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obs-studio/deps/w32-pthreads/ptw32_OLL_lock.c

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2013-09-30 19:37:13 -07:00
/*
* ptw32_OLL_lock.c
*
* Description:
* This translation unit implements extended reader/writer queue-based locks.
*
* --------------------------------------------------------------------------
*
* Pthreads-win32 - POSIX Threads Library for Win32
* Copyright(C) 1998 John E. Bossom
* Copyright(C) 1999,2005 Pthreads-win32 contributors
*
* Contact Email: rpj@callisto.canberra.edu.au
*
* The current list of contributors is contained
* in the file CONTRIBUTORS included with the source
* code distribution. The list can also be seen at the
* following World Wide Web location:
* http://sources.redhat.com/pthreads-win32/contributors.html
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library in the file COPYING.LIB;
* if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
/*
* About the OLL lock (Scalable Reader-Writer Lock):
*
* OLL locks are queue-based locks similar to the MCS queue lock, where the queue
* nodes are local to the thread but where reader threads can enter the critical
* section immediately without going through a central guard lock if there are
* already readers holding the lock.
*
* Covered by United States Patent Application 20100241774 (Oracle)
*/
#include "pthread.h"
#include "sched.h"
#include "implement.h"
/*
* C-SNZI support
*/
typedef union ptw32_oll_counter_t_ ptw32_oll_counter_t;
typedef struct ptw32_oll_snziRoot_t_ ptw32_oll_snziRoot_t;
typedef struct ptw32_oll_snziNode_t_ ptw32_oll_snziNode_t;
typedef union ptw32_oll_snziNodeOrRoot_t_ ptw32_oll_snziNodeOrRoot_t;
typedef struct ptw32_oll_queryResult_t_ ptw32_oll_queryResult_t;
typedef struct ptw32_oll_ticket_t_ ptw32_oll_ticket_t;
typedef struct ptw32_oll_csnzi_t_ ptw32_oll_csnzi_t;
enum
{
ptw32_archWidth = sizeof(size_t)*8,
ptw32_oll_countWidth = ptw32_archWidth-2
};
#define PTW32_OLL_MAXREADERS (((size_t)2<<(ptw32_oll_countWidth-1))-1)
union ptw32_oll_counter_t_
{
size_t word : ptw32_archWidth;
struct
{
/*
* This needs to be a single word
*
* ------------------------------------
* | STATE | ROOT | COUNT (readers) |
* ------------------------------------
* 63 / 31 62 / 30 61 / 29 .. 0
*/
size_t count : ptw32_oll_countWidth;
size_t root : 1; /* ROOT or NODE */
size_t state : 1; /* OPEN or CLOSED (root only) */
} internal;
};
struct ptw32_oll_snziRoot_t_
{
/*
* "counter" must be at same offset in both
* ptw32_oll_snziNode_t and ptw32_oll_snziRoot_t
*/
ptw32_oll_counter_t counter;
};
enum
{
ptw32_oll_snziRoot_open = 0,
ptw32_oll_snziRoot_closed = 1
};
enum
{
ptw32_oll_snzi_root = 0,
ptw32_oll_snzi_node = 1
};
/*
* Some common SNZI root whole-word states that can be used to set or compare
* root words with a single operation.
