build source

vendor/k8s.io/klog/v2/internal/serialize/keyvalues.go

@@ -0,0 +1,292 @@
+/*
+Copyright 2021 The Kubernetes 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 serialize
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"strconv"
+
+	"github.com/go-logr/logr"
+)
+
+type textWriter interface {
+	WriteText(*bytes.Buffer)
+}
+
+// WithValues implements LogSink.WithValues. The old key/value pairs are
+// assumed to be well-formed, the new ones are checked and padded if
+// necessary. It returns a new slice.
+func WithValues(oldKV, newKV []interface{}) []interface{} {
+	if len(newKV) == 0 {
+		return oldKV
+	}
+	newLen := len(oldKV) + len(newKV)
+	hasMissingValue := newLen%2 != 0
+	if hasMissingValue {
+		newLen++
+	}
+	// The new LogSink must have its own slice.
+	kv := make([]interface{}, 0, newLen)
+	kv = append(kv, oldKV...)
+	kv = append(kv, newKV...)
+	if hasMissingValue {
+		kv = append(kv, missingValue)
+	}
+	return kv
+}
+
+// MergeKVs deduplicates elements provided in two key/value slices.
+//
+// Keys in each slice are expected to be unique, so duplicates can only occur
+// when the first and second slice contain the same key. When that happens, the
+// key/value pair from the second slice is used. The first slice must be well-formed
+// (= even key/value pairs). The second one may have a missing value, in which
+// case the special "missing value" is added to the result.
+func MergeKVs(first, second []interface{}) []interface{} {
+	maxLength := len(first) + (len(second)+1)/2*2
+	if maxLength == 0 {
+		// Nothing to do at all.
+		return nil
+	}
+
+	if len(first) == 0 && len(second)%2 == 0 {
+		// Nothing to be overridden, second slice is well-formed
+		// and can be used directly.
+		return second
+	}
+
+	// Determine which keys are in the second slice so that we can skip
+	// them when iterating over the first one. The code intentionally
+	// favors performance over completeness: we assume that keys are string
+	// constants and thus compare equal when the string values are equal. A
+	// string constant being overridden by, for example, a fmt.Stringer is
+	// not handled.
+	overrides := map[interface{}]bool{}
+	for i := 0; i < len(second); i += 2 {
+		overrides[second[i]] = true
+	}
+	merged := make([]interface{}, 0, maxLength)
+	for i := 0; i+1 < len(first); i += 2 {
+		key := first[i]
+		if overrides[key] {
+			continue
+		}
+		merged = append(merged, key, first[i+1])
+	}
+	merged = append(merged, second...)
+	if len(merged)%2 != 0 {
+		merged = append(merged, missingValue)
+	}
+	return merged
+}
+
+type Formatter struct {
+	AnyToStringHook AnyToStringFunc
+}
+
+type AnyToStringFunc func(v interface{}) string
+
+// MergeKVsInto is a variant of MergeKVs which directly formats the key/value
+// pairs into a buffer.
+func (f Formatter) MergeAndFormatKVs(b *bytes.Buffer, first, second []interface{}) {
+	if len(first) == 0 && len(second) == 0 {
+		// Nothing to do at all.
+		return
+	}
+
+	if len(first) == 0 && len(second)%2 == 0 {
+		// Nothing to be overridden, second slice is well-formed
+		// and can be used directly.
+		for i := 0; i < len(second); i += 2 {
+			f.KVFormat(b, second[i], second[i+1])
+		}
+		return
+	}
+
+	// Determine which keys are in the second slice so that we can skip
+	// them when iterating over the first one. The code intentionally
+	// favors performance over completeness: we assume that keys are string
+	// constants and thus compare equal when the string values are equal. A
+	// string constant being overridden by, for example, a fmt.Stringer is
+	// not handled.
+	overrides := map[interface{}]bool{}
+	for i := 0; i < len(second); i += 2 {
+		overrides[second[i]] = true
+	}
+	for i := 0; i < len(first); i += 2 {
+		key := first[i]
+		if overrides[key] {
+			continue
+		}
+		f.KVFormat(b, key, first[i+1])
+	}
+	// Round down.
+	l := len(second)
+	l = l / 2 * 2
+	for i := 1; i < l; i += 2 {
+		f.KVFormat(b, second[i-1], second[i])
+	}
+	if len(second)%2 == 1 {
+		f.KVFormat(b, second[len(second)-1], missingValue)
+	}
+}
+
+func MergeAndFormatKVs(b *bytes.Buffer, first, second []interface{}) {
+	Formatter{}.MergeAndFormatKVs(b, first, second)
+}
+
+const missingValue = "(MISSING)"
+
+// KVListFormat serializes all key/value pairs into the provided buffer.
