README

PhpRQ

This library is set of php files and Lua scripts which enables you to easily implement queuing system based on Redis. The library is completely tested using integration tests (because of heavy usage of Lua scripts). There are multiple types of queues implemented in this library so you can choose the one that fits your needs best.

All the queues works well in multi-threaded environment. The only thing you have to keep in mind is that with multiple consumers the order of the items is impossible to preserve. E.g. if multiple consumers exits unexpectedly and then you use re-enqueue method to get the items back to the queue then you will most probably lose the order of the items. If you want to rely on the order of the items then you are required to use only one consumer at a time, reject whole batch after failure and re-enqueue everything before getting another chunk of items.

Queue

This is the most basic type of queue. If you don't require uniqueness of the items in the queue then you probably want to use Queue.

There is no possible way to guarantee order of the items if you reject them randomly or if the queue is used in multi-threaded environment. The Queue tries to maintain the order of the items as best as it can but you have to keep in mind that it is just the best effort method. The order of the items is guaranteed only if you use single consumer, reject whole batch after failure and re-enqueue failed items before getting the new ones.

Queue - General usage

You can add items to the queue using addItem and addItems methods. If you want to get items from the queue then you can use getItems and getAllItems methods. When you have the items from the queue you must either acknowledge (success; ackItem, ackItems) or reject (failure; rejectItem, rejectItems, rejectBatch) them. If you reject an item it is then moved on the head of the queue. If you miss to acknowledge or revoke an item then it will stay in the processing queue until you clear it using reEnqueueTimedOutItems, reEnqueueAllItems, dropTimedOutItems or dropAllItems (depends on your requirements). You must clear the failed processing queues somehow, otherwise the forgotten data will fill your Redis.

Queue::getRedisClient

Returns the used instance of a Redis client (PhpRQ\ClientInterface). This is useful in multi-threaded environment when you want to reconnect the connection.

Queue::getCount

Returns the number of items in the queue.

Queue::addItem

param: $item Anything that can be converted to string

Adds an item to the queue.

Queue::addItems

param: (array) $items Array containing anything that can be converted to string

Adds multiple items to the queue.

Queue::getItems

param: (int) $size Number of items you want to return from the queue

Returns $size elements from the queue. You can set the $size to any number you like - the items are fetched from the queue by chunks with a fixed safe size so the server isn't overwhelmed.

Items that are fetched from the queue are added to a processing queue. That way if the process exits unexpectedly the items fetched from the queue can be preserved using re-enqueue methods.

Queue::getAllItems

Returns all items from the queue. The items are fetched from the queue by chunks of a fixed safe size so the server isn't overwhelmed.

Items that are fetched from the queue are added to a processing queue. That way if the process exits unexpectedly the items fetched from the queue can be preserved using re-enqueue methods.

Queue::ackItem

param: $item Anything that can be converted to string

Acknowledges the item - removes the item from the processing queue.

Queue::ackItems

param: (array) $items Array containing anything that can be converted to string

Acknowledges multiple items - removes them from the processing queue.

Queue::rejectItem

param: $item Anything that can be converted to string

Revokes the item - removes the item from the processing queue and puts it back at the head of the queue (i.e. it will be the first item to fetch)

Be aware: Order is guaranteed only by the best effort method, e.g. if you reject some items and then acknowledge another then the order is lost.

Queue::rejectItems

param: (array) $items Array containing anything that can be converted to string

Revokes multiple items - removes the items from the processing queue and puts them back at the head of the queue in the reversed order (i.e. they will be the first items to fetch, in the same order as they were fetched before).

Be aware: Order is guaranteed only by the best effort method, e.g. if you reject some items and then acknowledge another then the order is lost.

Queue::rejectBatch

Revokes all the remaining items in the processing queue and puts them back at the head of the queue in the reversed order (i.e. they will be the first items to fetch, in the same order as they were fetched before).

Queue::reEnqueueTimedOutItems

param: (int) $timeout Number of seconds after which the processing queue and all the items in it are considered as failed

You should call this method (or the reEnqueueAllItems) periodically (or before fetching items from the queue) to put the timed out items from the processing queues back to the head of the queue in the reversed order (i.e. they will be the first items to fetch, in the same order as they were fetched before).

Be aware: Order is guaranteed only by the best effort method, e.g. if the first batch fails, the seconds successes and the third fails again, the order of the items cannot be preserved because the first batch now "gets after the second one"

Queue::reEnqueueAllItems

You should call this method before fetching items from the queue but only if you have a single consumer. This method puts the items for all the processing queues back to the head of the queue in the reversed order (i.e. they will be the first items to fetch, in the same order as they were fetched before). Keep in mind that this method can re-enqueue still valid processing queues (i.e. not the failed ones).

