Projections #9
Projections #9
Conversation
|
Please carefully check the locking mechanisms! |
| $statement->execute(); | ||
|
|
||
| $row = $statement->fetch(PDO::FETCH_OBJ); | ||
| //die; |
| */ | ||
| protected function acquireLock(): void | ||
| { | ||
| $statement = $this->connection->prepare("SELECT GET_LOCK('$this->name', 1) as 'lock';"); |
There was a problem hiding this comment.
no need to surround aliases with quotes
There was a problem hiding this comment.
No.
mysql> SELECT get_lock('ff', 3) as lock;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'lock' at line 1
There was a problem hiding this comment.
oh ok, fair enough, the 'lock' keyword is reserved :)
There was a problem hiding this comment.
btw, I see you pass 1 as a second parameter of GET_LOCK, which means your lock will be released after 1 second. This is not what we want, right?
There was a problem hiding this comment.
damn, that's a bug. or maybe we do the same implementation as in psql?
There was a problem hiding this comment.
I think having the same implementation in place might be the best scenario. Will update the code tomorrow.
There was a problem hiding this comment.
Ok but don't forget to expose the timeout value in the config of the package so the user can configure it. I would actually be in favor of letting the user chose how he really wants to manage his locks by exposing a locking interface. Another solution would be to make your locked column a datetime meaning until when the projection is locked (instead of storing a random int).
| //die; | ||
| if (false === $row) { | ||
| $sql = <<<EOT | ||
| INSERT INTO $this->projectionsTable (name, position, state, locked) |
There was a problem hiding this comment.
so you use GET_LOCK() for MySQL but a locked column for Postgres?
There was a problem hiding this comment.
Yes. PostgreSQL has not the same feature.
|
There is also a pthreads implementation planned for multi stream processing. Problem is different threads cannot share db connection. So how to construct this object? Inject a container and service names? Any ideas? |
| @@ -151,6 +151,10 @@ public function __construct( | |||
| $sql = 'INSERT INTO ' . $tableName . ' (' . implode(', ', $columnNames) . ') VALUES ' . $allPlaces; | |||
|
|
|||
| $statement = $this->connection->prepare($sql); | |||
| /* | |||
I followed @bendavies suggestion in the chat and took a look at icicle. I played a bit with reactPHP in the past and also read a few things about icicle. |
|
| $lockUntilString = $now->modify('+' . (string) $this->lockTimeoutMs . ' ms')->format('Y-m-d\TH:i:s.u'); | ||
|
|
||
| $sql = <<<EOT | ||
| UPDATE $this->projectionsTable SET locked_until = ? WHERE name = ? AND (locked_until IS NuLL OR locked_until < ?); |
|
About multi-stream-processing: This will require pthreads and will probably be added with in a distinct implementation (much stuff differs then). This will be added later and is not required at the moment. |
|
Note: This PR is now also cleaned up, so a DistributedLock interface can be added very easy (but is not yet done in this PR). |
| $this->connection->beginTransaction(); | ||
|
|
||
| $listener = $this->eventStore->getActionEventEmitter()->attachListener( | ||
| ActionEventEmitterAware::EVENT_APPEND_TO, |
| $this->connection->beginTransaction(); | ||
|
|
||
| $listener = $this->eventStore->getActionEventEmitter()->attachListener( | ||
| ActionEventEmitterAware::EVENT_APPEND_TO, |
No description provided.