*/
ptw32_oll_snziRoot_t ptw32_oll_snziRoot_openAndZero = {.counter.internal.count = 0,
.counter.internal.root = ptw32_oll_snzi_root,
.counter.internal.state = ptw32_oll_snziRoot_open};
ptw32_oll_snziRoot_t ptw32_oll_snziRoot_closedAndZero = {.counter.internal.count = 0,
.counter.internal.root = ptw32_oll_snzi_root,
.counter.internal.state = ptw32_oll_snziRoot_closed};
struct ptw32_oll_queryResult_t_
{
BOOL nonZero;
BOOL open;
};
union ptw32_oll_snziNodeOrRoot_t_
{
ptw32_oll_snziRoot_t* rootPtr;
ptw32_oll_snziNode_t* nodePtr;
};
struct ptw32_oll_snziNode_t_
{
/* "counter" must be at same offset in both
* ptw32_oll_snziNode_t and ptw32_oll_snziRoot_t
*/
ptw32_oll_counter_t counter;
ptw32_oll_snziNodeOrRoot_t parentPtr;
};
struct ptw32_oll_ticket_t_
{
ptw32_oll_snziNodeOrRoot_t snziNodeOrRoot;
};
ptw32_oll_ticket_t ptw32_oll_ticket_null = {NULL};
struct ptw32_oll_csnzi_t_
{
ptw32_oll_snziRoot_t proxyRoot;
ptw32_oll_snziNode_t leafs[];
};
/*
* FOLL lock support
*/
typedef struct ptw32_foll_node_t_ ptw32_foll_node_t;
typedef struct ptw32_foll_local_t_ ptw32_foll_local_t;
typedef struct ptw32_foll_rwlock_t_ ptw32_foll_rwlock_t;
enum
{
ptw32_srwl_reader,
ptw32_srwl_writer
};
enum
{
ptw32_srwl_free,
ptw32_srwl_in_use
};
struct ptw32_foll_node_t_
{
ptw32_foll_node_t* qNextPtr;
ptw32_oll_csnzi_t* csnziPtr;
ptw32_foll_node_t* nextPtr;
int kind;
int allocState;
BOOL spin;
};
struct ptw32_foll_local_t_
{
ptw32_foll_node_t* rNodePtr; // Default read node. Immutable
ptw32_foll_node_t* wNodePtr; // Write node. Immutable.
ptw32_foll_node_t* departFromPtr; // List node we last arrived at.
ptw32_oll_ticket_t ticket; // C-SNZI ticket
};
struct ptw32_foll_rwlock_t_
{
ptw32_foll_node_t* tailPtr;
ptw32_foll_node_t* rNodesPtr; // Head of reader node
};
/*
* ShouldArriveAtTree() returns true if:
* the compare_exchange in Arrive() fails too often under read access; or
* ??
* Note that this is measured across all access to
* this lock, not just this attempt, so that highly
* read-contended locks will use C-SNZI. Lightly
* read-contended locks can reduce memory usage and some
* processing by using the root directly.
*/
BOOL
ptw32_oll_ShouldArriveAtTree()
{
return PTW32_FALSE;
}
size_t
ptw32_oll_GetLeafForThread()
{
return 0;
}
/*
* Only readers call ptw32_oll_Arrive()
*
* Checks whether the C-SNZI state is OPEN, and if so,
* increments the surplus of the C-SNZI by either directly
* arriving at the root node, or calling TreeArrive on one
* of the leaf nodes. Returns a ticket pointing to the node
* that was arrived at. If the state is CLOSED, makes no
* change and returns a ticket that contains no pointer.
*/
ptw32_oll_ticket_t
ptw32_oll_Arrive(ptw32_oll_csnzi_t* csnzi)
{
for (;;)
{
ptw32_oll_ticket_t ticket;
ptw32_oll_snziRoot_t oldProxy = csnzi->proxyRoot;
if (oldProxy.counter.internal.state != ptw32_oll_snziRoot_open)
{
ticket.snziNodeOrRoot.rootPtr = (ptw32_oll_snziRoot_t*)NULL;
return ticket;
}
if (!ptw32_oll_ShouldArriveAtTree())
{
ptw32_oll_snziRoot_t newProxy = oldProxy;
newProxy.counter.internal.count++;
if (PTW32_INTERLOCKED_COMPARE_EXCHANGE_SIZE(
(PTW32_INTERLOCKED_SIZEPTR)&csnzi->proxyRoot.counter,
(PTW32_INTERLOCKED_SIZE)newProxy.counter.word,
(PTW32_INTERLOCKED_SIZE)oldProxy.counter.word)
== (PTW32_INTERLOCKED_SIZE)oldProxy.counter.word)
{
/* Exchange successful */
ticket.snziNodeOrRoot.rootPtr = &csnzi->proxyRoot;
return ticket;
}
}
else
{
ptw32_oll_snziNode_t* leafPtr = &csnzi->leafs[ptw32_oll_GetLeafForThread()];
ticket.snziNodeOrRoot.nodePtr = (ptw32_oll_TreeArrive(leafPtr) ? leafPtr : (ptw32_oll_snziNode_t*)NULL);
return ticket;
}
}
}
/*
* Decrements the C-SNZI surplus. Returns false iff the
* resulting state is CLOSED and the surplus is zero.
* Ticket must have been returned by an arrival. Must have
* received this ticket from Arrive more times than Depart
* has been called with the ticket. (Thus, the surplus
* must be greater than zero.)
