Main Page | Namespace List | Class Hierarchy | Alphabetical List | Class List | Directories | File List | Namespace Members | Class Members | File Members | Related Pages

wvtask.h

Go to the documentation of this file.
00001 /* -*- Mode: C++ -*-
00002  * Worldvisions Weaver Software:
00003  *   Copyright (C) 1997-2002 Net Integration Technologies, Inc.
00004  *
00005  * A set of classes that provide co-operative multitasking support.  By
00006  * default there's no scheduler -- you have to provide it yourself.  As it
00007  * stands, this is just a convenient way to switch from one context to
00008  * another when you know exactly what you want to do.
00009  * 
00010  * This is mainly intended for use by WvStream, but that's probably not the
00011  * only possible use... see also WvCont.
00012  */
00013 #ifndef __WVTASK_H
00014 #define __WVTASK_H
00015 
00016 #ifdef _WIN32
00017 
00018 #include "wvwin32task.h"
00019 
00020 #else
00021 
00022 #include "wvstring.h"
00023 #include "wvlinklist.h"
00024 #include "setjmp.h"
00025 
00026 #define WVTASK_MAGIC 0x123678
00027 
00028 class WvTaskMan;
00029 
00030 /** Represents a single thread of control. */
00031 class WvTask
00032 {
00033     friend class WvTaskMan;
00034     
00035     // you might think it would be useful to have this return an int, since
00036     // yield() and run() both return int.  But that ends up being more
00037     // confusing than you think, because if you call task1->run(), and he
00038     // calls task2->run(), and task2 calls yield(), then task1->run() returns
00039     // the value *task2* passed to yield!  So we avoid the confusion by not
00040     // using return values here, which discourages people from thinking of
00041     // them as return values.
00042     typedef void TaskFunc(void *userdata);
00043     
00044     static int taskcount, numtasks, numrunning;
00045     int magic_number, *stack_magic;
00046     WvString name;
00047     int tid;
00048     
00049     size_t stacksize;
00050     bool running, recycled;
00051     
00052     WvTaskMan &man;
00053     jmp_buf mystate;    // used for resuming the task
00054     
00055     TaskFunc *func;
00056     void *userdata;
00057     
00058     WvTask(WvTaskMan &_man, size_t _stacksize = 64*1024);
00059     
00060 public:
00061     virtual ~WvTask();
00062     
00063     void start(WvStringParm _name, TaskFunc *_func, void *_userdata);
00064     bool isrunning() const
00065         { return running; }
00066     void recycle();
00067 };
00068 
00069 
00070 DeclareWvList(WvTask);
00071 
00072 /** Provides co-operative multitasking support among WvTask instances. */
00073 class WvTaskMan
00074 {
00075     friend class WvTask;
00076     
00077     static WvTaskMan *singleton;
00078     static int links;
00079     
00080     static int magic_number;
00081     static WvTaskList free_tasks;
00082     
00083     static void get_stack(WvTask &task, size_t size);
00084     static void stackmaster();
00085     static void _stackmaster();
00086     static void do_task();
00087 
00088     static char *stacktop;
00089     static jmp_buf stackmaster_task;
00090     
00091     static WvTask *stack_target;
00092     static jmp_buf get_stack_return;
00093     
00094     static WvTask *current_task;
00095     static jmp_buf toplevel;
00096     
00097     WvTaskMan();
00098     virtual ~WvTaskMan();
00099     
00100 public:
00101     /// get/dereference the singleton global WvTaskMan
00102     static WvTaskMan *get();
00103     static void unlink();
00104     
00105     WvTask *start(WvStringParm name,
00106                   WvTask::TaskFunc *func, void *userdata,
00107                   size_t stacksize = 64*1024);
00108     
00109     // run() and yield() return the 'val' passed to run() when this task
00110     // was started.
00111     static int run(WvTask &task, int val = 1);
00112     static int yield(int val = 1);
00113     
00114     static WvTask *whoami()
00115         { return current_task; }
00116 };
00117 
00118 
00119 #endif // ifdef _WIN32
00120 #endif // __WVTASK_H

Generated on Wed Dec 15 15:08:11 2004 for WvStreams by  doxygen 1.3.9.1