cvs update pthreads

1 files changed, 263 insertions, 210 deletions

diff --git a/pthreads/ptw32_MCS_lock.c b/pthreads/ptw32_MCS_lock.c
index 1a143ea14..270c31e9c 100644
--- a/pthreads/ptw32_MCS_lock.c
+++ b/pthreads/ptw32_MCS_lock.c
@@ -1,210 +1,263 @@
-/*
- * ptw32_MCS_lock.c
- *
- * Description:
- * This translation unit implements 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 MCS locks:
- *
- * MCS locks are queue-based locks, where the queue nodes are local to the
- * thread. The 'lock' is nothing more than a global pointer that points to
- * the last node in the queue, or is NULL if the queue is empty.
- * 
- * Originally designed for use as spin locks requiring no kernel resources
- * for synchronisation or blocking, the implementation below has adapted
- * the MCS spin lock for use as a general mutex that will suspend threads
- * when there is lock contention.
- *
- * Because the queue nodes are thread-local, most of the memory read/write
- * operations required to add or remove nodes from the queue do not trigger
- * cache-coherence updates.
- *
- * Like 'named' mutexes, MCS locks consume system resources transiently -
- * they are able to acquire and free resources automatically - but MCS
- * locks do not require any unique 'name' to identify the lock to all
- * threads using it.
- *
- * Usage of MCS locks:
- *
- * - you need a global ptw32_mcs_lock_t instance initialised to 0 or NULL.
- * - you need a local thread-scope ptw32_mcs_local_node_t instance, which
- *   may serve several different locks but you need at least one node for
- *   every lock held concurrently by a thread.
- *
- * E.g.:
- * 
- * ptw32_mcs_lock_t lock1 = 0;
- * ptw32_mcs_lock_t lock2 = 0;
- *
- * void *mythread(void *arg)
- * {
- *   ptw32_mcs_local_node_t node;
- *
- *   ptw32_mcs_acquire (&lock1, &node);
- *   ptw32_mcs_release (&node);
- *
- *   ptw32_mcs_acquire (&lock2, &node);
- *   ptw32_mcs_release (&node);
- *   {
- *      ptw32_mcs_local_node_t nodex;
- *
- *      ptw32_mcs_acquire (&lock1, &node);
- *      ptw32_mcs_acquire (&lock2, &nodex);
- *
- *      ptw32_mcs_release (&nodex);
- *      ptw32_mcs_release (&node);
- *   }
- *   return (void *)0;
- * }
- */
-
-#include "implement.h"
-#include "pthread.h"
-
-/*
- * ptw32_mcs_flag_set -- notify another thread about an event.
- * 
- * Set event if an event handle has been stored in the flag, and
- * set flag to -1 otherwise. Note that -1 cannot be a valid handle value.
- */
-INLINE void 
-ptw32_mcs_flag_set (LONG * flag)
-{
-  HANDLE e = (HANDLE)PTW32_INTERLOCKED_COMPARE_EXCHANGE(
-						(PTW32_INTERLOCKED_LPLONG)flag,
-						(PTW32_INTERLOCKED_LONG)-1,
-						(PTW32_INTERLOCKED_LONG)0);
-  if ((HANDLE)0 != e)
-    {
-      /* another thread has already stored an event handle in the flag */
