A Fast, Thread-Safe Pooling Library for Common Lisp.
A Trivial, Fast & Thread-Safe Pooling Library for Common Lisp.
We need pools for items which have heavy cost of creation and which we can reuse. A typical use case is connection pools.
Pool item creation (as required) is automatic on fetch-from pool. Pool-item's are created and destroyed using user supplied funcitons. The pool has a idle timeout after which all the existing pool-item's are destroyed and new ones created (pool-init). The pool has a threshold number of items which it tries to maintain.
Licence : MIT
Structure POOL
NAME : Is a text string identifying the POOL
QUEUE : A queue to store the POOL-ITEMs
POOL-LOCK : A lock we hold when we want to update the POOL
ITEM-MAKER : A function which returns a POOL-ITEM.
ITEM-DESTROYER : A function which sanely destroys a POOL-ITEM
CAPACITY : The max number of POOL-ITEMs to store in the POOL
THRESHOLD : The min number of POOL-ITEMs we should ideally keep in the POOL.
TIMEOUT : The number of seconds of idleness after which the POOL will be re-init.
LAST-ACCESS : The last access time for the POOL.
CURRENT-SIZE : The current number of POOL-ITEMs in the POOL
TOTAL-USES : Total number of times the POOL-ITEMs have been taken out of the POOL
TOTAL-CREATED : Total number of new POOL-ITEMs created and added to the POOL
TOTAL-POOL-INITS : How many times the POOL was 'INIT'.
make-pool &key name max-capacity min-threshold pool-item-maker pool-item-destroyer
Makes and returns a new POOL.
grow-pool pool &optional grow-by
Creates and adds POOL-ITEMs to the pool. In case grow-by is not provided then it takes ( threshold pool ) as the value
fetch-from-aux pool
Fetches a POOL-ITEM from the POOL. Tell us if the pool has become old.
fetch-from pool &key (tries 3)
Is a wrapper around fetch-from-aux and will try tries number of times to fetch POOL-ITEM from POOL. In case POOL-ITEM is not returned then it grows the POOL and tries again.
return-to pool pool-item
Returns a POOL-ITEM to the POOL. In case the pool is at CAPACITY the POOL-ITEM will be sanely destroyed using the given function
pool-init pool
Sanely destroys all the POOL-ITEMS and then re-creates THRESHOLD number of POOL-ITEMS.
with-pool pool-item pool &body body
Executes the body where pool-item is fetched from the pool and available. Sanely returns pool-item to the pool on finish of body.
POOLER> (defvar *x* nil)
*X*
POOLER> (setf *x* (make-pool :name "Test Pool"))
#<POOL Test Pool Max:4 Current:0 >
POOLER> (fetch-from+ *x*)
SAMPLE-ITEM
POOLER> *x*
#<POOL Test Pool Max:4 Current:1 >
POOLER> (return-to *x* **)
2
POOLER> (with-pool (pool-item *x*) (print pool-item))
SAMPLE-ITEM
SAMPLE-ITEM
POOLER> *x*
#<POOL Test Pool Max:4 Current:2 >
Another
CL-USER> (pooler:make-pool :item-maker #'(lambda () (clsql:connect '("127.0.0.1" "quasidb" "quasi" "*****")
:database-type :mysql
:if-exists :new))
:item-destroyer #'(lambda (item) (clsql:disconnect :database item)))
#S(POOLER::POOL
:NAME "Default Pool"
:QUEUE #S(SB-CONCURRENCY:QUEUE
:HEAD (SB-CONCURRENCY::.DUMMY.)
:TAIL (SB-CONCURRENCY::.DUMMY.)
:NAME NIL)
:LOCK #<SB-THREAD:MUTEX "Pool Lock" (free)>
:ITEM-MAKER #<FUNCTION (LAMBDA #) {1005C9BFAB}>
:ITEM-DESTROYER #<FUNCTION (LAMBDA #) {1005CCAAAB}>
:CAPACITY 40
:THRESHOLD 2
:TIMEOUT 300
:LAST-ACCESS 0
:CURRENT-SIZE 0
:TOTAL-USES 0
:TOTAL-CREATED 0
:TOTAL-POOL-INITS 0)
CL-USER> (defvar *mysql-pool* *)
CL-USER> (pooler:fetch-from *mysql-pool*)
#<CLSQL-MYSQL:MYSQL-DATABASE 127.0.0.1/quasidb/quasi OPEN {1007571373}>
CL-USER> (pooler:return-to *mysql-pool* *)
2
CL-USER> (pooler:with-pool (db *mysql-pool*) (clsql:query "show tables;" :database db))
(("LOGIN_DATA"))
("Tables_in_quasidb")
Abhijit Rao a.k.a quasi