omnithread.h

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// -*- Mode: C++; -*-
//                              Package : omnithread
// omnithread.h                 Created : 7/94 tjr
//
//    Copyright (C) 2006 Free Software Foundation, Inc.
//    Copyright (C) 1994,1995,1996, 1997 Olivetti & Oracle Research Laboratory
//
//    This file is part of the omnithread library
//
//    The omnithread library is free software; you can redistribute it and/or
//    modify it under the terms of the GNU Library General Public
//    License as published by the Free Software Foundation; either
//    version 2 of the License, or (at your option) any later version.
//
//    This library is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//    Library General Public License for more details.
//
//    You should have received a copy of the GNU Library General Public
//    License along with this library; if not, write to the Free
//    Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  
//    02111-1307, USA
//

//
// Interface to OMNI thread abstraction.
//
// This file declares classes for threads and synchronisation objects
// (mutexes, condition variables and counting semaphores).
//
// Wherever a seemingly arbitrary choice has had to be made as to the interface
// provided, the intention here has been to be as POSIX-like as possible.  This
// is why there is no semaphore timed wait, for example.
//

#ifndef __omnithread_h_
#define __omnithread_h_

#ifndef NULL
#define NULL 0
#endif

class omni_mutex;
class omni_condition;
class omni_semaphore;
class omni_thread;

//
// OMNI_THREAD_EXPOSE can be defined as public or protected to expose the
// implementation class - this may be useful for debugging.  Hopefully this
// won't change the underlying structure which the compiler generates so that
// this can work without recompiling the library.
//

#ifndef OMNI_THREAD_EXPOSE
#define OMNI_THREAD_EXPOSE private
#endif

//
// Include implementation-specific header file.
//
// This must define 4 CPP macros of the form OMNI_x_IMPLEMENTATION for mutex,
// condition variable, semaphore and thread.  Each should define any
// implementation-specific members of the corresponding classes.
//


//
// For now, we assume they've always got a Posix Threads implementation.
// If not, it'll take some configure hacking to sort it out, along with
// the relevant libraries to link with, etc.
//

#if !defined(OMNITHREAD_POSIX) && !defined(OMNITHREAD_NT) && defined HAVE_CONFIG_H
#include <config.h>
#endif

#if defined(OMNITHREAD_POSIX)
#include <ot_posix.h>

#elif defined(OMNITHREAD_NT)
#include <ot_nt.h>

#ifdef _MSC_VER

// Using MSVC++ to compile. If compiling library as a DLL,
// define _OMNITHREAD_DLL. If compiling as a statuc library, define
// _WINSTATIC
// If compiling an application that is to be statically linked to omnithread,
// define _WINSTATIC (if the application is  to be dynamically linked, 
// there is no need to define any of these macros).

#if defined (_OMNITHREAD_DLL) && defined(_WINSTATIC)
#error "Both _OMNITHREAD_DLL and _WINSTATIC are defined."
#elif defined(_OMNITHREAD_DLL)
#define _OMNITHREAD_NTDLL_ __declspec(dllexport)
#elif !defined(_WINSTATIC)
#define _OMNITHREAD_NTDLL_ __declspec(dllimport)
#elif defined(_WINSTATIC)
#define _OMNITHREAD_NTDLL_
#endif
 // _OMNITHREAD_DLL && _WINSTATIC

#else

// Not using MSVC++ to compile
#define _OMNITHREAD_NTDLL_

#endif
 // _MSC_VER
 
#elif defined(__vxWorks__)
#include <ot_VxThread.h>

#elif defined(__sunos__)
#if __OSVERSION__ != 5
// XXX Workaround for SUN C++ compiler (seen on 4.2) Template.DB code
//     regeneration bug. See omniORB2/CORBA_sysdep.h for details.
#if !defined(__SUNPRO_CC) || __OSVERSION__ != '5'
#error "Only SunOS 5.x or later is supported."
#endif
#endif
#ifdef UseSolarisThreads
#include <ot_solaris.h>
#else
#include <ot_posix.h>
#endif

#elif defined(__rtems__)
#include <ot_posix.h>
#include <sched.h>

#elif defined(__macos__)
#include <ot_posix.h>
#include <sched.h>

#else
#error "No implementation header file"
#endif


#if !defined(__WIN32__)
#define _OMNITHREAD_NTDLL_
#endif

#if (!defined(OMNI_MUTEX_IMPLEMENTATION)        || \
     !defined(OMNI_MUTEX_LOCK_IMPLEMENTATION)   || \
     !defined(OMNI_MUTEX_TRYLOCK_IMPLEMENTATION)|| \
     !defined(OMNI_MUTEX_UNLOCK_IMPLEMENTATION) || \
     !defined(OMNI_CONDITION_IMPLEMENTATION)    || \
     !defined(OMNI_SEMAPHORE_IMPLEMENTATION)    || \
     !defined(OMNI_THREAD_IMPLEMENTATION))
#error "Implementation header file incomplete"
#endif


