Changes in src/libcfa/concurrency/monitor.c [cb0e6de:5ea06d6]

File:

• src/libcfa/concurrency/monitor.c (modified) (2 diffs)

src/libcfa/concurrency/monitor.c

@@ -18 +18 @@
 
 #include "kernel_private.h"
+#include "libhdr.h"
+
+void set_owner( monitor_desc * this, thread_desc * owner ) {
+        //Pass the monitor appropriately
+        this->owner = owner;
+
+        //We are passing the monitor to someone else, which means recursion level is not 0
+        this->recursion = owner ? 1 : 0;
+}
 
 extern "C" {
-        void __enter_monitor_desc(monitor_desc * this) {
+        void __enter_monitor_desc(monitor_desc * this, monitor_desc * leader) {
                 lock( &this->lock );
                 thread_desc * thrd = this_thread();
+
+                //Update the stack owner
+                this->stack_owner = leader;
 
                 if( !this->owner ) {
@@ -44 +56 @@
 
                 unlock( &this->lock );
-        }
-
-        void __leave_monitor_desc(monitor_desc * this) {
+                return;
+        }
+
+        // leave pseudo code :
+        //      decrement level
+        //      leve == 0 ?
+        //              no : done
+        //              yes :
+        //                      signal stack empty ?
+        //                              has leader :
+        //                                      bulk acquiring means we don't own the signal stack
+        //                                      ignore it but don't release the monitor
+        //                              yes :
+        //                                      next in entry queue is new owner
+        //                              no :
+        //                                      top of the signal stack is the owner
+        //                                      context switch to him right away
+        //
+        void __leave_monitor_desc(monitor_desc * this, monitor_desc * leader) {
                 lock( &this->lock );
 
                 thread_desc * thrd = this_thread();
-                assert( thrd == this->owner );
+                assert( thrd == this->owner || this->stack_owner );
 
                 //Leaving a recursion level, decrement the counter
                 this->recursion -= 1;
 
-                //If we left the last level of recursion it means we are changing who owns the monitor
+                //If we haven't left the last level of recursion
+                //it means we don't need to do anything
+                if( this->recursion != 0) {
+                        this->stack_owner = leader;
+                        unlock( &this->lock );
+                        return;
+                }
+                        
+                //If we don't own the signal stack then just leave it to the owner
+                if( this->stack_owner ) {
+                        this->stack_owner = leader;
+                        unlock( &this->lock );
+                        return;
+                }
+
+                //We are the stack owner and have left the last recursion level.
+                //We are in charge of passing the monitor
                 thread_desc * new_owner = 0;
-                if( this->recursion == 0) {
-                        //Get the next thread in the list
-                        new_owner = this->owner = pop_head( &this->entry_queue );
-
-                        //We are passing the monitor to someone else, which means recursion level is not 0
-                        this->recursion = new_owner ? 1 : 0;
-                }       
-
+
+                //Check the signaller stack
+                new_owner = pop( &this->signal_stack );
+                if( new_owner ) {
+                        //The signaller stack is not empty,
+                        //transfer control immediately
+                        set_owner( this, new_owner );
+                        this->stack_owner = leader;
+                        ScheduleInternal( &this->lock, new_owner );
+                        return;
+                }
+                
+                // No signaller thread
+                // Get the next thread in the entry_queue
+                new_owner = pop_head( &this->entry_queue );
+                set_owner( this, new_owner );
+
+                //Update the stack owner
+                this->stack_owner = leader;
+
+                //We can now let other threads in safely
                 unlock( &this->lock );
 
