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root/gclib/gclib/GYarn.h
Revision: 107
Committed: Tue Oct 11 12:31:50 2011 UTC (8 years, 1 month ago) by gpertea
File size: 6466 byte(s)
Log Message:
wip GYarn (threads)

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