tiny-level-ttl
v3.1.5
Published
Extension for node-level that enforces a time to live on a database (or sublevel db)
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tiny-level-ttl
Enforces a time to live (TTL) on a node-levelup
database.
- The ttl is specified in the constructor. (In
node-level-ttl
you can set the ttl in the constructor, and/or in adb.put()
call.) - Supports
level-sublevel
5 & 6, andlevel-spaces
1 & 2. (Defaults tolevel-spaces@2
.) - Respects
level-lock
locks.
Why use this instead of node-level-ttl
? Because level-sublevel
and node-level-ttl
conflict.
Bug reproduction test code here.
The bug was found using level-sublevel@6
with level-ttl@2
, and level-sublevel@5
with level-ttl 0.6
.
api
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
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 thedb
. Optional; defaults to3600000
, (1 hour).checkInterval
is a number of milliseconds for how long the interval between checking keys is. Optional; defaults to10000
, (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 keybar
, in the spacefoo
, the key will be~foo~bar
. Defaults to[ '~', '\xff', '\x00' ]
.
example
Basic usage:
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