commit 78bc44268e10aa4fd34f7ba111a994c1030d522e parent 763976b3b92514daff5c99d489d79cdf04df778f Author: oblique <psyberbits@gmail.com> Date: Tue, 9 Apr 2013 09:23:10 +0300 rwlock.h: rephrase some comments Diffstat:
| M | include/rwlock.h | | | 26 | +++++++++++++------------- |
1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/include/rwlock.h b/include/rwlock.h @@ -4,16 +4,16 @@ #include <inttypes.h> #include <semaphore.h> -/* readers-writer lock - * implemented with 'Passing the Baton' technique +/* Readers-Writer lock + * Implemented with 'Passing the Baton' locking technique. * - * rules: - * 1) if we have an awakened writer or writers in the queue then - * a new reader will be added in readers' queue. - * 2) if all awakened readers are done then we awake a writer, - * even if we have readers in the queue. - * 3) if the awakened writer and all writers in the queue are done - * then we awake all the readers. */ + * Priority rules: + * 1) if we have an awakened writer or writers in the waiting queue + * then a new reader will be added in readers' waiting queue. + * 2) if all awakened readers are released then we awake a writer, + * even if readers are waiting in the queue. + * 3) if the awakened writer and all writers in the waiting queue are + * released then we awake all the readers. */ typedef struct { mutex_t lock; mutex_t writer_wait; @@ -127,20 +127,20 @@ rwlock_unlock(rwlock_t *rwl) { mutex_lock(&rwl->lock); - /* a reader is done */ + /* release reader */ if (rwl->nr_readers > 0) { rwl->nr_readers--; - /* a writer is done */ + /* release writer */ } else if (rwl->nr_writers > 0) { rwl->nr_writers--; } - /* if all awakened readers are done and we have writers in the queue + /* if all awakened readers are released and we have writers in the queue * then awake a writer */ if (rwl->nr_readers == 0 && rwl->nr_writers_queue > 0) { rwl->nr_writers_queue--; mutex_unlock(&rwl->writer_wait); - /* if the awakened writer and all writers from the queue are done + /* if the awakened writer and all writers from the queue are released * then awake a reader */ } else if (rwl->nr_writers == 0 && rwl->nr_writers_queue == 0 && rwl->nr_readers_queue > 0) {