source: libcfa/src/concurrency/locks.cfa@ be73f30

#include "locks.hfa"
#include "kernel_private.hfa"
#include <stdlib.h>
#include <stdio.h>

#include <kernel.hfa>
#include <stdlib.hfa>
#include <thread.hfa>

///////////////////////////////////////////////////////////////////
//// info_thread
///////////////////////////////////////////////////////////////////
forall(dtype L | is_blocking_lock(L)) {
        void ?{}( info_thread(L) & this, $thread * t ) {
                this.t = t;
                this.lock = 0p;
        }

        void ?{}( info_thread(L) & this, $thread * t, uintptr_t info ) {
                this.t = t;
                this.info = info;
                this.lock = 0p;
        }

        void ^?{}( info_thread(L) & this ){
                // default
        }

        info_thread(L) *& get_next( info_thread(L) & this ) {
                return this.next;
        }
}
///////////////////////////////////////////////////////////////////
//// Blocking Locks
///////////////////////////////////////////////////////////////////

void ?{}( blocking_lock & this, bool multi_acquisition, bool strict_owner ) {
        this.lock{};
        this.blocked_threads{};
        this.wait_count = 0;
        this.multi_acquisition = multi_acquisition;
        this.strict_owner = strict_owner;
        this.owner = 0p;
        this.recursion_count = 0;
}

void ^?{}( blocking_lock & this ) {
        // default
}

void ?{}( mutex_lock & this ) {
        ((blocking_lock &)this){ false, false };
}

void ^?{}( mutex_lock & this ) {
        // default
}

void ?{}( owner_lock & this ) {
        ((blocking_lock &)this){ true, true };
}

void ^?{}( owner_lock & this ) {
        // default
}

void ?{}( recursive_mutex_lock & this ) {
        ((blocking_lock &)this){ true, false };
}

void ^?{}( recursive_mutex_lock & this ) {
        // default
}

void lock( blocking_lock & this ) with( this ) {
        $thread * thrd = active_thread();
        lock( lock __cfaabi_dbg_ctx2 );
        if ( owner == thrd && !multi_acquisition) {
                fprintf(stderr, "A single acquisition lock holder attempted to reacquire the lock resulting in a deadlock."); // Possibly throw instead
                exit(EXIT_FAILURE);
        } else if ( owner != 0p && owner != thrd ) {
                append( blocked_threads, thrd );
                wait_count++;
                unlock( lock );
                park( __cfaabi_dbg_ctx );
        } else if ( owner == thrd && multi_acquisition ) {
                recursion_count++;
                unlock( lock );
        } else {
                owner = thrd;
                recursion_count = 1;
                unlock( lock );
        }
}

bool try_lock( blocking_lock & this ) with( this ) {
        $thread * thrd = active_thread();
        bool ret = false;
        lock( lock __cfaabi_dbg_ctx2 );
        if ( owner == 0p ) {
                owner = thrd;
                if ( multi_acquisition ) recursion_count = 1;
                ret = true;
        } else if ( owner == thrd && multi_acquisition ) {
                recursion_count++;
                ret = true;
        }
        unlock( lock );
        return ret;
}

void unlock( blocking_lock & this ) with( this ) {
        lock( lock __cfaabi_dbg_ctx2 );
        if ( owner == 0p ){ // no owner implies lock isn't held
                fprintf( stderr, "There was an attempt to release a lock that isn't held" );
                return;
        } else if ( strict_owner && owner != active_thread() ) {
                fprintf( stderr, "A thread other than the owner attempted to release an owner lock" );
                return;
        }
        recursion_count--;
        if ( recursion_count == 0 ) {
                $thread * thrd = pop_head( blocked_threads );
                owner = thrd;
                recursion_count = ( thrd && multi_acquisition ? 1 : 0 );
                wait_count--;
                unpark( thrd __cfaabi_dbg_ctx2 );
        }
        unlock( lock );
}

size_t wait_count( blocking_lock & this ) with( this ) {
        return wait_count;
}


void set_recursion_count( blocking_lock & this, size_t recursion ) with( this ) {
        recursion_count = recursion;
}

size_t get_recursion_count( blocking_lock & this ) with( this ) {
        return recursion_count;
}

