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
|
/*
* Copyright 2003-2020 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef MPD_BUFFERING_INPUT_STREAM_BUFFER_HXX
#define MPD_BUFFERING_INPUT_STREAM_BUFFER_HXX
#include "Ptr.hxx"
#include "Handler.hxx"
#include "thread/Thread.hxx"
#include "thread/Mutex.hxx"
#include "thread/Cond.hxx"
#include "util/SparseBuffer.hxx"
#include <exception>
/**
* A "huge" buffer which remembers the (partial) contents of an
* #InputStream. This works only if the #InputStream is a "file", not
* a "stream".
*/
class BufferingInputStream : InputStreamHandler {
InputStreamPtr input;
public:
Mutex &mutex;
private:
Thread thread;
/**
* This #Cond wakes up the #Thread. It is used by both the
* "client" thread (to submit commands) and #input's handler
* (to notify new data being available).
*/
Cond wake_cond;
/**
* This #Cond wakes up the client upon command completion.
*/
Cond client_cond;
SparseBuffer<uint8_t> buffer;
bool stop = false;
/* must be mutable because IsAvailable() acts as a hint to
modify this attribute */
mutable size_t want_offset = INVALID_OFFSET;
std::exception_ptr error, seek_error;
static constexpr size_t INVALID_OFFSET = ~size_t(0);
public:
/**
* Allocate a buffer which fits the given #InputStream and
* start a thread reading into the buffer.
*
* Throws on error.
*
* @param _input a seekable #InputStream with a known size
*/
explicit BufferingInputStream(InputStreamPtr _input);
~BufferingInputStream() noexcept;
/**
* Caller must lock the mutex.
*/
const auto &GetInput() const noexcept {
return *input;
}
auto size() const noexcept {
return buffer.size();
}
/**
* Wrapper for InputStream::Check().
*
* Throws on error.
*
* Caller must lock the mutex.
*/
void Check();
/**
* Check whether data is available in the buffer at the given
* offset..
*/
bool IsAvailable(size_t offset) const noexcept;
/**
* Copy data from the buffer into the given pointer.
*
* @return the number of bytes copied into the given pointer.
*/
size_t Read(std::unique_lock<Mutex> &lock, size_t offset,
void *ptr, size_t size);
protected:
/**
* This virtual method gets called each time data has been
* added to the buffer. During this method call, the mutex is
* locked.
*/
virtual void OnBufferAvailable() noexcept {}
private:
size_t FindFirstHole() const noexcept;
void RunThreadLocked(std::unique_lock<Mutex> &lock);
void RunThread() noexcept;
/* virtual methods from class InputStreamHandler */
void OnInputStreamReady() noexcept final {
/* this should never be called, because our input must
be "ready" already */
}
void OnInputStreamAvailable() noexcept final {
wake_cond.notify_one();
}
};
#endif
|
