linebuffer.go

Documentation: k8s.io/kubernetes/pkg/proxy/util

     1  /*
     2  Copyright 2023 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package util
    18  
    19  import (
    20  	"bytes"
    21  	"fmt"
    22  )
    23  
    24  // LineBuffer is an interface for writing lines of input to a bytes.Buffer
    25  type LineBuffer interface {
    26  	// Write takes a list of arguments, each a string or []string, joins all the
    27  	// individual strings with spaces, terminates with newline, and writes them to the
    28  	// buffer. Any other argument type will panic.
    29  	Write(args ...interface{})
    30  
    31  	// WriteBytes writes bytes to the buffer, and terminates with newline.
    32  	WriteBytes(bytes []byte)
    33  
    34  	// Reset clears the buffer
    35  	Reset()
    36  
    37  	// Bytes returns the contents of the buffer as a []byte
    38  	Bytes() []byte
    39  
    40  	// String returns the contents of the buffer as a string
    41  	String() string
    42  
    43  	// Lines returns the number of lines in the buffer. Note that more precisely, this
    44  	// returns the number of times Write() or WriteBytes() was called; it assumes that
    45  	// you never wrote any newlines to the buffer yourself.
    46  	Lines() int
    47  }
    48  
    49  type realLineBuffer struct {
    50  	b     bytes.Buffer
    51  	lines int
    52  }
    53  
    54  // NewLineBuffer returns a new "real" LineBuffer
    55  func NewLineBuffer() LineBuffer {
    56  	return &realLineBuffer{}
    57  }
    58  
    59  // Write is part of LineBuffer
    60  func (buf *realLineBuffer) Write(args ...interface{}) {
    61  	for i, arg := range args {
    62  		if i > 0 {
    63  			buf.b.WriteByte(' ')
    64  		}
    65  		switch x := arg.(type) {
    66  		case string:
    67  			buf.b.WriteString(x)
    68  		case []string:
    69  			for j, s := range x {
    70  				if j > 0 {
    71  					buf.b.WriteByte(' ')
    72  				}
    73  				buf.b.WriteString(s)
    74  			}
    75  		default:
    76  			panic(fmt.Sprintf("unknown argument type: %T", x))
    77  		}
    78  	}
    79  	buf.b.WriteByte('\n')
    80  	buf.lines++
    81  }
    82  
    83  // WriteBytes is part of LineBuffer
    84  func (buf *realLineBuffer) WriteBytes(bytes []byte) {
    85  	buf.b.Write(bytes)
    86  	buf.b.WriteByte('\n')
    87  	buf.lines++
    88  }
    89  
    90  // Reset is part of LineBuffer
    91  func (buf *realLineBuffer) Reset() {
    92  	buf.b.Reset()
    93  	buf.lines = 0
    94  }
    95  
    96  // Bytes is part of LineBuffer
    97  func (buf *realLineBuffer) Bytes() []byte {
    98  	return buf.b.Bytes()
    99  }
   100  
   101  // String is part of LineBuffer
   102  func (buf *realLineBuffer) String() string {
   103  	return buf.b.String()
   104  }
   105  
   106  // Lines is part of LineBuffer
   107  func (buf *realLineBuffer) Lines() int {
   108  	return buf.lines
   109  }
   110  
   111  type discardLineBuffer struct {
   112  	lines int
   113  }
   114  
   115  // NewDiscardLineBuffer returns a dummy LineBuffer that counts the number of writes but
   116  // throws away the data. (This is used for iptables proxy partial syncs, to keep track of
   117  // how many rules we managed to avoid having to sync.)
   118  func NewDiscardLineBuffer() LineBuffer {
   119  	return &discardLineBuffer{}
   120  }
   121  
   122  // Write is part of LineBuffer
   123  func (buf *discardLineBuffer) Write(args ...interface{}) {
   124  	buf.lines++
   125  }
   126  
   127  // WriteBytes is part of LineBuffer
   128  func (buf *discardLineBuffer) WriteBytes(bytes []byte) {
   129  	buf.lines++
   130  }
   131  
   132  // Reset is part of LineBuffer
   133  func (buf *discardLineBuffer) Reset() {
   134  	buf.lines = 0
   135  }
   136  
   137  // Bytes is part of LineBuffer
   138  func (buf *discardLineBuffer) Bytes() []byte {
   139  	return []byte{}
   140  }
   141  
   142  // String is part of LineBuffer
   143  func (buf *discardLineBuffer) String() string {
   144  	return ""
   145  }
   146  
   147  // Lines is part of LineBuffer
   148  func (buf *discardLineBuffer) Lines() int {
   149  	return buf.lines
   150  }
   151
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