Be aware: Order is guaranteed only by the best effort method, e.g. if the first batch fails, the second successes and the third fails again, the order of the items cannot be preserved because the first batch now "gets after the seconds one"

Queue::dropTimedOutItems

param: (int) $timeout Number of seconds after which the processing queue and all the items in it are considered as failed

You should call this method (or the dropAllItems) periodically (or before fetching items from the queue) to drop the timed out items from the processing queues.

Queue::dropAllItems

You should call this method before fetching items from the queue but only if you have a single consumer. This method drops the items for from all the processing queues. Keep in mind that this method can drop still valid processing queues (i.e. not the failed ones).

Queue::clearQueue

Removes all items from the queue and it's processing lists. Useful for testing purposes.

UniqueQueue

This type of queue is useful if you don't need all the items you push into the queue but just one of each "type". Let's say that you want to build a queue for refreshing your cached products per category. In that case you will probably want to send category IDs to the queue. If the processes which handles refreshing of the cache is too slow then it may happen that you will send multiple update requests (category IDs) into the queue. In that case it isn't necessary to refresh cache two times - you only need it once but the process just didn't get to your item yet. The solution is to ignore the second item. And this is exactly what UniqueQueue is intended for. It guarantees you the uniqueness of items in the queue.

There is no possible way to guarantee order of the items if you reject them randomly or if the queue is used in multi-threaded environment. The UniqueQueue tries to maintain the order of the items as best as it can but you have to keep in mind that it is just the best effort method. The order of the items is guaranteed only if you use single consumer, reject whole batch after failure and re-enqueue failed items before getting the new ones.

UniqueQueue - General usage

You can add items to the queue using addItem and addItems methods. If you want to get items from the queue then you can use getItems and getAllItems methods. When you have the items from the queue you must either acknowledge (success; ackItem, ackItems) or reject (failure; rejectItem, rejectItems, rejectBatch) them. If you reject an item it is then moved on the head of the queue. If you miss to acknowledge or revoke an item then it will stay in the processing queue until you clear it using reEnqueueTimedOutItems, reEnqueueAllItems, dropTimedOutItems or dropAllItems (depends on your requirements). You must clear the failed processing queues somehow, otherwise the forgotten data will fill your Redis.

UniqueQueue::getRedisClient

Returns the used instance of a Redis client (PhpRQ\ClientInterface). This is useful in multi-threaded environment when you want to reconnect the connection.

UniqueQueue::getCount

Returns the number of items in the queue.

UniqueQueue::addItem

param: $item Anything that can be converted to string

Adds an item to the queue.

UniqueQueue::addItems

param: (array) $items Array containing anything that can be converted to string

Adds multiple items to the queue.

UniqueQueue::getItems

param: (int) $size Number of items you want to return from the queue

Returns $size elements from the queue. You can set the $size to any number you like - the items are fetched from the queue by chunks with a fixed safe size so the server isn't overwhelmed.

Items that are fetched from the queue are added to a processing queue. That way if the process exits unexpectedly the items fetched from the queue can be preserved using re-enqueue methods.

UniqueQueue::getAllItems

Returns all items from the queue. The items are fetched from the queue by chunks of a fixed safe size so the server isn't overwhelmed.

Items that are fetched from the queue are added to a processing queue. That way if the process exits unexpectedly the items fetched from the queue can be preserved using re-enqueue methods.

UniqueQueue::ackItem

param: $item Anything that can be converted to string

Acknowledges the item - removes the item from the processing queue.

UniqueQueue::ackItems

param: (array) $items Array containing anything that can be converted to string

Acknowledges multiple items - removes them from the processing queue.

UniqueQueue::rejectItem

param: $item Anything that can be converted to string

Revokes the item - removes the item from the processing queue and puts it back at the head of the queue (i.e. it will be the first item to fetch)

Be aware: Order is guaranteed only by the best effort method, e.g. if you reject some items and then acknowledge another then the order is lost.

UniqueQueue::rejectItems

param: (array) $items Array containing anything that can be converted to string

Revokes multiple items - removes the items from the processing queue and puts them back at the head of the queue in the reversed order (i.e. they will be the first items to fetch, in the same order as they were fetched before).

Be aware: Order is guaranteed only by the best effort method, e.g. if you reject some items and then acknowledge another then the order is lost.

UniqueQueue::rejectBatch

Revokes all the remaining items in the processing queue and puts them back at the head of the queue in the reversed order (i.e. they will be the first items to fetch, in the same order as they were fetched before).