*/
BOOL
ptw32_oll_Depart(ptw32_oll_ticket_t ticket)
{
return ptw32_oll_TreeDepart(ticket.snziNodeOrRoot);
}
/*
* Increments the C-SNZI surplus and returns true if the
* C-SNZI is open or has a surplus. Calls TreeArrive
* recursively on the node’s parent if needed.
* Otherwise, returns false without making any changes.
*/
BOOL
ptw32_oll_TreeArrive(ptw32_oll_snziNodeOrRoot_t snziNodeOrRoot)
{
if (snziNodeOrRoot.nodePtr->counter.internal.root != ptw32_oll_snzi_root)
{
/* Non-root node */
ptw32_oll_counter_t newCounter, oldCounter;
BOOL arrivedAtParent = PTW32_FALSE;
do
{
oldCounter = snziNodeOrRoot.nodePtr->counter;
if (0 == oldCounter.internal.count && !arrivedAtParent)
{
if (ptw32_oll_TreeArrive(snziNodeOrRoot.nodePtr->parentPtr))
arrivedAtParent = PTW32_TRUE;
else
return PTW32_FALSE;
}
newCounter = oldCounter;
newCounter.internal.count++;
} while (PTW32_INTERLOCKED_COMPARE_EXCHANGE_SIZE(
(PTW32_INTERLOCKED_SIZEPTR)&snziNodeOrRoot.nodePtr->counter,
(PTW32_INTERLOCKED_SIZE)newCounter.word,
(PTW32_INTERLOCKED_SIZE)oldCounter.word)
!= (PTW32_INTERLOCKED_SIZE)oldCounter.word);
if (newCounter.internal.count != 0 && arrivedAtParent)
ptw32_oll_TreeDepart(snziNodeOrRoot.nodePtr->parentPtr);
return PTW32_TRUE;
}
else
{
/* Root node */
ptw32_oll_snziRoot_t newRoot, oldRoot;
do
{
oldRoot = *(ptw32_oll_snziRoot_t*)snziNodeOrRoot.rootPtr;
if (oldRoot.counter.word == ptw32_oll_snziRoot_closedAndZero.counter.word)
return PTW32_FALSE;
newRoot = oldRoot;
newRoot.counter.internal.count++;
} while (PTW32_INTERLOCKED_COMPARE_EXCHANGE_SIZE(
(PTW32_INTERLOCKED_SIZEPTR)&snziNodeOrRoot.rootPtr->counter,
(PTW32_INTERLOCKED_SIZE)newRoot.counter.word,
(PTW32_INTERLOCKED_SIZE)oldRoot.counter.word)
!= (PTW32_INTERLOCKED_SIZE)oldRoot.counter.word);
return PTW32_TRUE;
}
}
/*
* Decrements the C-SNZI surplus, calling TreeDepart
* recursively on the node’s parent if needed. Returns
* false iff the resulting state of the C-SNZI is CLOSED
* and the surplus is zero. Otherwise, returns true.
*/
BOOL
ptw32_oll_TreeDepart(ptw32_oll_snziNodeOrRoot_t snziNodeOrRoot)
{
if (snziNodeOrRoot.nodePtr->counter.internal.root != ptw32_oll_snzi_root)
{
/* Non-root node */
ptw32_oll_counter_t newCounter, oldCounter;
do
{
newCounter = oldCounter = snziNodeOrRoot.nodePtr->counter;
newCounter.internal.count--;
} while (PTW32_INTERLOCKED_COMPARE_EXCHANGE_SIZE(
(PTW32_INTERLOCKED_SIZEPTR)&snziNodeOrRoot.nodePtr->counter,
(PTW32_INTERLOCKED_SIZE)newCounter.word,
(PTW32_INTERLOCKED_SIZE)oldCounter.word)
!= (PTW32_INTERLOCKED_SIZE)oldCounter.word);
return (0 == newCounter.internal.count)
? ptw32_oll_TreeDepart(snziNodeOrRoot.nodePtr->parentPtr)
: PTW32_TRUE;
}
else
{
/* Root node */
ptw32_oll_snziRoot_t newRoot, oldRoot;
do
{
newRoot = oldRoot = *(ptw32_oll_snziRoot_t*)snziNodeOrRoot.rootPtr;
newRoot.counter.internal.count--;
} while (PTW32_INTERLOCKED_COMPARE_EXCHANGE_SIZE(
(PTW32_INTERLOCKED_SIZEPTR)&snziNodeOrRoot.rootPtr->counter,
(PTW32_INTERLOCKED_SIZE)newRoot.counter.word,
(PTW32_INTERLOCKED_SIZE)oldRoot.counter.word)
!= (PTW32_INTERLOCKED_SIZE)oldRoot.counter.word);
return (newRoot.counter.word != ptw32_oll_snziRoot_closedAndZero.counter.word);
}
}
/*
* Opens a C-SNZI object. Requires C-SNZI state to be
* CLOSED and the surplus to be zero.