void add_( blocking_lock & this, $thread * t ) with( this ) {
    lock( lock __cfaabi_dbg_ctx2 );
        if ( owner != 0p ) {
                append( blocked_threads, t );
                wait_count++;
                unlock( lock );
        } else {
                owner = t;
                if ( multi_acquisition ) recursion_count = 1;
                unpark( t __cfaabi_dbg_ctx2 );
                unlock( lock );
        }
}

void remove_( blocking_lock & this ) with( this ) {
    lock( lock __cfaabi_dbg_ctx2 );
        if ( owner == 0p ){ // no owner implies lock isn't held
                fprintf( stderr, "A lock that is not held was passed to a synchronization lock" );
        } else if ( strict_owner && owner != active_thread() ) {
                fprintf( stderr, "A thread other than the owner of a lock passed it to a synchronization lock" );
        } else {
                $thread * thrd = pop_head( blocked_threads );
                owner = thrd;
                recursion_count = ( thrd && multi_acquisition ? 1 : 0 );
                wait_count--;
                unpark( thrd __cfaabi_dbg_ctx2 );
        }
        unlock( lock );
}

///////////////////////////////////////////////////////////////////
//// Overloaded routines for traits
///////////////////////////////////////////////////////////////////

// In an ideal world this may not be necessary
// Is it possible for nominal inheritance to inherit traits??
// If that occurs we would avoid all this extra code

void lock( mutex_lock & this ){
        lock( (blocking_lock &)this );
}

void unlock( mutex_lock & this ){
        unlock( (blocking_lock &)this );
}

void add_( mutex_lock & this, struct $thread * t ){
        add_( (blocking_lock &)this, t );
}

void remove_( mutex_lock & this ){
        remove_( (blocking_lock &)this );
}

void set_recursion_count( mutex_lock & this, size_t recursion ){
        set_recursion_count( (blocking_lock &)this, recursion );
}

size_t get_recursion_count( mutex_lock & this ){
        get_recursion_count( (blocking_lock &)this );
}

void lock( recursive_mutex_lock & this ){
        lock( (blocking_lock &)this );
}

void unlock( recursive_mutex_lock & this ){
        unlock( (blocking_lock &)this );
}

void add_( recursive_mutex_lock & this, struct $thread * t ){
        add_( (blocking_lock &)this, t );
}

void remove_( recursive_mutex_lock & this ){
        remove_( (blocking_lock &)this );
}

void set_recursion_count( recursive_mutex_lock & this, size_t recursion ){
        set_recursion_count( (blocking_lock &)this, recursion );
}

size_t get_recursion_count( recursive_mutex_lock & this ){
        get_recursion_count( (blocking_lock &)this );
}

///////////////////////////////////////////////////////////////////
//// Synchronization Locks
///////////////////////////////////////////////////////////////////

forall(dtype L | is_blocking_lock(L)) {
        void ?{}( synchronization_lock(L) & this, bool reacquire_after_signal ){
                this.lock{};
                this.blocked_threads{};
                this.count = 0;
                this.reacquire_after_signal = reacquire_after_signal;
        }

        void ^?{}( synchronization_lock(L) & this ){
                // default
        }

        void ?{}( condition_variable(L) & this ){
                ((synchronization_lock(L) &)this){ true };
        }

        void ^?{}( condition_variable(L) & this ){
                // default
        }

        void ?{}( thread_queue(L) & this ){
                ((synchronization_lock(L) &)this){ false };
        }

        void ^?{}( thread_queue(L) & this ){
                // default
        }

        bool notify_one( synchronization_lock(L) & this ) with( this ) {
                lock( lock __cfaabi_dbg_ctx2 );
                bool ret = !!blocked_threads;
                info_thread(L) * popped = pop_head( blocked_threads );
                if(popped != 0p) {
                        if( reacquire_after_signal ){
                                add_(*popped->lock, popped->t);
                        } else {
                                unpark(
                                        popped->t __cfaabi_dbg_ctx2
                                );
                        }
                }
                unlock( lock );
                return ret;
        }

        bool notify_all( synchronization_lock(L) & this ) with(this) {
                lock( lock __cfaabi_dbg_ctx2 );
                bool ret = blocked_threads ? true : false;
                while( blocked_threads ) {
                        info_thread(L) * popped = pop_head( blocked_threads );
                        if(popped != 0p){
                                if( reacquire_after_signal ){
                                        add_(*popped->lock, popped->t);
                                } else {
                                        unpark(
                                                popped->t __cfaabi_dbg_ctx2
                                        );
                                }
                        }
                }
                unlock( lock );
                return ret;
        }

