1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
/*
* Copyright (c) 2020, the SerenityOS developers.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <AK/CircularQueue.h>
#include <AK/Stream.h>
namespace AK {
// FIXME: There are a lot of raw loops here, that's not necessary an issue but it
// has to be verified that the optimizer is able to insert memcpy instead.
template<size_t Capacity>
class CircularDuplexStream : public AK::DuplexStream {
public:
size_t write(ReadonlyBytes bytes) override
{
const auto nwritten = min(bytes.size(), Capacity - m_queue.size());
for (size_t idx = 0; idx < nwritten; ++idx)
m_queue.enqueue(bytes[idx]);
m_total_written += nwritten;
return nwritten;
}
bool write_or_error(ReadonlyBytes bytes) override
{
if (Capacity - m_queue.size() < bytes.size()) {
set_recoverable_error();
return false;
}
const auto nwritten = write(bytes);
VERIFY(nwritten == bytes.size());
return true;
}
size_t read(Bytes bytes) override
{
if (has_any_error())
return 0;
const auto nread = min(bytes.size(), m_queue.size());
for (size_t idx = 0; idx < nread; ++idx)
bytes[idx] = m_queue.dequeue();
return nread;
}
size_t read(Bytes bytes, size_t seekback)
{
if (seekback > Capacity || seekback > m_total_written) {
set_recoverable_error();
return 0;
}
const auto nread = min(bytes.size(), seekback);
for (size_t idx = 0; idx < nread; ++idx) {
const auto index = (m_total_written - seekback + idx) % Capacity;
bytes[idx] = m_queue.m_storage[index];
}
return nread;
}
bool read_or_error(Bytes bytes) override
{
if (m_queue.size() < bytes.size()) {
set_recoverable_error();
return false;
}
read(bytes);
return true;
}
bool discard_or_error(size_t count) override
{
if (m_queue.size() < count) {
set_recoverable_error();
return false;
}
for (size_t idx = 0; idx < count; ++idx)
m_queue.dequeue();
return true;
}
bool unreliable_eof() const override { return eof(); }
bool eof() const { return m_queue.size() == 0; }
size_t remaining_contigous_space() const
{
return min(Capacity - m_queue.size(), m_queue.capacity() - (m_queue.head_index() + m_queue.size()) % Capacity);
}
Bytes reserve_contigous_space(size_t count)
{
VERIFY(count <= remaining_contigous_space());
Bytes bytes { m_queue.m_storage + (m_queue.head_index() + m_queue.size()) % Capacity, count };
m_queue.m_size += count;
m_total_written += count;
return bytes;
}
private:
CircularQueue<u8, Capacity> m_queue;
size_t m_total_written { 0 };
};
}
using AK::CircularDuplexStream;
|
