/*
    Copyright (c) 2005-2019 Intel Corporation

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/

#ifndef __TBB_condition_variable_H
#define __TBB_condition_variable_H

#if _WIN32||_WIN64
#include "../machine/windows_api.h"

namespace tbb { 
namespace interface5 {
namespace internal { 
struct condition_variable_using_event
{
    //! Event for blocking waiting threads.
    HANDLE event;
    //! Protects invariants involving n_waiters, release_count, and epoch.
    CRITICAL_SECTION mutex;
    //! Number of threads waiting on this condition variable
    int n_waiters;
    //! Number of threads remaining that should no longer wait on this condition variable.
    int release_count;
    //! To keep threads from waking up prematurely with earlier signals.
    unsigned epoch;
};
}}} // namespace tbb::interface5::internal

#ifndef CONDITION_VARIABLE_INIT
typedef void* CONDITION_VARIABLE;
typedef CONDITION_VARIABLE* PCONDITION_VARIABLE;
#endif

#else /* if not _WIN32||_WIN64 */
#include <errno.h> // some systems need it for ETIMEDOUT
#include <pthread.h>
#if __linux__
#include <ctime>
#else /* generic Unix */
#include <sys/time.h>
#endif
#endif /* _WIN32||_WIN64 */

#include "../tbb_stddef.h"
#include "../mutex.h"
#include "../tbb_thread.h"
#include "../tbb_exception.h"
#include "../tbb_profiling.h"

namespace tbb {

namespace interface5 {

// C++0x standard working draft 30.4.3
// Lock tag types
struct defer_lock_t { }; //! do not acquire ownership of the mutex
struct try_to_lock_t { }; //! try to acquire ownership of the mutex without blocking
struct adopt_lock_t { }; //! assume the calling thread has already
const defer_lock_t defer_lock = {};
const try_to_lock_t try_to_lock = {};
const adopt_lock_t adopt_lock = {};

// C++0x standard working draft 30.4.3.1
//! lock_guard 
template<typename M>
class lock_guard : tbb::internal::no_copy {
public:
    //! mutex type
    typedef M mutex_type;

    //! Constructor
    /** precondition: If mutex_type is not a recursive mutex, the calling thread
        does not own the mutex m. */
    explicit lock_guard(mutex_type& m) : pm(m) {m.lock();}
    
    //! Adopt_lock constructor
    /** precondition: the calling thread owns the mutex m. */
    lock_guard(mutex_type& m, adopt_lock_t) : pm(m) {}

    //! Destructor
    ~lock_guard() { pm.unlock(); }
private:
    mutex_type& pm;
};

// C++0x standard working draft 30.4.3.2
//! unique_lock 
template<typename M>
class unique_lock : tbb::internal::no_copy {
    friend class condition_variable;
public:
    typedef M mutex_type;

    // 30.4.3.2.1 construct/copy/destroy
    // NB: Without constructors that take an r-value reference to a unique_lock, the following constructor is of little use.
    //! Constructor
    /** postcondition: pm==0 && owns==false */
    unique_lock() : pm(NULL), owns(false) {}

    //! Constructor
    /** precondition: if mutex_type is not a recursive mutex, the  calling thread
        does not own the mutex m.  If the precondition is not met, a deadlock occurs.
        postcondition: pm==&m and owns==true */
    explicit unique_lock(mutex_type& m) : pm(&m) {m.lock(); owns=true;}

    //! Defer_lock constructor
    /** postcondition: pm==&m and owns==false */
    unique_lock(mutex_type& m, defer_lock_t) : pm(&m), owns(false) {}

    //! Try_to_lock constructor
    /** precondition: if mutex_type is not a recursive mutex, the  calling thread
       does not own the mutex m.  If the precondition is not met, a deadlock occurs.
       postcondition: pm==&m and owns==res where res is the value returned by
       the call to m.try_lock(). */
    unique_lock(mutex_type& m, try_to_lock_t) : pm(&m) {owns = m.try_lock();}

    //! Adopt_lock constructor
    /** precondition: the calling thread owns the mutex. If it does not, mutex->unlock() would fail.
        postcondition: pm==&m and owns==true */
    unique_lock(mutex_type& m, adopt_lock_t) : pm(&m), owns(true) {}