        uintptr_t front( synchronization_lock(L) & this ) with(this) {
                return (*peek(blocked_threads)).info;
        }

        bool empty( synchronization_lock(L) & this ) with(this) {
                return blocked_threads ? false : true;
        }

        int counter( synchronization_lock(L) & this ) with(this) {
                return count;
        }

        void queue_info_thread( synchronization_lock(L) & this, info_thread(L) & i ) with(this) {
                lock( lock __cfaabi_dbg_ctx2 );
                append( blocked_threads, &i );
                count++;
                unlock( lock );
                park( __cfaabi_dbg_ctx );
        }


        void wait( synchronization_lock(L) & this ) with(this) {
                info_thread( L ) i = { active_thread() };
                queue_info_thread( this, i );
        }

        void wait( synchronization_lock(L) & this, uintptr_t info ) with(this) {
                info_thread( L ) i = { active_thread(), info };
                queue_info_thread( this, i );
        }
        // I still need to implement the time delay wait routines
        bool wait( synchronization_lock(L) & this, Duration duration ) with(this) {
                timeval tv = { time(0) };
                Time t = { tv };
                return wait( this, t + duration );
        }

        bool wait( synchronization_lock(L) & this, uintptr_t info, Duration duration ) with(this) {
                // TODO: ADD INFO
                return wait( this, duration );
        }

        bool wait( synchronization_lock(L) & this, Time time ) with(this) {
                return false; //default
        }

        bool wait( synchronization_lock(L) & this, uintptr_t info, Time time ) with(this) {
                // TODO: ADD INFO
                return wait( this, time );
        }

        void queue_info_thread_unlock( synchronization_lock(L) & this, L & l, info_thread(L) & i ) with(this) {
                lock( lock __cfaabi_dbg_ctx2 );
                append( this.blocked_threads, &i );
                count++;
                i.lock = &l;
                size_t recursion_count = get_recursion_count(l);
                remove_( l );
                unlock( lock );
                park( __cfaabi_dbg_ctx ); // blocks here

                set_recursion_count(l, recursion_count); // resets recursion count here after waking
        }

        void wait( synchronization_lock(L) & this, L & l ) with(this) {
                info_thread(L) i = { active_thread() };
                queue_info_thread_unlock( this, l, i );
        }

        void wait( synchronization_lock(L) & this, L & l, uintptr_t info ) with(this) {
                info_thread(L) i = { active_thread(), info };
                queue_info_thread_unlock( this, l, i );
        }

        bool wait( synchronization_lock(L) & this, L & l, Duration duration ) with(this) {
                timeval tv = { time(0) };
                Time t = { tv };
                return wait( this, l, t + duration );
        }

        bool wait( synchronization_lock(L) & this, L & l, uintptr_t info, Duration duration ) with(this) {
                // TODO: ADD INFO
                return wait( this, l, duration );
        }

        bool wait( synchronization_lock(L) & this, L & l, Time time ) with(this) {
                return false; //default
        }

        bool wait( synchronization_lock(L) & this, L & l, uintptr_t info, Time time ) with(this) {
                // TODO: ADD INFO
                return wait( this, l, time );
        }
}

///////////////////////////////////////////////////////////////////
//// condition lock alternative approach
///////////////////////////////////////////////////////////////////

// the solution below is less efficient but does not require the lock to have a specific add/remove routine

///////////////////////////////////////////////////////////////////
//// is_simple_lock
///////////////////////////////////////////////////////////////////

forall(dtype L | is_simple_lock(L)) {
        void ?{}( condition_lock(L) & this ){
                // default
        }

        void ^?{}( condition_lock(L) & this ){
                // default
        }

        bool notify_one( condition_lock(L) & this ) with(this) {
                return notify_one( c_var );
        }

        bool notify_all( condition_lock(L) & this ) with(this) {
                return notify_all( c_var );
        }

        void wait( condition_lock(L) & this, L & l ) with(this) {
                lock( m_lock );
                size_t recursion = get_recursion_count( l );
                unlock( l );
                wait( c_var, m_lock );
                lock( l );
                set_recursion_count( l , recursion );
                unlock( m_lock );
        }
}