High performance resource pool written with TypeScript
MIT License
High performance resource pool written with TypeScript.
npm install lightning-pool --save
import {Pool} from 'lightning-pool';
import dbDriver from 'some-db-driver';
/**
* Step 1 - Create a factory object
*/
const factory = {
create: async function(opts) {
const client = await DbDriver.createClient();
return client;
},
destroy: async function(client) {
await client.close();
},
reset: async function(client){
await client.rollback();
},
validate: async function(client) {
await client.query('select 1');
}
};
/**
* Step 2 - Create a the pool object
*/
const pool = new Pool(factory, {
max: 10, // maximum size of the pool
min: 2, // minimum size of the pool
minIdle: 2 // minimum idle resources
});
/**
* Step 3 - Use pool in your code to acquire/release resources
*/
// acquire connection - Promise is resolved
const client = await pool.acquire();
// once a resource becomes available
// Use resource
await client.query("select * from foo");
// return object back to pool
await pool.release(client);
/**
* Step 4 - Shutdown pool (optional)
* Call close(force) when you need to shutdown the pool
*/
// Wait for active resource for 5 sec than force shutdown
await pool.close(5000);
Pool
instancelightning-pool module exports createPool() method and Pool class. Both can be used to instantiate a Pool.
import {createPool} from 'lightning-pool';
const pool = createPool(factory, options);
import {Pool} from 'lightning-pool';
const pool = new Pool(factory, options);
Can be any object/instance with the following properties:
create
: The function that the Pool
will call when it needs a new resource. It should return a Promise<resouce>
.destroy
: The function that the Pool
will call when it wants to destroy a resource
. It should accept first argument as resource
, where resource
is whatever factory.create made. It should return a Promise<>
.reset
(optional) : The function that the Pool
will call before any resource
back to the Pool
. It should accept first argument as resource
, where resource
is whatever factory.create made. It should return a Promise<>
. Pool
will destroy and remove the resource from the Pool
on any error.validate
(optional) : The function that the Pool
will call when any resource needs to be validated. It should accept first argument as resource
, where resource
is whatever factory.create made. It should return a Promise<>
. Pool
will destroy and remove the resource from the Pool
on any error.acquireMaxRetries
: Maximum number that Pool
will try to create a resource before returning the error. (Default 0)acquireRetryWait
: Time in millis that Pool
will wait after each tries. (Default 2000)acquireTimeoutMillis
: Time in millis an acquire call will wait for a resource before timing out. (Default 0 - no limit)fifo
: If true resources will be allocated first-in-first-out order. resources will be allocated last-in-first-out order. (Default true)idleTimeoutMillis
: The minimum amount of time in millis that an resource
may sit idle in the Pool
. (Default 30000)houseKeepInterval
: Time period in millis that Pool
will make a cleanup. (Default 1000)min
: Minimum number of resources that Pool
will keep. (Default 0)minIdle
: Minimum number of resources that Pool
will keep in idle state. (Default 0)max
: Maximum number of resources that Pool
will create. (Default 10)maxQueue
: Maximum number of request that Pool
will accept. (Default 1000)resetOnReturn
: If true Pool
will call reset()
function of factory before moving it idle state. (Default true)validation
: If true Pool
will call validation()
function of factory when it needs it. If false, validation()
never been called. (Default true)Acquires a resource
from the Pool
or create a new one.
pool.acquire(): Promise<any>
pool.acquire(factoryCreateOptions: any): Promise<any>
pool.acquire(callback:Callback): Promise<any>
pool.acquire(factoryCreateOptions?: any, callback:Callback): Promise<any>
var promise = pool.acquire();
promise.then(resource => {
// Do what ever you want with resource
}).catch(err =>{
// Handle Error
});
Returns if a resource has been acquired from the Pool
and not yet released or destroyed.
pool.isAcquired(resource)
resource
: A previously acquired resourceif (pool.isAcquired(resource)) {
// Do any thing
}
Returns if the Pool
contains a resource
pool.includes(resource)
resource
: A resource objectPool
, else Falseif (pool.includes(resource)) {
// Do any thing
}
Releases an allocated resource
and let it back to pool.
pool.release(resource)
resource
: A previously acquired resourcepool.release(resource);
Releases, destroys and removes any resource
from Pool
.
pool.destroy(resource)
resource
: A previously acquired resourcepool.destroy(resource);
Starts the Pool
and begins creating of resources, starts house keeping and any other internal logic.