    //! Timed unique_lock acquisition.
    /** To avoid requiring support for namespace chrono, this method deviates from the working draft in that 
        it uses tbb::tick_count::interval_t to specify the time duration. */
    unique_lock(mutex_type& m, const tick_count::interval_t &i) : pm(&m) {owns = try_lock_for( i );}

#if __TBB_CPP11_RVALUE_REF_PRESENT
    //! Move constructor
    /** postconditions: pm == src_p.pm and owns == src_p.owns (where src_p is the state of src just prior to this
        construction), src.pm == 0 and src.owns == false. */
    unique_lock(unique_lock && src): pm(NULL), owns(false) {this->swap(src);}

    //! Move assignment
    /** effects: If owns calls pm->unlock().
        Postconditions: pm == src_p.pm and owns == src_p.owns (where src_p is the state of src just prior to this
        assignment), src.pm == 0 and src.owns == false. */
    unique_lock& operator=(unique_lock && src) {
        if (owns)
            this->unlock();
        pm = NULL;
        this->swap(src);
        return *this;
    }
#endif // __TBB_CPP11_RVALUE_REF_PRESENT

    //! Destructor
    ~unique_lock() { if( owns ) pm->unlock(); }

    // 30.4.3.2.2 locking
    //! Lock the mutex and own it.
    void lock() {
        if( pm ) {
            if( !owns ) {
                pm->lock();
                owns = true;
            } else 
                throw_exception_v4( tbb::internal::eid_possible_deadlock );
        } else 
            throw_exception_v4( tbb::internal::eid_operation_not_permitted );
        __TBB_ASSERT( owns, NULL );
    }

    //! Try to lock the mutex. 
    /** If successful, note that this lock owns it. Otherwise, set it false. */
    bool try_lock() {
        if( pm ) {
            if( !owns )
                owns = pm->try_lock();
            else
                throw_exception_v4( tbb::internal::eid_possible_deadlock );
        } else 
            throw_exception_v4( tbb::internal::eid_operation_not_permitted );
        return owns;
    }
 
    //! Try to lock the mutex. 
    bool try_lock_for( const tick_count::interval_t &i );

    //! Unlock the mutex
    /** And note that this lock no longer owns it. */
    void unlock() { 
        if( owns ) {
            pm->unlock();
            owns = false;
        } else
            throw_exception_v4( tbb::internal::eid_operation_not_permitted );
        __TBB_ASSERT( !owns, NULL );
    }

    // 30.4.3.2.3 modifiers
    //! Swap the two unique locks
    void swap(unique_lock& u) {
        mutex_type* t_pm = u.pm;    u.pm   = pm;    pm   = t_pm;
        bool t_owns      = u.owns;  u.owns = owns;  owns = t_owns;
    }

    //! Release control over the mutex.
    mutex_type* release() {
        mutex_type* o_pm = pm; 
        pm = NULL; 
        owns = false; 
        return o_pm; 
    }

    // 30.4.3.2.4 observers
    //! Does this lock own the mutex?
    bool owns_lock() const { return owns; }

    // TODO: Un-comment 'explicit' when the last non-C++0x compiler support is dropped
    //! Does this lock own the mutex?
    /*explicit*/ operator bool() const { return owns; }

    //! Return the mutex that this lock currently has.
    mutex_type* mutex() const { return pm; }

private:
    mutex_type* pm;
    bool owns;
};

template<typename M>
bool unique_lock<M>::try_lock_for( const tick_count::interval_t &i)
{ 
    const int unique_lock_tick = 100; /* microseconds; 0.1 milliseconds */
    // the smallest wait-time is 0.1 milliseconds.
    bool res = pm->try_lock();
    int duration_in_micro; 
    if( !res && (duration_in_micro=int(i.seconds()*1e6))>unique_lock_tick ) {
        tick_count::interval_t i_100( double(unique_lock_tick)/1e6 /* seconds */); // 100 microseconds = 0.1*10E-3
        do {
            this_tbb_thread::sleep(i_100); // sleep for 100 micro seconds
            duration_in_micro -= unique_lock_tick;
            res = pm->try_lock();
        } while( !res && duration_in_micro>unique_lock_tick );
    }
    return (owns=res);
}