-                //If we have a new owner, we need to wake-up the thread
-                if( new_owner ) {
-                        ScheduleThread( new_owner );
-                }
-        }
-}
-
-void enter(monitor_desc ** monitors, int count) {
-        for(int i = 0; i < count; i++) {
-                __enter_monitor_desc( monitors[i] );
-        }
-}
-
-void leave(monitor_desc ** monitors, int count) {
+                //We need to wake-up the thread
+                ScheduleThread( new_owner );
+        }
+}
+
+static inline void enter(monitor_desc ** monitors, int count) {
+        __enter_monitor_desc( monitors[0], NULL );
+        for(int i = 1; i < count; i++) {
+                __enter_monitor_desc( monitors[i], monitors[0] );
+        }
+}
+
+static inline void leave(monitor_desc ** monitors, int count) {
+        __leave_monitor_desc( monitors[0], NULL );
         for(int i = count - 1; i >= 0; i--) {
-                __leave_monitor_desc( monitors[i] );
-        }
-}
+                __leave_monitor_desc( monitors[i], monitors[0] );
+        }
+}
+
+void ?{}( monitor_guard_t * this, monitor_desc ** m, int count ) {
+        this->m = m;
+        this->count = count;
+        qsort(this->m, count);
+        enter( this->m, this->count );
+
+        this->prev_mntrs = this_thread()->current_monitors;
+        this->prev_count = this_thread()->current_monitor_count;
+
+        this_thread()->current_monitors      = m;
+        this_thread()->current_monitor_count = count;
+}
+
+void ^?{}( monitor_guard_t * this ) {
+        leave( this->m, this->count );
+
+        this_thread()->current_monitors      = this->prev_mntrs;
+        this_thread()->current_monitor_count = this->prev_count;
+}
+
+//-----------------------------------------------------------------------------
+// Internal scheduling
+void wait( condition * this ) {
+        // LIB_DEBUG_FPRINTF("Waiting\n");
+        thread_desc * this_thrd = this_thread();
+
+        if( !this->monitors ) {
+                this->monitors = this_thrd->current_monitors;
+                this->monitor_count = this_thrd->current_monitor_count;
+        }
+
+        unsigned short count = this->monitor_count;
+
+        //Check that everything is as expected
+        assert( this->monitors != NULL );
+        assert( this->monitor_count != 0 );
+
+        unsigned int recursions[ count ];               //Save the current recursion levels to restore them later
+        spinlock *   locks     [ count ];               //We need to pass-in an array of locks to ScheduleInternal
+
+        // LIB_DEBUG_FPRINTF("Getting ready to wait\n");
+
+        //Loop on all the monitors and release the owner
+        for( unsigned int i = 0; i < count; i++ ) {
+                monitor_desc * cur = this->monitors[i];
+
+                assert( cur );
+
+                // LIB_DEBUG_FPRINTF("cur %p lock %p\n", cur, &cur->lock);
+
+                //Store the locks for later
+                locks[i] = &cur->lock;
+
+                //Protect the monitors
+                lock( locks[i] );
+                {               
+                        //Save the recursion levels
+                        recursions[i] = cur->recursion;
+
+                        //Release the owner
+                        cur->recursion = 0;
+                        cur->owner = NULL;
+                }
+                //Release the monitor
+                unlock( locks[i] );
+        }
+
+        // LIB_DEBUG_FPRINTF("Waiting now\n");
+
+        //Everything is ready to go to sleep
+        ScheduleInternal( locks, count );
+
+
+        //WE WOKE UP
+
+
+        //We are back, restore the owners and recursions
+        for( unsigned int i = 0; i < count; i++ ) {
+                monitor_desc * cur = this->monitors[i];
+
+                //Protect the monitors
+                lock( locks[i] );
+                {
+                        //Release the owner
+                        cur->owner = this_thrd;
+                        cur->recursion = recursions[i];
+                }
+                //Release the monitor
+                unlock( locks[i] );
+        }
+}
+
+static void __signal_internal( condition * this ) {
+        if( !this->blocked.head ) return;
+
+        //Check that everything is as expected
+        assert( this->monitors );
+        assert( this->monitor_count != 0 );
+        
+        LIB_DEBUG_DO(
+                if ( this->monitors != this_thread()->current_monitors ) {
+                        abortf( "Signal on condition %p made outside of the correct monitor(s)", this );
+                } // if
+        );
+
+        monitor_desc * owner = this->monitors[0];
+        lock( &owner->lock );
+        {
+                thread_desc * unblock = pop_head( &this->blocked );
+                push( &owner->signal_stack, unblock );
+        }
+        unlock( &owner->lock );
+}
+
+void signal( condition * this ) {
+        __signal_internal( this );
+}