dyld-851.27.tar.gz

[apple/dyld.git] / src / dyldLock.h

diff --git a/src/dyldLock.h b/src/dyldLock.h
index d6291fbb5a7cebb99347dfd162baf9d10c1a56f8..461012d6841d0d51c27d7b28b031a3ea0b118ae1 100644 (file)
--- a/src/dyldLock.h
+++ b/src/dyldLock.h
@@ -1,6 +1,6 @@
 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
  *
- * Copyright (c) 2004-2005 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2004-2012 Apple Inc. All rights reserved.
  *
  * @APPLE_LICENSE_HEADER_START@
  * 
@@ -27,26 +27,17 @@
 #define __DYLDLOCK__
 
 //
-// This file contains the syncronization utilities used by dyld to be thread safe.
-// Access to all dyld data structures is protected by a reader-writer lock.
-// This lock allows multiple "reader" threads to access dyld data structures at
-// the same time.  If there is a "writer" thread, it is the only thread allowed
-// access to dyld data structures.  
+// This file contains the synchronization utilities used to make dyld APIs be thread safe.
 //
-// The implementation of all dyld API's must acquire the global lock around accesses
-// to dyld's data structures.  This is done using the macros DYLD_*_LOCK_THIS_BLOCK.
+// The implementation of all dyld API's must hold acquire global lock (in libSystem)
+// before calling into dyld proper, and release the lock after returning from dyld.
+// This is done using the macros DYLD_LOCK_THIS_BLOCK.
 // Example:
 //
-//  void dyld_api_modifying_dyld() {
-//             DYLD_WRITER_LOCK_THIS_BLOCK;
+//  void dyld_api() {
+//             DYLD_LOCK_THIS_BLOCK;
 //             // free to do stuff here 
-//             // that modifies dyld data structures
-//     }
-//
-//  void dyld_api_examinging_dyld() {
-//             DYLD_READER_LOCK_THIS_BLOCK
-//             // can only do stuff here 
-//             // that examines but does not modify dyld data structures
+//             // that accesses dyld internal data structures
 //     }
 //
 //  void dyld_api_state_free() {
@@ -56,32 +47,22 @@
 //     }
 //
 
-
-#define DYLD_READER_LOCK_THIS_BLOCK            LockReaderHelper _dyld_lock;
-#define DYLD_WRITER_LOCK_THIS_BLOCK            LockWriterHelper _dyld_lock;
+#define DYLD_LOCK_THIS_BLOCK                   LockHelper _dyld_lock;
 #define DYLD_NO_LOCK_THIS_BLOCK
 
 // used by dyld wrapper functions in libSystem
-class LockReaderHelper
-{
-public:
-       LockReaderHelper() __attribute__((visibility("hidden")));
-       ~LockReaderHelper() __attribute__((visibility("hidden")));
-};
-
-// used by dyld wrapper functions in libSystem
-class LockWriterHelper
+class __attribute__((visibility("hidden"))) LockHelper
 {
 public:
-       LockWriterHelper() __attribute__((visibility("hidden")));
-       ~LockWriterHelper() __attribute__((visibility("hidden")));
+       LockHelper();
+       ~LockHelper();
 };
 
-// used by lazy binding
-extern void lockForLazyBinding() __attribute__((visibility("hidden")));
-extern void unlockForLazyBinding() __attribute__((visibility("hidden")));
-
 
+// to initialize
+extern void dyldGlobalLockInitialize()         __attribute__((visibility("hidden")));
+extern void dyldGlobalLockAcquire()                    __attribute__((visibility("hidden")));
+extern void dyldGlobalLockRelease()                    __attribute__((visibility("hidden")));
 
 #endif // __DYLDLOCK__