//
// This exception is thrown in the event of a fatal error.
//

class _OMNITHREAD_NTDLL_ omni_thread_fatal {
public:
    int error;
    omni_thread_fatal(int e = 0) : error(e) {}
};


//
// This exception is thrown when an operation is invoked with invalid
// arguments.
//

class _OMNITHREAD_NTDLL_ omni_thread_invalid {};


//
// Mutex
//

class _OMNITHREAD_NTDLL_ omni_mutex {

public:
    omni_mutex(void);
    ~omni_mutex(void);

    inline void lock(void)    { OMNI_MUTEX_LOCK_IMPLEMENTATION   }
    inline void unlock(void)  { OMNI_MUTEX_UNLOCK_IMPLEMENTATION }
    inline int trylock(void)  { return OMNI_MUTEX_TRYLOCK_IMPLEMENTATION }
        // if mutex is unlocked, lock it and return 1 (true).
        // If it's already locked then return 0 (false).

    inline void acquire(void) { lock(); }
    inline void release(void) { unlock(); }
        // the names lock and unlock are preferred over acquire and release
        // since we are attempting to be as POSIX-like as possible.

    friend class omni_condition;

private:
    // dummy copy constructor and operator= to prevent copying
    omni_mutex(const omni_mutex&);
    omni_mutex& operator=(const omni_mutex&);

OMNI_THREAD_EXPOSE:
    OMNI_MUTEX_IMPLEMENTATION
};

//
// As an alternative to:
// {
//   mutex.lock();
//   .....
//   mutex.unlock();
// }
//
// you can use a single instance of the omni_mutex_lock class:
//
// {
//   omni_mutex_lock l(mutex);
//   ....
// }
//
// This has the advantage that mutex.unlock() will be called automatically
// when an exception is thrown.
//

class _OMNITHREAD_NTDLL_ omni_mutex_lock {
    omni_mutex& mutex;
public:
    omni_mutex_lock(omni_mutex& m) : mutex(m) { mutex.lock(); }
    ~omni_mutex_lock(void) { mutex.unlock(); }
private:
    // dummy copy constructor and operator= to prevent copying
    omni_mutex_lock(const omni_mutex_lock&);
    omni_mutex_lock& operator=(const omni_mutex_lock&);
};


//
// Condition variable
//

class _OMNITHREAD_NTDLL_ omni_condition {

    omni_mutex* mutex;

public:
    omni_condition(omni_mutex* m);
        // constructor must be given a pointer to an existing mutex. The
        // condition variable is then linked to the mutex, so that there is an
        // implicit unlock and lock around wait() and timed_wait().

    ~omni_condition(void);

    void wait(void);
        // wait for the condition variable to be signalled.  The mutex is
        // implicitly released before waiting and locked again after waking up.
        // If wait() is called by multiple threads, a signal may wake up more
        // than one thread.  See POSIX threads documentation for details.

    int timedwait(unsigned long secs, unsigned long nanosecs = 0);
        // timedwait() is given an absolute time to wait until.  To wait for a
        // relative time from now, use omni_thread::get_time. See POSIX threads
        // documentation for why absolute times are better than relative.
        // Returns 1 (true) if successfully signalled, 0 (false) if time
        // expired.

    void signal(void);
        // if one or more threads have called wait(), signal wakes up at least
        // one of them, possibly more.  See POSIX threads documentation for
        // details.

    void broadcast(void);
        // broadcast is like signal but wakes all threads which have called
        // wait().

private:
    // dummy copy constructor and operator= to prevent copying
    omni_condition(const omni_condition&);
    omni_condition& operator=(const omni_condition&);

OMNI_THREAD_EXPOSE:
    OMNI_CONDITION_IMPLEMENTATION
};


//
// Counting (or binary) semaphore
//

class _OMNITHREAD_NTDLL_ omni_semaphore {

public:
    // if max_count == 1, you've got a binary semaphore.
    omni_semaphore(unsigned int initial = 1, unsigned int max_count = 0x7fffffff);
    ~omni_semaphore(void);

    void wait(void);
        // if semaphore value is > 0 then decrement it and carry on. If it's
        // already 0 then block.

    int trywait(void);
        // if semaphore value is > 0 then decrement it and return 1 (true).
        // If it's already 0 then return 0 (false).

