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security/nss/lib/util/nssrwlk.h@b8a032363ba2 (annotated)

security/nss/lib/util/nssrwlk.h

Thu, 22 Jan 2015 13:21:57 +0100

author
Michael Schloh von Bennewitz <michael@schloh.com>
date
Thu, 22 Jan 2015 13:21:57 +0100
branch
TOR_BUG_9701
changeset 15
b8a032363ba2
permissions
-rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

michael@0 1 /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0 2 * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0 3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0 4
michael@0 5 /*
michael@0 6 ** File: nsrwlock.h
michael@0 7 ** Description: API to basic reader-writer lock functions of NSS.
michael@0 8 ** These are re-entrant reader writer locks; that is,
michael@0 9 ** If I hold the write lock, I can ask for it and get it again.
michael@0 10 ** If I hold the write lock, I can also ask for and get a read lock.
michael@0 11 ** I can then release the locks in any order (read or write).
michael@0 12 ** I must release each lock type as many times as I acquired it.
michael@0 13 ** Otherwise, these are normal reader/writer locks.
michael@0 14 **
michael@0 15 ** For deadlock detection, locks should be ranked, and no lock may be aquired
michael@0 16 ** while I hold a lock of higher rank number.
michael@0 17 ** If you don't want that feature, always use NSS_RWLOCK_RANK_NONE.
michael@0 18 ** Lock name is for debugging, and is optional (may be NULL)
michael@0 19 **/
michael@0 20
michael@0 21 #ifndef nssrwlk_h___
michael@0 22 #define nssrwlk_h___
michael@0 23
michael@0 24 #include "utilrename.h"
michael@0 25 #include "prtypes.h"
michael@0 26 #include "nssrwlkt.h"
michael@0 27
michael@0 28 #define NSS_RWLOCK_RANK_NONE 0
michael@0 29
michael@0 30 /* SEC_BEGIN_PROTOS */
michael@0 31 PR_BEGIN_EXTERN_C
michael@0 32
michael@0 33 /***********************************************************************
michael@0 34 ** FUNCTION: NSSRWLock_New
michael@0 35 ** DESCRIPTION:
michael@0 36 ** Returns a pointer to a newly created reader-writer lock object.
michael@0 37 ** INPUTS: Lock rank
michael@0 38 ** Lock name
michael@0 39 ** OUTPUTS: void
michael@0 40 ** RETURN: NSSRWLock*
michael@0 41 ** If the lock cannot be created because of resource constraints, NULL
michael@0 42 ** is returned.
michael@0 43 **
michael@0 44 ***********************************************************************/
michael@0 45 extern NSSRWLock* NSSRWLock_New(PRUint32 lock_rank, const char *lock_name);
michael@0 46
michael@0 47 /***********************************************************************
michael@0 48 ** FUNCTION: NSSRWLock_AtomicCreate
michael@0 49 ** DESCRIPTION:
michael@0 50 ** Given the address of a NULL pointer to a NSSRWLock,
michael@0 51 ** atomically initializes that pointer to a newly created NSSRWLock.
michael@0 52 ** Returns the value placed into that pointer, or NULL.
michael@0 53 **
michael@0 54 ** INPUTS: address of NSRWLock pointer
michael@0 55 ** Lock rank
michael@0 56 ** Lock name
michael@0 57 ** OUTPUTS: NSSRWLock*
michael@0 58 ** RETURN: NSSRWLock*
michael@0 59 ** If the lock cannot be created because of resource constraints,
michael@0 60 ** the pointer will be left NULL.
michael@0 61 **
michael@0 62 ***********************************************************************/
michael@0 63 extern NSSRWLock *
michael@0 64 nssRWLock_AtomicCreate( NSSRWLock ** prwlock,
michael@0 65 PRUint32 lock_rank,
michael@0 66 const char * lock_name);
michael@0 67
michael@0 68 /***********************************************************************
michael@0 69 ** FUNCTION: NSSRWLock_Destroy
michael@0 70 ** DESCRIPTION:
michael@0 71 ** Destroys a given RW lock object.
michael@0 72 ** INPUTS: NSSRWLock *lock - Lock to be freed.
michael@0 73 ** OUTPUTS: void
michael@0 74 ** RETURN: None
michael@0 75 ***********************************************************************/
michael@0 76 extern void NSSRWLock_Destroy(NSSRWLock *lock);
michael@0 77
michael@0 78 /***********************************************************************
michael@0 79 ** FUNCTION: NSSRWLock_LockRead
michael@0 80 ** DESCRIPTION:
michael@0 81 ** Apply a read lock (non-exclusive) on a RWLock
michael@0 82 ** INPUTS: NSSRWLock *lock - Lock to be read-locked.
michael@0 83 ** OUTPUTS: void
michael@0 84 ** RETURN: None
michael@0 85 ***********************************************************************/
michael@0 86 extern void NSSRWLock_LockRead(NSSRWLock *lock);
michael@0 87
michael@0 88 /***********************************************************************
michael@0 89 ** FUNCTION: NSSRWLock_LockWrite
michael@0 90 ** DESCRIPTION:
michael@0 91 ** Apply a write lock (exclusive) on a RWLock
michael@0 92 ** INPUTS: NSSRWLock *lock - Lock to write-locked.
michael@0 93 ** OUTPUTS: void
michael@0 94 ** RETURN: None
michael@0 95 ***********************************************************************/
michael@0 96 extern void NSSRWLock_LockWrite(NSSRWLock *lock);
michael@0 97
michael@0 98 /***********************************************************************
michael@0 99 ** FUNCTION: NSSRWLock_UnlockRead
michael@0 100 ** DESCRIPTION:
michael@0 101 ** Release a Read lock. Unlocking an unlocked lock has undefined results.
michael@0 102 ** INPUTS: NSSRWLock *lock - Lock to unlocked.
michael@0 103 ** OUTPUTS: void
michael@0 104 ** RETURN: void
michael@0 105 ***********************************************************************/
michael@0 106 extern void NSSRWLock_UnlockRead(NSSRWLock *lock);
michael@0 107
michael@0 108 /***********************************************************************
michael@0 109 ** FUNCTION: NSSRWLock_UnlockWrite
michael@0 110 ** DESCRIPTION:
michael@0 111 ** Release a Write lock. Unlocking an unlocked lock has undefined results.
michael@0 112 ** INPUTS: NSSRWLock *lock - Lock to unlocked.
michael@0 113 ** OUTPUTS: void
michael@0 114 ** RETURN: void
michael@0 115 ***********************************************************************/
michael@0 116 extern void NSSRWLock_UnlockWrite(NSSRWLock *lock);
michael@0 117
michael@0 118 /***********************************************************************
michael@0 119 ** FUNCTION: NSSRWLock_HaveWriteLock
michael@0 120 ** DESCRIPTION:
michael@0 121 ** Tells caller whether the current thread holds the write lock, or not.
michael@0 122 ** INPUTS: NSSRWLock *lock - Lock to test.
michael@0 123 ** OUTPUTS: void
michael@0 124 ** RETURN: PRBool PR_TRUE IFF the current thread holds the write lock.
michael@0 125 ***********************************************************************/
michael@0 126
michael@0 127 extern PRBool NSSRWLock_HaveWriteLock(NSSRWLock *rwlock);
michael@0 128
michael@0 129 /* SEC_END_PROTOS */
michael@0 130 PR_END_EXTERN_C
michael@0 131
michael@0 132 #endif /* nsrwlock_h___ */

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