[WIP] Initial commit

vendor/github.com/cockroachdb/errors/withstack/withstack.go

@@ -0,0 +1,84 @@
+// Copyright 2019 The Cockroach Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+// implied. See the License for the specific language governing
+// permissions and limitations under the License.
+
+package withstack
+
+import (
+	"fmt"
+
+	"github.com/cockroachdb/errors/errbase"
+)
+
+// This file mirrors the WithStack functionality from
+// github.com/pkg/errors. We would prefer to reuse the withStack
+// struct from that package directly (the library recognizes it well)
+// unfortunately github.com/pkg/errors does not enable client code to
+// customize the depth at which the stack trace is captured.
+
+// WithStack annotates err with a stack trace at the point WithStack was called.
+//
+// Detail is shown:
+// - via `errors.GetSafeDetails()`
+// - when formatting with `%+v`.
+// - in Sentry reports.
+// - when innermost stack capture, with `errors.GetOneLineSource()`.
+func WithStack(err error) error {
+	// Skip the frame of WithStack itself, this mirrors the behavior
+	// of WithStack() in github.com/pkg/errors.
+	return WithStackDepth(err, 1)
+}
+
+// WithStackDepth annotates err with a stack trace starting from the
+// given call depth. The value zero identifies the caller
+// of WithStackDepth itself.
+// See the documentation of WithStack() for more details.
+func WithStackDepth(err error, depth int) error {
+	if err == nil {
+		return nil
+	}
+	return &withStack{cause: err, stack: callers(depth + 1)}
+}
+
+type withStack struct {
+	cause error
+
+	*stack
+}
+
+var _ error = (*withStack)(nil)
+var _ fmt.Formatter = (*withStack)(nil)
+var _ errbase.SafeFormatter = (*withStack)(nil)
+var _ errbase.SafeDetailer = (*withStack)(nil)
+
+func (w *withStack) Error() string { return w.cause.Error() }
+func (w *withStack) Cause() error  { return w.cause }
+func (w *withStack) Unwrap() error { return w.cause }
+
+// Format implements the fmt.Formatter interface.
+func (w *withStack) Format(s fmt.State, verb rune) { errbase.FormatError(w, s, verb) }
+
+// SafeFormatError implements the errbase.SafeFormatter interface.
+func (w *withStack) SafeFormatError(p errbase.Printer) error {
+	if p.Detail() {
+		p.Printf("attached stack trace")
+	}
+	// We do not print the stack trace ourselves - errbase.FormatError()
+	// does this for us.
+	return w.cause
+}
+
+// SafeDetails implements the errbase.SafeDetailer interface.
+func (w *withStack) SafeDetails() []string {
+	return []string{fmt.Sprintf("%+v", w.StackTrace())}
+}