1 files changed, 172 insertions, 0 deletions
diff --git a/modules/web/routing/funcinfo.go b/modules/web/routing/funcinfo.go
new file mode 100644
index 00000000..f4e9731a
--- /dev/null
+++ b/modules/web/routing/funcinfo.go
@@ -0,0 +1,172 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package routing
+
+import (
+	"fmt"
+	"reflect"
+	"runtime"
+	"strings"
+	"sync"
+)
+
+var (
+	funcInfoMap     = map[uintptr]*FuncInfo{}
+	funcInfoNameMap = map[string]*FuncInfo{}
+	funcInfoMapMu   sync.RWMutex
+)
+
+// FuncInfo contains information about the function to be logged by the router log
+type FuncInfo struct {
+	file      string
+	shortFile string
+	line      int
+	name      string
+	shortName string
+}
+
+// String returns a string form of the FuncInfo for logging
+func (info *FuncInfo) String() string {
+	if info == nil {
+		return "unknown-handler"
+	}
+	return fmt.Sprintf("%s:%d(%s)", info.shortFile, info.line, info.shortName)
+}
+
+// GetFuncInfo returns the FuncInfo for a provided function and friendlyname
+func GetFuncInfo(fn any, friendlyName ...string) *FuncInfo {
+	// ptr represents the memory position of the function passed in as v.
+	// This will be used as program counter in FuncForPC below
+	ptr := reflect.ValueOf(fn).Pointer()
+
+	// if we have been provided with a friendlyName look for the named funcs
+	if len(friendlyName) == 1 {
+		name := friendlyName[0]
+		funcInfoMapMu.RLock()
+		info, ok := funcInfoNameMap[name]
+		funcInfoMapMu.RUnlock()
+		if ok {
+			return info
+		}
+	}
+
+	// Otherwise attempt to get pre-cached information for this function pointer
+	funcInfoMapMu.RLock()
+	info, ok := funcInfoMap[ptr]
+	funcInfoMapMu.RUnlock()
+
+	if ok {
+		if len(friendlyName) == 1 {
+			name := friendlyName[0]
+			info = copyFuncInfo(info)
+			info.shortName = name
+
+			funcInfoNameMap[name] = info
+			funcInfoMapMu.Lock()
+			funcInfoNameMap[name] = info
+			funcInfoMapMu.Unlock()
+		}
+		return info
+	}
+
+	// This is likely the first time we have seen this function
+	//
+	// Get the runtime.func for this function (if we can)
+	f := runtime.FuncForPC(ptr)
+	if f != nil {
+		info = convertToFuncInfo(f)
+
+		// cache this info globally
+		funcInfoMapMu.Lock()
+		funcInfoMap[ptr] = info
+
+		// if we have been provided with a friendlyName override the short name we've generated
+		if len(friendlyName) == 1 {
+			name := friendlyName[0]
+			info = copyFuncInfo(info)
+			info.shortName = name
+			funcInfoNameMap[name] = info
+		}
+		funcInfoMapMu.Unlock()
+	}
+	return info
+}
+
+// convertToFuncInfo take a runtime.Func and convert it to a logFuncInfo, fill in shorten filename, etc
+func convertToFuncInfo(f *runtime.Func) *FuncInfo {
+	file, line := f.FileLine(f.Entry())
+
+	info := &FuncInfo{
+		file: strings.ReplaceAll(file, "\\", "/"),
+		line: line,
+		name: f.Name(),
+	}
+
+	// only keep last 2 names in path, fall back to funcName if not
+	info.shortFile = shortenFilename(info.file, info.name)
+
+	// remove package prefix. eg: "xxx.com/pkg1/pkg2.foo" => "pkg2.foo"
+	pos := strings.LastIndexByte(info.name, '/')
+	if pos >= 0 {
+		info.shortName = info.name[pos+1:]
+	} else {
+		info.shortName = info.name
+	}
+
+	// remove ".func[0-9]*" suffix for anonymous func
+	info.shortName = trimAnonymousFunctionSuffix(info.shortName)
+
+	return info
+}
+
+func copyFuncInfo(l *FuncInfo) *FuncInfo {
+	return &FuncInfo{
+		file:      l.file,
+		shortFile: l.shortFile,
+		line:      l.line,
+		name:      l.name,
+		shortName: l.shortName,
+	}
+}
+
+// shortenFilename generates a short source code filename from a full package path, eg: "code.gitea.io/routers/common/logger_context.go" => "common/logger_context.go"
+func shortenFilename(filename, fallback string) string {
+	if filename == "" {
+		return fallback
+	}
+	if lastIndex := strings.LastIndexByte(filename, '/'); lastIndex >= 0 {
+		if secondLastIndex := strings.LastIndexByte(filename[:lastIndex], '/'); secondLastIndex >= 0 {
+			return filename[secondLastIndex+1:]
+		}
+	}
+	return filename
+}
+
+// trimAnonymousFunctionSuffix trims ".func[0-9]*" from the end of anonymous function names, we only want to see the main function names in logs
+func trimAnonymousFunctionSuffix(name string) string {
+	// if the name is an anonymous name, it should be like "{main-function}.func1", so the length can not be less than 7
+	if len(name) < 7 {
+		return name
+	}
+
+	funcSuffixIndex := strings.LastIndex(name, ".func")
+	if funcSuffixIndex < 0 {
+		return name
+	}
+
+	hasFuncSuffix := true
+
+	// len(".func") = 5
+	for i := funcSuffixIndex + 5; i < len(name); i++ {
+		if name[i] < '0' || name[i] > '9' {
+			hasFuncSuffix = false
+			break
+		}
+	}
+
+	if hasFuncSuffix {
+		return name[:funcSuffixIndex]
+	}
+	return name
+}