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
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
|
/*
* This file is part of the KDE libraries
* Copyright (C) 2001 Thiago Macieira <[email protected]>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include "config.h"
#include <string.h>
#include <tqptrlist.h>
#include <tqcstring.h>
#include "kbufferedio.h"
/**
* @section impldetails Implementation Details
*
* The TDEBufferedIO class has two purposes: first, it defines an API on how
* that classes providing buffered I/O should provide. Next, it implements on
* top of that API a generic buffering, that should suffice for most cases.
*
* The buffering implemented consists of two separate buffer areas, one for
* the input (or read) buffer, and one for the output (or write) buffer. Each
* of those buffers is implemented through a QList of QByteArrays instead of
* simply QByteArrays. The idea is that, instead of having one large, contiguous
* buffer area, we have several small ones. Even though this could be seen as
* a waste of memory, it makes our life easier, because we can just append a new
* TQByteArray to the list and not have to worry with copying the rest of the
* buffer, should we need to expand.
*
* This way, we have the capability of unlimited buffering, which can grow to
* the extent of available memory.
*
* For each buffer, we provide three kinds of functions, available as protected
* members: consume, feed and size. The size functions calculate the current
* size of the buffer, by adding each individual TQByteArray size. The feed
* functions are used by the I/O functions that receive data from somewhere,
* i.e., from the system, in the case of the input buffer, and from the user,
* in the case of the output buffer. These two functions are used to give
* the buffers more data. And the consume functions are used by the functions
* that send out data (to the system, for the write buffer, and to the user,
* for the read buffer).
*
* Note that for your own implementation, you can have your readBlock function
* merely call consumeReadBuffer, similarly to peekBlock. As for
* the writeBlock function, you'd call feedWriteBuffer.
*
* Now, the function receiving data from the system will need to simply call
* feedReadBuffer, much in the same way of unreadBlock. The tricky part is
* for the output function. We do not provide a member function that copies
* data from the output buffer into another buffer for sending. We believe that
* would be a waste of resources and CPU time, since you'd have to allocate
* that buffer, copy data into it and then call the OS, which will likely just
* copy data out of it.
*
* Instead, we found it better to leave it to you to access outBuf member
* variable directly and use the buffers there. Should you want to copy that
* into a larger buffer before sending, that's up to you.
*
* Both buffers work in the same way: they're an "array" of buffers, each
* concatenated to the other. All data in all buffers is valid data, except
* for the first TQByteArray, whose valid data starts at inBufIndex/outBufIndex
* bytes from the start. That is, the data starts in the first TQByteArray buffer
* that many bytes from the start and goes on contiguously until the last
* TQByteArray. This has been decided like that because we didn't want to
* create a new TQByteArray of the remaining bytes in the first buffer, after
* a consume operation, because that could take some time. It is faster
* this way, although not really easy.
*
* If you want to take a look at an implementation of a buffered I/O class,
* refer to KExtendedSocket's source code.
