rewrite to use the helpers in the thread/ directory and to define weak alias macros

1 files changed, 91 insertions, 135 deletions

diff --git a/lib/libc/include/thread_private.h b/lib/libc/include/thread_private.h
index 0027468269b..b2677fad0e0 100644
--- a/lib/libc/include/thread_private.h
+++ b/lib/libc/include/thread_private.h
@@ -1,179 +1,135 @@
-/*
- *
- * Support for thread-safety in libc and libc_r common code using macros 
- * to declare thread-safe data structures.
- *
- * $OpenBSD: thread_private.h,v 1.2 1999/01/06 05:19:32 d Exp $
- */
+/* $OpenBSD: thread_private.h,v 1.3 2000/01/06 07:47:09 d Exp $ */
 
 #ifndef _THREAD_PRIVATE_H_
 #define _THREAD_PRIVATE_H_
 
-/*
- * Parts of this file are
- * Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>.
- * All rights reserved.
- *
- * $Id: thread_private.h,v 1.2 1999/01/06 05:19:32 d Exp $
- * $OpenBSD: thread_private.h,v 1.2 1999/01/06 05:19:32 d Exp $
- */
+#include <pthread.h>
 
 /*
- * This global flag is non-zero when a process has created one
- * or more threads. It is used to avoid calling locking functions
- * when they are not required. In libc, this is always assumed
- * to be zero.
+ * This variable is initally 0 when there is exactly one thread.
+ * It should never decrease.
  */
-
-extern volatile int	__isthreaded;
-
-#ifdef _THREAD_SAFE
-
-#include <pthread.h>
-#include "pthread_private.h"
+extern int __isthreaded;
 
 /*
- * File lock contention is difficult to diagnose without knowing
- * where locks were set. Allow a debug library to be built which
- * records the source file and line number of each lock call.
+ * Weak symbols are used in libc so that the thread library can
+ * efficiently wrap libc functions.
+ * 
+ * Use WEAK_NAME(n) to get a libc-private name for n (_weak_n),
+ *     WEAK_ALIAS(n) to generate the weak symbol n pointing to _weak_n,
+ *     WEAK_PROTOTYPE(n) to generate a prototype for _weak_n (based on n).
+ *
+ * If the symbol _NO_WEAK_ALIASES is defined, then symbols will be
  */
-#ifdef	_FLOCK_DEBUG
-#define _FLOCKFILE(x)	_flockfile_debug(x, __FILE__, __LINE__)
+
+#ifdef _NO_WEAK_ALIASES
+#defined _THREAD_SAFE
+#define WEAK_NAME(name)			__CONCAT(_weak,name)
+#else
+#define WEAK_NAME(name)			name
+#endif
+#define WEAK_ALIAS(name)		/* unavailable */
+#define WEAK_PROTOTYPE(name)		/* unnecessary */
+#else /* !_NO_WEAK_AILASES */
+#define WEAK_NAME(name)			__CONCAT(_weak_,name)
+#define WEAK_ALIAS(name)		__weak_alias(name, WEAK_NAME(name))
+#ifdef __GNUC__
+#define WEAK_PROTOTYPE(name)		__typeof__(name) WEAK_NAME(name)
 #else
-#define _FLOCKFILE(x)	flockfile(x)
+#define WEAK_PROTOTYPE(name)		/* typeof() only in gcc */
 #endif
+#endif /* !_NO_WEAK_ALIASES */
 
 /*
  * These macros help in making persistent storage thread-specific.
  * Libc makes extensive use of private static data structures
  * that hold state across function invocation, and these macros
- * are no-ops when _THREAD_SAFE is not defined. 
- * In a thread-safe library, the static variables are used only for
- * initialising the per-thread instances of the state variables.
+ * are no-ops when running single-threaded.
+ *
+ * Linking against the user-thread library causes these macros to
+ * allocate storage on a per-thread basis.
  */
+	
+#define __THREAD_MUTEX_NAME(name)	__CONCAT(_libc_storage_mutex_,name)
+#define __THREAD_KEY_NAME(name)		__CONCAT(_libc_storage_key_,name)
 
