Add a lock for plugins to use if using async code

Ref #1539

cmd/micro/initlua.go

@@ -56,6 +56,7 @@ func luaImportMicro() *lua.LTable {
 	ulua.L.SetField(pkg, "Tabs", luar.New(ulua.L, func() *action.TabList {
 		return action.Tabs
 	}))
+	ulua.L.SetField(pkg, "Lock", luar.New(ulua.L, ulua.Lock))
 
 	return pkg
 }

cmd/micro/micro.go

@@ -17,6 +17,7 @@ import (
 	"github.com/zyedidia/micro/v2/internal/action"
 	"github.com/zyedidia/micro/v2/internal/buffer"
 	"github.com/zyedidia/micro/v2/internal/config"
+	ulua "github.com/zyedidia/micro/v2/internal/lua"
 	"github.com/zyedidia/micro/v2/internal/screen"
 	"github.com/zyedidia/micro/v2/internal/shell"
 	"github.com/zyedidia/micro/v2/internal/util"
@@ -344,7 +345,9 @@ func main() {
 	// okay to be inefficient and run it via a function every time
 	// We do this so we can recover from panics without crashing the editor
 	for {
+		ulua.Lock.Lock()
 		DoEvent()
+		ulua.Lock.Unlock()
 	}
 }
 

internal/lua/lua.go

@@ -15,6 +15,7 @@ import (
 	"regexp"
 	"runtime"
 	"strings"
+	"sync"
 	"time"
 	"unicode/utf8"
 
@@ -24,6 +25,7 @@ import (
 )
 
 var L *lua.LState
+var Lock sync.Mutex
 
 // LoadFile loads a lua file
 func LoadFile(module string, file string, data []byte) error {