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Code Issues Releases Wiki Activity

Remove all optimistic lock code from Lisk

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Summary: We never use this and almost certainly never will. It's been in Lisk for ~7 years but is a solution in search of a problem. It causes a conflict with any DAO that has a `version` column.

Test Plan: Browsed around, performed inserts and updates. Edited a Phriction document.

Reviewers: vrana, btrahan

Reviewed By: btrahan

CC: aran, leslie.chong

Differential Revision: https://secure.phabricator.com/D3625
This commit is contained in:
epriestley 2012-10-04 13:55:43 -07:00
parent fe355f7905
commit ea32c541e4
1 changed files with 22 additions and 96 deletions
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118
src/infrastructure/storage/lisk/LiskDAO.php
View file

@ -182,7 +182,6 @@
*/
abstract class LiskDAO {
const CONFIG_OPTIMISTIC_LOCKS = 'enable-locks';
const CONFIG_IDS = 'id-mechanism';
const CONFIG_TIMESTAMPS = 'timestamps';
const CONFIG_AUX_PHID = 'auxiliary-phid';
@ -211,7 +210,6 @@ abstract class LiskDAO {
protected $id;
protected $phid;
protected $version;
protected $dateCreated;
protected $dateModified;
@ -329,7 +327,7 @@ abstract class LiskDAO {
/**
* Change Lisk behaviors, like optimistic locks and timestamps. If you want
* Change Lisk behaviors, like ID configuration and timestamps. If you want
* to change these behaviors, you should override this method in your child
* class and change the options you're interested in. For example:
*
@ -341,21 +339,6 @@ abstract class LiskDAO {
*
* The available options are:
*
* CONFIG_OPTIMISTIC_LOCKS
* Lisk automatically performs optimistic locking on objects, which protects
* you from read-modify-write concurrency problems. Lock failures are
* detected at write time and arise when two users read an object, then both
* save it. In theory, you should detect these failures and accommodate them
* in some sensible way (for instance, by showing the user differences
* between the original record and the copy they are trying to update, and
* prompting them to merge them). In practice, most Lisk tools are quick
* and dirty and don't get to that level of sophistication, but optimistic
* locks can still protect you from yourself sometimes. If you don't want
* to use optimistic locks, you can disable them. The performance cost of
* doing this locking is very very small (optimistic locks were chosen
* because they're simple and cheap, and highly optimized for the case where
* collisions are rare). By default, this option is OFF.
*
* CONFIG_IDS
* Lisk objects need to have a unique identifying ID. The three mechanisms
* available for generating this ID are IDS_AUTOINCREMENT (default, assumes
@ -405,7 +388,6 @@ abstract class LiskDAO {
*/
protected function getConfiguration() {
return array(
self::CONFIG_OPTIMISTIC_LOCKS => false,
self::CONFIG_IDS => self::IDS_AUTOINCREMENT,
self::CONFIG_TIMESTAMPS => true,
self::CONFIG_PARTIAL_OBJECTS => false,
@ -605,9 +587,8 @@ abstract class LiskDAO {
/**
* Reload an object from the database, discarding any changes to persistent
* properties. If the object uses optimistic locks and you are in a locking
* mode while transactional, this will effectively synchronize the locks.
* This is pretty heady. It is unlikely you need to use this method.
* properties. This is primarily useful after entering a transaction but
* before applying changes to an object.
*
* @return this
*
@ -619,24 +600,13 @@ abstract class LiskDAO {
throw new Exception("Unable to reload object that hasn't been loaded!");
}
$use_locks = $this->getConfigOption(self::CONFIG_OPTIMISTIC_LOCKS);
if (!$use_locks) {
$result = $this->loadOneWhere(
'%C = %d',
$this->getIDKeyForUse(),