*/
void
ptw32_oll_Open(ptw32_oll_csnzi_t* csnziPtr)
{
csnziPtr->proxyRoot = ptw32_oll_snziRoot_openAndZero;
}
/*
* Opens a C-SNZI object while atomically performing count
* arrivals. Requires C-SNZI state to be CLOSED and
* the surplus to be zero.
*/
void
ptw32_oll_OpenWithArrivals(ptw32_oll_csnzi_t* csnziPtr, size_t count, BOOL close)
{
csnziPtr->proxyRoot.counter.internal.count = count;
csnziPtr->proxyRoot.counter.internal.state = (close ? ptw32_oll_snziRoot_closed : ptw32_oll_snziRoot_open);
}
/*
* Closes a C-SNZI object. Returns true iff the C-SNZI
* state changed from OPEN to CLOSED and the surplus is
* zero.
*/
BOOL
ptw32_oll_Close(ptw32_oll_csnzi_t* csnziPtr)
{
ptw32_oll_snziRoot_t newProxy, oldProxy;
do
{
oldProxy = csnziPtr->proxyRoot;
if (oldProxy.counter.internal.state != ptw32_oll_snziRoot_open)
{
return PTW32_FALSE;
}
newProxy = oldProxy;
newProxy.counter.internal.state = ptw32_oll_snziRoot_closed;
} while (PTW32_INTERLOCKED_COMPARE_EXCHANGE_SIZE(
(PTW32_INTERLOCKED_SIZEPTR)&csnziPtr->proxyRoot.counter,
(PTW32_INTERLOCKED_SIZE)newProxy.counter.word,
(PTW32_INTERLOCKED_SIZE)oldProxy.counter.word)
!= (PTW32_INTERLOCKED_SIZE)oldProxy.counter.word);
return (newProxy.counter.word == ptw32_oll_snziRoot_closedAndZero.counter.word);
}
/*
* Closes a C-SNZI if its surplus is zero. Otherwise, does
* nothing. Returns true iff C-SNZI state changed from
* OPEN to CLOSED.
*/
BOOL
ptw32_oll_CloseIfEmpty(ptw32_oll_csnzi_t* csnziPtr)
{
ptw32_oll_snziRoot_t newProxy, oldProxy;
do
{
oldProxy = csnziPtr->proxyRoot;
if (oldProxy.counter.word != ptw32_oll_snziRoot_openAndZero.counter.word)
{
return PTW32_FALSE;
}
newProxy = ptw32_oll_snziRoot_closedAndZero;
} while (PTW32_INTERLOCKED_COMPARE_EXCHANGE_SIZE(
(PTW32_INTERLOCKED_SIZEPTR)&csnziPtr->proxyRoot.counter,
(PTW32_INTERLOCKED_SIZE)newProxy.counter.word,
(PTW32_INTERLOCKED_SIZE)oldProxy.counter.word)
!= (PTW32_INTERLOCKED_SIZE)oldProxy.counter.word);
return PTW32_TRUE;
}
/*
* Returns whether the C-SNZI has a nonzero surplus and
* whether the C-SNZI is open.
* "nonZero" doesn't appear to be used anywhere in the algorithms.
*/
ptw32_oll_queryResult_t
ptw32_oll_Query(ptw32_oll_csnzi_t* csnziPtr)
{
ptw32_oll_queryResult_t query;
ptw32_oll_snziRoot_t proxy = csnziPtr->proxyRoot;
query.nonZero = (proxy.counter.internal.count > 0);
query.open = (proxy.counter.internal.state == ptw32_oll_snziRoot_open);
return query;
}
/*
* Returns whether the Arrive operation that returned
* the ticket succeeded.
