The R13B03 release.OTP_R13B03

1 files changed, 164 insertions, 0 deletions

diff --git a/lib/erl_interface/src/misc/ei_locking.c b/lib/erl_interface/src/misc/ei_locking.c
new file mode 100644
index 0000000000..e3f57d5ba2
--- /dev/null
+++ b/lib/erl_interface/src/misc/ei_locking.c
@@ -0,0 +1,164 @@
+/*
+ * %CopyrightBegin%
+ * 
+ * Copyright Ericsson AB 1997-2009. All Rights Reserved.
+ * 
+ * The contents of this file are subject to the Erlang Public License,
+ * Version 1.1, (the "License"); you may not use this file except in
+ * compliance with the License. You should have received a copy of the
+ * Erlang Public License along with this software. If not, it can be
+ * retrieved online at http://www.erlang.org/.
+ * 
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ * 
+ * %CopyrightEnd%
+ *
+
+ */
+/* 
+ * common interface to some simple synchronisation primitives for
+ * internal use by ei.
+ */
+
+/* Note that these locks are NOT recursive on Win32 or Solaris,
+ * i.e. self-deadlock will occur if a thread tries to obtain a lock it
+ * is already holding. The primitives used on VxWorks are recursive however.
+ */
+
+#include "eidef.h"
+
+#ifdef __WIN32__
+#include <winsock2.h>
+#include <windows.h>
+#include <winbase.h>
+
+#elif VXWORKS
+#include <vxWorks.h>
+#include <semLib.h>
+
+#else /* unix */
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+#endif /* platforms */
+
+#include "ei_malloc.h"
+#include "ei_locking.h"
+
+#ifdef _REENTRANT
+
+/* 
+ * Create a new mutex object. 
+ * Returns a pointer to the mutex if successful, NULL otherwise.
+ */
+ei_mutex_t *ei_mutex_create(void)
+{
+    ei_mutex_t *l;
+
+    if ((l = ei_malloc(sizeof(*l))) == NULL) return NULL;
+
+#ifdef __WIN32__
+  l->lock = CreateMutex(NULL,FALSE,NULL);
+
+#elif VXWORKS
+  if (!(l->lock = semMCreate(SEM_DELETE_SAFE))) {
+    ei_free(l);
+    return NULL;
+  }
+#else /* unix */
+  l->lock = ei_m_create();
+#endif
+
+  return l;
+}
+
+/* 
+ * Free a mutex and the structure asociated with it.
+ *
+ * This function attempts to obtain the mutex before releasing it;
+ * If nblock == 1 and the mutex was unavailable, the function will
+ * return failure and the mutex will not have been removed.
+ *
+ * If nblock == 0 the function will block until the mutex becomes
+ * available, at which time it will be removed and the function will
+ * succeed.
+ *
+ * returns 0 if the mutex is removed, -1 on failure (busy) 
+ */
+int ei_mutex_free(ei_mutex_t *l, int nblock)
+{
+  /* attempt to lock it first, to make sure it's really free */
+  if (ei_mutex_lock(l,nblock)) return -1; /* attempt failed */
+    
+  /* we are now holding the lock */
+#ifdef __WIN32__
+  CloseHandle(l->lock);
+
+#elif VXWORKS
+  if (semDelete(l->lock) == ERROR) return -1;
+
+#else /* unix */
+  ei_m_destroy(l->lock);
+#endif
+
+  ei_free(l);
+
+  return 0;
+}
+
+/* Grab a mutex. If the mutex is not held by any other process the
+ * function returns so that the caller may enter a critical section.
+ * Processes subsequently wishing to obtain the lock will block 
+ * until this process releases it.
+ *
+ * If the mutex is busy (held by some other process) and nblock == 0,
+ * the function will block until the mutex is freed by the process
+ * holding it, returning only when the mutex has been grabbed.
+ *
+ * If the mutex is busy and nblock != 0, the function will not block.
+ * Instead it will return -1 immediately, indicating that the
+ * operation failed. 
+
+ * Returns 0 on success, -1 on failure.
+ */
+int ei_mutex_lock(ei_mutex_t *l, int nblock)
+{
+#ifdef __WIN32__
+  /* check valid values for timeout: is 0 ok? */
+  if (WaitForSingleObject(l->lock,(nblock? 0 : INFINITE)) != WAIT_OBJECT_0) 
+    return -1; 
+
+#elif VXWORKS
+  if (semTake(l->lock,(nblock? NO_WAIT : WAIT_FOREVER)) == ERROR)
+    return -1;
+
+#else /* unix */
+  if (nblock) {
+    if (ei_m_trylock(l->lock) < 0) return -1;
+  }
+  else ei_m_lock(l->lock);
+#endif
+
+  return 0;
+}
+
+/* Release a mutex */
+int ei_mutex_unlock(ei_mutex_t *l)
+{
+#ifdef __WIN32__
+  ReleaseMutex(l->lock);
+
+#elif VXWORKS
+  semGive(l->lock);
+
+#else /* unix */
+  ei_m_unlock(l->lock);
+#endif
+
+  return 0;
+}
+
+#endif /* _REENTRANT */