mattermost/wsapi/websocket_handler.go
Agniva De Sarker e39569b358
MM-23805: Refactor web_hub (#14277)
* MM-23800: remove goroutineID and stack printing

Each hub has a goroutineID which is calculated with a known hack.
The FAQ clearly explains why goroutines don't have an id:
https://golang.org/doc/faq#no_goroutine_id.

We only added that because sometimes the hub would be deadlocked and
having the goroutineID would be useful when getting the stack trace.
This is also problematic in stress tests because the hubs would
frequently get overloaded and the logs would unnecessarily have stack traces.

But that was in the past, and we have done extensive testing with
load tests and fuzz testing to smooth any rough edges remaining.
Including adding additional metrics for hub buffer size.

Monitoring the metrics is a better way to approach this problem.
Therefore, we remove these kludges from the code.

* Also remove deadlock checking code

There is no need for that anymore since
we are getting rid of the stack printing anyways.

Let's do a wholesale refactor and clean up the codebase.

* MM-23805: Refactor web_hub

This is a beginning of the refactoring of the websocket code.

To start off with, we unexport some methods and constants which did not
need to be exported. There are more remaining but some are out of scope for this PR.

The main chunk of refactor is to unexport the webconn send channel
which was the main cause of panics. Since we were directly sending
to the connection from various parts of the codebase, it would be possible
that the send channel would be closed and we could still send a message.
This would crash the server.

To fix this, we refactor the code to centralize all sending from the main
hub goroutine. This means we can leverage the connections map to check
if the connection exists or not, and only then send the message.

We also move the cluster calls to cluster.go.

* bring back cluster code inside hub

* Incorporate review comments

* Address review comments

* rename index

* MM-23807: Refactor web_conn

- Unexport some struct fields and constants which are not necessary
to be accessed from outside the package. This will help us moving
the entire websocket handling code to a separate package later.

- Change some empty string checks to check for empty string rather
than doing a len check which is more idiomatic. Both of them compile
to the same code. So it doesn't make a difference performance-wise.

- Remove redundant ToJson calls to get the length.

- Incorporate review comments

- Unexport some more methods

* Fix field name

* Run make app-layers

* Add note on hub check
2020-04-23 13:16:18 +05:30

79 lines
2.4 KiB
Go

// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.
package wsapi
import (
"net/http"
"github.com/mattermost/mattermost-server/v5/app"
"github.com/mattermost/mattermost-server/v5/mlog"
"github.com/mattermost/mattermost-server/v5/model"
"github.com/mattermost/mattermost-server/v5/utils"
)
func (api *API) ApiWebSocketHandler(wh func(*model.WebSocketRequest) (map[string]interface{}, *model.AppError)) webSocketHandler {
return webSocketHandler{api.App, wh}
}
type webSocketHandler struct {
app *app.App
handlerFunc func(*model.WebSocketRequest) (map[string]interface{}, *model.AppError)
}
func (wh webSocketHandler) ServeWebSocket(conn *app.WebConn, r *model.WebSocketRequest) {
mlog.Debug("Websocket request", mlog.String("action", r.Action))
hub := wh.app.GetHubForUserId(conn.UserId)
if hub == nil {
return
}
session, sessionErr := wh.app.GetSession(conn.GetSessionToken())
if sessionErr != nil {
mlog.Error(
"websocket session error",
mlog.String("action", r.Action),
mlog.Int64("seq", r.Seq),
mlog.String("user_id", conn.UserId),
mlog.String("error_message", sessionErr.SystemMessage(utils.T)),
mlog.Err(sessionErr),
)
sessionErr.DetailedError = ""
errResp := model.NewWebSocketError(r.Seq, sessionErr)
hub.SendMessage(conn, errResp)
return
}
r.Session = *session
r.T = conn.T
r.Locale = conn.Locale
var data map[string]interface{}
var err *model.AppError
if data, err = wh.handlerFunc(r); err != nil {
mlog.Error(
"websocket request handling error",
mlog.String("action", r.Action),
mlog.Int64("seq", r.Seq),
mlog.String("user_id", conn.UserId),
mlog.String("error_message", err.SystemMessage(utils.T)),
mlog.Err(err),
)
err.DetailedError = ""
errResp := model.NewWebSocketError(r.Seq, err)
hub.SendMessage(conn, errResp)
return
}
resp := model.NewWebSocketResponse(model.STATUS_OK, r.Seq, data)
hub.SendMessage(conn, resp)
}
func NewInvalidWebSocketParamError(action string, name string) *model.AppError {
return model.NewAppError("websocket: "+action, "api.websocket_handler.invalid_param.app_error", map[string]interface{}{"Name": name}, "", http.StatusBadRequest)
}
func NewServerBusyWebSocketError(action string) *model.AppError {
return model.NewAppError("websocket: "+action, "api.websocket_handler.server_busy.app_error", nil, "", http.StatusServiceUnavailable)
}