1 /****************************************************************************** 2 * 3 * Copyright (C) 2014 Google, Inc. 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at: 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 ******************************************************************************/ 18 19 #ifndef __FUTURE_H__ 20 #define __FUTURE_H__ 21 22 #include "osi/semaphore.h" 23 24 struct future { 25 bool ready_can_be_called; 26 osi_sem_t semaphore; // NULL semaphore means immediate future 27 void *result; 28 }; 29 typedef struct future future_t; 30 31 #define FUTURE_SUCCESS ((void *)1) 32 #define FUTURE_FAIL ((void *)0) 33 34 // Constructs a new future_t object. Returns NULL on failure. 35 future_t *future_new(void); 36 37 // Constructs a new future_t object with an immediate |value|. No waiting will 38 // occur in the call to |future_await| because the value is already present. 39 // Returns NULL on failure. 40 future_t *future_new_immediate(void *value); 41 42 // Signals that the |future| is ready, passing |value| back to the context 43 // waiting for the result. Must only be called once for every future. 44 // |future| may not be NULL. 45 void future_ready(future_t *future, void *value); 46 47 // Waits for the |future| to be ready. Returns the value set in |future_ready|. 48 // Frees the future before return. |future| may not be NULL. 49 void *future_await(future_t *async_result); 50 51 //Free the future if this "future" is not used 52 void future_free(future_t *future); 53 #endif /* __FUTURE_H__ */ 54
