69 lines
2.6 KiB
Go
69 lines
2.6 KiB
Go
/*
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GoToSocial
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Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package httpclient
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import (
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"strings"
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"sync"
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"github.com/superseriousbusiness/gotosocial/internal/log"
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)
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type requestQueue struct {
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hostQueues sync.Map // map of `hostQueue`
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maxOpenConns int // max open conns per host per request method
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}
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type hostQueue struct {
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slotsByMethod sync.Map
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}
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// getWaitSpot returns a wait channel and release function for http clients
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// that want to do requests politely: that is, wait for their turn.
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//
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// To wait, a caller should do a select on an attempted insert into the
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// returned wait channel. Once the insert succeeds, then the caller should
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// proceed with the http request that pertains to the given host + method.
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// It doesn't matter what's put into the wait channel, just any interface{}.
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//
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// When the caller is finished with their http request, they should free up the
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// slot they were occupying in the wait queue, by calling the release function.
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//
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// The reason for the caller needing to provide host and method, is that each
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// remote host has a separate wait queue, and there's a separate wait queue
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// per method for that host as well. This ensures that outgoing requests can still
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// proceed for others hosts and methods while other requests are undergoing,
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// while also preventing one host from being spammed with, for example, a
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// shitload of GET requests all at once.
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func (rc *requestQueue) getWaitSpot(host string, method string) (wait chan<- interface{}, release func()) {
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hostQueueI, _ := rc.hostQueues.LoadOrStore(host, new(hostQueue))
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hostQueue, ok := hostQueueI.(*hostQueue)
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if !ok {
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log.Panic("hostQueueI was not a *hostQueue")
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}
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waitSlotI, _ := hostQueue.slotsByMethod.LoadOrStore(strings.ToUpper(method), make(chan interface{}, rc.maxOpenConns))
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methodQueue, ok := waitSlotI.(chan interface{})
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if !ok {
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log.Panic("waitSlotI was not a chan interface{}")
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}
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return methodQueue, func() { <-methodQueue }
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}
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