-      SetEvent(e);
-    }
-}
-
-/*
- * ptw32_mcs_flag_set -- wait for notification from another.
- * 
- * Store an event handle in the flag and wait on it if the flag has not been
- * set, and proceed without creating an event otherwise.
- */
-INLINE void 
-ptw32_mcs_flag_wait (LONG * flag)
-{
-  if (0 == InterlockedExchangeAdd((LPLONG)flag, 0)) /* MBR fence */
-    {
-      /* the flag is not set. create event. */
-
-      HANDLE e = CreateEvent(NULL, PTW32_FALSE, PTW32_FALSE, NULL);
-
-      if (0 == PTW32_INTERLOCKED_COMPARE_EXCHANGE(
-			                  (PTW32_INTERLOCKED_LPLONG)flag,
-			                  (PTW32_INTERLOCKED_LONG)e,
-			                  (PTW32_INTERLOCKED_LONG)0))
-	{
-	  /* stored handle in the flag. wait on it now. */
-	  WaitForSingleObject(e, INFINITE);
-	}
-
-      CloseHandle(e);
-    }
-}
-
-/*
- * ptw32_mcs_lock_acquire -- acquire an MCS lock.
- * 
- * See: 
- * J. M. Mellor-Crummey and M. L. Scott.
- * Algorithms for Scalable Synchronization on Shared-Memory Multiprocessors.
- * ACM Transactions on Computer Systems, 9(1):21-65, Feb. 1991.
- */
-INLINE void 
-ptw32_mcs_lock_acquire (ptw32_mcs_lock_t * lock, ptw32_mcs_local_node_t * node)
-{
-  ptw32_mcs_local_node_t  *pred;
-  
-  node->lock = lock;
-  node->nextFlag = 0;
-  node->readyFlag = 0;
-  node->next = 0; /* initially, no successor */
-  
-  /* queue for the lock */
-  pred = (ptw32_mcs_local_node_t *)PTW32_INTERLOCKED_EXCHANGE((LPLONG)lock,
-						              (LONG)node);
-
-  if (0 != pred)
-    {
-      /* the lock was not free. link behind predecessor. */
-      pred->next = node;
-      ptw32_mcs_flag_set(&pred->nextFlag);
-      ptw32_mcs_flag_wait(&node->readyFlag);
-    }
-}
-
-/*
- * ptw32_mcs_lock_release -- release an MCS lock.
- * 
- * See: 
- * J. M. Mellor-Crummey and M. L. Scott.
- * Algorithms for Scalable Synchronization on Shared-Memory Multiprocessors.
- * ACM Transactions on Computer Systems, 9(1):21-65, Feb. 1991.
- */
-INLINE void 
-ptw32_mcs_lock_release (ptw32_mcs_local_node_t * node)
-{
-  ptw32_mcs_lock_t *lock = node->lock;
-  ptw32_mcs_local_node_t *next = (ptw32_mcs_local_node_t *)
-    InterlockedExchangeAdd((LPLONG)&node->next, 0); /* MBR fence */
-
-  if (0 == next)
-    {
-      /* no known successor */
-
-      if (node == (ptw32_mcs_local_node_t *)
-	  PTW32_INTERLOCKED_COMPARE_EXCHANGE((PTW32_INTERLOCKED_LPLONG)lock,
-					     (PTW32_INTERLOCKED_LONG)0,
-					     (PTW32_INTERLOCKED_LONG)node))
-	{
-	  /* no successor, lock is free now */
-	  return;
-	}
-  
-      /* wait for successor */
-      ptw32_mcs_flag_wait(&node->nextFlag);
-      next = (ptw32_mcs_local_node_t *)
-	InterlockedExchangeAdd((LPLONG)&node->next, 0); /* MBR fence */
-    }
-
-  /* pass the lock */
-  ptw32_mcs_flag_set(&next->readyFlag);
-}
+/*