Note: This method is not need to be called. Pool
instance will automatically be started when acquire() method is called
pool.start()
pool.start();
Shuts down the Pool
and destroys all resources.
close(callback: Callback): void;
close(terminateWait: number, callback?: Callback): Promise<void>;
close(force: boolean, callback?: Callback): void;
force
: If true, Pool
will immediately destroy resources instead of waiting to be releasedterminateWait
: If specified, Pool
will wait for active resources to releasecallback
: If specified, callback will be called after close. If not specified a promise returns.var promise = pool.close();
promise.then(() => {
console.log('Pool has been shut down')
}).catch(err => {
console.error(err);
});
acquired
(Number): Returns number of acquired resources.available
(Number): Returns number of idle resources.creating
(Number): Returns number of resources currently been created.pending
(Number): Returns number of acquire request waits in the Pool
queue.size
(Number): Returns number of total resources.state
(PoolState): Returns current state of the Pool
.options
(PoolOptions): Returns object instance that holds configuration properties
acquireMaxRetries
(Get/Set): Maximum number that Pool
will try to create a resource before returning the error. (Default 0)acquireRetryWait
(Get/Set): Time in millis that Pool
will wait after each tries. (Default 2000)acquireTimeoutMillis
(Get/Set): Time in millis an acquire call will wait for a resource before timing out. (Default 0 - no limit)fifo
(Get/Set): If true resources will be allocated first-in-first-out order. resources will be allocated last-in-first-out order. (Default true)idleTimeoutMillis
(Get/Set): The minimum amount of time in millis that an resource
may sit idle in the Pool
. (Default 30000)houseKeepInterval
(Get/Set): Time period in millis that Pool
will make a cleanup. (Default 1000)min
(Get/Set): Minimum number of resources that Pool
will keep. (Default 0)minIdle
(Get/Set): Minimum number of resources that Pool
will keep in idle state. (Default 0)max
(Get/Set): Maximum number of resources that Pool
will create. (Default 10)maxQueue
(Get/Set): Maximum number of request that Pool
will acceps. (Default 1000)resetOnReturn
(Get/Set): If true Pool
will call reset()
function of factory before moving it idle state. (Default true)validation
(Get/Set): If true Pool
will call validation()
function of factory when it needs it. If false, validation()
never been called. (Default true)Pool derives from EventEmitter and produce the following events:
acquire
: Emitted when a resource acquired.pool.on('acquire', function(resource){
//....
})
create
: Emitted when a new resource is added to the Pool
.pool.on('create', function(resource){
//....
})
create-error
: Emitted when a factory.create informs any error.pool.on('create-error', function(error){
//Log stuff maybe
})
destroy
: Emitted when a resource is destroyed and removed from the Pool
.destroy-error
: Emitted when a factory.destroy informs any error.pool.on('destroy-error', function(error, resource){
//Log stuff maybe
})
return
: Emitted when an acquired resource returns to the Pool
.pool.on('start', function(resource){
//...
})
start
: Emitted when the Pool
started.pool.on('start', function(){
//...
})
closing
: Emitted when before closing the Pool
.pool.on('closing', function(){
//...
})
close
: Emitted when after closing the Pool
.pool.on('close', function(){
//...
})
validate-error
: Emitted when a factory.validate informs any error.pool.on('validate-error', function(error, resource){
//Log stuff maybe
})
Pool.PoolState (Number):
IDLE: 0, // Pool has not been started
STARTED: 1, // Pool has been started
CLOSING: 2, // Pool shutdown in progress
CLOSED: 3 // Pool has been shut down
>= 16.0
;