamp();
$dirtyTableWrites = [];
foreach ($tables as $table) {
$lastAccess = $this->tableDirtyWrites[$table] ?? 0;
// Only very recent writes are considered dirty
if ($lastAccess >= ($now - 3)) {
$dirtyTableWrites[] = $table;
}
}
if ($this->isTransactionActive()) {
// Transacted queries go to the primary. The consistency of the primary guarantees that we can not run
// into a dirty read.
} elseif (count(array_intersect($this->tableDirtyWrites, $tables)) === 0) {
} elseif (count($dirtyTableWrites) === 0) {
// No tables read that could have been written already in the same request and no transaction active
// so we can switch back to the replica for reading as long as no writes happen that switch back to the primary
// We cannot log here as this would log too early in the server boot process
@ -280,7 +295,7 @@ class Connection extends PrimaryReadReplicaConnection {
(int) ($this->systemConfig->getValue('loglevel_dirty_database_queries', null) ?? 0),
'dirty table reads: ' . $sql,
[
'tables' => $this->tableDirtyWrites,
'tables' => array_keys($this->tableDirtyWrites),
'reads' => $tables,
'exception' => new \Exception('dirty table reads: ' . $sql),
],
@ -335,7 +350,9 @@ class Connection extends PrimaryReadReplicaConnection {
*/
public function executeStatement($sql, array $params = [], array $types = []): int {
$tables = $this->getQueriedTables($sql);
$this->tableDirtyWrites = array_unique(array_merge($this->tableDirtyWrites, $tables));
foreach ($tables as $table) {
$this->tableDirtyWrites[$table] = $this->clock->now()->getTimestamp();
}
$sql = $this->replaceTablePrefix($sql);
$sql = $this->adapter->fixupStatement($sql);
$this->queriesExecuted++;