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root/gclib/gclib/yarn.h
Revision: 107
Committed: Tue Oct 11 12:31:50 2011 UTC (8 years, 1 month ago) by gpertea
File size: 6350 byte(s)
Log Message:
wip GYarn (threads)

Line User Rev File contents
1 gpertea 107 /* 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 *);