+ * ptw32_MCS_lock.c

+ *

+ * Description:

+ * This translation unit implements 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 MCS locks:

+ *

+ * MCS locks are queue-based locks, where the queue nodes are local to the

+ * thread. The 'lock' is nothing more than a global pointer that points to

+ * the last node in the queue, or is NULL if the queue is empty.

+ * 

+ * Originally designed for use as spin locks requiring no kernel resources

+ * for synchronisation or blocking, the implementation below has adapted

+ * the MCS spin lock for use as a general mutex that will suspend threads

+ * when there is lock contention.

+ *

+ * Because the queue nodes are thread-local, most of the memory read/write

+ * operations required to add or remove nodes from the queue do not trigger

+ * cache-coherence updates.

+ *

+ * Like 'named' mutexes, MCS locks consume system resources transiently -

+ * they are able to acquire and free resources automatically - but MCS

+ * locks do not require any unique 'name' to identify the lock to all

+ * threads using it.

+ *

+ * Usage of MCS locks:

+ *

+ * - you need a global ptw32_mcs_lock_t instance initialised to 0 or NULL.

+ * - you need a local thread-scope ptw32_mcs_local_node_t instance, which

+ *   may serve several different locks but you need at least one node for

+ *   every lock held concurrently by a thread.

+ *

+ * E.g.:

+ * 

+ * ptw32_mcs_lock_t lock1 = 0;

+ * ptw32_mcs_lock_t lock2 = 0;

+ *

+ * void *mythread(void *arg)

+ * {

+ *   ptw32_mcs_local_node_t node;

+ *

+ *   ptw32_mcs_acquire (&lock1, &node);

+ *   ptw32_mcs_release (&node);

+ *

+ *   ptw32_mcs_acquire (&lock2, &node);

+ *   ptw32_mcs_release (&node);

+ *   {

+ *      ptw32_mcs_local_node_t nodex;

+ *

+ *      ptw32_mcs_acquire (&lock1, &node);

+ *      ptw32_mcs_acquire (&lock2, &nodex);

+ *

+ *      ptw32_mcs_release (&nodex);

+ *      ptw32_mcs_release (&node);

+ *   }

+ *   return (void *)0;

+ * }

+ */

+

+#include "implement.h"

+#include "pthread.h"

+

+/*

+ * ptw32_mcs_flag_set -- notify another thread about an event.

+ * 

+ * Set event if an event handle has been stored in the flag, and

+ * set flag to -1 otherwise. Note that -1 cannot be a valid handle value.

+ */

+INLINE void 

+ptw32_mcs_flag_set (LONG * flag)

+{

+  HANDLE e = (HANDLE)PTW32_INTERLOCKED_COMPARE_EXCHANGE(

+						(PTW32_INTERLOCKED_LPLONG)flag,

+						(PTW32_INTERLOCKED_LONG)-1,

+						(PTW32_INTERLOCKED_LONG)0);

+  if ((HANDLE)0 != e)

+    {

+      /* another thread has already stored an event handle in the flag */

+      SetEvent(e);

+    }

+}

+

+/*

+ * ptw32_mcs_flag_set -- wait for notification from another.

+ * 

+ * Store an event handle in the flag and wait on it if the flag has not been

+ * set, and proceed without creating an event otherwise.

+ */

+INLINE void 

+ptw32_mcs_flag_wait (LONG * flag)

+{

+  if (0 == InterlockedExchangeAdd((LPLONG)flag, 0)) /* MBR fence */

+    {

+      /* the flag is not set. create event. */

+

+      HANDLE e = CreateEvent(NULL, PTW32_FALSE, PTW32_FALSE, NULL);

+

+      if (0 == PTW32_INTERLOCKED_COMPARE_EXCHANGE(

+			                  (PTW32_INTERLOCKED_LPLONG)flag,

+			                  (PTW32_INTERLOCKED_LONG)e,

+			                  (PTW32_INTERLOCKED_LONG)0))

+	{

+	  /* stored handle in the flag. wait on it now. */

+	  WaitForSingleObject(e, INFINITE);

+	}

+

+      CloseHandle(e);

+    }

+}

+

+/*

+ * ptw32_mcs_lock_acquire -- acquire an MCS lock.

+ * 

+ * See: 

+ * J. M. Mellor-Crummey and M. L. Scott.

+ * Algorithms for Scalable Synchronization on Shared-Memory Multiprocessors.

+ * ACM Transactions on Computer Systems, 9(1):21-65, Feb. 1991.

+ */

+INLINE void 

+ptw32_mcs_lock_acquire (ptw32_mcs_lock_t * lock, ptw32_mcs_local_node_t * node)

+{

+  ptw32_mcs_local_node_t  *pred;

+  

+  node->lock = lock;

+  node->nextFlag = 0;

+  node->readyFlag = 0;

+  node->next = 0; /* initially, no successor */

+  

+  /* queue for the lock */

+  pred = (ptw32_mcs_local_node_t *)PTW32_INTERLOCKED_EXCHANGE((PTW32_INTERLOCKED_LPLONG)lock,

+						              (PTW32_INTERLOCKED_LONG)node);

+

+  if (0 != pred)

+    {

+      /* the lock was not free. link behind predecessor. */

+      pred->next = node;

+      ptw32_mcs_flag_set(&pred->nextFlag);

+      ptw32_mcs_flag_wait(&node->readyFlag);

+    }

+}

+

+/*

+ * ptw32_mcs_lock_release -- release an MCS lock.

