From 5301ce47f40a3a8b94f4d0f0ee954abaa487bc4e Mon Sep 17 00:00:00 2001
From: Edward Mack <ed@edwardmack.com>
Date: Tue, 5 Oct 2021 15:38:28 -0400
Subject: [PATCH] feat(runtime): implement custom logging handler that print
 function name (#1825)

* implement custom logging handler that print function name

* move log handler to runtime package
---
 lib/runtime/log_handler.go     | 34 ++++++++++++++++++++++++++++++++++
 lib/runtime/wasmer/instance.go |  2 +-
 2 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 lib/runtime/log_handler.go

diff --git a/lib/runtime/log_handler.go b/lib/runtime/log_handler.go
new file mode 100644
index 0000000000..e73f63f1d7
--- /dev/null
+++ b/lib/runtime/log_handler.go
@@ -0,0 +1,34 @@
+// Copyright 2019 ChainSafe Systems (ON) Corp.
+// This file is part of gossamer.
+//
+// The gossamer library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The gossamer library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the gossamer library. If not, see <http://www.gnu.org/licenses/>.
+
+package runtime
+
+import (
+	"fmt"
+	"path/filepath"
+	"strings"
+
+	log "github.com/ChainSafe/log15"
+)
+
+// CustomFileHandler returns a Handler that adds the name of the calling function to the context with key "func"
+//  and the line number and file of the calling function to the context with key "caller".
+func CustomFileHandler(h log.Handler) log.Handler {
+	return log.FuncHandler(func(r *log.Record) error {
+		r.Ctx = append(r.Ctx, "func", strings.TrimLeft(filepath.Ext(r.Call.Frame().Function), "."), "caller", fmt.Sprint(r.Call))
+		return h.Log(r)
+	})
+}
diff --git a/lib/runtime/wasmer/instance.go b/lib/runtime/wasmer/instance.go
index 85eabbe730..64720bdba1 100644
--- a/lib/runtime/wasmer/instance.go
+++ b/lib/runtime/wasmer/instance.go
@@ -108,7 +108,7 @@ func newInstance(code []byte, cfg *Config) (*Instance, error) {
 	// if cfg.LogLvl set to < 0, then don't change package log level
 	if cfg.LogLvl >= 0 {
 		h := log.StreamHandler(os.Stdout, log.TerminalFormat())
-		h = log.CallerFileHandler(h)
+		h = runtime.CustomFileHandler(h)
 		logger.SetHandler(log.LvlFilterHandler(cfg.LogLvl, h))
 	}