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Diffstat (limited to 'security/nss/lib/util/nssrwlk.h')
| -rw-r--r-- | security/nss/lib/util/nssrwlk.h | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/security/nss/lib/util/nssrwlk.h b/security/nss/lib/util/nssrwlk.h new file mode 100644 index 0000000000..8e1fa6fbe1 --- /dev/null +++ b/security/nss/lib/util/nssrwlk.h @@ -0,0 +1,133 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +/* +** File: nsrwlock.h +** Description: API to basic reader-writer lock functions of NSS. +** These locks allow re-entry from writers but not readers. That is, +** If I hold the write lock, I can ask for it and get it again. +** If I hold the write lock, I can also ask for and get a read lock. +** I can then release the locks in any order (read or write). +** If I hold a read lock, I must not ask for another read lock or +** the write lock. +** I must release each lock type as many times as I acquired it. +** +** For deadlock detection, locks should be ranked, and no lock may be aquired +** while I hold a lock of higher rank number. +** If you don't want that feature, always use NSS_RWLOCK_RANK_NONE. +** Lock name is for debugging, and is optional (may be NULL) +**/ + +#ifndef nssrwlk_h___ +#define nssrwlk_h___ + +#include "utilrename.h" +#include "prtypes.h" +#include "nssrwlkt.h" + +#define NSS_RWLOCK_RANK_NONE 0 + +/* SEC_BEGIN_PROTOS */ +PR_BEGIN_EXTERN_C + +/*********************************************************************** +** FUNCTION: NSSRWLock_New +** DESCRIPTION: +** Returns a pointer to a newly created reader-writer lock object. +** INPUTS: Lock rank +** Lock name +** OUTPUTS: void +** RETURN: NSSRWLock* +** If the lock cannot be created because of resource constraints, NULL +** is returned. +** +***********************************************************************/ +extern NSSRWLock *NSSRWLock_New(PRUint32 lock_rank, const char *lock_name); + +/*********************************************************************** +** FUNCTION: NSSRWLock_AtomicCreate +** DESCRIPTION: +** Given the address of a NULL pointer to a NSSRWLock, +** atomically initializes that pointer to a newly created NSSRWLock. +** Returns the value placed into that pointer, or NULL. +** +** INPUTS: address of NSRWLock pointer +** Lock rank +** Lock name +** OUTPUTS: NSSRWLock* +** RETURN: NSSRWLock* +** If the lock cannot be created because of resource constraints, +** the pointer will be left NULL. +** +***********************************************************************/ +extern NSSRWLock * +nssRWLock_AtomicCreate(NSSRWLock **prwlock, + PRUint32 lock_rank, + const char *lock_name); + +/*********************************************************************** +** FUNCTION: NSSRWLock_Destroy +** DESCRIPTION: +** Destroys a given RW lock object. +** INPUTS: NSSRWLock *lock - Lock to be freed. +** OUTPUTS: void +** RETURN: None +***********************************************************************/ +extern void NSSRWLock_Destroy(NSSRWLock *lock); + +/*********************************************************************** +** FUNCTION: NSSRWLock_LockRead +** DESCRIPTION: +** Apply a read lock (non-exclusive) on a RWLock +** INPUTS: NSSRWLock *lock - Lock to be read-locked. +** OUTPUTS: void +** RETURN: None +***********************************************************************/ +extern void NSSRWLock_LockRead(NSSRWLock *lock); + +/*********************************************************************** +** FUNCTION: NSSRWLock_LockWrite +** DESCRIPTION: +** Apply a write lock (exclusive) on a RWLock +** INPUTS: NSSRWLock *lock - Lock to write-locked. +** OUTPUTS: void +** RETURN: None +***********************************************************************/ +extern void NSSRWLock_LockWrite(NSSRWLock *lock); + +/*********************************************************************** +** FUNCTION: NSSRWLock_UnlockRead +** DESCRIPTION: +** Release a Read lock. Unlocking an unlocked lock has undefined results. +** INPUTS: NSSRWLock *lock - Lock to unlocked. +** OUTPUTS: void +** RETURN: void +***********************************************************************/ +extern void NSSRWLock_UnlockRead(NSSRWLock *lock); + +/*********************************************************************** +** FUNCTION: NSSRWLock_UnlockWrite +** DESCRIPTION: +** Release a Write lock. Unlocking an unlocked lock has undefined results. +** INPUTS: NSSRWLock *lock - Lock to unlocked. +** OUTPUTS: void +** RETURN: void +***********************************************************************/ +extern void NSSRWLock_UnlockWrite(NSSRWLock *lock); + +/*********************************************************************** +** FUNCTION: NSSRWLock_HaveWriteLock +** DESCRIPTION: +** Tells caller whether the current thread holds the write lock, or not. +** INPUTS: NSSRWLock *lock - Lock to test. +** OUTPUTS: void +** RETURN: PRBool PR_TRUE IFF the current thread holds the write lock. +***********************************************************************/ + +extern PRBool NSSRWLock_HaveWriteLock(NSSRWLock *rwlock); + +/* SEC_END_PROTOS */ +PR_END_EXTERN_C + +#endif /* nsrwlock_h___ */ |