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
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
|
#ifndef UTIL_STREAM_CHAIN_H
#define UTIL_STREAM_CHAIN_H
#include "util/stream/block.hh"
#include "util/stream/config.hh"
#include "util/stream/multi_progress.hh"
#include "util/scoped.hh"
#include <boost/ptr_container/ptr_vector.hpp>
#include <boost/thread/thread.hpp>
#include <cstddef>
#include <cassert>
namespace util {
template <class T> class PCQueue;
namespace stream {
class ChainConfigException : public Exception {
public:
ChainConfigException() throw();
~ChainConfigException() throw();
};
class Chain;
class RewindableStream;
/**
* Encapsulates a @ref PCQueue "producer queue" and a @ref PCQueue "consumer queue" within a @ref Chain "chain".
*
* Specifies position in chain for Link constructor.
*/
class ChainPosition {
public:
const Chain &GetChain() const { return *chain_; }
private:
friend class Chain;
friend class Link;
friend class RewindableStream;
ChainPosition(PCQueue<Block> &in, PCQueue<Block> &out, Chain *chain, MultiProgress &progress)
: in_(&in), out_(&out), chain_(chain), progress_(progress.Add()) {}
PCQueue<Block> *in_, *out_;
Chain *chain_;
WorkerProgress progress_;
};
/**
* Encapsulates a worker thread processing data at a given position in the chain.
*
* Each instance of this class owns one boost thread in which the worker is Run().
*/
class Thread {
public:
/**
* Constructs a new Thread in which the provided Worker is Run().
*
* Position is usually ChainPosition but if there are multiple streams involved, this can be ChainPositions.
*
* After a call to this constructor, the provided worker will be running within a boost thread owned by the newly constructed Thread object.
*/
template <class Position, class Worker> Thread(const Position &position, const Worker &worker)
: thread_(boost::ref(*this), position, worker) {}
~Thread();
/**
* Launches the provided worker in this object's boost thread.
*
* This method is called automatically by this class's @ref Thread() "constructor".
*/
template <class Position, class Worker> void operator()(const Position &position, Worker &worker) {
try {
worker.Run(position);
} catch (const std::exception &e) {
UnhandledException(e);
}
}
private:
void UnhandledException(const std::exception &e);
boost::thread thread_;
};
/**
* This resets blocks to full valid size. Used to close the loop in Chain by recycling blocks.
*/
class Recycler {
public:
/**
* Resets the blocks in the chain such that the blocks' respective valid sizes match the chain's block size.
*
* @see Block::SetValidSize()
* @see Chain::BlockSize()
*/
void Run(const ChainPosition &position);
};
extern const Recycler kRecycle;
class WriteAndRecycle;
class PWriteAndRecycle;
/**
* Represents a sequence of workers, through which @ref Block "blocks" can pass.
*/
class Chain {
private:
template <class T, void (T::*ptr)(const ChainPosition &) = &T::Run> struct CheckForRun {
typedef Chain type;
};
public:
/**
* Constructs a configured Chain.
*
* @param config Specifies how to configure the Chain.
*/
explicit Chain(const ChainConfig &config);
/**
* Destructs a Chain.
*
* This method waits for the chain's threads to complete,
* and frees the memory held by this chain.
*/
~Chain();
void ActivateProgress() {
assert(!Running());
progress_.Activate();
}
void SetProgressTarget(uint64_t target) {
progress_.SetTarget(target);
}
/**
* Gets the number of bytes in each record of a Block.
*
* @see ChainConfig::entry_size
*/
std::size_t EntrySize() const {
return config_.entry_size;
}
/**
* Gets the inital @ref Block::ValidSize "valid size" for @ref Block "blocks" in this chain.
*
* @see Block::ValidSize
*/
std::size_t BlockSize() const {
return block_size_;
}
/** Two ways to add to the chain: Add() or operator>>. */
ChainPosition Add();
/**
* Adds a new worker to this chain,
* and runs that worker in a new Thread owned by this chain.
*
* The worker must have a Run method that accepts a position argument.