    void post(void);
        // if any threads are blocked in wait(), wake one of them up. Otherwise
        // increment the value of the semaphore.

private:
    // dummy copy constructor and operator= to prevent copying
    omni_semaphore(const omni_semaphore&);
    omni_semaphore& operator=(const omni_semaphore&);

OMNI_THREAD_EXPOSE:
    OMNI_SEMAPHORE_IMPLEMENTATION
};

//
// A helper class for semaphores, similar to omni_mutex_lock above.
//

class _OMNITHREAD_NTDLL_ omni_semaphore_lock {
    omni_semaphore& sem;
public:
    omni_semaphore_lock(omni_semaphore& s) : sem(s) { sem.wait(); }
    ~omni_semaphore_lock(void) { sem.post(); }
private:
    // dummy copy constructor and operator= to prevent copying
    omni_semaphore_lock(const omni_semaphore_lock&);
    omni_semaphore_lock& operator=(const omni_semaphore_lock&);
};


//
// Thread
//

class _OMNITHREAD_NTDLL_ omni_thread {

public:

    enum priority_t {
        PRIORITY_LOW,
        PRIORITY_NORMAL,
        PRIORITY_HIGH
    };

    enum state_t {
        STATE_NEW,              // thread object exists but thread hasn't
                                // started yet.
        STATE_RUNNING,          // thread is running.
        STATE_TERMINATED        // thread has terminated but storage has not
                                // been reclaimed (i.e. waiting to be joined).
    };

    //
    // Constructors set up the thread object but the thread won't start until
    // start() is called. The create method can be used to construct and start
    // a thread in a single call.
    //

    omni_thread(void (*fn)(void*), void* arg = NULL,
                priority_t pri = PRIORITY_NORMAL);
    omni_thread(void* (*fn)(void*), void* arg = NULL,
                priority_t pri = PRIORITY_NORMAL);
        // these constructors create a thread which will run the given function
        // when start() is called.  The thread will be detached if given a
        // function with void return type, undetached if given a function
        // returning void*. If a thread is detached, storage for the thread is
        // reclaimed automatically on termination. Only an undetached thread
        // can be joined.

    void start(void);
        // start() causes a thread created with one of the constructors to
        // start executing the appropriate function.

protected:

    omni_thread(void* arg = NULL, priority_t pri = PRIORITY_NORMAL);
        // this constructor is used in a derived class.  The thread will
        // execute the run() or run_undetached() member functions depending on
        // whether start() or start_undetached() is called respectively.

    void start_undetached(void);
        // can be used with the above constructor in a derived class to cause
        // the thread to be undetached.  In this case the thread executes the
        // run_undetached member function.

    virtual ~omni_thread(void);
        // destructor cannot be called by user (except via a derived class).
        // Use exit() or cancel() instead. This also means a thread object must
        // be allocated with new - it cannot be statically or automatically
        // allocated. The destructor of a class that inherits from omni_thread
        // shouldn't be public either (otherwise the thread object can be
        // destroyed while the underlying thread is still running).

public:

    void join(void**);
        // join causes the calling thread to wait for another's completion,
        // putting the return value in the variable of type void* whose address
        // is given (unless passed a null pointer). Only undetached threads
        // may be joined. Storage for the thread will be reclaimed.

    void set_priority(priority_t);
        // set the priority of the thread.

    static omni_thread* create(void (*fn)(void*), void* arg = NULL,
                               priority_t pri = PRIORITY_NORMAL);
    static omni_thread* create(void* (*fn)(void*), void* arg = NULL,
                               priority_t pri = PRIORITY_NORMAL);
        // create spawns a new thread executing the given function with the
        // given argument at the given priority. Returns a pointer to the
        // thread object. It simply constructs a new thread object then calls
        // start.

    static void exit(void* return_value = NULL);
        // causes the calling thread to terminate.

    static omni_thread* self(void);
        // returns the calling thread's omni_thread object.  If the
        // calling thread is not the main thread and is not created
        // using this library, returns 0. (But see create_dummy()
        // below.)

    static void yield(void);
        // allows another thread to run.

    static void sleep(unsigned long secs, unsigned long nanosecs = 0);
        // sleeps for the given time.

    static void get_time(unsigned long* abs_sec, unsigned long* abs_nsec,
                         unsigned long rel_sec = 0, unsigned long rel_nsec=0);
        // calculates an absolute time in seconds and nanoseconds, suitable for
        // use in timed_waits on condition variables, which is the current time
        // plus the given relative offset.


    static void stacksize(unsigned long sz);
    static unsigned long stacksize();
        // Use this value as the stack size when spawning a new thread.
        // The default value (0) means that the thread library default is
        // to be used.