-/*
- * Give names to the private variables used to hold per-thread
- * data structures.
- */
-#ifdef __STDC__
-#define __THREAD_MUTEXP_NAME(name)	_thread_mutexp_inst__ ## name
-#define __THREAD_MUTEX_NAME(name)	_thread_mutex_inst__ ## name
-#define __THREAD_KEY_NAME(name)		_thread_key_inst__ ## name
-#else
-#define __THREAD_MUTEXP_NAME(name)	_thread_mutexp_inst__/**/name
-#define __THREAD_MUTEX_NAME(name)	_thread_mutex_inst__/**/name
-#define __THREAD_KEY_NAME(name)		_thread_key_inst__/**/name
-#endif
+struct _thread_private_key_struct {
+	pthread_once_t		once;
+	void			(*cleanfn)__P((void *));
+	pthread_key_t		key;
+};
 
-/*
- * Mutex declare, lock and unlock macros.
- */
+void	_libc_private_storage_lock(pthread_mutex_t *);
+void	_libc_private_storage_unlock(pthread_mutex_t *);
+void *	_libc_private_storage(volatile struct _thread_private_key_struct *,
+	void *, size_t, void *);
+
+/* Declare a module mutex. */
 #define _THREAD_PRIVATE_MUTEX(name)					\
-	static struct pthread_mutex __THREAD_MUTEXP_NAME(name) =	\
-		PTHREAD_MUTEX_STATIC_INITIALIZER;			\
 	static pthread_mutex_t __THREAD_MUTEX_NAME(name) = 		\
-		&__THREAD_MUTEXP_NAME(name);
+		PTHREAD_MUTEX_INITIALIZER			
 		
+/* Lock a module mutex against use by any other threads. */
 #define _THREAD_PRIVATE_MUTEX_LOCK(name) 				\
-	pthread_mutex_lock(&__THREAD_MUTEX_NAME(name))
+	_libc_private_storage_lock(&__THREAD_MUTEX_NAME(name))
 		
+/* Unlock a module mutex. */
 #define _THREAD_PRIVATE_MUTEX_UNLOCK(name) 				\
-	pthread_mutex_unlock(&__THREAD_MUTEX_NAME(name))
+	_libc_private_storage_unlock(&__THREAD_MUTEX_NAME(name))
 
-/*
- * A mutexed data structure used to hold the persistent state's key.
- */
-struct _thread_private_key_struct {
-	struct pthread_mutex	lockd;
-	pthread_mutex_t		lock;
-	int			init;
-	pthread_key_t		key;
-};
-
-/*
- * Declaration of a per-thread state key.
- */
+/* Declare a thread-private storage key. */
 #define _THREAD_PRIVATE_KEY(name)					\
 	static volatile struct _thread_private_key_struct		\
 	__THREAD_KEY_NAME(name) = {					\
-		PTHREAD_MUTEX_STATIC_INITIALIZER, 			\
-		&__THREAD_KEY_NAME(name).lockd,				\
+		PTHREAD_ONCE_INIT, 					\
 		0							\
-	};
+	}
 
