When you have many workers (threads/servers) giving service, and a cached item expensive to produce expires, you may get several workers doing the job at the same time. More...
Public Member Functions | |
| acquireForAnyone () | |
| I want to do this task, but if anyone else does it instead, it's also fine for me. More... | |
| acquireForMe () | |
| I want to do this task and I need to do it myself. More... | |
| getKey () | |
| release () | |
| I have successfully finished my task. More... | |
Static Public Member Functions | |
| static | factory ( $type, $key) |
| Create a Pool counter. More... | |
Public Attributes | |
| const | DONE = 3 |
| const | ERROR = -1 |
| const | LOCK_HELD = -5 |
| const | LOCKED = 1 |
| const | NOT_LOCKED = -2 |
| const | QUEUE_FULL = -3 |
| const | RELEASED = 2 |
| const | TIMEOUT = -4 |
Protected Member Functions | |
| __construct ( $conf, $type, $key) | |
Protected Attributes | |
| string | $key |
| All workers with the same key share the lock *. More... | |
| $maxqueue | |
| float | $timeout |
| Maximum time in seconds to wait for the lock *. More... | |
| integer | $workers |
| Maximum number of workers doing the task simultaneously *. More... | |
Detailed Description
When you have many workers (threads/servers) giving service, and a cached item expensive to produce expires, you may get several workers doing the job at the same time.
Given enough requests and the item expiring fast (non-cacheable, lots of edits...) that single work can end up unfairly using most (all) of the cpu of the pool. This is also known as 'Michael Jackson effect' since this effect triggered on the english wikipedia on the day Michael Jackson died, the biographical article got hit with several edits per minutes and hundreds of read hits.
The PoolCounter provides semaphore semantics for restricting the number of workers that may be concurrently performing such single task.
By default PoolCounter_Stub is used, which provides no locking. You can get a useful one in the PoolCounter extension.
Definition at line 42 of file PoolCounter.php.
Constructor & Destructor Documentation
◆ __construct()
|
protected |
- Parameters
-
array $conf string $type string $key
Reimplemented in PoolCounterRedis.
Definition at line 65 of file PoolCounter.php.
Member Function Documentation
◆ acquireForAnyone()
|
abstract |
I want to do this task, but if anyone else does it instead, it's also fine for me.
I will read its cached data.
- Returns
- Status Value is one of Locked/Done/Error
Reimplemented in PoolCounter_Stub, and PoolCounterRedis.
◆ acquireForMe()
|
abstract |
I want to do this task and I need to do it myself.
- Returns
- Status Value is one of Locked/Error
Reimplemented in PoolCounter_Stub, and PoolCounterRedis.
◆ factory()
|
static |
Create a Pool counter.
This should only be called from the PoolWorks.
- Parameters
-
$type $key
- Returns
- PoolCounter
Definition at line 80 of file PoolCounter.php.
References $key, $type, and global.
Referenced by PoolCounterWork\__construct().
◆ getKey()
| PoolCounter::getKey | ( | ) |
◆ release()
|
abstract |
I have successfully finished my task.
Lets another one grab the lock, and returns the workers waiting on acquireForAnyone()
- Returns
- Status value is one of Released/NotLocked/Error
Reimplemented in PoolCounter_Stub, and PoolCounterRedis.
Member Data Documentation
◆ $key
|
protected |
All workers with the same key share the lock *.
Definition at line 54 of file PoolCounter.php.
Referenced by __construct(), PoolCounterRedis\__construct(), factory(), and getKey().
◆ $maxqueue
|
protected |
Definition at line 57 of file PoolCounter.php.
◆ $timeout
|
protected |
Maximum time in seconds to wait for the lock *.
Definition at line 58 of file PoolCounter.php.
◆ $workers
|
protected |
Maximum number of workers doing the task simultaneously *.
Definition at line 55 of file PoolCounter.php.
◆ DONE
| const PoolCounter::DONE = 3 |
Definition at line 46 of file PoolCounter.php.
Referenced by PoolCounterWork\execute(), and PoolCounterRedis\waitForSlotOrNotif().
◆ ERROR
| const PoolCounter::ERROR = -1 |
Definition at line 48 of file PoolCounter.php.
Referenced by PoolCounterWork\execute().
◆ LOCK_HELD
| const PoolCounter::LOCK_HELD = -5 |
Definition at line 52 of file PoolCounter.php.
Referenced by PoolCounterRedis\waitForSlotOrNotif().
◆ LOCKED
| const PoolCounter::LOCKED = 1 |
Definition at line 44 of file PoolCounter.php.
Referenced by PoolCounter_Stub\acquireForAnyone(), PoolCounter_Stub\acquireForMe(), PoolCounterWork\execute(), and PoolCounterRedis\waitForSlotOrNotif().
◆ NOT_LOCKED
| const PoolCounter::NOT_LOCKED = -2 |
Definition at line 49 of file PoolCounter.php.
Referenced by PoolCounterRedis\release().
◆ QUEUE_FULL
| const PoolCounter::QUEUE_FULL = -3 |
Definition at line 50 of file PoolCounter.php.
Referenced by PoolCounterWork\execute(), and PoolCounterRedis\waitForSlotOrNotif().
◆ RELEASED
| const PoolCounter::RELEASED = 2 |
Definition at line 45 of file PoolCounter.php.
Referenced by PoolCounterRedis\release(), and PoolCounter_Stub\release().
◆ TIMEOUT
| const PoolCounter::TIMEOUT = -4 |
Definition at line 51 of file PoolCounter.php.
Referenced by PoolCounterWork\execute(), and PoolCounterRedis\waitForSlotOrNotif().
The documentation for this class was generated from the following file:
- includes/poolcounter/PoolCounter.php
