*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/include/storage/s_lock.h,v 1.31 1998/05/04 02:02:06 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/include/storage/s_lock.h,v 1.32 1998/05/04 16:58:59 scrappy Exp $
*
*-------------------------------------------------------------------------
*/
/*
* DESCRIPTION
- * The public functions that must be provided are:
+ * The public functions that must be provided are:
*
- * void S_INIT_LOCK(slock_t *lock)
+ * void S_INIT_LOCK(slock_t *lock)
*
* void S_LOCK(slock_t *lock)
*
- * void S_UNLOCK(slock_t *lock)
+ * void S_UNLOCK(slock_t *lock)
*
- * int S_LOCK_FREE(slock_t *lock)
- * Tests if the lock is free. Returns non-zero if free, 0 if locked.
+ * void S_LOCK_FREE(slock_t *lock)
+ * Tests if the lock is free. Returns non-zero if free, 0 if locked.
*
- * The S_LOCK() function (in s_lock.c) implements a primitive but
- * still useful random backoff to avoid hordes of busywaiting lockers
- * chewing CPU.
+ * The S_LOCK() macro implements a primitive but still useful random
+ * backoff to avoid hordes of busywaiting lockers chewing CPU.
*
+ * Effectively:
* void
* S_LOCK(slock_t *lock)
* {
- * while (TAS(lock))
- * {
+ * while (TAS(lock))
+ * {
* // back off the cpu for a semi-random short time
- * }
+ * }
* }
*
- * This implementation takes advantage of a tas function written
- * (in assembly language) on machines that have a native test-and-set
- * instruction. Alternative mutex implementations may also be used.
+ * This implementation takes advantage of a tas function written
+ * (in assembly language) on machines that have a native test-and-set
+ * instruction. Alternative mutex implementations may also be used.
* This function is hidden under the TAS macro to allow substitutions.
*
* #define TAS(lock) tas(lock)
* override them.
*
*/
-#ifndef S_LOCK_H
+#if !defined(S_LOCK_H)
#define S_LOCK_H
#include "storage/ipc.h"
#define S_UNLOCK(lock) { __asm__("mb"); *(lock) = 0; }
-#endif /* defined(__alpha__) && defined(linux) */
+#endif /* __alpha__ */
-#else /* defined(linux) */
+#else /* linux */
/***************************************************************************
* All non Linux
*/
-#endif
#if defined (nextstep)
/*
/* For Mach, we have to delve inside the entrails of `struct mutex'. Ick! */
#define S_LOCK_FREE(alock) ((alock)->lock == 0)
-#endif /* nextstep */
+#endif /* nextstep */
* assembly from his NECEWS SVR4 port, but we probably ought to retain this
* for the R3000 chips out there.
*/
-#define S_LOCK(lock) do \
- { \
- while (!acquire_lock(lock)) \
- ; \
- } while (0)
+#define TAS(lock) (!acquire_lock(lock))
#define S_UNLOCK(lock) release_lock(lock)
#define S_INIT_LOCK(lock) init_lock(lock)
-/* S_LOCK_FREE should return 1 if lock is free; 0 if lock is locked */
-
#define S_LOCK_FREE(lock) (stat_lock(lock) == UNLOCKED)
-#endif /* __sgi */
+#endif /* __sgi */
+
+#if (defined(__alpha__)
/*
* OSF/1 (Alpha AXP)
*
* Note that slock_t on the Alpha AXP is msemaphore instead of char
* (see storage/ipc.h).
*/
-
-#if defined(__alpha) && !defined(linux)
-
-#define S_LOCK(lock) do \
- { \
- while (msem_lock((lock), MSEM_IF_NOWAIT) < 0) \
- ; \
- } while (0)
+#define TAS(lock) (msem_lock((lock), MSEM_IF_NOWAIT) < 0)
#define S_UNLOCK(lock) msem_unlock((lock), 0)
#define S_LOCK_FREE(lock) (!(lock)->msem_state)
-#endif /* alpha */
-
-/*
- * Solaris 2
- */
-
-#if (defined(__i386__) || defined(__sparc__)) && defined(__sun__)
-/* for xxxxx_solaris, this is defined in port/.../tas.s */
+#endif /* __alpha__ */
-static int tas(slock_t *lock);
-#define S_LOCK(lock) do \
- { \
- while (tas(lock)) \
- ; \
- } while (0)
-
-#define S_UNLOCK(lock) (*(lock) = 0)
-
-#define S_INIT_LOCK(lock) S_UNLOCK(lock)
-
-#endif /* i86pc_solaris || sparc_solaris */
+#if defined(_AIX)
/*
* AIX (POWER)
*
* Note that slock_t on POWER/POWER2/PowerPC is int instead of char
* (see storage/ipc.h).
