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1#ifndef BU_ITO_CONDITION_H
2#define BU_ITO_CONDITION_H
3
4#include <pthread.h>
5
6#include "itomutex.h"
7
8namespace Bu
9{
10 /**
11 * Ito condition. This is a fairly simple condition mechanism. As you may
12 * notice this class inherits from the ItoMutex class, this is because all
13 * conditions must be within a locked block. The standard usage of a condition
14 * is to pause one thread, perhaps indefinately, until another thread signals
15 * that it is alright to procede.
16 * <br>
17 * Standard usage for the thread that wants to wait is as follows:
18 * <pre>
19 * ItoCondition cond;
20 * ... // Perform setup and enter your run loop
21 * cond.lock();
22 * while( !isFinished() ) // Could be anything you're waiting for
23 * cond.wait();
24 * ... // Take care of what you have to.
25 * cond.unlock();
26 * </pre>
27 * The usage for the triggering thread is much simpler, when it needs to tell
28 * the others that it's time to grab some data it calls either signal or
29 * broadcast. See both of those functions for the difference.
30 *@author Mike Buland
31 */
32 class ItoCondition : public ItoMutex
33 {
34 public:
35 /**
36 * Create a condition.
37 */
38 ItoCondition();
39
40 /**
41 * Destroy a condition.
42 */
43 ~ItoCondition();
44
45 /**
46 * Wait forever, or until signalled. This has to be called from within a
47 * locked section, i.e. before calling this this object's lock function
48 * should be called.
49 */
50 int wait();
51
52 /**
53 * Wait for a maximum of nSec seconds and nUSec micro-seconds or until
54 * signalled. This is a little more friendly function if you want to
55 * perform other operations in the thrad loop that calls this function.
56 * Like the other wait function, this must be inside a locked section.
57 *@param nSec The seconds to wait.
58 *@param nUSec the micro-seconds to wait.
59 */
60 int wait( int nSec, int nUSec );
61
62 /**
63 * Notify the next thread waiting on this condition that they can go ahead.
64 * This only signals one thread, the next one in the condition queue, that
65 * it is safe to procede with whatever operation was being waited on.
66 */
67 int signal();
68
69 /**
70 * Notify all threads waiting on this condition that they can go ahead now.
71 * This function is slower than signal, but more effective in certain
72 * situations where you may not know how many threads should be activated.
73 */
74 int broadcast();
75
76 private:
77 pthread_cond_t cond; /**< Internal condition reference. */
78 };
79}
80
81#endif