*/
BOOL
ptw32_oll_Arrived(ptw32_oll_ticket_t t)
{
return (t.snziNodeOrRoot.nodePtr != NULL);
}
/*
* Constructs and returns a ticket that can be used to
* depart from the root node.
*/
ptw32_oll_ticket_t
ptw32_oll_DirectTicket(ptw32_oll_csnzi_t* csnziPtr)
{
ptw32_oll_ticket_t ticket;
ticket.snziNodeOrRoot.rootPtr = &csnziPtr->proxyRoot;
return ticket;
}
/* Scalable RW Locks */
typedef struct ptw32_srwl_rwlock_t_ ptw32_srwl_rwlock_t;
typedef struct ptw32_srwl_node_t_ ptw32_srwl_node_t;
typedef struct ptw32_srwl_local_t_ ptw32_srwl_local_t;
enum
{
ptw32_srwl_reader = 0,
ptw32_srwl_writer = 1
};
enum
{
ptw32_srwl_free = 0,
ptw32_srwl_in_use = 1
};
struct ptw32_srwl_rwlock_t_
{
ptw32_srwl_node_t* tailPtr;
ptw32_srwl_node_t* readerNodePtr;
};
struct ptw32_srwl_node_t_
{
ptw32_srwl_node_t* qNextPtr;
ptw32_oll_csnzi_t* csnziPtr;
ptw32_srwl_node_t* nextReaderPtr;
int kind; /* ptw32_srwl_reader, ptw32_srwl_writer */
int allocState; /* ptw32_srwl_free, ptw32_srwl_in_use */
BOOL spin;
};
/*
* When a ptw32_srwl_local_t is instantiated the "kind" of each of
* rNode and wNode must be set as appropriate. This is the only
* time "kind" is set.
*/
struct ptw32_srwl_local_t_
{
ptw32_srwl_node_t* rNodePtr;
ptw32_srwl_node_t* wNodePtr;
ptw32_srwl_node_t* departFromPtr;
ptw32_oll_ticket_t ticket;
};
/* Allocates a new reader node. */
ptw32_srwl_node_t*
ptw32_srwl_AllocReaderNode(ptw32_srwl_local_t* local)
{
ptw32_srwl_node_t* currNodePtr = local->rNodePtr;
for (;;)
{
if (currNodePtr->allocState == ptw32_srwl_free)
{
if (PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG(
(PTW32_INTERLOCKED_LONGPTR)&currNodePtr->allocState,
(PTW32_INTERLOCKED_LONG)ptw32_srwl_in_use,
(PTW32_INTERLOCKED_LONG)ptw32_srwl_free)
== (PTW32_INTERLOCKED_LONG)ptw32_srwl_in_use)
{
return currNodePtr;
}
}
currNodePtr = currNodePtr->next;
}
}
/*
* Frees a reader node. Requires that its allocState
* is ptw32_srwl_in_use.
*/
void
ptw32_srwl_FreeReaderNode(ptw32_srwl_node_t* nodePtr)
{
nodePtr->allocState := ptw32_srwl_free;
}
void
ptw32_srwl_WriterLock(ptw32_srwl_rwlock_t* lockPtr, ptw32_srwl_local_t* localPtr)
{
oldTailPtr = (ptw32_srwl_rwlock_t*)PTW32_INTERLOCKED_EXCHANGE_PTR(
(PTW32_INTERLOCKED_PVOID_PTR)&lockPtr->tailPtr,
(PTW32_INTERLOCKED_PVOID)localPtr->wNodePtr);
if (oldTailPtr != NULL)
{
localPtr->wNodePtr->spin := PTW32_TRUE;
oldTailPtr->qNextPtr = localPtr->wNodePtr;
if (oldTailPtr->kind == ptw32_srwl_writer)
{
while (localPtr->wNodePtr->spin);
}
else
{
/* Wait until node is properly recycled */
while (ptw32_oll_Query(oldTailPtr->csnzi).open);
/*
* Close C-SNZI of previous reader node.
* If there are no readers to signal us, spin on
* previous node and free it before entering
* critical section.
