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
144
145
146
147
148
149
150
151
152
153
154
155
156
157
/*
* Copyright 2003-2019 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_NFS_FILE_READER_HXX
#define MPD_NFS_FILE_READER_HXX
#include "Lease.hxx"
#include "Callback.hxx"
#include "event/DeferEvent.hxx"
#include "util/Compiler.h"
#include <string>
#include <exception>
#include <stdint.h>
#include <stddef.h>
#include <sys/stat.h>
struct nfsfh;
class NfsConnection;
/**
* A helper class which helps with reading from a file. It obtains a
* connection lease (#NfsLease), opens the given file, "stats" the
* file, and finally allos you to read its contents.
*
* To get started, derive your class from it and implement the pure
* virtual methods, construct an instance, and call Open().
*/
class NfsFileReader : NfsLease, NfsCallback {
enum class State {
INITIAL,
DEFER,
MOUNT,
OPEN,
STAT,
READ,
IDLE,
};
State state = State::INITIAL;
std::string server, export_name;
const char *path;
NfsConnection *connection;
nfsfh *fh;
DeferEvent defer_open;
public:
NfsFileReader() noexcept;
~NfsFileReader() noexcept;
auto &GetEventLoop() const noexcept {
return defer_open.GetEventLoop();
}
void Close() noexcept;
void DeferClose() noexcept;
/**
* Open the file. This method is thread-safe.
*
* Throws std::runtime_error on error.
*/
void Open(const char *uri);
/**
* Attempt to read from the file. This may only be done after
* OnNfsFileOpen() has been called. Only one read operation
* may be performed at a time.
*
* This method is not thread-safe and must be called from
* within the I/O thread.
*
* Throws std::runtime_error on error.
*/
void Read(uint64_t offset, size_t size);
/**
* Cancel the most recent Read() call.
*
* This method is not thread-safe and must be called from
* within the I/O thread.
*/
void CancelRead() noexcept;
bool IsIdle() const noexcept {
return state == State::IDLE;
}
protected:
/**
* The file has been opened successfully. It is a regular
* file, and its size is known. It is ready to be read from
* using Read().
*
* This method will be called from within the I/O thread.
*/
virtual void OnNfsFileOpen(uint64_t size) noexcept = 0;
/**
* A Read() has completed successfully.
*
* This method will be called from within the I/O thread.
*/
virtual void OnNfsFileRead(const void *data, size_t size) noexcept = 0;
/**
* An error has occurred, which can be either while waiting
* for OnNfsFileOpen(), or while waiting for OnNfsFileRead(),
* or if disconnected while idle.
*/
virtual void OnNfsFileError(std::exception_ptr &&e) noexcept = 0;
private:
/**
* Cancel the current operation, if any. The NfsLease must be
* unregistered already.
*/
void CancelOrClose() noexcept;
void OpenCallback(nfsfh *_fh) noexcept;
void StatCallback(const struct stat *st) noexcept;
/* virtual methods from NfsLease */
void OnNfsConnectionReady() noexcept final;
void OnNfsConnectionFailed(std::exception_ptr e) noexcept final;
void OnNfsConnectionDisconnected(std::exception_ptr e) noexcept final;
/* virtual methods from NfsCallback */
void OnNfsCallback(unsigned status, void *data) noexcept final;
void OnNfsError(std::exception_ptr &&e) noexcept final;
/* DeferEvent callback */
void OnDeferredOpen() noexcept;
};
#endif