//! Swap the two unique locks that have the mutexes of same type 
template<typename M>
void swap(unique_lock<M>& x, unique_lock<M>& y) { x.swap( y ); }

namespace internal {

#if _WIN32||_WIN64
union condvar_impl_t {
    condition_variable_using_event cv_event;
    CONDITION_VARIABLE             cv_native;
};
void __TBB_EXPORTED_FUNC internal_initialize_condition_variable( condvar_impl_t& cv );
void __TBB_EXPORTED_FUNC internal_destroy_condition_variable(    condvar_impl_t& cv );
void __TBB_EXPORTED_FUNC internal_condition_variable_notify_one( condvar_impl_t& cv );
void __TBB_EXPORTED_FUNC internal_condition_variable_notify_all( condvar_impl_t& cv );
bool __TBB_EXPORTED_FUNC internal_condition_variable_wait( condvar_impl_t& cv, mutex* mtx, const tick_count::interval_t* i = NULL );

#else /* if !(_WIN32||_WIN64), i.e., POSIX threads */
typedef pthread_cond_t condvar_impl_t;
#endif

} // namespace internal

//! cv_status
/** C++0x standard working draft 30.5 */
enum cv_status { no_timeout, timeout }; 

//! condition variable
/** C++0x standard working draft 30.5.1 
    @ingroup synchronization */
class condition_variable : tbb::internal::no_copy {
public:
    //! Constructor
    condition_variable() { 
#if _WIN32||_WIN64
        internal_initialize_condition_variable( my_cv ); 
#else
        pthread_cond_init( &my_cv, NULL );
#endif
    }

    //! Destructor
    ~condition_variable() { 
        //precondition: There shall be no thread blocked on *this.
#if _WIN32||_WIN64
        internal_destroy_condition_variable( my_cv );
#else
        pthread_cond_destroy( &my_cv );
#endif
    }

    //! Notify one thread and wake it up
    void notify_one() { 
#if _WIN32||_WIN64
        internal_condition_variable_notify_one( my_cv ); 
#else
        pthread_cond_signal( &my_cv );
#endif
    }

    //! Notify all threads 
    void notify_all() { 
#if _WIN32||_WIN64
        internal_condition_variable_notify_all( my_cv ); 
#else
        pthread_cond_broadcast( &my_cv );
#endif
    }

    //! Release the mutex associated with the lock and wait on this condition variable
    void wait(unique_lock<mutex>& lock);

    //! Wait on this condition variable while pred is false
    template <class Predicate>
    void wait(unique_lock<mutex>& lock, Predicate pred) {
        while( !pred() )
            wait( lock );
    }

    //! Timed version of wait()
    cv_status wait_for(unique_lock<mutex>& lock, const tick_count::interval_t &i );

    //! Timed version of the predicated wait
    /** The loop terminates when pred() returns true or when the time duration specified by rel_time (i) has elapsed. */
    template<typename Predicate>
    bool wait_for(unique_lock<mutex>& lock, const tick_count::interval_t &i, Predicate pred)
    {
        while( !pred() ) {
            cv_status st = wait_for( lock, i );
            if( st==timeout )
                return pred();
        }
        return true;
    }

    // C++0x standard working draft. 30.2.3
    typedef internal::condvar_impl_t* native_handle_type;

    native_handle_type native_handle() { return (native_handle_type) &my_cv; }

private:
    internal::condvar_impl_t my_cv;
};


