wide/event/events.go

146 lines
3.6 KiB
Go

// Copyright (c) 2014-2018, b3log.org & hacpai.com
//
// 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
//
// https://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 event includes event related manipulations.
package event
import (
"os"
"github.com/b3log/wide/log"
"github.com/b3log/wide/util"
)
const (
// EvtCodeGOPATHNotFound indicates an event: not found $GOPATH env variable
EvtCodeGOPATHNotFound = iota
// EvtCodeGOROOTNotFound indicates an event: not found $GOROOT env variable
EvtCodeGOROOTNotFound
// EvtCodeGocodeNotFound indicates an event: not found gocode
EvtCodeGocodeNotFound
// EvtCodeIDEStubNotFound indicates an event: not found gotools
EvtCodeIDEStubNotFound
// EvtCodeServerInternalError indicates an event: server internal error
EvtCodeServerInternalError
)
// Max length of queue.
const maxQueueLength = 10
// Logger.
var logger = log.NewLogger(os.Stdout)
// Event represents an event.
type Event struct {
Code int `json:"code"` // event code
Sid string `json:"sid"` // wide session id related
Data interface{} `json:"data"` // event data
}
// Global event queue.
//
// Every event in this queue will be dispatched to each user event queue.
var EventQueue = make(chan *Event, maxQueueLength)
// UserEventQueue represents a user event queue.
type UserEventQueue struct {
Sid string // wide session id related
Queue chan *Event // queue
Handlers []Handler // event handlers
}
type queues map[string]*UserEventQueue
// User event queues.
//
// <sid, *UserEventQueue>
var UserEventQueues = queues{}
// Load initializes the event handling.
func Load() {
go func() {
defer util.Recover()
for event := range EventQueue {
logger.Debugf("Received a global event [code=%d]", event.Code)
// dispatch the event to each user event queue
for _, userQueue := range UserEventQueues {
event.Sid = userQueue.Sid
userQueue.Queue <- event
}
}
}()
}
// AddHandler adds the specified handlers to user event queues.
func (uq *UserEventQueue) AddHandler(handlers ...Handler) {
uq.Handlers = append(uq.Handlers, handlers...)
}
// New initializes a user event queue with the specified wide session id.
func (ueqs queues) New(sid string) *UserEventQueue {
if q, ok := ueqs[sid]; ok {
logger.Warnf("Already exist a user queue in session [%s]", sid)
return q
}
q := &UserEventQueue{
Sid: sid,
Queue: make(chan *Event, maxQueueLength),
}
ueqs[sid] = q
go func() { // start listening
defer util.Recover()
for evt := range q.Queue {
logger.Debugf("Session [%s] received an event [%d]", sid, evt.Code)
// process event by each handlers
for _, handler := range q.Handlers {
handler.Handle(evt)
}
}
}()
return q
}
// Close closes a user event queue with the specified wide session id.
func (ueqs queues) Close(sid string) {
if q, ok := ueqs[sid]; ok {
close(q.Queue)
delete(ueqs, sid)
}
}
// Handler represents an event handler.
type Handler interface {
Handle(event *Event)
}
// HandleFunc represents a handler function.
type HandleFunc func(event *Event)
// Default implementation of event handling.
func (fn HandleFunc) Handle(event *Event) {
fn(event)
}