*/
+#define TAS(lock) cs((int *) (lock), 0, 1)
-#if defined(_AIX)
-
-#define S_LOCK(lock) do \
- { \
- while (cs((int *) (lock), 0, 1)) \
- ; \
- } while (0)
+#endif /* _AIX */
-#define S_UNLOCK(lock) (*(lock) = 0)
-#define S_INIT_LOCK(lock) S_UNLOCK(lock)
-
-#endif /* _AIX */
+#if defined(__hpux)
/*
* HP-UX (PA-RISC)
*
* Note that slock_t on PA-RISC is a structure instead of char
* (see storage/ipc.h).
+ *
+ * a "set" slock_t has a single word cleared. a "clear" slock_t has
+ * all words set to non-zero. tas() in tas.s
*/
-
-#if defined(__hpux)
-
-/*
-* a "set" slock_t has a single word cleared. a "clear" slock_t has
-* all words set to non-zero.
-*/
-static slock_t clear_lock = {-1, -1, -1, -1};
-
-static int tas(slock_t *lock);
-
-#define S_LOCK(lock) do \
- { \
- while (tas(lock)) \
- ; \
- } while (0)
+static slock_t clear_lock =
+{-1, -1, -1, -1};
#define S_UNLOCK(lock) (*(lock) = clear_lock) /* struct assignment */
-#define S_INIT_LOCK(lock) S_UNLOCK(lock)
-
#define S_LOCK_FREE(lock) ( *(int *) (((long) (lock) + 15) & ~15) != 0)
-#endif /* __hpux */
+#endif /* __hpux */
-/*
- * sun3
- */
-
-#if defined(sun3)
-static int tas(slock_t *lock);
-#define S_LOCK(lock) do \
- { \
- while (tas(lock)) \
- ; \
- } while (0)
+#endif /* else defined(linux) */
-#define S_UNLOCK(lock) (*(lock) = 0)
-#define S_INIT_LOCK(lock) S_UNLOCK(lock)
-static int
-tas_dummy()
-{
- asm("LLA0:");
- asm(" .data");
- asm(" .text");
- asm("|#PROC# 04");
- asm(" .globl _tas");
- asm("_tas:");
- asm("|#PROLOGUE# 1");
- asm(" movel sp@(0x4),a0");
- asm(" tas a0@");
- asm(" beq LLA1");
- asm(" moveq #-128,d0");
- asm(" rts");
- asm("LLA1:");
- asm(" moveq #0,d0");
- asm(" rts");
- asm(" .data");
-}
-
-#endif /* sun3 */
-/*
- * sparc machines
- */
-
-#if defined(NEED_SPARC_TAS_ASM)
-
-/* if we're using -ansi w/ gcc, use __asm__ instead of asm */
-#if defined(__STRICT_ANSI__)
-#define asm(x) __asm__(x)
-#endif
-
-static int tas(slock_t *lock);
-
-static void
-tas_dummy()
-{
- asm(".seg \"data\"");
- asm(".seg \"text\"");
- asm("_tas:");
-
- /*
- * Sparc atomic test and set (sparc calls it "atomic load-store")
- */
-
- asm("ldstub [%r8], %r8");
-
- /*
- * Did test and set actually do the set?
- */
-
- asm("tst %r8");
-
- asm("be,a ReturnZero");
-
- /*
- * otherwise, just return.
- */
-
- asm("clr %r8");
- asm("mov 0x1, %r8");
- asm("ReturnZero:");
- asm("retl");
- asm("nop");
-}
-
-#define S_LOCK(addr) do \
- { \
- while (tas(addr)) \
- ; \
- } while (0)
-
-/*
- * addr should be as in the above S_LOCK routine
+/****************************************************************************
+ * Default Definitions - override these above as needed.