UniqueQueue::reEnqueueTimedOutItems

param: (int) $timeout Number of seconds after which the processing queue and all the items in it are considered as failed

You should call this method (or the reEnqueueAllItems) periodically (or before fetching items from the queue) to put the timed out items from the processing queues back to the head of the queue in the reversed order (i.e. they will be the first items to fetch, in the same order as they were fetched before).

Be aware: Order is guaranteed only by the best effort method, e.g. if the first batch fails, the seconds successes and the third fails again, the order of the items cannot be preserved because the first batch now "gets after the second one"

UniqueQueue::reEnqueueAllItems

You should call this method before fetching items from the queue but only if you have a single consumer. This method puts the items for all the processing queues back to the head of the queue in the reversed order (i.e. they will be the first items to fetch, in the same order as they were fetched before). Keep in mind that this method can re-enqueue still valid processing queues (i.e. not the failed ones).

Be aware: Order is guaranteed only by the best effort method, e.g. if the first batch fails, the second successes and the third fails again, the order of the items cannot be preserved because the first batch now "gets after the seconds one"

UniqueQueue::dropTimedOutItems

param: (int) $timeout Number of seconds after which the processing queue and all the items in it are considered as failed

You should call this method (or the dropAllItems) periodically (or before fetching items from the queue) to drop the timed out items from the processing queues.

UniqueQueue::dropAllItems

You should call this method before fetching items from the queue but only if you have a single consumer. This method drops the items for from all the processing queues. Keep in mind that this method can drop still valid processing queues (i.e. not the failed ones).

UniqueQueue::clearQueue

Removes all items from the queue and it's processing lists. Useful for testing purposes.

Pool

If you have a certain unique actions that needs to be processed for example each day then Pool is great tool for you. Items in the pool gets processed by the time mark they have assigned. When an item is successfully processed it's time mark gets increased by the set period of time (5 minutes, hour, day, week, ...) and it won't be processed again until it's time mark is lower than the actual time.

This is useful if the items in the pool are constant most of the time. Then it is wise to use Pool instead of a Queue

Pool - General usage

You can add items to the pool using addItem and addItems methods. If you want to get items from the pool then you can use getItems and getAllItems methods. When you have the items from the pool you can acknowledge (success; ackItem, ackItems) or just ignore them. If you no longer wish to process certain items then you can remove them from the pool with removeItem and removeItems. You can also clear the whole pool with the clearPool method.

Pool::getRedisClient

Returns the used instance of a Redis client (PhpRQ\ClientInterface). This is useful in multi-threaded environment when you want to reconnect the connection.

Pool::getCount

Returns the number of items in the pool.

Pool::getCountToProcess

Returns the number of items in the pool which needs to be processed

Pool::isInPool

param: (array|mixed) $item Single item or array of items which can be converted to string

Checks if the given item (or multiple items) is in the pool - returns boolean. For multiple items returns array of booleans indexed by the items.

Pool::addItem

param: $item Anything that can be converted to string

Adds an item to the pool.

Pool::addItems

param: (array) $items Array containing anything that can be converted to string

Adds multiple items to the pool.

Pool::getItems

param: (int) $size Number of items you want to return from the pool

Returns $size elements from the pool that should be processed. You can set the $size to any number you like - the items are fetched from the pool one by one so the server isn't overwhelmed.

Time mark of the items that are fetched from the pool is changed to a float number (a "processing" tag). This way you can be sure that all the items gets processed (for example if the process crashes).

Pool::getAllItems

Returns all items from the pool that should be processed. The items are fetched from the pool one by one so the server isn't overwhelmed.

Time mark of the items that are fetched from the pool is changed to a float number (a "processing" tag). This way you can be sure that all the items gets processed (for example if the process crashes).

Pool::ackItem

param: $item Anything that can be converted to string

Acknowledges the item - increases the time mark of the item.

Pool::ackItems

param: (array) $items Array containing anything that can be converted to string

Acknowledges multiple items - increases the time mark of the items.

Pool::removeItem

param: $item Anything that can be converted to string

Removes the given item from the pool

Pool::removeItems

param: (array) $items Array containing anything that can be converted to string

Removes the given items from the pool

Pool::clearPool

Removes all the items from the pool. Useful for testing purposes.

Base

This functionality is implemented in the abstract class Base therefore you can call it from all object types in the library (like Queue, Pool,..).

safeExecution()

Functional wrapper for retrying call of a PhpRQ method to avoid raising Predis\Connection\ConnectionException in case of a packet loss.

Example:

$queue = new \PhpRQ\Queue($predisConnection);

$items = $queue->safeExecution(
    function() use ($queue) {$queue->getItems(1);},
    function($returnValue) { /* what should happen in case of success */ },
    function() { /* what should happen in case of failure */ },
    $retryWait,  // Microseconds to wait between retries.
    $maxAttempts // Maximal count of attempts.
);