X-Git-Url: http://ftp.carnet.hr/carnet-debian/scm?a=blobdiff_plain;f=pgsql_s_lock.c;fp=pgsql_s_lock.c;h=0000000000000000000000000000000000000000;hb=a34ea625346aecd2d2b227b8ca4f114eaa607213;hp=cfcd036cd0fe092853e8831b850ee7ec8de9e77e;hpb=b0895ef8074c6dd090f9b0a65d58179941541756;p=php5-apc.git diff --git a/pgsql_s_lock.c b/pgsql_s_lock.c deleted file mode 100644 index cfcd036..0000000 --- a/pgsql_s_lock.c +++ /dev/null @@ -1,481 +0,0 @@ -/* - +----------------------------------------------------------------------+ - | APC | - +----------------------------------------------------------------------+ - | Copyright (c) 2008 The PHP Group | - +----------------------------------------------------------------------+ - | This source file is subject to version 3.01 of the PHP license, | - | that is bundled with this package in the file LICENSE, and is | - | available through the world-wide-web at the following url: | - | http://www.php.net/license/3_01.txt | - | If you did not receive a copy of the PHP license and are unable to | - | obtain it through the world-wide-web, please send a note to | - | license@php.net so we can mail you a copy immediately. | - +----------------------------------------------------------------------+ - | The following code was ported from the PostgreSQL project, please | - | see appropriate copyright notices that follow. | - | Initial conversion by Brian Shire | - +----------------------------------------------------------------------+ - - */ - -/* $Id: pgsql_s_lock.c,v 3.2.2.1 2008/05/11 18:57:00 rasmus Exp $ */ - -/*------------------------------------------------------------------------- - * - * s_lock.c - * Hardware-dependent implementation of spinlocks. - * - * - * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group - * Portions Copyright (c) 1994, Regents of the University of California - * - * - * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/storage/lmgr/s_lock.c,v 1.47 2006/10/04 00:29:58 momjian Exp $ - * - *------------------------------------------------------------------------- - */ -/* #include "postgres.h" -- Removed for APC */ - -/* -- Added for APC -- */ -#include "apc.h" -#ifdef APC_SPIN_LOCKS - -#ifdef S_LOCK_TEST -#include -#endif -#ifndef WIN32 -#include -#endif -/* ---- */ - -#include -#include - -/* #include "storage/s_lock.h" -- Removed for APC */ -#include "pgsql_s_lock.h" - -static int spins_per_delay = DEFAULT_SPINS_PER_DELAY; - - -/* -- APC specific additions ------------------------------*/ -/* The following dependencies have been copied from - * other pgsql source files. The original locations - * have been noted. - */ - -/* -- from include/c.h -- */ -#ifndef TRUE -#define TRUE 1 -#endif - -#ifndef FALSE -#define FALSE 0 -#endif - -/* -- from include/pg_config_manual.h -- */ -#define MAX_RANDOM_VALUE (0x7FFFFFFF) - -/* - * Max - * Return the maximum of two numbers. - */ -#define Max(x, y) ((x) > (y) ? (x) : (y)) - -/* -- from include/c.h -- */ -/* - * Min - * Return the minimum of two numbers. - */ -#define Min(x, y) ((x) < (y) ? (x) : (y)) - - -/* -- from backend/port/win32/signal.c -- */ -/* - * pg_usleep --- delay the specified number of microseconds. - * - * NOTE: although the delay is specified in microseconds, the effective - * resolution is only 1/HZ, or 10 milliseconds, on most Unixen. Expect - * the requested delay to be rounded up to the next resolution boundary. - * - * On machines where "long" is 32 bits, the maximum delay is ~2000 seconds. - */ -void -pg_usleep(long microsec) -{ - if (microsec > 0) - { -#ifndef WIN32 - struct timeval delay; - - delay.tv_sec = microsec / 1000000L; - delay.tv_usec = microsec % 1000000L; - (void) select(0, NULL, NULL, NULL, &delay); -#else - SleepEx((microsec < 500 ? 1 : (microsec + 500) / 1000), FALSE); -#endif - } -} - -/* -- End APC specific additions ------------------------------*/ - - -/* - * s_lock_stuck() - complain about a stuck spinlock - */ -static void -s_lock_stuck(volatile slock_t *lock, const char *file, int line) -{ -#if defined(S_LOCK_TEST) - fprintf(stderr, - "\nStuck spinlock (%p) detected at %s:%d.