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AphrontMySQLDatabaseConnectionBase.php
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Wed, Dec 11, 15:09

AphrontMySQLDatabaseConnectionBase.php
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<?php
/*
* Copyright 2012 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @group storage
*/
abstract class AphrontMySQLDatabaseConnectionBase
extends AphrontDatabaseConnection {
private $configuration;
private $connection;
private $nextError;
private static $connectionCache = array();
abstract protected function connect();
abstract protected function rawQuery($raw_query);
abstract protected function fetchAssoc($result);
abstract protected function getErrorCode($connection);
abstract protected function getErrorDescription($connection);
public function __construct(array $configuration) {
$this->configuration = $configuration;
}
public function escapeColumnName($name) {
return '`'.str_replace('`', '``', $name).'`';
}
public function escapeMultilineComment($comment) {
// These can either terminate a comment, confuse the hell out of the parser,
// make MySQL execute the comment as a query, or, in the case of semicolon,
// are quasi-dangerous because the semicolon could turn a broken query into
// a working query plus an ignored query.
static $map = array(
'--' => '(DOUBLEDASH)',
'*/' => '(STARSLASH)',
'//' => '(SLASHSLASH)',
'#' => '(HASH)',
'!' => '(BANG)',
';' => '(SEMICOLON)',
);
$comment = str_replace(
array_keys($map),
array_values($map),
$comment);
// For good measure, kill anything else that isn't a nice printable
// character.
$comment = preg_replace('/[^\x20-\x7F]+/', ' ', $comment);
return '/* '.$comment.' */';
}
public function escapeStringForLikeClause($value) {
$value = $this->escapeString($value);
// Ideally the query shouldn't be modified after safely escaping it,
// but we need to escape _ and % within LIKE terms.
$value = str_replace(
// Even though we've already escaped, we need to replace \ with \\
// because MYSQL unescapes twice inside a LIKE clause. See note
// at mysql.com. However, if the \ is being used to escape a single
// quote ('), then the \ should not be escaped. Thus, after all \
// are replaced with \\, we need to revert instances of \\' back to
// \'.
array('\\', '\\\\\'', '_', '%'),
array('\\\\', '\\\'', '\_', '\%'),
$value);
return $value;
}
protected function getConfiguration($key, $default = null) {
return idx($this->configuration, $key, $default);
}
private function closeConnection() {
if ($this->connection) {
$this->connection = null;
$key = $this->getConnectionCacheKey();
unset(self::$connectionCache[$key]);
}
}
private function getConnectionCacheKey() {
$user = $this->getConfiguration('user');
$host = $this->getConfiguration('host');
$database = $this->getConfiguration('database');
return "{$user}:{$host}:{$database}";
}
private function establishConnection() {
$this->closeConnection();
$key = $this->getConnectionCacheKey();
if (isset(self::$connectionCache[$key])) {
$this->connection = self::$connectionCache[$key];
return;
}
$start = microtime(true);
$host = $this->getConfiguration('host');
$database = $this->getConfiguration('database');
$profiler = PhutilServiceProfiler::getInstance();
$call_id = $profiler->beginServiceCall(
array(
'type' => 'connect',
'host' => $host,
'database' => $database,
));
$retries = max(1, PhabricatorEnv::getEnvConfig('mysql.connection-retries'));
while ($retries--) {
try {
$conn = $this->connect();
$profiler->endServiceCall($call_id, array());
break;
} catch (AphrontQueryException $ex) {
if ($retries && $ex->getCode() == 2003) {
$class = get_class($ex);
$message = $ex->getMessage();
phlog("Retrying ({$retries}) after {$class}: {$message}");
} else {
$profiler->endServiceCall($call_id, array());
throw $ex;
}
}
}
self::$connectionCache[$key] = $conn;
$this->connection = $conn;
}
protected function requireConnection() {
if (!$this->connection) {
$this->establishConnection();
}
return $this->connection;
}
public function selectAllResults() {
$result = array();
$res = $this->lastResult;
if ($res == null) {
throw new Exception('No query result to fetch from!');
}
while (($row = $this->fetchAssoc($res))) {
$result[] = $row;
}
return $result;
}
public function executeRawQuery($raw_query) {
$this->lastResult = null;
$retries = max(1, PhabricatorEnv::getEnvConfig('mysql.connection-retries'));
while ($retries--) {
try {
$this->requireConnection();
// TODO: Do we need to include transactional statements here?
$is_write = !preg_match('/^(SELECT|SHOW|EXPLAIN)\s/', $raw_query);
if ($is_write) {
AphrontWriteGuard::willWrite();
}
$start = microtime(true);
$profiler = PhutilServiceProfiler::getInstance();
$call_id = $profiler->beginServiceCall(
array(
'type' => 'query',
'config' => $this->configuration,
'query' => $raw_query,
'write' => $is_write,
));
$result = $this->rawQuery($raw_query);
$profiler->endServiceCall($call_id, array());
if ($this->nextError) {
$result = null;
}
if ($result) {
$this->lastResult = $result;
break;
}
$this->throwQueryException($this->connection);
} catch (AphrontQueryConnectionLostException $ex) {
if ($this->isInsideTransaction()) {
// Zero out the transaction state to prevent a second exception
// ("program exited with open transaction") from being thrown, since
// we're about to throw a more relevant/useful one instead.
$state = $this->getTransactionState();
while ($state->getDepth()) {
$state->decreaseDepth();
}
// We can't close the connection before this because
// isInsideTransaction() and getTransactionState() depend on the
// connection.
$this->closeConnection();
throw $ex;
}
$this->closeConnection();
if (!$retries) {
throw $ex;
}
$class = get_class($ex);
$message = $ex->getMessage();
phlog("Retrying ({$retries}) after {$class}: {$message}");
}
}
}
protected function throwQueryException($connection) {
if ($this->nextError) {
$errno = $this->nextError;
$error = 'Simulated error.';
$this->nextError = null;
} else {
$errno = $this->getErrorCode($connection);
$error = $this->getErrorDescription($connection);
}
$exmsg = "#{$errno}: {$error}";
switch ($errno) {
case 2013: // Connection Dropped
case 2006: // Gone Away
throw new AphrontQueryConnectionLostException($exmsg);
case 1213: // Deadlock
case 1205: // Lock wait timeout exceeded
throw new AphrontQueryRecoverableException($exmsg);
case 1062: // Duplicate Key
// NOTE: In some versions of MySQL we get a key name back here, but
// older versions just give us a key index ("key 2") so it's not
// portable to parse the key out of the error and attach it to the
// exception.
throw new AphrontQueryDuplicateKeyException($exmsg);
case 1044: // Access denied to database
case 1045: // Access denied (auth)
case 1142: // Access denied to table
case 1143: // Access denied to column
throw new AphrontQueryAccessDeniedException($exmsg);
case 1146: // No such table
case 1054: // Unknown column "..." in field list
throw new AphrontQuerySchemaException($exmsg);
default:
// TODO: 1064 is syntax error, and quite terrible in production.
throw new AphrontQueryException($exmsg);
}
}
/**
* Force the next query to fail with a simulated error. This should be used
* ONLY for unit tests.
*/
public function simulateErrorOnNextQuery($error) {
$this->nextError = $error;
return $this;
}
}

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