[WIP] Initial commit

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

@@ -0,0 +1,165 @@
+// 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 hintdetail
+
+import (
+	"bytes"
+	"fmt"
+
+	"github.com/cockroachdb/errors/errbase"
+)
+
+// WithHint decorates an error with a textual hint.
+// The hint may contain PII and thus will not reportable.
+// The suggested use case for hint is to relay information to end users.
+//
+// Hint is shown:
+// - when formatting with `%+v`.
+// - with `GetAllHints()` / `FlattenHints()` below.
+//
+// Note: the hint does not appear in the main error message returned
+// with Error(). Use GetAllHints() or FlattenHints() to retrieve it.
+func WithHint(err error, msg string) error {
+	if err == nil {
+		return nil
+	}
+
+	return &withHint{cause: err, hint: msg}
+}
+
+// WithHintf is a helper that formats the hint.
+func WithHintf(err error, format string, args ...interface{}) error {
+	if err == nil {
+		return nil
+	}
+
+	return &withHint{cause: err, hint: fmt.Sprintf(format, args...)}
+}
+
+// GetAllHints retrieves the hints from the error using in post-order
+// traversal. The hints are de-duplicated. Assertion failures, issue
+// links and unimplemented errors are detected and receive standard
+// hints.
+func GetAllHints(err error) []string {
+	return getAllHintsInternal(err, nil, make(map[string]struct{}))
+}
+
+// FlattenHints retrieves the hints as per GetAllHints() and
+// concatenates them into a single string.
+func FlattenHints(err error) string {
+	var b bytes.Buffer
+	sep := ""
+	for _, h := range GetAllHints(err) {
+		b.WriteString(sep)
+		b.WriteString(h)
+		sep = "\n--\n"
+	}
+	return b.String()
+}
+
+func getAllHintsInternal(err error, hints []string, seen map[string]struct{}) []string {
+	if c := errbase.UnwrapOnce(err); c != nil {
+		hints = getAllHintsInternal(c, hints, seen)
+	}
+
+	hint := ""
+	if w, ok := err.(ErrorHinter); ok {
+		hint = w.ErrorHint()
+	}
+
+	if hint != "" {
+		// De-duplicate hints.
+		if _, ok := seen[hint]; !ok {
+			hints = append(hints, hint)
+			seen[hint] = struct{}{}
+		}
+	}
+	return hints
+}
+
+// ErrorHinter is implemented by types that can provide
+// user-informing detail strings. This is implemented by withHint
+// here, withIssueLink, assertionFailure and pgerror.Error.
+type ErrorHinter interface {
+	ErrorHint() string
+}
+
+// WithDetail decorates an error with a textual detail.
+// The detail may contain PII and thus will not reportable.
+// The suggested use case for detail is to augment errors with information
+// useful for debugging.
+//
+// Detail is shown:
+// - when formatting with `%+v`.
+// - with `GetAllDetails()` / `FlattenDetails()` below.
+//
+// Note: the detail does not appear in the main error message returned
+// with Error(). Use GetAllDetails() or FlattenDetails() to retrieve
+// it.
+func WithDetail(err error, msg string) error {
+	if err == nil {
+		return nil
+	}
+
+	return &withDetail{cause: err, detail: msg}
+}
+
+// WithDetailf is a helper that formats the detail string.
+func WithDetailf(err error, format string, args ...interface{}) error {
+	if err == nil {
+		return nil
+	}
+
+	return &withDetail{cause: err, detail: fmt.Sprintf(format, args...)}
+}
+
+// GetAllDetails retrieves the details from the error using in post-order
+// traversal.
+func GetAllDetails(err error) []string {
+	return getAllDetailsInternal(err, nil)
+}
+
+// FlattenDetails retrieves the details as per GetAllDetails() and
+// concatenates them into a single string.
+func FlattenDetails(err error) string {
+	var b bytes.Buffer
+	sep := ""
+	for _, h := range GetAllDetails(err) {
+		b.WriteString(sep)
+		b.WriteString(h)
+		sep = "\n--\n"
+	}
+	return b.String()
+}
+
+func getAllDetailsInternal(err error, details []string) []string {
+	if c := errbase.UnwrapOnce(err); c != nil {
+		details = getAllDetailsInternal(c, details)
+	}
+	if w, ok := err.(ErrorDetailer); ok {
+		d := w.ErrorDetail()
+		if d != "" {
+			details = append(details, w.ErrorDetail())
+		}
+	}
+	return details
+}
+
+// ErrorDetailer is implemented by types that can provide
+// user-informing detail strings. This is implemented by withDetail
+// here and pgerror.Error.
+type ErrorDetailer interface {
+	ErrorDetail() string
+}