diff options
Diffstat (limited to 'nss/lib/util/nssrwlk.c')
| -rw-r--r-- | nss/lib/util/nssrwlk.c | 165 |
1 files changed, 83 insertions, 82 deletions
diff --git a/nss/lib/util/nssrwlk.c b/nss/lib/util/nssrwlk.c index fbbfbd6..dbaeca2 100644 --- a/nss/lib/util/nssrwlk.c +++ b/nss/lib/util/nssrwlk.c @@ -11,18 +11,18 @@ PR_BEGIN_EXTERN_C * Reader-writer lock */ struct nssRWLockStr { - PZLock * rw_lock; - char * rw_name; /* lock name */ - PRUint32 rw_rank; /* rank of the lock */ - PRInt32 rw_writer_locks; /* == 0, if unlocked */ - PRInt32 rw_reader_locks; /* == 0, if unlocked */ - /* > 0 , # of read locks */ - PRUint32 rw_waiting_readers; /* number of waiting readers */ - PRUint32 rw_waiting_writers; /* number of waiting writers */ - PZCondVar * rw_reader_waitq; /* cvar for readers */ - PZCondVar * rw_writer_waitq; /* cvar for writers */ - PRThread * rw_owner; /* lock owner for write-lock */ - /* Non-null if write lock held. */ + PZLock *rw_lock; + char *rw_name; /* lock name */ + PRUint32 rw_rank; /* rank of the lock */ + PRInt32 rw_writer_locks; /* == 0, if unlocked */ + PRInt32 rw_reader_locks; /* == 0, if unlocked */ + /* > 0 , # of read locks */ + PRUint32 rw_waiting_readers; /* number of waiting readers */ + PRUint32 rw_waiting_writers; /* number of waiting writers */ + PZCondVar *rw_reader_waitq; /* cvar for readers */ + PZCondVar *rw_writer_waitq; /* cvar for writers */ + PRThread *rw_owner; /* lock owner for write-lock */ + /* Non-null if write lock held. */ }; PR_END_EXTERN_C @@ -30,34 +30,34 @@ PR_END_EXTERN_C #include <string.h> #ifdef DEBUG_RANK_ORDER -#define NSS_RWLOCK_RANK_ORDER_DEBUG /* enable deadlock detection using - rank-order for locks +#define NSS_RWLOCK_RANK_ORDER_DEBUG /* enable deadlock detection using \ + rank-order for locks \ */ #endif #ifdef NSS_RWLOCK_RANK_ORDER_DEBUG -static PRUintn nss_thread_rwlock_initialized; -static PRUintn nss_thread_rwlock; /* TPD key for lock stack */ -static PRUintn nss_thread_rwlock_alloc_failed; +static PRUintn nss_thread_rwlock_initialized; +static PRUintn nss_thread_rwlock; /* TPD key for lock stack */ +static PRUintn nss_thread_rwlock_alloc_failed; #define _NSS_RWLOCK_RANK_ORDER_LIMIT 10 typedef struct thread_rwlock_stack { - PRInt32 trs_index; /* top of stack */ - NSSRWLock *trs_stack[_NSS_RWLOCK_RANK_ORDER_LIMIT]; /* stack of lock + PRInt32 trs_index; /* top of stack */ + NSSRWLock *trs_stack[_NSS_RWLOCK_RANK_ORDER_LIMIT]; /* stack of lock pointers */ } thread_rwlock_stack; /* forward static declarations. */ static PRUint32 nssRWLock_GetThreadRank(PRThread *me); -static void nssRWLock_SetThreadRank(PRThread *me, NSSRWLock *rwlock); -static void nssRWLock_UnsetThreadRank(PRThread *me, NSSRWLock *rwlock); -static void nssRWLock_ReleaseLockStack(void *lock_stack); +static void nssRWLock_SetThreadRank(PRThread *me, NSSRWLock *rwlock); +static void nssRWLock_UnsetThreadRank(PRThread *me, NSSRWLock *rwlock); +static void nssRWLock_ReleaseLockStack(void *lock_stack); #endif -#define UNTIL(x) while(!