| Class | EventMachine::Pool |
| In: |
lib/em/pool.rb
|
| Parent: | Object |
A simple async resource pool based on a resource and work queue. Resources are enqueued and work waits for resources to become available.
Example:
EM.run do
pool = EM::Pool.new
spawn = lambda { pool.add EM::HttpRequest.new('http://example.org') }
10.times { spawn[] }
done, scheduled = 0, 0
check = lambda do
done += 1
if done >= scheduled
EM.stop
end
end
pool.on_error { |conn| spawn[] }
100.times do
pool.perform do |conn|
req = conn.get :path => '/', :keepalive => true
req.callback do
p [:success, conn.object_id, i, req.response.size]
check[]
end
req.errback { check[] }
req
end
end
end
Resources are expected to be controlled by an object responding to a deferrable/completion style API with callback and errback blocks.
Returns a list for introspection purposes only. You should NEVER call modification or work oriented methods on objects in this list. A good example use case is periodic statistics collection against a set of connection resources.
For example:
pool.contents.inject(0) { |sum, connection| connection.num_bytes }
Define a default catch-all for when the deferrables returned by work blocks enter a failed state. By default all that happens is that the resource is returned to the pool. If on_error is defined, this block is responsible for re-adding the resource to the pool if it is still usable. In other words, it is generally assumed that on_error blocks explicitly handle the rest of the lifetime of the resource.
Perform a given call-able object or block. The callable object will be called with a resource from the pool as soon as one is available, and is expected to return a deferrable.
The deferrable will have callback and errback added such that when the deferrable enters a finished state, the object is returned to the pool.
If on_error is defined, then objects are not automatically returned to the pool.
Removed will show resources in a partial pruned state. Resources in the removed list may not appear in the contents list if they are currently in use.