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/* lockan.c: ANSI RECURSIVE LOCKS
*
* $Id$
* Copyright (c) 2001-2020 Ravenbrook Limited. See end of file for license.
*
* .purpose: This is a trivial implementation of recursive locks
* that assumes we are not running in a multi-threaded environment.
* This provides stubs for the locking code where locking is not
* applicable. The stubs provide some amount of checking.
*
* .limit: The limit on the number of recursive claims is ULONG_MAX.
*/
#include "lock.h"
#include "mpmtypes.h"
SRCID(lockan, "$Id$");
typedef struct LockStruct { /* ANSI fake lock structure */
Sig sig; /* design.mps.sig.field */
unsigned long claims; /* # claims held by owner */
} LockStruct;
size_t (LockSize)(void)
{
return sizeof(LockStruct);
}
Bool (LockCheck)(Lock lock)
{
CHECKS(Lock, lock);
return TRUE;
}
void (LockInit)(Lock lock)
{
AVER(lock != NULL);
lock->claims = 0;
lock->sig = LockSig;
AVERT(Lock, lock);
}
void (LockFinish)(Lock lock)
{
AVERT(Lock, lock);
AVER(lock->claims == 0);
lock->sig = SigInvalid;
}
void (LockClaim)(Lock lock)
{
AVERT(Lock, lock);
AVER(lock->claims == 0);
lock->claims = 1;
}
void (LockRelease)(Lock lock)
{
AVERT(Lock, lock);
AVER(lock->claims == 1);
lock->claims = 0;
}
void (LockClaimRecursive)(Lock lock)
{
AVERT(Lock, lock);
++lock->claims;
AVER(lock->claims>0);
}
void (LockReleaseRecursive)(Lock lock)
{
AVERT(Lock, lock);
AVER(lock->claims > 0);
--lock->claims;
}
Bool (LockIsHeld)(Lock lock)
{
AVERT(Lock, lock);
return lock->claims > 0;
}
/* Global locking is performed by normal locks.
* A separate lock structure is used for recursive and
* non-recursive locks so that each may be differently ordered
* with respect to client-allocated locks.
*/
static LockStruct globalLockStruct = {
LockSig,
0
};
static LockStruct globalRecursiveLockStruct = {
LockSig,
0
};
static Lock globalLock = &globalLockStruct;
static Lock globalRecLock = &globalRecursiveLockStruct;
void LockInitGlobal(void)
{
globalLock->claims = 0;
LockInit(globalLock);
globalRecLock->claims = 0;
LockInit(globalRecLock);
}
void (LockClaimGlobalRecursive)(void)
{
LockClaimRecursive(globalRecLock);
}
void (LockReleaseGlobalRecursive)(void)
{
LockReleaseRecursive(globalRecLock);
}
void (LockClaimGlobal)(void)
{
LockClaim(globalLock);
}
void (LockReleaseGlobal)(void)
{
LockRelease(globalLock);
}
void LockSetup(void)
{
/* Nothing to do as ANSI platform does not have fork(). */
}
/* C. COPYRIGHT AND LICENSE
*
* Copyright (C) 2001-2020 Ravenbrook Limited <https://www.ravenbrook.com/>.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
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