tiny-level-ttl
==============

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Enforces a [time to live (TTL)][wiki-ttl] on a [node-levelup][levelup] database.

- The ttl is specified in the constructor. (In [node-level-ttl][ttl] you can set the ttl in the constructor, and/or in a db.put() call.)
- Supports [level-sublevel][sublevel] 5 & 6, and [level-spaces][spaces] 1 & 2. (Defaults to [level-spaces@2][spaces].)
- Respects [level-lock][lock] locks.

Why use this instead of [node-level-ttl][ttl]? Because [level-sublevel][sublevel] and [node-level-ttl][ttl] conflict.

[Bug reproduction test code here.][bug-code]
The bug was found using level-sublevel@6 with level-ttl@2, and level-sublevel@5 with level-ttl 0.6.

api

``js var ttl = require('tiny-level-ttl')`

ttl(db[, opts])

Adds a refreshTtl method to the db. When db.refreshTtl(key) is called, it will refresh the ttl on the key. This adds the ability to make the ttl act like a session manager by calling refreshTtl() every time you do db.get().

Also, this respects the locks that [level-lock][lock] creates. If tiny-level-ttl attempts to delete a key, and the key's write access is locked, it will restart the key's life. (In most cases, this is the desired outcome. If the key is being written to, you would've restarted the key's life anyway. If the key is being deleted, restarting its life will not mess anything up.)

- dbis a levelup database. -optsis an object with the following properties: -ttl is a number of milliseconds for how long a key lives in the db. Optional; defaults to 3600000, (1 hour). -checkInterval is a number of milliseconds for how long the interval between checking keys is. Optional; defaults to 10000, (10 seconds). -separator can be a string, buffer, or array of strings/buffers. These represent the separator used in the sub-database. For example, level-spaces by default has the separator ~, so if you store the key bar, in the space foo, the key will be ~foo~bar. Defaults to [ '~', '\xff', '\x00' ].

`example`

Basic usage:

`js var level = require('level-mem') var ttl = require('tiny-level-ttl')

var db = level('/levelmem/does/not/care') ttl(db, { ttl: 1000, checkInterval: 50 })

db.put('hi', 'wuzzup') //this sets the ttl

setTimeout(function () { //before key expires db.get('hi', function (err, value) { console.log(err && err.notFound) // -> null console.log(value) // -> 'wazzup' }) }, 900)

setTimeout(function () { //after key expires db.get('hi', function (err, value) { console.log(err && err.notFound) // -> true console.log(value) // -> undefined }) }, 1100)`

`install`

With npm do:

`npm install tiny-level-ttl``

license

VOL

[bug-code]: https://gist.github.com/ArtskydJ/65ebbd9cdbcdea9f091e
[levelup]: https://github.com/rvagg/node-levelup
[lock]: https://github.com/substack/level-lock
[spaces]: https://github.com/rvagg/level-spaces
[sublevel]: https://github.com/dominictarr/level-sublevel
[ttl]: https://github.com/rvagg/node-level-ttl
[wiki-ttl]:https://en.wikipedia.org/wiki/Time_to_live

ttl(db[, opts])

Also, this respects the locks that [level-lock][lock] creates. If tiny-level-ttl

 attempts to delete a key, and the key's write access is locked, it will restart the key's life. (In most cases, this is the desired outcome. If the key is being written to, you would've restarted the key's life anyway. If the key is being deleted, restarting its life will not mess anything up.)

- db

 is a levelup database.
-

opts

 is an object with the following properties:
	-

ttl is a number of milliseconds for how long a key lives in the db. Optional; defaults to 3600000

, (1 hour).
	-

checkInterval is a number of milliseconds for how long the interval between checking keys is. Optional; defaults to 10000

, (10 seconds).
	-

separator

 can be a string, buffer, or array of strings/buffers. These represent the separator used in the sub-database. For example,

level-spaces by default has the separator ~, so if you store the key bar, in the space foo, the key will be ~foo~bar. Defaults to [ '~', '\xff', '\x00' ].

example

Basic usage:

js
var level = require('level-mem')
var ttl = require('tiny-level-ttl')

var db = level('/levelmem/does/not/care')
ttl(db, {
	ttl: 1000,
	checkInterval: 50
})

db.put('hi', 'wuzzup') //this sets the ttl

setTimeout(function () { //before key expires
	db.get('hi', function (err, value) {
		console.log(err && err.notFound) // -> null
		console.log(value) // -> 'wazzup'
	})
}, 900)

setTimeout(function () { //after key expires
	db.get('hi', function (err, value) {
		console.log(err && err.notFound) // -> true
		console.log(value) // -> undefined
	})
}, 1100)

license