*/
// constructor
TDEBufferedIO::TDEBufferedIO() :
inBufIndex(0), outBufIndex(0)
{
inBuf.setAutoDelete(true);
outBuf.setAutoDelete(true);
}
// destructor
TDEBufferedIO::~TDEBufferedIO()
{
}
// sets the buffer sizes
// this implementation doesn't support setting the buffer sizes
// if any parameter is different than -1 or -2, fail
bool TDEBufferedIO::setBufferSize(int rsize, int wsize /* = -2 */)
{
if (wsize != -2 && wsize != -1)
return false;
if (rsize != -2 && rsize != -1)
return false;
return true;
}
int TDEBufferedIO::bytesAvailable() const
{
return readBufferSize();
}
int TDEBufferedIO::bytesToWrite() const
{
return writeBufferSize();
}
// This function will scan the read buffer for a '\n'
bool TDEBufferedIO::canReadLine() const
{
if (bytesAvailable() == 0)
return false; // no new line in here
TQByteArray* buf;
// scan each TQByteArray for the occurrence of '\n'
TQPtrList<TQByteArray> &buflist = ((TDEBufferedIO*)this)->inBuf;
buf = buflist.first();
char *p = buf->data() + inBufIndex;
int n = buf->size() - inBufIndex;
while (buf != NULL)
{
while (n--)
if (*p++ == '\n')
return true;
buf = buflist.next();
if (buf != NULL)
{
p = buf->data();
n = buf->size();
}
}
return false; // no new line found
}
// unreads the current data
// that is, writes into the read buffer, at the beginning
int TDEBufferedIO::unreadBlock(const char *data, uint len)
{
return feedReadBuffer(len, data, true);
}
//
// protected member functions
//
unsigned TDEBufferedIO::consumeReadBuffer(unsigned nbytes, char *destbuffer, bool discard)
{
{
unsigned u = readBufferSize();
if (nbytes > u)
nbytes = u; // we can't consume more than there is
}
TQByteArray *buf;
unsigned copied = 0;
unsigned index = inBufIndex;
buf = inBuf.first();
while (nbytes && buf)
{
// should we copy it all?
unsigned to_copy = buf->size() - index;
if (to_copy > nbytes)
to_copy = nbytes;
if (destbuffer)
memcpy(destbuffer + copied, buf->data() + index, to_copy);
nbytes -= to_copy;
copied += to_copy;
if (buf->size() - index > to_copy)
{
index += to_copy;
break; // we aren't copying everything, that means that's
// all the user wants
}
else
{
index = 0;
if (discard)
{
inBuf.remove();
buf = inBuf.first();
}
else
buf = inBuf.next();
}
}
if (discard)
inBufIndex = index;
return copied;
}
void TDEBufferedIO::consumeWriteBuffer(unsigned nbytes)
{
TQByteArray *buf = outBuf.first();
if (buf == NULL)
return; // nothing to consume
if (nbytes < buf->size() - outBufIndex)
// we want to consume less than there is in the first buffer
outBufIndex += nbytes;
else
{
nbytes -= buf->size() - outBufIndex;
outBufIndex = 0;
outBuf.remove();
while ((buf = outBuf.current()) != NULL)
if (buf->size() <= nbytes)
{
nbytes -= buf->size();
outBuf.remove();
}
else
{
outBufIndex = nbytes;
break;
}
}
}
unsigned TDEBufferedIO::feedReadBuffer(unsigned nbytes, const char *buffer, bool atBeginning)
{
if (nbytes == 0)
return 0;
TQByteArray *a = new TQByteArray(nbytes);
a->duplicate(buffer, nbytes);
if (atBeginning)
inBuf.prepend(a);
else
inBuf.append(a);
return nbytes;
}
unsigned TDEBufferedIO::feedWriteBuffer(unsigned nbytes, const char *buffer)
{
if (nbytes == 0)
return 0;
TQByteArray *a = new TQByteArray(nbytes);
a->duplicate(buffer, nbytes);
outBuf.append(a);
return nbytes;
}
unsigned TDEBufferedIO::readBufferSize() const
{
unsigned count = 0;
TQByteArray *buf = ((TDEBufferedIO*)this)->inBuf.first();
while (buf != NULL)
{
count += buf->size();
buf = ((TDEBufferedIO*)this)->inBuf.next();
}
return count - inBufIndex;
}
unsigned TDEBufferedIO::writeBufferSize() const
{
unsigned count = 0;
TQByteArray *buf = ((TDEBufferedIO*)this)->outBuf.first();
while (buf != NULL)
{
count += buf->size();
buf = (const_cast<TDEBufferedIO*>(this))->outBuf.next();
}
return count - outBufIndex;
}
void TDEBufferedIO::virtual_hook( int id, void* data )
{ KAsyncIO::virtual_hook( id, data ); }
#include "kbufferedio.moc"
|