*/
-#define S_UNLOCK(addr) (*(addr) = 0)
-#define S_INIT_LOCK(addr) (*(addr) = 0)
+#if !defined(S_LOCK)
-#endif /* NEED_SPARC_TAS_ASM */
+#include <sys/time.h>
-/*
- * VAXen -- even multiprocessor ones
- */
+#define S_NSPINCYCLE 16
+#define S_MAX_BUSY 1000 * S_NSPINCYCLE
-#if defined(NEED_VAX_TAS_ASM)
+extern int s_spincycle[];
+extern void s_lock_stuck(slock_t *lock, char *file, int line);
-#define S_LOCK(addr) __asm__("1: bbssi $0,(%0),1b": :"r"(addr))
-#define S_UNLOCK(addr) (*(addr) = 0)
-#define S_INIT_LOCK(addr) (*(addr) = 0)
+#if defined(S_LOCK_DEBUG)
-#endif /* NEED_VAX_TAS_ASM */
+extern void s_lock(slock_t *lock);
-/*
- * i386 based things
- */
+#define S_LOCK(lock) s_lock(lock, __FILE__, __LINE__)
-#if defined(NEED_I386_TAS_ASM)
-
-#if defined(USE_UNIVEL_CC)
-asm void
-S_LOCK(char *lval)
-{
-% lab again;
-/* Upon entry, %eax will contain the pointer to the lock byte */
- pushl %ebx
- xchgl %eax, %ebx
- movb $255, %al
-again:
- lock
- xchgb %al, (%ebx)
- cmpb $0, %al
- jne again
- popl %ebx
-}
-
-#else
-#define S_LOCK(lock) do \
- { \
- slock_t _res; \
- do \
- { \
- __asm__("lock; xchgb %0,%1": "=q"(_res), "=m"(*lock):"0"(0x1)); \
- } while (_res != 0); \
- } while (0)
-#endif
-
-#define S_UNLOCK(lock) (*(lock) = 0)
+#else /* S_LOCK_DEBUG */
-#define S_INIT_LOCK(lock) S_UNLOCK(lock)
+#define S_LOCK(lock) if (1) { \
+ int spins = 0; \
+ while (TAS(lock)) { \
+ struct timeval delay; \
+ delay.tv_sec = 0; \
+ delay.tv_usec = s_spincycle[spins++ % S_NSPINCYCLE]; \
+ (void) select(0, NULL, NULL, NULL, &delay); \
+ if (spins > S_MAX_BUSY) { \
+ /* It's been well over a minute... */ \
+ s_lock_stuck(lock, __FILE__, __LINE__); \
+ } \
+ } \
+} else
-#endif /* NEED_I386_TAS_ASM */
+#endif /* S_LOCK_DEBUG */
+#endif /* S_LOCK */
-#if defined(__alpha) && defined(linux)
-void S_LOCK(slock_t *lock);
+#if !defined(S_LOCK_FREE)
+#define S_LOCK_FREE(lock) ((*lock) == 0)
+#endif /* S_LOCK_FREE */
-#define S_UNLOCK(lock) { __asm__("mb"); *(lock) = 0; }
+#if !defined(S_UNLOCK)
+#define S_UNLOCK(lock) (*(lock) = 0)
+#endif /* S_UNLOCK */
+#if !defined(S_INIT_LOCK)
#define S_INIT_LOCK(lock) S_UNLOCK(lock)
+#endif /* S_INIT_LOCK */
-#endif /* defined(__alpha) && defined(linux) */
-
-#if defined(linux) && defined(sparc)
-
-#define S_LOCK(lock) do \
- { \
- slock_t _res; \
- slock_t *tmplock = lock ; \
- do \
- { \
- __asm__("ldstub [%1], %0" \
- : "=&r"(_res), "=r"(tmplock) \
- : "1"(tmplock)); \
- } while (_res != 0); \
- } while (0)
-
-#define S_UNLOCK(lock) (*(lock) = 0)
-
-#define S_INIT_LOCK(lock) S_UNLOCK(lock)
-
-#endif /* defined(linux) && defined(sparc) */
-
-#if defined(linux) && defined(PPC)
-
-static int
-tas_dummy()
-{
- __asm__(" \n\
-tas: \n\
- lwarx 5,0,3 \n\
- cmpwi 5,0 \n\
- bne fail \n\
- addi 5,5,1 \n\
- stwcx. 5,0,3 \n\
- beq success \n\
-fail: li 3,1 \n\
- blr \n\
-success: \n\
- li 3,0 \n\
- blr \n\
- ");
-}
-
-#define S_LOCK(lock) do \
- { \
- while (tas(lock)) \
- ; \
- } while (0)
-
-#define S_UNLOCK(lock) (*(lock) = 0)
-
-#define S_INIT_LOCK(lock) S_UNLOCK(lock)
+#if !defined(TAS)
+int tas(slock_t *lock); /* port/.../tas.s, or s_lock.c */
-#endif /* defined(linux) && defined(PPC) */
+#define TAS(lock) tas(lock)
+#endif /* TAS */
-#ifndef S_LOCK_FREE /* for those who have not already defined
- * it */
-#define S_LOCK_FREE(lock) ((*lock) == 0)
-#endif
-#endif /* HAS_TEST_AND_SET */
+#endif /* HAS_TEST_AND_SET */
-#endif /* S_LOCK_H */
+#endif /* S_LOCK_H */
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