buffer_interface.h revision 4e180b6a0b4720a9b8e9e959a882386f690f08ff 
1// Copyright 2013 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef NET_TOOLS_BALSA_BUFFER_INTERFACE_H__
6#define NET_TOOLS_BALSA_BUFFER_INTERFACE_H__
7
8namespace net {
9
10class BufferInterface {
11 public:
12
13  //   Returns the bytes which can be read from the buffer.  There is no
14  //   guarantee that the bytes are contiguous.
15  virtual int ReadableBytes() const = 0;
16
17  // Summary:
18  //   returns the size of this buffer
19  // Returns:
20  //   size of this buffer.
21  virtual int BufferSize() const = 0;
22
23  // Summary:
24  //   returns the number of bytes free in this buffer.
25  // Returns:
26  //   number of bytes free.
27  virtual int BytesFree() const = 0;
28
29  // Summary:
30  //   Returns true if empty.
31  // Returns:
32  //   true - if empty
33  //   false - otherwise
34  virtual bool Empty() const = 0;
35
36  // Summary:
37  //   Returns true if the buffer is full.
38  virtual bool Full() const = 0;
39
40  // Summary:
41  //   returns the number of characters written.
42  //   appends up-to-'size' bytes to the buffer.
43  // Args:
44  //   bytes - bytes which are read, and copied into the buffer.
45  //   size  - number of bytes which are read and copied.
46  //           this number shall be >= 0.
47  virtual int Write(const char* bytes, int size) = 0;
48
49  // Summary:
50  //   Gets a pointer which can be written to (assigned to).
51  //   this pointer (and size) can be used in functions like
52  //   recv() or read(), etc.
53  //   If *size is zero upon returning from this function, that it
54  //   is unsafe to dereference *ptr.
55  // Args:
56  //   ptr - assigned a pointer to which we can write
57  //   size - the amount of data (in bytes) that it is safe to write to ptr.
58  virtual void GetWritablePtr(char **ptr, int* size) const = 0;
59
60  // Summary:
61  //   Gets a pointer which can be read from
62  //   this pointer (and size) can be used in functions like
63  //   send() or write(), etc.
64  //   If *size is zero upon returning from this function, that it
65  //   is unsafe to dereference *ptr.
66  // Args:
67  //   ptr - assigned a pointer from which we may read
68  //   size - the amount of data (in bytes) that it is safe to read
69  virtual void GetReadablePtr(char **ptr, int* size) const = 0;
70
71  // Summary:
72  //   Reads bytes out of the buffer, and writes them into 'bytes'.
73  //   Returns the number of bytes read.
74  //   Consumes bytes from the buffer (possibly, but not necessarily
75  //   rendering them free)
76  // Args:
77  //   bytes - the pointer into which bytes are read from this buffer
78  //           and written into
79  //   size  - number of bytes which are read and copied.
80  //           this number shall be >= 0.
81  // Returns:
82  //   the number of bytes read from 'bytes'
83  virtual int Read(char* bytes, int size) = 0;
84
85  // Summary:
86  //   removes all data from the buffer
87  virtual void Clear() = 0;
88
89  // Summary:
90  //   reserves contiguous writable empty space in the buffer of size bytes.
91  //   Returns true if the reservation is successful.
92  //   If a derive class chooses not to implement reservation, its
93  //   implementation should return false.
94  virtual bool Reserve(int size) = 0;
95
96  // Summary:
97  //   removes the oldest 'amount_to_consume' characters from this buffer,
98  // Args:
99  //   amount_to_advance - .. this should be self-explanatory =)
100  //                       this number shall be >= 0.
101  virtual void AdvanceReadablePtr(int amount_to_advance) = 0;
102
103  // Summary:
104  //   Moves the internal pointers around such that the
105  //   amount of data specified here is expected to
106  //   already be resident (as if it was Written)
107  // Args:
108  //   amount_to_advance - self explanatory.
109  //                       this number shall be >= 0.
110  virtual void AdvanceWritablePtr(int amount_to_advance) = 0;
111
112  virtual ~BufferInterface() {}
113
114 protected:
115  BufferInterface() {}
116};
117
118}  // namespace net
119
120#endif  // NET_TOOLS_BALSA_BUFFER_INTERFACE__H__
121
122