[Bug]SyncedCachedEnforcer cannot use LoadFilteredPolicy and LoadPolicy concurrently

[longtengz]

Describe the bug

I'm trying to use LoadFilteredPolicy and LoadPolicy on SyncedCachedEnforcer in different places, thus they might be called in the same time. I think these two might interfere with each other, because sometimes my backend would wait on LoadFilteredPolicy, it's kind of random and does not have a particular pattern that I can debug with, so I think it's lock-related.

I'm using SyncedCachedEnforcer with this adapter https://github.com/pckhoi/casbin-pgx-adapter

To Reproduce

Just change https://github.com/casbin/casbin/blob/master/enforcer_cached_synced_test.go to have it run LoadPolicy and LoadFilteredPolicy concurrently, and the bug persists. It's pretty easy to reproduce.

Expected behavior

No deadlock and no bug.

Related Issue: #1268

[casbin-bot]

@tangyang9464 @JalinWang

[hsluoyz]

@PokIsemaine

[PokIsemaine]

@longtengz Hey,I remember the issue, but it wasn't dealt with because the consistency wasn't reproduced

I tried the following code, but no error occurred.

package main

import (
	"fmt"
	"sync"
	"time"

	"github.com/casbin/casbin/v2"
	fileadapter "github.com/casbin/casbin/v2/persist/file-adapter"
	pgxadapter "github.com/pckhoi/casbin-pgx-adapter/v3"
)

func main() {
	a, err := pgxadapter.NewAdapter("postgresql://postgres:root@localhost:5432/postgres?sslmode=disable") // Your driver and data source.
	if err != nil {
		panic(err)
	}
	e, err := casbin.NewSyncedCachedEnforcer("examples/basic_model.conf", a)
	if err != nil {
		panic(err)
	}

	wg := sync.WaitGroup{}
	wg.Add(2000)
	for i := 0; i < 1000; i++ {
		go func(id int) {
			_, _ = e.AddPolicy("alice", "data"+fmt.Sprintln(id), "read")
			wg.Done()
		}(i)
		go func(id int) {
			_, _ = e.AddPolicy("bob", "data"+fmt.Sprintln(id), "read")
			wg.Done()
		}(i)
	}

	wg.Wait()
	fmt.Println("init policy finished")

	filter := &fileadapter.Filter{
		P: []string{"alice", "", ""},
	}
	g := sync.WaitGroup{}
	for {
		g.Add(2)
		go func() {
			_ = e.LoadPolicy()
			g.Done()
		}()

		go func() {
			_ = e.LoadFilteredPolicy(filter)
			g.Done()
		}()
		g.Wait()
		fmt.Println(time.Now())
	}
}

Just change https://github.com/casbin/casbin/blob/master/enforcer_cached_synced_test.go to have it run LoadPolicy and LoadFilteredPolicy concurrently, and the bug persists. It's pretty easy to reproduce.

So, can you please tell us more about how it was changed? Can you show the modified code directly? Thank you so much!