entrypool v0.3.0
EntryPool
Simple array pooling with entry (i.e. time) adding/counting for simple rate limiting. See the example at the bottom for help with using this for rate limiting.
EntryPool Methods
pool = new EntryPool(initialSize, arrayLength,stepSize)
Returns a new pool of arrays of length arrayLength
with an initial size of initialSize
.
stepSize
is used when adding to the poll and defaults to initialSize
or "double pool".
pool.get()
Gets a new EntryArray
of length arrayLength
from the pool.
pool.put(array)
Puts back an EntryArray
once its done being used.
pool.add(num)
Adds num
arrays of length arrayLength
to the pool. If no num
is passed, it will
use the step size.
pool.trim(minSize)
Reduces pool size to at least minSize
(or 0) by removing unused arrays from the pool.
EntryArray Methods
arr.add(timestamp, value)
Adds an entry to the array. You should add an entry for each thing you want to limit. Returns the index at which entry was added or -1 if array is full.
arr.remove(timestamp)
Removes an entry from array. Returns true
if array is now empty. timestamp
and value
are both optional and to omit timestamp
but send value
pass undefined
as timestamp
.
arr.cleanup(maxEntry)
Removes any entries with a timestamp older than maxEntry
from array. Returns number of
entries left.
arr.numEntries()
Removes the number of entries in array.
Example
var connectionsPerIP = {},
//only allow up to 5 connections every minute
maxAllowedConnections = 5,
maxAllowedTimeframe = 60 * 1000,
pool = new EntryPool(100, maxAllowedConnections);
// server is a http.Server
server.on('connection', function(socket) {
var now = Date.now(),
ip = socket.remoteAddress;
if (!connectionsPerIP[ip]) {
connectionsPerIP[ip] = pool.get();
} else {
// remove any entries older than the allowed timeframe
connectionsPerIP[ip].cleanup(now - maxAllowedTimeframe);
}
// store that they just connected
if (connectionsPerIP[ip].add(now) < 0) {
// the user is over the rate-limit so end the connection immediately
socket.end();
return;
}
socket.on('close', function() {
// if the array is now empty then we need to remove it
if (connectionsPerIP[ip].cleanup(now - maxAllowedTimeframe) === 0) {
pool.put(connectionsPerIP[ip]);
delete connectionsPerIP[ip];
}
});
};
// if a connection was open for less than maxAllowedTimeframe then we didn't remove the entry from
// the array when they closed. this interval will cleanup any that are expired
setInterval(function() {
var cleanupIfBefore = Date.now() - maxAllowedTimeframe;
for (var ip in connectionsPerIP) {
if (connectionsPerIP[ip].cleanup(cleanupIfBefore) === 0) {
pool.put(connectionsPerIP[ip]);
delete connectionsPerIP[ip];
}
}
}, 10 * maxAllowedTimeframe);
By James Hartig