+ * 

+ * See: 

+ * J. M. Mellor-Crummey and M. L. Scott.

+ * Algorithms for Scalable Synchronization on Shared-Memory Multiprocessors.

+ * ACM Transactions on Computer Systems, 9(1):21-65, Feb. 1991.

+ */

+INLINE void 

+ptw32_mcs_lock_release (ptw32_mcs_local_node_t * node)

+{

+  ptw32_mcs_lock_t *lock = node->lock;

+  ptw32_mcs_local_node_t *next = (ptw32_mcs_local_node_t *)

+    InterlockedExchangeAdd((LPLONG)&node->next,

+                           (LONG)0); /* MBR fence */

+

+  if (0 == next)

+    {

+      /* no known successor */

+

+      if (node == (ptw32_mcs_local_node_t *)

+	  PTW32_INTERLOCKED_COMPARE_EXCHANGE((PTW32_INTERLOCKED_LPLONG)lock,

+					     (PTW32_INTERLOCKED_LONG)0,

+					     (PTW32_INTERLOCKED_LONG)node))

+	{

+	  /* no successor, lock is free now */

+	  return;

+	}

+  

+      /* wait for successor */

+      ptw32_mcs_flag_wait(&node->nextFlag);

+      next = (ptw32_mcs_local_node_t *)

+	InterlockedExchangeAdd((LPLONG)&node->next, 0); /* MBR fence */

+    }

+

+  /* pass the lock */

+  ptw32_mcs_flag_set(&next->readyFlag);

+}

+

+/*

+  * ptw32_mcs_lock_try_acquire

+ */

+INLINE int

+ptw32_mcs_lock_try_acquire (ptw32_mcs_lock_t * lock, ptw32_mcs_local_node_t * node)

+{

+  node->lock = lock;

+  node->nextFlag = 0;

+  node->readyFlag = 0;

+  node->next = 0; /* initially, no successor */

+

+  return ((PTW32_INTERLOCKED_LPLONG)PTW32_INTERLOCKED_COMPARE_EXCHANGE(

+                                      (PTW32_INTERLOCKED_LPLONG)lock,

+                                      (PTW32_INTERLOCKED_LONG)node,

+                                      (PTW32_INTERLOCKED_LONG)0)

+               == (PTW32_INTERLOCKED_LPLONG)0) ? 0 : EBUSY;

+}

+

+/*

+ * ptw32_mcs_node_substitute -- move an MCS lock local node, usually from thread

+ * space to, for example, global space so that another thread can release

+ * the lock on behalf of the current lock owner.

+ *

+ * Example: used in pthread_barrier_wait where we want the last thread out of

+ * the barrier to release the lock owned by the last thread to enter the barrier

+ * (the one that releases all threads but not necessarily the last to leave).

+ *

+ * Should only be called by the thread that has the lock.

+ */

+INLINE void

+ptw32_mcs_node_substitute (ptw32_mcs_local_node_t * new_node, ptw32_mcs_local_node_t * old_node)

+{

+  new_node->lock = old_node->lock;

+  new_node->nextFlag = 0; /* Not needed - used only in initial Acquire */

+  new_node->readyFlag = 0; /* Not needed - we were waiting on this */

+  new_node->next = 0;

+

+  if ((ptw32_mcs_local_node_t *)PTW32_INTERLOCKED_COMPARE_EXCHANGE((PTW32_INTERLOCKED_LPLONG)new_node->lock,

+                                                                   (PTW32_INTERLOCKED_LONG)new_node,

+                                                                   (PTW32_INTERLOCKED_LONG)old_node) != old_node)

+    {

+      /*

+       * A successor has queued after us, so wait for them to link to us

+       */

+      while (old_node->next == 0)

+        {

+          Sleep(0);

+        }

+      new_node->next = old_node->next;

+    }

+}