(x)) +#define UNTIL(x) while (!(x)) /* * Reader/Writer Locks @@ -80,36 +80,36 @@ NSSRWLock_New(PRUint32 lock_rank, const char *lock_name) rwlock->rw_lock = PZ_NewLock(nssILockRWLock); if (rwlock->rw_lock == NULL) { - goto loser; + goto loser; } rwlock->rw_reader_waitq = PZ_NewCondVar(rwlock->rw_lock); if (rwlock->rw_reader_waitq == NULL) { - goto loser; + goto loser; } rwlock->rw_writer_waitq = PZ_NewCondVar(rwlock->rw_lock); if (rwlock->rw_writer_waitq == NULL) { - goto loser; + goto loser; } if (lock_name != NULL) { - rwlock->rw_name = (char*) PR_Malloc((PRUint32)strlen(lock_name) + 1); + rwlock->rw_name = (char *)PR_Malloc((PRUint32)strlen(lock_name) + 1); if (rwlock->rw_name == NULL) { - goto loser; + goto loser; } strcpy(rwlock->rw_name, lock_name); } else { rwlock->rw_name = NULL; } - rwlock->rw_rank = lock_rank; + rwlock->rw_rank = lock_rank; rwlock->rw_waiting_readers = 0; rwlock->rw_waiting_writers = 0; - rwlock->rw_reader_locks = 0; - rwlock->rw_writer_locks = 0; + rwlock->rw_reader_locks = 0; + rwlock->rw_writer_locks = 0; return rwlock; loser: NSSRWLock_Destroy(rwlock); - return(NULL); + return (NULL); } /* @@ -124,13 +124,13 @@ NSSRWLock_Destroy(NSSRWLock *rwlock) /* XXX Shouldn't we lock the PZLock before destroying this?? */ if (rwlock->rw_name) - PR_Free(rwlock->rw_name); + PR_Free(rwlock->rw_name); if (rwlock->rw_reader_waitq) - PZ_DestroyCondVar(rwlock->rw_reader_waitq); + PZ_DestroyCondVar(rwlock->rw_reader_waitq); if (rwlock->rw_writer_waitq) - PZ_DestroyCondVar(rwlock->rw_writer_waitq); + PZ_DestroyCondVar(rwlock->rw_writer_waitq); if (rwlock->rw_lock) - PZ_DestroyLock(rwlock->rw_lock); + PZ_DestroyLock(rwlock->rw_lock); PR_DELETE(rwlock); } @@ -156,20 +156,21 @@ NSSRWLock_LockRead(NSSRWLock *rwlock) /* * wait if write-locked or if a writer is waiting; preference for writers */ - UNTIL ( (rwlock->rw_owner == me) || /* I own it, or */ - ((rwlock->rw_owner == NULL) && /* no-one owns it, and */ - (rwlock->rw_waiting_writers == 0))) { /* no-one is waiting to own */ - - rwlock->rw_waiting_readers++; - PZ_WaitCondVar(rwlock->rw_reader_waitq, PR_INTERVAL_NO_TIMEOUT); - rwlock->rw_waiting_readers--; + UNTIL((rwlock->rw_owner == me) || /* I own it, or */ + ((rwlock->rw_owner == NULL) && /* no-one owns it, and */ + (rwlock->rw_waiting_writers == 0))) + { /* no-one is waiting to own */ + + rwlock->rw_waiting_readers++; + PZ_WaitCondVar(rwlock->rw_reader_waitq, PR_INTERVAL_NO_TIMEOUT); + rwlock->rw_waiting_readers--; } - rwlock->rw_reader_locks++; /* Increment read-lock count */ + rwlock->rw_reader_locks++; /* Increment read-lock count */ PZ_Unlock(rwlock->rw_lock); #ifdef NSS_RWLOCK_RANK_ORDER_DEBUG - nssRWLock_SetThreadRank(me, rwlock);/* update thread's lock rank */ + nssRWLock_SetThreadRank(me, rwlock); /* update thread's lock rank */ #endif } @@ -182,12 +183,12 @@ NSSRWLock_UnlockRead(NSSRWLock *rwlock) PR_ASSERT(rwlock->rw_reader_locks > 0); /* lock must be read locked */ - if (( rwlock->rw_reader_locks > 0) && /* caller isn't screwey */ - (--rwlock->rw_reader_locks == 0) && /* not read locked any more */ - ( rwlock->rw_owner == NULL) && /* not write locked */ - ( rwlock->rw_waiting_writers > 0)) { /* someone's waiting. */ + if ((rwlock->rw_reader_locks > 0) && /* caller isn't screwey */ + (--rwlock->rw_reader_locks == 0) && /* not read locked any more */ + (rwlock->rw_owner == NULL) && /* not write locked */ + (rwlock->rw_waiting_writers > 0)) { /* someone's waiting. */ - PZ_NotifyCondVar(rwlock->rw_writer_waitq); /* wake him up. */ + PZ_NotifyCondVar(rwlock->rw_writer_waitq); /* wake him up. */ } PZ_Unlock(rwlock->rw_lock); @@ -217,7 +218,7 @@ NSSRWLock_LockWrite(NSSRWLock *rwlock) * the thread. */ PR_ASSERT((rwlock->rw_rank == NSS_RWLOCK_RANK_NONE) || - (rwlock->rw_rank >= nssRWLock_GetThreadRank(me))); + (rwlock->rw_rank >= nssRWLock_GetThreadRank(me))); #endif /* * wait if read locked or write locked. @@ -225,14 +226,15 @@ NSSRWLock_LockWrite(NSSRWLock *rwlock) PR_ASSERT(rwlock->rw_reader_locks >= 0); PR_ASSERT(me != NULL); - UNTIL ( (rwlock->rw_owner == me) || /* I own write lock, or */ - ((rwlock->rw_owner == NULL) && /* no writer and */ - (rwlock->rw_reader_locks == 0))) { /* no readers, either. */ + UNTIL((rwlock->rw_owner == me) || /* I own write lock, or */ + ((rwlock->rw_owner == NULL) && /* no writer and */ + (rwlock->rw_reader_locks == 0))) + { /* no readers, either. */ rwlock->rw_waiting_writers++; PZ_WaitCondVar(rwlock->rw_writer_waitq, PR_INTERVAL_NO_TIMEOUT); rwlock->rw_waiting_writers--; - PR_ASSERT(rwlock->rw_reader_locks >= 0); + PR_ASSERT(rwlock->rw_reader_locks >= 0); } PR_ASSERT(rwlock->rw_reader_locks == 0); @@ -240,7 +242,7 @@ NSSRWLock_LockWrite(NSSRWLock *rwlock) * apply write lock */ rwlock->rw_owner = me; - rwlock->rw_writer_locks++; /* Increment write-lock count */ + rwlock->rw_writer_locks++; /* Increment write-lock count */ PZ_Unlock(rwlock->rw_lock); @@ -248,7 +250,7 @@ NSSRWLock_LockWrite(NSSRWLock *rwlock) /* * update thread's lock rank */ - nssRWLock_SetThreadRank(me,rwlock); + nssRWLock_SetThreadRank(me, rwlock); #endif } @@ -260,22 +262,22 @@ NSSRWLock_UnlockWrite(NSSRWLock *rwlock) PRThread *me = PR_GetCurrentThread(); PZ_Lock(rwlock->rw_lock); - PR_ASSERT(rwlock->rw_owner == me); /* lock must be write-locked by me. */ + PR_ASSERT(rwlock->rw_owner == me); /* lock must be write-locked by me. */ PR_ASSERT(rwlock->rw_writer_locks > 0); /* lock must be write locked */ - if ( rwlock->rw_owner == me && /* I own it, and */ - rwlock->rw_writer_locks > 0 && /* I own it, and */ - --rwlock->rw_writer_locks == 0) { /* I'm all done with it */ + if (rwlock->rw_owner == me && /* I own it, and */ + rwlock->rw_writer_locks > 0 && /* I own it, and */ + --rwlock->rw_writer_locks == 0) { /* I'm all done with it */ - rwlock->rw_owner = NULL; /* I don't own it any more. */ + rwlock->rw_owner = NULL; /* I don't own it any more. */ - /* Give preference to waiting writers. */ - if (rwlock->rw_waiting_writers > 0) { - if (rwlock->rw_reader_locks == 0) - PZ_NotifyCondVar(rwlock->rw_writer_waitq); - } else if (rwlock->rw_waiting_readers > 0) { - PZ_NotifyAllCondVar(rwlock->rw_reader_waitq); - } + /* Give preference to waiting writers. */ + if (rwlock->rw_waiting_writers > 0) { + if (rwlock->rw_reader_locks == 0) + PZ_NotifyCondVar(rwlock->rw_writer_waitq); + } else if (rwlock->rw_waiting_readers > 0) { + PZ_NotifyAllCondVar(rwlock->rw_reader_waitq); + } } PZ_Unlock(rwlock->rw_lock); @@ -290,18 +292,19 @@ NSSRWLock_UnlockWrite(NSSRWLock *rwlock) /* This is primarily for debugging, i.e. for inclusion in ASSERT calls. */ PRBool -NSSRWLock_HaveWriteLock(NSSRWLock *rwlock) { +NSSRWLock_HaveWriteLock(NSSRWLock *rwlock) +{ PRBool ownWriteLock; PRThread *me = PR_GetCurrentThread(); - /* This lock call isn't really necessary. +/* This lock call isn't really necessary. ** If this thread is the owner, that fact cannot change during this call, ** because this thread is in this call. - ** If this thread is NOT the owner, the owner could change, but it - ** could not become this thread. + ** If this thread is NOT the owner, the owner could change, but it + ** could not become this thread. */ #if UNNECESSARY - PZ_Lock(rwlock->rw_lock); + PZ_Lock(rwlock->rw_lock); #endif ownWriteLock = (PRBool)(me == rwlock->rw_owner); #if UNNECESSARY @@ -334,8 +337,7 @@ nssRWLock_SetThreadRank(PRThread *me, NSSRWLock *rwlock) */ if (!nss_thread_rwlock_alloc_failed) { if (PR_NewThreadPrivateIndex(&nss_thread_rwlock, - nssRWLock_ReleaseLockStack) - == PR_FAILURE) { + nssRWLock_ReleaseLockStack) == PR_FAILURE) { nss_thread_rwlock_alloc_failed = 1; return; } @@ -347,7 +349,7 @@ nssRWLock_SetThreadRank(PRThread *me, NSSRWLock *rwlock) */ if ((lock_stack = PR_GetThreadPrivate(nss_thread_rwlock)) == NULL) { lock_stack = (thread_rwlock_stack *) - PR_CALLOC(1 * sizeof(thread_rwlock_stack)); + PR_CALLOC(1 * sizeof(thread_rwlock_stack)); if (lock_stack) { rv = PR_SetThreadPrivate(nss_thread_rwlock, lock_stack); if (rv == PR_FAILURE) { @@ -393,10 +395,10 @@ nssRWLock_GetThreadRank(PRThread *me) if ((lock_stack = PR_GetThreadPrivate(nss_thread_rwlock)) == NULL) return (NSS_RWLOCK_RANK_NONE); else - return(lock_stack->trs_stack[lock_stack->trs_index - 1]->rw_rank); + return (lock_stack->trs_stack[lock_stack->trs_index - 1]->rw_rank); } else - return (NSS_RWLOCK_RANK_NONE); + return (NSS_RWLOCK_RANK_NONE); } /* @@ -421,7 +423,7 @@ nssRWLock_UnsetThreadRank(PRThread *me, NSSRWLock *rwlock) index = lock_stack->trs_index - 1; while (index-- >= 0) { - if ((lock_stack->trs_stack[index] == rwlock) && !done) { + if ((lock_stack->trs_stack[index] == rwlock) && !done) { /* * reset the slot for rwlock */ @@ -441,7 +443,6 @@ nssRWLock_UnsetThreadRank(PRThread *me, NSSRWLock *rwlock) * set top of stack to highest numbered empty slot */ lock_stack->trs_index = new_index; - } -#endif /* NSS_RWLOCK_RANK_ORDER_DEBUG */ +#endif /* NSS_RWLOCK_RANK_ORDER_DEBUG */ |