*/
if (ptw32_oll_Close(oldTailPtr->csnzi))
{
while (oldTailPtr->spin);
ptw32_srwl_FreeReaderNode(oldTailPtr);
}
else
{
while (localPtr->wNodePtr->spin);
}
}
}
}
void
ptw32_srwl_WriterUnlock(ptw32_srwl_rwlock_t* lockPtr, ptw32_srwl_local_t* localPtr)
{
if (localPtr->wNodePtr->qNextPtr == NULL)
{
if (PTW32_INTERLOCKED_COMPARE_EXCHANGE_PTR(
(PTW32_INTERLOCKED_PVOIDPTR)&lockPtr->tailPtr,
(PTW32_INTERLOCKED_PVOID)NULL,
(PTW32_INTERLOCKED_PVOID)localPtr->wNodePtr)
== (PTW32_INTERLOCKED_PVOID)NULL)
{
return;
}
else
{
while (localPtr->wNodePtr->qNextPtr == NULL);
}
}
/* Clean up */
localPtr->wNodePtr->qNextPtr->spin = PTW32_FALSE;
localPtr->wNodePtr->qNextPtr = NULL;
}
void
ptw32_srwl_ReaderLock(ptw32_srwl_rwlock_t* lockPtr, ptw32_srwl_local_t* localPtr)
{
ptw32_srwl_node_t* rNodePtr = NULL;
for (;;)
{
ptw32_srwl_node_t* tailPtr = lockPtr->tailPtr;
/* If no nodes are in the queue */
if (tailPtr == NULL)
{
if (rNodePtr == NULL)
{
rNodePtr = ptw32_srwl_AllocReaderNode(localPtr);
}
rNodePtr->spin = PTW32_FALSE;
if (PTW32_INTERLOCKED_COMPARE_EXCHANGE_PTR(
(PTW32_INTERLOCKED_PVOIDPTR)&lockPtr->tailPtr,
(PTW32_INTERLOCKED_PVOID)rNodePtr,
(PTW32_INTERLOCKED_PVOID)NULL)
== (PTW32_INTERLOCKED_PVOID)rNodePtr)
{
ptw32_oll_Open(rNodePtr->csnzi);
localPtr->ticket = ptw32_oll_Arrive(rNodePtr->csnzi);
if (ptw32_oll_Arrived(localPtr->ticket))
{
localPtr->departFromPtr = rNodePtr;
return;
}
/* Avoid reusing inserted node */
rNodePtr = NULL;
}
}
/* Otherwise, there is a node in the queue */
else
{
/* Is last node a writer node? */
if (tailPtr->kind == ptw32_srwl_writer)
{
if (rNodePtr == NULL)
{
rNodePtr = ptw32_srwl_AllocReaderNode(localPtr);
}
rNodePtr->spin = PTW32_TRUE;
if (PTW32_INTERLOCKED_COMPARE_EXCHANGE_PTR(
(PTW32_INTERLOCKED_PVOIDPTR)&lockPtr->tailPtr,
(PTW32_INTERLOCKED_PVOID)rNodePtr,
(PTW32_INTERLOCKED_PVOID)tailPtr)
== (PTW32_INTERLOCKED_PVOID)rNodePtr)
{
tailPtr->qNextPtr = rNodePtr;
localPtr->ticket = ptw32_oll_Arrive(rNodePtr->csnzi);
if (ptw32_oll_Arrived(localPtr->ticket))
{
localPtr->departFromPtr = rNodePtr;
while (rNodePtr->spin);
return;
}
/* Avoid reusing inserted node */
rNodePtr = NULL;
}
}
/*
* Otherwise, last node is a reader node.
* (tailPtr->kind == ptw32_srwl_reader)
*/
else
{
localPtr->ticket = ptw32_oll_Arrive(tailPtr->csnzi);
if (ptw32_oll_Arrived(localPtr->ticket))
{
if (rNodePtr != NULL)
{
ptw32_srwl_FreeReaderNode(rNodePtr);
}
localPtr->departFromPtr = tailPtr;
while (tailPtr->spin);
return;
}
}
}
}
}
void
ptw32_srwl_ReaderUnlock(ptw32_srwl_rwlock_t* lockPtr, ptw32_srwl_local_t* localPtr)
{
if (ptw32_oll_Depart(localPtr->departFromPtr->csnzi, localPtr->ticket))
{
return;
}
/* Clean up */
localPtr->departFromPtr->qNextPtr->spin = PTW32_FALSE;
localPtr->departFromPtr->qNextPtr = NULL;
ptw32_srwl_FreeReaderNode(localPtr->departFromPtr);
}
#include <stdio.h>
int main()
{
printf("%lx\n", PTW32_OLL_MAXREADERS);
return 0;
}