129 lines
2.8 KiB
C
129 lines
2.8 KiB
C
#ifndef LOCK_H
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#define LOCK_H
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/* lock.h - benaphore locking, "faster semaphores", read/write locks
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** sorry for all those macros; I wish C would support C++-style
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** inline functions.
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**
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** Initial version by Axel Dörfler, axeld@pinc-software.de
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**
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** This file may be used under the terms of the OpenBeOS License.
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*/
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#include <SupportDefs.h>
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// for read/write locks
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#define MAX_READERS 100000
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struct benaphore {
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sem_id sem;
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int32 count;
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};
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typedef struct benaphore benaphore;
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// it may make sense to add a status field to the rw_lock to
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// be able to check if the semaphore could be locked
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struct rw_lock {
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sem_id sem;
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int32 count;
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benaphore writeLock;
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};
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typedef struct rw_lock rw_lock;
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#ifndef _KERNEL_MODE
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#define INIT_BENAPHORE(lock,name) \
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{ \
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(lock).count = 1; \
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(lock).sem = create_sem(0, name); \
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}
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#else
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#define INIT_BENAPHORE(lock,name) \
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{ \
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(lock).count = 1; \
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(lock).sem = create_sem(0, name); \
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set_sem_owner((lock).sem, B_SYSTEM_TEAM); \
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}
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#endif
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#define CHECK_BENAPHORE(lock) \
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((lock).sem)
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#define UNINIT_BENAPHORE(lock) \
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delete_sem((lock).sem);
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#define ACQUIRE_BENAPHORE(lock) \
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(atomic_add(&((lock).count), -1) <= 0 ? \
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acquire_sem_etc((lock).sem, 1, B_CAN_INTERRUPT, 0) \
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: B_OK)
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#define RELEASE_BENAPHORE(lock) \
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{ \
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if (atomic_add(&((lock).count), 1) < 0) \
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release_sem((lock).sem); \
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}
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/* read/write lock */
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#ifndef _KERNEL_MODE
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#define INIT_RW_LOCK(lock,name) \
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{ \
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(lock).sem = create_sem(0, name); \
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(lock).count = MAX_READERS; \
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INIT_BENAPHORE((lock).writeLock, "r/w write lock"); \
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}
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#else
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#define INIT_RW_LOCK(lock,name) \
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{ \
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(lock).sem = create_sem(0, name); \
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set_sem_owner((lock).sem, B_SYSTEM_TEAM); \
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(lock).count = MAX_READERS; \
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INIT_BENAPHORE((lock).writeLock, "r/w write lock"); \
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}
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#endif
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#define CHECK_RW_LOCK(lock) \
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((lock).sem)
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#define UNINIT_RW_LOCK(lock) \
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delete_sem((lock).sem); \
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UNINIT_BENAPHORE((lock).writeLock)
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#define ACQUIRE_READ_LOCK(lock) \
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{ \
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if (atomic_add(&(lock).count, -1) <= 0) \
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acquire_sem((lock).sem); \
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}
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#define RELEASE_READ_LOCK(lock) \
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{ \
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if (atomic_add(&(lock).count, 1) < 0) \
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release_sem((lock).sem); \
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}
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#define ACQUIRE_WRITE_LOCK(lock) \
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{ \
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int32 readers; \
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ACQUIRE_BENAPHORE((lock).writeLock); \
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readers = atomic_add(&(lock).count, -MAX_READERS); \
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if (readers < MAX_READERS) \
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acquire_sem_etc((lock).sem,readers <= 0 ? 1 : MAX_READERS - readers,0,0); \
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RELEASE_BENAPHORE((lock).writeLock); \
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}
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#define RELEASE_WRITE_LOCK(lock) \
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{ \
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int32 readers = atomic_add(&(lock).count,MAX_READERS); \
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if (readers < 0) \
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release_sem_etc((lock).sem,readers <= -MAX_READERS ? 1 : -readers,B_CAN_INTERRUPT); \
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}
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#endif /* LOCK_H */
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