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root/gclib/gclib/yarn.h
Revision: 107
Committed: Tue Oct 11 12:31:50 2011 UTC (7 years, 9 months ago) by gpertea
File size: 6350 byte(s)
Log Message:
wip GYarn (threads)

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