$this->getID());
} else {
$result = $this->loadOneWhere(
'%C = %d AND %C = %d',
$this->getIDKeyForUse(),
$this->getID(),
'version',
$this->getVersion());
}
$result = $this->loadOneWhere(
'%C = %d',
$this->getIDKeyForUse(),
$this->getID());
if (!$result) {
throw new AphrontQueryObjectMissingException($use_locks);
throw new AphrontQueryObjectMissingException();
}
return $this;
@ -952,10 +922,6 @@ abstract class LiskDAO {
unset($properties['id']);
}
if (!$this->getConfigOption(self::CONFIG_OPTIMISTIC_LOCKS)) {
unset($properties['version']);
}
if (!$this->getConfigOption(self::CONFIG_TIMESTAMPS)) {
unset($properties['datecreated']);
unset($properties['datemodified']);
@ -1155,7 +1121,6 @@ abstract class LiskDAO {
*/
public function update() {
$this->isEphemeralCheck();
$use_locks = $this->getConfigOption(self::CONFIG_OPTIMISTIC_LOCKS);
$this->willSaveObject();
$data = $this->getPropertyValues();
@ -1166,9 +1131,6 @@ abstract class LiskDAO {
$map = array();
foreach ($data as $k => $v) {
if ($use_locks && $k == 'version') {
continue;
}
$map[$k] = $v;
}
@ -1179,31 +1141,16 @@ abstract class LiskDAO {
}
$map = implode(', ', $map);
if ($use_locks) {
$conn->query(
'UPDATE %T SET %Q, version = version + 1 WHERE %C = %d AND %C = %d',
$this->getTableName(),
$map,
$this->getIDKeyForUse(),
$this->getID(),
'version',
$this->getVersion());
if ($conn->getAffectedRows() !== 1) {
throw new AphrontQueryObjectMissingException($use_locks);
}
$this->setVersion($this->getVersion() + 1);
} else {
$id = $this->getID();
$conn->query(
'UPDATE %T SET %Q WHERE %C = '.(is_int($id) ? '%d' : '%s'),
$this->getTableName(),
$map,
$this->getIDKeyForUse(),
$id);
// We can't detect a missing object because updating an object without
// changing any values doesn't affect rows. We could jiggle timestamps
// to catch this for objects which track them if we wanted.
}
$id = $this->getID();
$conn->query(
'UPDATE %T SET %Q WHERE %C = '.(is_int($id) ? '%d' : '%s'),
$this->getTableName(),
$map,
$this->getIDKeyForUse(),
$id);
// We can't detect a missing object because updating an object without
// changing any values doesn't affect rows. We could jiggle timestamps
// to catch this for objects which track them if we wanted.
$this->didWriteData();
@ -1274,10 +1221,6 @@ abstract class LiskDAO {
throw new Exception('Unknown CONFIG_IDs mechanism!');
}
if ($this->getConfigOption(self::CONFIG_OPTIMISTIC_LOCKS)) {
$data['version'] = 0;
}
$this->willWriteData($data);
$conn = $this->establishConnection('w');
@ -1296,11 +1239,6 @@ abstract class LiskDAO {
$columns,
$data);
// Update the object with the initial Version value
if ($this->getConfigOption(self::CONFIG_OPTIMISTIC_LOCKS)) {
$this->setVersion(0);
}
// Only use the insert id if this table is using auto-increment ids
if ($id_mechanism === self::IDS_AUTOINCREMENT) {
$this->setID($conn->getInsertID());
@ -1323,24 +1261,12 @@ abstract class LiskDAO {
*/
protected function shouldInsertWhenSaved() {
$key_type = $this->getConfigOption(self::CONFIG_IDS);
$use_locks = $this->getConfigOption(self::CONFIG_OPTIMISTIC_LOCKS);
if ($key_type == self::IDS_MANUAL) {
if ($use_locks) {
// If we are manually keyed and the object has a version (which means
// that it has been saved to the DB before), do an update, otherwise
// perform an insert.
if ($this->getID() && $this->getVersion() !== null) {
return false;
} else {
return true;
}
} else {
throw new Exception(
'You are not using optimistic locks, but are using manual IDs. You '.
'must override the shouldInsertWhenSaved() method to properly '.
'detect when to insert a new record.');
}
throw new Exception(
'You are using manual IDs. You must override the '.
'shouldInsertWhenSaved() method to properly detect '.
'when to insert a new record.');
} else {
return !$this->getID();
}