dendrite/internal/hooks/hooks.go

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// Copyright 2020 The Matrix.org Foundation C.I.C.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package hooks exposes places in Dendrite where custom code can be executed, useful for MSCs.
// Hooks can only be run in monolith mode.
package hooks
import "sync"
const (
// KindNewEventPersisted is a hook which is called with *gomatrixserverlib.HeaderedEvent
// It is run when a new event is persisted in the roomserver.
// Usage:
// hooks.Attach(hooks.KindNewEventPersisted, func(headeredEvent interface{}) { ... })
KindNewEventPersisted = "new_event_persisted"
// KindNewEventReceived is a hook which is called with *gomatrixserverlib.HeaderedEvent
// It is run before a new event is processed by the roomserver. This hook can be used
// to modify the event before it is persisted by adding data to `unsigned`.
// Usage:
// hooks.Attach(hooks.KindNewEventReceived, func(headeredEvent interface{}) {
// ev := headeredEvent.(*gomatrixserverlib.HeaderedEvent)
// _ = ev.SetUnsignedField("key", "val")
// })
KindNewEventReceived = "new_event_received"
)
var (
hookMap = make(map[string][]func(interface{}))
hookMu = sync.Mutex{}
enabled = false
)
// Enable all hooks. This may slow down the server slightly. Required for MSCs to work.
func Enable() {
enabled = true
}
// Run any hooks
func Run(kind string, data interface{}) {
if !enabled {
return
}
cbs := callbacks(kind)
for _, cb := range cbs {
cb(data)
}
}
// Attach a hook
func Attach(kind string, callback func(interface{})) {
if !enabled {
return
}
hookMu.Lock()
defer hookMu.Unlock()
hookMap[kind] = append(hookMap[kind], callback)
}
func callbacks(kind string) []func(interface{}) {
hookMu.Lock()
defer hookMu.Unlock()
return hookMap[kind]
}