whatcanGOwrong

go/pkg/mod/golang.org/x/exp@v0.0.0-20230224173230-c95f2b4c22f2/slog/pc.go

@@ -0,0 +1,63 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !nopc
+
+package slog
+
+import (
+	"context"
+	"runtime"
+	"time"
+)
+
+// These functions compute the pc early and pass it down the call chain,
+// which is faster than computing it later with a larger skip.
+
+// LogDepth is like [Logger.Log], but accepts a call depth to adjust the
+// file and line number in the log record. 1 refers to the caller
+// of LogDepth; 2 refers to the caller's caller; and so on.
+func (l *Logger) logDepth(ctx context.Context, calldepth int, level Level, msg string, args ...any) {
+	if !l.Enabled(ctx, level) {
+		return
+	}
+	var pcs [1]uintptr
+	runtime.Callers(calldepth+2, pcs[:])
+	l.logPC(ctx, nil, pcs[0], level, msg, args...)
+}
+
+// LogAttrsDepth is like [Logger.LogAttrs], but accepts a call depth argument
+// which it interprets like [Logger.LogDepth].
+func (l *Logger) logAttrsDepth(ctx context.Context, calldepth int, level Level, msg string, attrs ...Attr) {
+	if !l.Enabled(ctx, level) {
+		return
+	}
+	var pcs [1]uintptr
+	runtime.Callers(calldepth+2, pcs[:])
+	r := NewRecord(time.Now(), level, msg, pcs[0])
+	r.AddAttrs(attrs...)
+	_ = l.Handler().Handle(ctx, r)
+}
+
+// logDepthErr is a trivial wrapper around logDepth, just to make the call
+// depths on all paths the same. This is important only for the defaultHandler,
+// which passes a fixed call depth to log.Output.
+// TODO: When slog moves to the standard library, replace the fixed call depth
+// with logic based on the Record's pc, and remove this function. See the
+// comment on TestConnections/wrap_default_handler.
+func (l *Logger) logDepthErr(ctx context.Context, err error, calldepth int, level Level, msg string, args ...any) {
+	if !l.Enabled(ctx, level) {
+		return
+	}
+	var pcs [1]uintptr
+	runtime.Callers(calldepth+2, pcs[:])
+	l.logPC(ctx, err, pcs[0], level, msg, args...)
+}
+
+// callerPC returns the program counter at the given stack depth.
+func callerPC(depth int) uintptr {
+	var pcs [1]uintptr
+	runtime.Callers(depth, pcs[:])
+	return pcs[0]
+}