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/*
GoToSocial
Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package log
import (
"runtime"
"strings"
"sync"
)
var (
// fnCache is a cache of PCs to their calculated function names.
fnCache = map[uintptr]string{}
// strCache is a cache of strings to the originally allocated version
// of that string contents. so we don't have hundreds of the same instances
// of string floating around in memory.
strCache = map[string]string{}
// cacheMu protects fnCache and strCache.
cacheMu sync.Mutex
)
// Caller fetches the calling function name, skipping 'depth'. Results are cached per PC.
func Caller(depth int) string {
var rpc [1]uintptr
// Fetch pcs of callers
n := runtime.Callers(depth, rpc[:])
if n > 0 {
// Look for value in cache
cacheMu.Lock()
fn, ok := fnCache[rpc[0]]
cacheMu.Unlock()
if ok {
return fn
}
// Fetch frame info for caller pc
frame, _ := runtime.CallersFrames(rpc[:]).Next()
if frame.PC != 0 {
name := frame.Function
// Drop all but the package name and function name, no mod path
if idx := strings.LastIndex(name, "/"); idx >= 0 {
name = name[idx+1:]
}
// Drop any generic type parameter markers
if idx := strings.Index(name, "[...]"); idx >= 0 {
name = name[:idx] + name[idx+5:]
}
// Cache this func name
cacheMu.Lock()
fn, ok := strCache[name]
if !ok {
// Cache ptr to this allocated str
strCache[name] = name
fn = name
}
fnCache[rpc[0]] = fn
cacheMu.Unlock()
return fn
}
}
return "???"
}
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