+// A space gets inserted before the first pair and between each pair.
+func (f Formatter) KVListFormat(b *bytes.Buffer, keysAndValues ...interface{}) {
+	for i := 0; i < len(keysAndValues); i += 2 {
+		var v interface{}
+		k := keysAndValues[i]
+		if i+1 < len(keysAndValues) {
+			v = keysAndValues[i+1]
+		} else {
+			v = missingValue
+		}
+		f.KVFormat(b, k, v)
+	}
+}
+
+func KVListFormat(b *bytes.Buffer, keysAndValues ...interface{}) {
+	Formatter{}.KVListFormat(b, keysAndValues...)
+}
+
+func KVFormat(b *bytes.Buffer, k, v interface{}) {
+	Formatter{}.KVFormat(b, k, v)
+}
+
+// formatAny is the fallback formatter for a value. It supports a hook (for
+// example, for YAML encoding) and itself uses JSON encoding.
+func (f Formatter) formatAny(b *bytes.Buffer, v interface{}) {
+	b.WriteRune('=')
+	if f.AnyToStringHook != nil {
+		b.WriteString(f.AnyToStringHook(v))
+		return
+	}
+	formatAsJSON(b, v)
+}
+
+func formatAsJSON(b *bytes.Buffer, v interface{}) {
+	encoder := json.NewEncoder(b)
+	l := b.Len()
+	if err := encoder.Encode(v); err != nil {
+		// This shouldn't happen. We discard whatever the encoder
+		// wrote and instead dump an error string.
+		b.Truncate(l)
+		b.WriteString(fmt.Sprintf(`"<internal error: %v>"`, err))
+		return
+	}
+	// Remove trailing newline.
+	b.Truncate(b.Len() - 1)
+}
+
+// StringerToString converts a Stringer to a string,
+// handling panics if they occur.
+func StringerToString(s fmt.Stringer) (ret string) {
+	defer func() {
+		if err := recover(); err != nil {
+			ret = fmt.Sprintf("<panic: %s>", err)
+		}
+	}()
+	ret = s.String()
+	return
+}
+
+// MarshalerToValue invokes a marshaler and catches
+// panics.
+func MarshalerToValue(m logr.Marshaler) (ret interface{}) {
+	defer func() {
+		if err := recover(); err != nil {
+			ret = fmt.Sprintf("<panic: %s>", err)
+		}
+	}()
+	ret = m.MarshalLog()
+	return
+}
+
+// ErrorToString converts an error to a string,
+// handling panics if they occur.
+func ErrorToString(err error) (ret string) {
+	defer func() {
+		if err := recover(); err != nil {
+			ret = fmt.Sprintf("<panic: %s>", err)
+		}
+	}()
+	ret = err.Error()
+	return
+}
+
+func writeTextWriterValue(b *bytes.Buffer, v textWriter) {
+	b.WriteByte('=')
+	defer func() {
+		if err := recover(); err != nil {
+			fmt.Fprintf(b, `"<panic: %s>"`, err)
+		}
+	}()
+	v.WriteText(b)
+}
+
+func writeStringValue(b *bytes.Buffer, v string) {
+	data := []byte(v)
+	index := bytes.IndexByte(data, '\n')
+	if index == -1 {
+		b.WriteByte('=')
+		// Simple string, quote quotation marks and non-printable characters.
+		b.WriteString(strconv.Quote(v))
+		return
+	}
+
+	// Complex multi-line string, show as-is with indention like this:
+	// I... "hello world" key=<
+	// <tab>line 1
+	// <tab>line 2
+	//  >
+	//
+	// Tabs indent the lines of the value while the end of string delimiter
+	// is indented with a space. That has two purposes:
+	// - visual difference between the two for a human reader because indention
+	//   will be different
+	// - no ambiguity when some value line starts with the end delimiter
+	//
+	// One downside is that the output cannot distinguish between strings that
+	// end with a line break and those that don't because the end delimiter
+	// will always be on the next line.
+	b.WriteString("=<\n")
+	for index != -1 {
+		b.WriteByte('\t')
+		b.Write(data[0 : index+1])
+		data = data[index+1:]
+		index = bytes.IndexByte(data, '\n')
+	}
+	if len(data) == 0 {
+		// String ended with line break, don't add another.
+		b.WriteString(" >")
+	} else {
+		// No line break at end of last line, write rest of string and
+		// add one.
+		b.WriteByte('\t')
+		b.Write(data)
+		b.WriteString("\n >")
+	}
+}