Improved panic log handling

Author: cmaglie

handler/builder.go

@@ -10,6 +10,7 @@ import (
 	"github.com/arduino/arduino-cli/arduino/libraries"
 	"github.com/arduino/arduino-cli/executils"
 	"github.com/arduino/go-paths-helper"
+	"github.com/bcmi-labs/arduino-language-server/streams"
 	"github.com/pkg/errors"
 )
 
@@ -21,6 +22,8 @@ func (handler *InoHandler) scheduleRebuildEnvironment() {
 }
 
 func (handler *InoHandler) rebuildEnvironmentLoop() {
+	defer streams.CatchAndLogPanic()
+
 	grabDeadline := func() *time.Time {
 		handler.rebuildSketchDeadlineMutex.Lock()
 		defer handler.rebuildSketchDeadlineMutex.Unlock()

handler/handler.go

@@ -109,6 +109,8 @@ func (handler *InoHandler) StopClangd() {
 
 // HandleMessageFromIDE handles a message received from the IDE client (via stdio).
 func (handler *InoHandler) HandleMessageFromIDE(ctx context.Context, conn *jsonrpc2.Conn, req *jsonrpc2.Request) (interface{}, error) {
+	defer streams.CatchAndLogPanic()
+
 	needsWriteLock := map[string]bool{
 		"initialize":             true,
 		"textDocument/didOpen":   true,
@@ -1131,6 +1133,8 @@ func (handler *InoHandler) cpp2inoDiagnostics(cppDiags *lsp.PublishDiagnosticsPa
 
 // FromClangd handles a message received from clangd.
 func (handler *InoHandler) FromClangd(ctx context.Context, connection *jsonrpc2.Conn, req *jsonrpc2.Request) (interface{}, error) {
+	defer streams.CatchAndLogPanic()
+
 	handler.synchronizer.DataMux.RLock()
 	defer handler.synchronizer.DataMux.RUnlock()
 
@@ -1238,6 +1242,8 @@ func (handler *InoHandler) FromClangd(ctx context.Context, connection *jsonrpc2.
 }
 
 func (handler *InoHandler) showMessage(ctx context.Context, msgType lsp.MessageType, message string) {
+	defer streams.CatchAndLogPanic()
+
 	params := lsp.ShowMessageParams{
 		Type:    msgType,
 		Message: message,

main.go

@@ -2,9 +2,9 @@ package main
 
 import (
 	"flag"
+	"io"
 	"log"
 	"os"
-	"syscall"
 
 	"github.com/arduino/go-paths-helper"
 	"github.com/bcmi-labs/arduino-language-server/handler"
@@ -38,22 +38,11 @@ func main() {
 
 	if enableLogging {
 		logfile := streams.OpenLogFileAs("inols-err.log")
-		// log.SetOutput(io.MultiWriter(logfile, os.Stderr))
-		defer func() {
-			// // In case of panic output the stack trace in the log file before exiting
-			// if r := recover(); r != nil {
-			// 	log.Println(string(debug.Stack()))
-			// }
-
-			logfile.Close()
-		}()
-		err := syscall.Dup2(int(logfile.Fd()), int(os.Stderr.Fd()))
-		if err != nil {
-			log.Fatalf("Failed to redirect stderr to file: %v", err)
-		}
-		// log.SetOutput(logfile)
+		log.SetOutput(io.MultiWriter(logfile, os.Stderr))
+		defer streams.CatchAndLogPanic()
+	} else {
+		log.SetOutput(os.Stderr)
 	}
-	log.SetOutput(os.Stderr)
 
 	handler.Setup(cliPath, clangdPath, enableLogging, true)
 	initialBoard := lsp.Board{Fqbn: initialFqbn, Name: initialBoardName}

streams/panics.go

@@ -0,0 +1,17 @@
+package streams
+
+import (
+	"fmt"
+	"log"
+	"runtime/debug"
+)
+
+// CatchAndLogPanic will recover a panic, log it on standard logger, and rethrow it
+// to continue stack unwinding.
+func CatchAndLogPanic() {
+	if r := recover(); r != nil {
+		reason := fmt.Sprintf("%v", r)
+		log.Println(fmt.Sprintf("Panic: %s\n\n%s", reason, string(debug.Stack())))
+		panic(reason)
+	}
+}