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root/gclib/gclib/GYarn.h
Revision: 107
Committed: Tue Oct 11 12:31:50 2011 UTC (9 years, 3 months ago) by gpertea
File size: 6466 byte(s)
Log Message: 
wip GYarn (threads)
Line File contents
1 /*
2 * cpp-ification of yarn.h -- generic interface for thread operations
3 * Copyright (C) 2008 Mark Adler
4 * Version 1.1 26 Oct 2008 Mark Adler
5 */
6
7 /*
8 This software is provided 'as-is', without any express or implied
9 warranty. In no event will the author be held liable for any damages
10 arising from the use of this software.
11
12 Permission is granted to anyone to use this software for any purpose,
13 including commercial applications, and to alter it and redistribute it
14 freely, subject to the following restrictions:
15
16 1. The origin of this software must not be misrepresented; you must not
17 claim that you wrote the original software. If you use this software
18 in a product, an acknowledgment in the product documentation would be
19 appreciated but is not required.
20 2. Altered source versions must be plainly marked as such, and must not be
21 misrepresented as being the original software.
22 3. This notice may not be removed or altered from any source distribution.
23
24 Mark Adler
25 madler@alumni.caltech.edu
26 */
27
28 /* Basic thread operations
29
30 This interface isolates the local operating system implementation of threads
31 from the application in order to facilitate platform independent use of
32 threads. All of the implementation details are deliberately hidden.
33
34 Assuming adequate system resources and proper use, none of these functions
35 can fail. As a result, any errors encountered will cause an exit() to be
36 executed.
37
38 These functions allow the simple launching and joining of threads, and the
39 locking of objects and synchronization of changes of objects. The latter is
40 implemented with a single lock type that contains an integer value. The
41 value can be ignored for simple exclusive access to an object, or the value
42 can be used to signal and wait for changes to an object.
43
44 -- Arguments --
45
46 thread *thread; identifier for launched thread, used by join
47 void probe(void *); pointer to function "probe", run when thread starts
48 void *payload; single argument passed to the probe function
49 lock *lock; a lock with a value -- used for exclusive access to
50 an object and to synchronize threads waiting for
51 changes to an object
52 long val; value to set lock, increment lock, or wait for
53 int n; number of threads joined
54
55 -- Thread functions --
56
57 thread = launch(probe, payload) - launch a thread -- exit via probe() return
58 join(thread) - join a thread and by joining end it, waiting for the thread
59 to exit if it hasn't already -- will free the resources allocated by
60 launch() (don't try to join the same thread more than once)
61 n = join_all() - join all threads launched by launch() that are not joined
62 yet and free the resources allocated by the launches, usually to clean
63 up when the thread processing is done -- join_all() returns an int with
64 the count of the number of threads joined (join_all() should only be
65 called from the main thread, and should only be called after any calls
66 of join() have completed)
67 destruct(thread) - terminate the thread in mid-execution and join it
68 (depending on the implementation, the termination may not be immediate,
69 but may wait for the thread to execute certain thread or file i/o
70 operations)
71
72 -- Lock functions --
73
74 lock = new_lock(val) - create a new lock with initial value val (lock is
75 created in the released state)
76 possess(lock) - acquire exclusive possession of a lock, waiting if necessary
77 twist(lock, [TO | BY], val) - set lock to or increment lock by val, signal
78 all threads waiting on this lock and then release the lock -- must
79 possess the lock before calling (twist releases, so don't do a
80 release() after a twist() on the same lock)
81 wait_for(lock, [TO_BE | NOT_TO_BE | TO_BE_MORE_THAN | TO_BE_LESS_THAN], val)
82 - wait on lock value to be, not to be, be greater than, or be less than
83 val -- must possess the lock before calling, will possess the lock on
84 return but the lock is released while waiting to permit other threads
85 to use twist() to change the value and signal the change (so make sure
86 that the object is in a usable state when waiting)
87 release(lock) - release a possessed lock (do not try to release a lock that
88 the current thread does not possess)
89 val = peek_lock(lock) - return the value of the lock (assumes that lock is
90 already possessed, no possess or release is done by peek_lock())
91 free_lock(lock) - free the resources allocated by new_lock() (application
92 must assure that the lock is released before calling free_lock())
93
94 -- Memory allocation ---
95
96 yarn_mem(better_malloc, better_free) - set the memory allocation and free
97 routines for use by the yarn routines where the supplied routines have
98 the same interface and operation as malloc() and free(), and may be
99 provided in order to supply thread-safe memory allocation routines or
100 for any other reason -- by default malloc() and free() will be used
101
102 -- Error control --
103
104 yarn_name - a char pointer to a string that will be the prefix for any error
105 messages that these routines generate before exiting -- if not changed
106 by the application, "yarn" will be used
107 yarn_abort - an external function that will be executed when there is an
108 internal yarn error, due to out of memory or misuse -- this function
109 may exit to abort the application, or if it returns, the yarn error
110 handler will exit (set to NULL by default for no action)
111 */
112
113 extern char *yarn_prefix;
114 extern void (*yarn_abort)(int);
115 typedef struct thread_s thread;
116 typedef struct lock_s lock;
117
118 class GYarn {
119 public:
120 //void yarn_mem(void *(*)(size_t), void (*)(void *));
121 void mem(void *(*)(size_t), void (*)(void *));
122 thread *launch(void (*)(void *), void *);
123 void join(thread *);
124 int join_all(void);
125 void destruct(thread *);
126
127 };
128
129
130
131
132 lock *new_lock(long);
133 void possess(lock *);
134 void release(lock *);
135 enum twist_op { TO, BY };
136 void twist(lock *, enum twist_op, long);
137 enum wait_op {
138 TO_BE, /* or */ NOT_TO_BE, /* that is the question */
139 TO_BE_MORE_THAN, TO_BE_LESS_THAN };
140 void wait_for(lock *, enum wait_op, long);
141 long peek_lock(lock *);
142 void free_lock(lock *);