1 files changed, 147 insertions, 0 deletions
diff --git a/pthreads/ptw32_reuse.c b/pthreads/ptw32_reuse.c
new file mode 100644
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+++ b/pthreads/ptw32_reuse.c
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+/*
+ * ptw32_threadReuse.c
+ *
+ * Description:
+ * This translation unit implements miscellaneous thread functions.
+ *
+ * --------------------------------------------------------------------------
+ *
+ *      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
+ */
+
+#include "pthread.h"
+#include "implement.h"
+
+
+/*
+ * How it works:
+ * A pthread_t is a struct (2x32 bit scalar types on IA-32, 2x64 bit on IA-64)
+ * which is normally passed/returned by value to/from pthreads routines.
+ * Applications are therefore storing a copy of the struct as it is at that
+ * time.
+ *
+ * The original pthread_t struct plus all copies of it contain the address of
+ * the thread state struct ptw32_thread_t_ (p), plus a reuse counter (x). Each
+ * ptw32_thread_t contains the original copy of it's pthread_t.
+ * Once malloced, a ptw32_thread_t_ struct is not freed until the process exits.
+ * 
+ * The thread reuse stack is a simple LILO stack managed through a singly
+ * linked list element in the ptw32_thread_t.
+ *
+ * Each time a thread is destroyed, the ptw32_thread_t address is pushed onto the
+ * reuse stack after it's ptHandle's reuse counter has been incremented.
+ * 
+ * The following can now be said from this:
+ * - two pthread_t's are identical if their ptw32_thread_t reference pointers
+ * are equal and their reuse counters are equal. That is,
+ *
+ *   equal = (a.p == b.p && a.x == b.x)
+ *
+ * - a pthread_t copy refers to a destroyed thread if the reuse counter in
+ * the copy is not equal to the reuse counter in the original.
+ *
+ *   threadDestroyed = (copy.x != ((ptw32_thread_t *)copy.p)->ptHandle.x)
+ *
+ */
+
+/*
+ * Pop a clean pthread_t struct off the reuse stack.
+ */
+pthread_t
+ptw32_threadReusePop (void)
+{
+  pthread_t t = {NULL, 0};
+
+  EnterCriticalSection (&ptw32_thread_reuse_lock);
+
+  if (PTW32_THREAD_REUSE_EMPTY != ptw32_threadReuseTop)
+    {
+      ptw32_thread_t * tp;
+
+      tp = ptw32_threadReuseTop;
+
+      ptw32_threadReuseTop = tp->prevReuse;
+
+      if (PTW32_THREAD_REUSE_EMPTY == ptw32_threadReuseTop)
+        {
+          ptw32_threadReuseBottom = PTW32_THREAD_REUSE_EMPTY;
+        }
+
+      tp->prevReuse = NULL;
+
+      t = tp->ptHandle;
+    }
+
+  LeaveCriticalSection (&ptw32_thread_reuse_lock);
+
+  return t;
+
+}
+
+/*
+ * Push a clean pthread_t struct onto the reuse stack.
+ * Must be re-initialised when reused.
+ * All object elements (mutexes, events etc) must have been either
+ * detroyed before this, or never initialised.
+ */
+void
+ptw32_threadReusePush (pthread_t thread)
+{
+  ptw32_thread_t * tp = (ptw32_thread_t *) thread.p;
+  pthread_t t;
+
+  EnterCriticalSection (&ptw32_thread_reuse_lock);
+
+  t = tp->ptHandle;
+  memset(tp, 0, sizeof(ptw32_thread_t));
+
+  /* Must restore the original POSIX handle that we just wiped. */
+  tp->ptHandle = t;
+
+  /* Bump the reuse counter now */
+#ifdef PTW32_THREAD_ID_REUSE_INCREMENT
+  tp->ptHandle.x += PTW32_THREAD_ID_REUSE_INCREMENT;
+#else
+  tp->ptHandle.x++;
+#endif
+
+  tp->prevReuse = PTW32_THREAD_REUSE_EMPTY;
+
+  if (PTW32_THREAD_REUSE_EMPTY != ptw32_threadReuseBottom)
+    {
+      ptw32_threadReuseBottom->prevReuse = tp;
+    }
+  else
+    {
+      ptw32_threadReuseTop = tp;
+    }
+
+  ptw32_threadReuseBottom = tp;
+
+  LeaveCriticalSection (&ptw32_thread_reuse_lock);
+}