//
// Cforall Version 1.0.0 Copyright (C) 2020 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// io/types.hfa --
//
// Author           : Thierry Delisle & Peiran Hong
// Created On       : Wed Jan 06 17:33:18 2021
// Last Modified By :
// Last Modified On :
// Update Count     :
//

#pragma once

#include "bits/locks.hfa"
#include "monitor.hfa"

forall( T ) {
	struct future {
		inline future_t;
		T result;
	};

	static inline {
		// Reset future back to original state
		void reset(future(T) & this) { reset( (future_t&)this ); }

		// check if the future is available
		bool available( future(T) & this ) { return available( (future_t&)this ); }

		// Mark the future as abandoned, meaning it will be deleted by the server
		// This doesn't work beause of the potential need for a destructor
		void abandon( future(T) & this );

		// Fulfil the future, returns whether or not someone was unblocked
		thread$ * fulfil( future(T) & this, T result ) {
			this.result = result;
			return fulfil( (future_t&)this );
		}

		// Wait for the future to be fulfilled
		// Also return whether the thread had to block or not
		[T, bool] wait( future(T) & this ) {
			bool r = wait( (future_t&)this );
			return [this.result, r];
		}

		// Wait for the future to be fulfilled
		T wait( future(T) & this ) {
			[T, bool] tt;
			tt = wait(this);
			return tt.0;
		}
	}
}

forall( T ) {
	monitor multi_future {
		inline future_t;
		condition blocked;
		bool has_first;
		T result;
	};

	static inline {
		void ?{}(multi_future(T) & this) {
			this.has_first = false;
		}

		bool $first( multi_future(T) & mutex this ) {
			if (this.has_first) {
				wait( this.blocked );
				return false;
			}

			this.has_first = true;
			return true;
		}

		void $first_done( multi_future(T) & mutex this ) {
			this.has_first = false;
			signal_all( this.blocked );
		}

		// Reset future back to original state
		void reset(multi_future(T) & mutex this) {
			if( this.has_first != false) abort("Attempting to reset a multi_future with at least one blocked threads");
			if( !is_empty(this.blocked) ) abort("Attempting to reset a multi_future with multiple blocked threads");
			reset( (future_t&)this );
		}

		// Fulfil the future, returns whether or not someone was unblocked
		bool fulfil( multi_future(T) & this, T result ) {
			this.result = result;
			return fulfil( (future_t&)this ) != 0p;
		}

		// Wait for the future to be fulfilled
		// Also return whether the thread had to block or not
		[T, bool] wait( multi_future(T) & this ) {
			bool sw = $first( this );
			bool w = !sw;
			if ( sw ) {
				w = wait( (future_t&)this );
				$first_done( this );
			}

			return [this.result, w];
		}

		// Wait for the future to be fulfilled
		T wait( multi_future(T) & this ) {
			return wait(this).0;
		}
	}
}