Files
mattermost/app/plugin_deadlock_test.go
Jesse Hallam 835c0871a0 MM-11431: handle plugin deadlocks (#9167)
* ensure plugin is always shutdown

Once we call `.client.Client()` the plugin has started, and must be shut
down. `newSupervisor` sometimes returned with an error (and without a
reference to the supervisor), leaving the client running indefinitely.

* Clarify the documentation to explain that plugin hooks will not trigger until `OnActivate` returns successfully, and will stop triggering just before `OnDeactivate` is called.

* test for plugin deadlock

* plugin/environment.go: switch to sync.Map

From: https://golang.org/pkg/sync/#Map

> If a goroutine holds a RWMutex for reading and another goroutine might call Lock, no goroutine should expect to be able to acquire a read lock until the initial read lock is released. In particular, this prohibits recursive read locking. This is to ensure that the lock eventually becomes available; a blocked Lock call excludes new readers from acquiring the lock.

The previous `RWMutex` was not safe given that we effectively acquired read locks recursively (hook -> api -> hook). This worked up until we activated or deactivated plugins, tried to acquire a write lock, and the plugin used the API to effectively trigger another hook.

Switching to sync.Map avoids this by divesting the need to lock at all, avoiding the potential for a recursive lock in the first place.
2018-07-27 11:37:17 -04:00

212 lines
4.3 KiB
Go

// Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
// See License.txt for license information.
package app
import (
"os"
"strings"
"testing"
"text/template"
"time"
"github.com/mattermost/mattermost-server/model"
)
func TestPluginDeadlock(t *testing.T) {
t.Run("Single Plugin", func(t *testing.T) {
th := Setup().InitBasic()
defer th.TearDown()
pluginPostOnActivate := template.Must(template.New("pluginPostOnActivate").Parse(`
package main
import (
"github.com/mattermost/mattermost-server/plugin"
"github.com/mattermost/mattermost-server/model"
)
type MyPlugin struct {
plugin.MattermostPlugin
}
func (p *MyPlugin) OnActivate() error {
_, err := p.API.CreatePost(&model.Post{
UserId: "{{.User.Id}}",
ChannelId: "{{.Channel.Id}}",
Message: "message",
})
if err != nil {
panic(err.Error())
}
return nil
}
func (p *MyPlugin) MessageWillBePosted(c *plugin.Context, post *model.Post) (*model.Post, string) {
if _, from_plugin := post.Props["from_plugin"]; from_plugin {
return post, ""
}
p.API.CreatePost(&model.Post{
UserId: "{{.User.Id}}",
ChannelId: "{{.Channel.Id}}",
Message: "message",
Props: map[string]interface{}{
"from_plugin": true,
},
})
return post, ""
}
func main() {
plugin.ClientMain(&MyPlugin{})
}
`,
))
templateData := struct {
User *model.User
Channel *model.Channel
}{
th.BasicUser,
th.BasicChannel,
}
plugins := []string{}
pluginTemplates := []*template.Template{
pluginPostOnActivate,
}
for _, pluginTemplate := range pluginTemplates {
b := &strings.Builder{}
pluginTemplate.Execute(b, templateData)
plugins = append(plugins, b.String())
}
done := make(chan bool)
go func() {
SetAppEnvironmentWithPlugins(t, plugins, th.App, th.App.NewPluginAPI)
close(done)
}()
select {
case <-done:
case <-time.After(30 * time.Second):
t.Fatal("plugin failed to activate: likely deadlocked")
go func() {
time.Sleep(5 * time.Second)
os.Exit(1)
}()
}
})
t.Run("Multiple Plugins", func(t *testing.T) {
th := Setup().InitBasic()
defer th.TearDown()
pluginPostOnHasBeenPosted := template.Must(template.New("pluginPostOnHasBeenPosted").Parse(`
package main
import (
"github.com/mattermost/mattermost-server/plugin"
"github.com/mattermost/mattermost-server/model"
)
type MyPlugin struct {
plugin.MattermostPlugin
}
func (p *MyPlugin) MessageWillBePosted(c *plugin.Context, post *model.Post) (*model.Post, string) {
if _, from_plugin := post.Props["from_plugin"]; from_plugin {
return post, ""
}
p.API.CreatePost(&model.Post{
UserId: "{{.User.Id}}",
ChannelId: "{{.Channel.Id}}",
Message: "message",
Props: map[string]interface{}{
"from_plugin": true,
},
})
return post, ""
}
func main() {
plugin.ClientMain(&MyPlugin{})
}
`,
))
pluginPostOnActivate := template.Must(template.New("pluginPostOnActivate").Parse(`
package main
import (
"github.com/mattermost/mattermost-server/plugin"
"github.com/mattermost/mattermost-server/model"
)
type MyPlugin struct {
plugin.MattermostPlugin
}
func (p *MyPlugin) OnActivate() error {
_, err := p.API.CreatePost(&model.Post{
UserId: "{{.User.Id}}",
ChannelId: "{{.Channel.Id}}",
Message: "message",
})
if err != nil {
panic(err.Error())
}
return nil
}
func main() {
plugin.ClientMain(&MyPlugin{})
}
`,
))
templateData := struct {
User *model.User
Channel *model.Channel
}{
th.BasicUser,
th.BasicChannel,
}
plugins := []string{}
pluginTemplates := []*template.Template{
pluginPostOnHasBeenPosted,
pluginPostOnActivate,
}
for _, pluginTemplate := range pluginTemplates {
b := &strings.Builder{}
pluginTemplate.Execute(b, templateData)
plugins = append(plugins, b.String())
}
done := make(chan bool)
go func() {
SetAppEnvironmentWithPlugins(t, plugins, th.App, th.App.NewPluginAPI)
close(done)
}()
select {
case <-done:
case <-time.After(30 * time.Second):
t.Fatal("plugin failed to activate: likely deadlocked")
go func() {
time.Sleep(5 * time.Second)
os.Exit(1)
}()
}
})
}