*
* @see Thread::operator()()
*/
template <class Worker> typename CheckForRun<Worker>::type &operator>>(const Worker &worker) {
assert(!complete_called_);
threads_.push_back(new Thread(Add(), worker));
return *this;
}
/**
* Adds a new worker to this chain (but avoids copying that worker),
* and runs that worker in a new Thread owned by this chain.
*
* The worker must have a Run method that accepts a position argument.
*
* @see Thread::operator()()
*/
template <class Worker> typename CheckForRun<Worker>::type &operator>>(const boost::reference_wrapper<Worker> &worker) {
assert(!complete_called_);
threads_.push_back(new Thread(Add(), worker));
return *this;
}
// Note that Link and Stream also define operator>> outside this class.
// To complete the loop, call CompleteLoop(), >> kRecycle, or the destructor.
void CompleteLoop() {
threads_.push_back(new Thread(Complete(), kRecycle));
}
/**
* Adds a Recycler worker to this chain,
* and runs that worker in a new Thread owned by this chain.
*/
Chain &operator>>(const Recycler &) {
CompleteLoop();
return *this;
}
/**
* Adds a WriteAndRecycle worker to this chain,
* and runs that worker in a new Thread owned by this chain.
*/
Chain &operator>>(const WriteAndRecycle &writer);
Chain &operator>>(const PWriteAndRecycle &writer);
// Chains are reusable. Call Wait to wait for everything to finish and free memory.
void Wait(bool release_memory = true);
// Waits for the current chain to complete (if any) then starts again.
void Start();
bool Running() const { return !queues_.empty(); }
private:
ChainPosition Complete();
ChainConfig config_;
std::size_t block_size_;
scoped_malloc memory_;
boost::ptr_vector<PCQueue<Block> > queues_;
bool complete_called_;
boost::ptr_vector<Thread> threads_;
MultiProgress progress_;
};
// Create the link in the worker thread using the position token.
/**
* Represents a C++ style iterator over @ref Block "blocks".
*/
class Link {
public:
// Either default construct and Init or just construct all at once.
/**
* Constructs an @ref Init "initialized" link.
*
* @see Init
*/
explicit Link(const ChainPosition &position);
/**
* Constructs a link that must subsequently be @ref Init "initialized".
*
* @see Init
*/
Link();
/**
* Initializes the link with the input @ref PCQueue "consumer queue" and output @ref PCQueue "producer queue" at a given @ref ChainPosition "position" in the @ref Chain "chain".
*
* @see Link()
*/
void Init(const ChainPosition &position);
/**
* Destructs the link object.
*
* If necessary, this method will pass a poison block
* to this link's output @ref PCQueue "producer queue".
*
* @see Block::SetToPoison()
*/
~Link();
/**
* Gets a reference to the @ref Block "block" at this link.
*/
Block &operator*() { return current_; }
/**
* Gets a const reference to the @ref Block "block" at this link.
*/
const Block &operator*() const { return current_; }
/**
* Gets a pointer to the @ref Block "block" at this link.
*/
Block *operator->() { return ¤t_; }
/**
* Gets a const pointer to the @ref Block "block" at this link.
*/
const Block *operator->() const { return ¤t_; }
/**
* Gets the link at the next @ref ChainPosition "position" in the @ref Chain "chain".
*/
Link &operator++();
/**
* Returns true if the @ref Block "block" at this link encapsulates a valid (non-NULL) block of memory.
*
* This method is a user-defined implicit conversion function to boolean;
* among other things, this method enables bare instances of this class
* to be used as the condition of an if statement.
*/
operator bool() const { return current_; }
/**
* @ref Block::SetToPoison() "Poisons" the @ref Block "block" at this link,
* and passes this now-poisoned block to this link's output @ref PCQueue "producer queue".
*
* @see Block::SetToPoison()
*/
void Poison();
private:
Block current_;
PCQueue<Block> *in_, *out_;
bool poisoned_;
WorkerProgress progress_;
};
inline Chain &operator>>(Chain &chain, Link &link) {
link.Init(chain.Add());
return chain;
}
} // namespace stream
} // namespace util
#endif // UTIL_STREAM_CHAIN_H
|