#if _WIN32||_WIN64
inline void condition_variable::wait( unique_lock<mutex>& lock )
{
    __TBB_ASSERT( lock.owns, NULL );
    lock.owns = false;
    if( !internal_condition_variable_wait( my_cv, lock.mutex() ) ) {
        int ec = GetLastError();
        // on Windows 7, SleepConditionVariableCS() may return ERROR_TIMEOUT while the doc says it returns WAIT_TIMEOUT
        __TBB_ASSERT_EX( ec!=WAIT_TIMEOUT&&ec!=ERROR_TIMEOUT, NULL );
        lock.owns = true;
        throw_exception_v4( tbb::internal::eid_condvar_wait_failed );
    }
    lock.owns = true;
}

inline cv_status condition_variable::wait_for( unique_lock<mutex>& lock, const tick_count::interval_t& i )
{
    cv_status rc = no_timeout;
    __TBB_ASSERT( lock.owns, NULL );
    lock.owns = false;
    // condvar_wait could be SleepConditionVariableCS (or SleepConditionVariableSRW) or our own pre-vista cond_var_wait()
    if( !internal_condition_variable_wait( my_cv, lock.mutex(), &i ) ) {
        int ec = GetLastError();
        if( ec==WAIT_TIMEOUT || ec==ERROR_TIMEOUT )
            rc = timeout;
        else {
            lock.owns = true;
            throw_exception_v4( tbb::internal::eid_condvar_wait_failed );
        }
    }
    lock.owns = true;
    return rc;
}

#else /* !(_WIN32||_WIN64) */
inline void condition_variable::wait( unique_lock<mutex>& lock )
{
    __TBB_ASSERT( lock.owns, NULL );
    lock.owns = false;
    if( pthread_cond_wait( &my_cv, lock.mutex()->native_handle() ) ) {
        lock.owns = true;
        throw_exception_v4( tbb::internal::eid_condvar_wait_failed );
    }
    // upon successful return, the mutex has been locked and is owned by the calling thread.
    lock.owns = true;
}

inline cv_status condition_variable::wait_for( unique_lock<mutex>& lock, const tick_count::interval_t& i )
{
#if __linux__
    struct timespec req;
    double sec = i.seconds();
    clock_gettime( CLOCK_REALTIME, &req );
    req.tv_sec  += static_cast<long>(sec);
    req.tv_nsec += static_cast<long>( (sec - static_cast<long>(sec))*1e9 );
#else /* generic Unix */
    struct timeval tv;
    struct timespec req;
    double sec = i.seconds();
    int status = gettimeofday(&tv, NULL);
    __TBB_ASSERT_EX( status==0, "gettimeofday failed" );
    req.tv_sec  = tv.tv_sec + static_cast<long>(sec);
    req.tv_nsec = tv.tv_usec*1000 + static_cast<long>( (sec - static_cast<long>(sec))*1e9 );
#endif /*(choice of OS) */
    if( req.tv_nsec>=1e9 ) {
        req.tv_sec  += 1;
        req.tv_nsec -= static_cast<long int>(1e9);
    }
    __TBB_ASSERT( 0<=req.tv_nsec && req.tv_nsec<1e9, NULL );

    int ec;
    cv_status rc = no_timeout;
    __TBB_ASSERT( lock.owns, NULL );
    lock.owns = false;
    if( ( ec=pthread_cond_timedwait( &my_cv, lock.mutex()->native_handle(), &req ) ) ) {
        if( ec==ETIMEDOUT )
            rc = timeout;
        else {
            __TBB_ASSERT( lock.try_lock()==false, NULL );
            lock.owns = true;
            throw_exception_v4( tbb::internal::eid_condvar_wait_failed );
        }
    }
    lock.owns = true;
    return rc;
}
#endif /* !(_WIN32||_WIN64) */

} // namespace interface5

__TBB_DEFINE_PROFILING_SET_NAME(interface5::condition_variable)

} // namespace tbb 

#if TBB_IMPLEMENT_CPP0X

namespace std {

using tbb::interface5::defer_lock_t;
using tbb::interface5::try_to_lock_t;
using tbb::interface5::adopt_lock_t;
using tbb::interface5::defer_lock;
using tbb::interface5::try_to_lock;
using tbb::interface5::adopt_lock;
using tbb::interface5::lock_guard;
using tbb::interface5::unique_lock;
using tbb::interface5::swap;   /* this is for void std::swap(unique_lock<M>&,unique_lock<M>&) */
using tbb::interface5::condition_variable;
using tbb::interface5::cv_status;
using tbb::interface5::timeout;
using tbb::interface5::no_timeout;

} // namespace std 

#endif /* TBB_IMPLEMENT_CPP0X */

#endif /* __TBB_condition_variable_H */