 /*
- * Initialisation of storage space for a per-thread state variable.
- * A pointer to a per-thread *copy* of the _initv parameter is returned.
- * It calls malloc the first time and the space is automatically free'd
- * when the thread dies. If you need something a bit more complicated
- * than free() you will need to roll-your-own.
+ * In threaded mode, return a pointer to thread-private memory of
+ * the same size as, and (initially) with the same contents as 'storage'. If
+ * an error occurs, the 'error' parameter is returned.
+ * In single-threaded mode, no storage is allocated. Instead, a pointer
+ * to storage is always returned.
+ * The 'cleanfn' function of the key structure is called to free the storage.
+ * If 'cleanfn' is NULL, then free() is used. This hook can be useful for
+ * getting rid of memory leaks.
  */
-#define _THREAD_PRIVATE(keyname, _initv, _errv) 			\
-	({								\
-		struct _thread_private_key_struct * __k = 		\
-			&__THREAD_KEY_NAME(keyname);			\
-		void* __p;						\
-		extern void free __P((void*));				\
-		extern void* malloc __P((size_t));			\
-									\
-		if (!__isthreaded) {					\
-			/* non-threaded behaviour */			\
-			__p = &(_initv);				\
-			goto _ok;					\
-		}							\
-									\
-		/* create key for first thread */			\
-		pthread_mutex_lock(&__k->lock);				\
-		if (__k->init == 0) {					\
-			if (pthread_key_create(&__k->key, free)) {	\
-				pthread_mutex_unlock(&__k->lock);	\
-				goto _err;				\
-			}						\
-			__k->init = 1;					\
-		}							\
-		pthread_mutex_unlock(&__k->lock);			\
-									\
-		if ((__p = pthread_getspecific(__k->key)) == NULL) {	\
-			/* alloc space on 1st call in this thread */	\
-			if ((__p = malloc(sizeof(_initv))) == NULL) 	\
-				goto _err;				\
-				if (pthread_setspecific(__k->key, __p) != 0) { \
-					free(__p);			\
-					goto _err;			\
-				}					\
-			/* initialise with _initv */			\
-		memcpy(__p, &_initv, sizeof(_initv));			\
-		}							\
-		goto _ok;						\
-	_err:								\
-		__p = (_errv);						\
-	_ok:								\
-		__p;							\
-	})
+#define _THREAD_PRIVATE(keyname, storage, error) 			\
+	_libc_private_storage(&__THREAD_KEY_NAME(keyname),		\
+		&(storage), sizeof (storage), error)
 
 /*
  * Macros for locking and unlocking FILEs. These test if the
  * process is threaded to avoid locking when not required.
  */
-#define	FLOCKFILE(fp)		if (__isthreaded) _FLOCKFILE(fp)
-#define	FUNLOCKFILE(fp)		if (__isthreaded) funlockfile(fp)
-
-#else /* !_THREAD_SAFE */
+#ifdef	_FLOCK_DEBUG
+#define FLOCKFILE(fp)		_flockfile_debug(fp, __FILE__, __LINE__)
+#else
+#define FLOCKFILE(fp)		flockfile(fp)
+#endif
+#define	FUNLOCKFILE(fp)		funlockfile(fp)
 
 /*
- * Do-nothing macros for single-threaded case.
+ * File descriptor locking definitions.
  */
-#define _FD_LOCK(f,o,p)				(0)
-#define _FD_UNLOCK(f,o)				/* nothing */
-#define _THREAD_PRIVATE_KEY(_key)		/* nothing */
-#define _THREAD_PRIVATE(keyname, _initv, _errv)	(&(_initv))
-#define _THREAD_PRIVATE_MUTEX(_name)		/* nothing */
-#define _THREAD_PRIVATE_MUTEX_LOCK(_name)	/* nothing */
-#define _THREAD_PRIVATE_MUTEX_UNLOCK(_name)	/* nothing */
-#define	FLOCKFILE(fp)				/* nothing */
-#define	FUNLOCKFILE(fp)				/* nothing */
-
-#endif /* !_THREAD_SAFE */
+#define FD_READ		    0x1
+#define FD_WRITE	    0x2
+#define FD_RDWR		    (FD_READ | FD_WRITE)
+
+#ifdef	_LOCK_DEBUG
+#define _FD_LOCK(_fd,_type,_ts)		_thread_fd_lock_debug(_fd, _type, \
+						_ts, __FILE__, __LINE__)
+#define _FD_UNLOCK(_fd,_type)		_thread_fd_unlock_debug(_fd, _type, \
+						__FILE__, __LINE__)
+#else
+#define _FD_LOCK(_fd,_type,_ts)		_thread_fd_lock(_fd, _type, _ts)
+#define _FD_UNLOCK(_fd,_type)		_thread_fd_unlock(_fd, _type)
+#endif
+
+int	_thread_fd_lock(int, int, struct timespec *);
+int	_thread_fd_lock_debug(int, int, struct timespec *, const char *, int);
+void	_thread_fd_unlock(int, int);
+void	_thread_fd_unlock_debug(int, int, const char *, int);
 
 #endif _THREAD_PRIVATE_H_