    // Per-thread data
    //
    // These functions allow you to attach additional data to an
    // omni_thread. First allocate a key for yourself with
    // allocate_key(). Then you can store any object whose class is
    // derived from value_t. Any values still stored in the
    // omni_thread when the thread exits are deleted.
    //
    // These functions are NOT thread safe, so you should be very
    // careful about setting/getting data in a different thread to the
    // current thread.

    typedef unsigned int key_t;
    static key_t allocate_key();

    class value_t {
    public:
      virtual ~value_t() {}
    };

    value_t* set_value(key_t k, value_t* v);
        // Sets a value associated with the given key. The key must
        // have been allocated with allocate_key(). If a value has
        // already been set with the specified key, the old value_t
        // object is deleted and replaced. Returns the value which was
        // set, or zero if the key is invalid.

    value_t* get_value(key_t k);
        // Returns the value associated with the key. If the key is
        // invalid, or there is no value for the key, returns zero.

    value_t* remove_value(key_t k);
        // Removes the value associated with the key and returns it.
        // If the key is invalid, or there is no value for the key,
        // returns zero.


    // Dummy omni_thread
    //
    // Sometimes, an application finds itself with threads created
    // outside of omnithread which must interact with omnithread
    // features such as the per-thread data. In this situation,
    // omni_thread::self() would normally return 0. These functions
    // allow the application to create a suitable dummy omni_thread
    // object.

    static omni_thread* create_dummy(void);
        // creates a dummy omni_thread for the calling thread. Future
        // calls to self() will return the dummy omni_thread. Throws
        // omni_thread_invalid if this thread already has an
        // associated omni_thread (real or dummy).

    static void release_dummy();
        // release the dummy omni_thread for this thread. This
        // function MUST be called before the thread exits. Throws
        // omni_thread_invalid if the calling thread does not have a
        // dummy omni_thread.

    // class ensure_self should be created on the stack. If created in
    // a thread without an associated omni_thread, it creates a dummy
    // thread which is released when the ensure_self object is deleted.

    class ensure_self {
    public:
      inline ensure_self() : _dummy(0)
      {
        _self = omni_thread::self();
        if (!_self) {
          _dummy = 1;
          _self  = omni_thread::create_dummy();
        }
      }
      inline ~ensure_self()
      {
        if (_dummy)
          omni_thread::release_dummy();
      }
      inline omni_thread* self() { return _self; }
    private:
      omni_thread* _self;
      int          _dummy;
    };


private:

    virtual void run(void* /*arg*/) {}
    virtual void* run_undetached(void* /*arg*/) { return NULL; }
        // can be overridden in a derived class.  When constructed using the
        // the constructor omni_thread(void*, priority_t), these functions are
        // called by start() and start_undetached() respectively.

    void common_constructor(void* arg, priority_t pri, int det);
        // implements the common parts of the constructors.

    omni_mutex mutex;
        // used to protect any members which can change after construction,
        // i.e. the following 2 members.

    state_t _state;
    priority_t _priority;

    static omni_mutex* next_id_mutex;
    static int next_id;
    int _id;

    void (*fn_void)(void*);
    void* (*fn_ret)(void*);
    void* thread_arg;
    int detached;
    int _dummy;
    value_t**     _values;
    unsigned long _value_alloc;

    omni_thread(const omni_thread&);
    omni_thread& operator=(const omni_thread&);
    // Not implemented

public:

    priority_t priority(void) {

        // return this thread's priority.

        omni_mutex_lock l(mutex);
        return _priority;
    }

    state_t state(void) {

        // return thread state (invalid, new, running or terminated).

        omni_mutex_lock l(mutex);
        return _state;
    }

    int id(void) { return _id; }
        // return unique thread id within the current process.


    // This class plus the instance of it declared below allows us to execute
    // some initialisation code before main() is called.

    class _OMNITHREAD_NTDLL_ init_t {
    public:
        init_t(void);
        ~init_t(void);
    };

    friend class init_t;
    friend class omni_thread_dummy;

OMNI_THREAD_EXPOSE:
    OMNI_THREAD_IMPLEMENTATION
};

#ifndef __rtems__
static omni_thread::init_t omni_thread_init;
#else
// RTEMS calls global Ctor/Dtor in a context that is not
// a posix thread. Calls to functions to pthread_self() in
// that context returns NULL. 
// So, for RTEMS we will make the thread initialization at the
// beginning of the Init task that has a posix context.
#endif

#endif

---