\n", - lock, file, line); - exit(1); -#else - /* -- Removed for APC - elog(PANIC, "stuck spinlock (%p) detected at %s:%d", - lock, file, line); - */ - apc_eprint("Stuck spinlock (%p) detected", lock); -#endif -} - - -/* - * s_lock(lock) - platform-independent portion of waiting for a spinlock. - */ -void -s_lock(volatile slock_t *lock, const char *file, int line) -{ - /* - * We loop tightly for awhile, then delay using pg_usleep() and try again. - * Preferably, "awhile" should be a small multiple of the maximum time we - * expect a spinlock to be held. 100 iterations seems about right as an - * initial guess. However, on a uniprocessor the loop is a waste of - * cycles, while in a multi-CPU scenario it's usually better to spin a bit - * longer than to call the kernel, so we try to adapt the spin loop count - * depending on whether we seem to be in a uniprocessor or multiprocessor. - * - * Note: you might think MIN_SPINS_PER_DELAY should be just 1, but you'd - * be wrong; there are platforms where that can result in a "stuck - * spinlock" failure. This has been seen particularly on Alphas; it seems - * that the first TAS after returning from kernel space will always fail - * on that hardware. - * - * Once we do decide to block, we use randomly increasing pg_usleep() - * delays. The first delay is 1 msec, then the delay randomly increases to - * about one second, after which we reset to 1 msec and start again. The - * idea here is that in the presence of heavy contention we need to - * increase the delay, else the spinlock holder may never get to run and - * release the lock. (Consider situation where spinlock holder has been - * nice'd down in priority by the scheduler --- it will not get scheduled - * until all would-be acquirers are sleeping, so if we always use a 1-msec - * sleep, there is a real possibility of starvation.) But we can't just - * clamp the delay to an upper bound, else it would take a long time to - * make a reasonable number of tries. - * - * We time out and declare error after NUM_DELAYS delays (thus, exactly - * that many tries). With the given settings, this will usually take 2 or - * so minutes. It seems better to fix the total number of tries (and thus - * the probability of unintended failure) than to fix the total time - * spent. - * - * The pg_usleep() delays are measured in milliseconds because 1 msec is a - * common resolution limit at the OS level for newer platforms. On older - * platforms the resolution limit is usually 10 msec, in which case the - * total delay before timeout will be a bit more. - */ -#define MIN_SPINS_PER_DELAY 10 -#define MAX_SPINS_PER_DELAY 1000 -#define NUM_DELAYS 1000 -#define MIN_DELAY_MSEC 1 -#define MAX_DELAY_MSEC 1000 - - int spins = 0; - int delays = 0; - int cur_delay = 0; - - while (TAS(lock)) - { - /* CPU-specific delay each time through the loop */ - SPIN_DELAY(); - - /* Block the process every spins_per_delay tries */ - if (++spins >= spins_per_delay) - { - if (++delays > NUM_DELAYS) - s_lock_stuck(lock, file, line); - - if (cur_delay == 0) /* first time to delay? */ - cur_delay = MIN_DELAY_MSEC; - - pg_usleep(cur_delay * 1000L); - -#if defined(S_LOCK_TEST) - fprintf(stdout, "*"); - fflush(stdout); -#endif - - /* increase delay by a random fraction between 1X and 2X */ - cur_delay += (int) (cur_delay * - ((double) random() / (double) MAX_RANDOM_VALUE) + 0.5); - /* wrap back to minimum delay when max is exceeded */ - if (cur_delay > MAX_DELAY_MSEC) - cur_delay = MIN_DELAY_MSEC; - - spins = 0; - } - } - - /* - * If we were able to acquire the lock without delaying, it's a good - * indication we are in a multiprocessor. If we had to delay, it's a sign - * (but not a sure thing) that we are in a uniprocessor. Hence, we - * decrement spins_per_delay slowly when we had to delay, and increase it - * rapidly when we didn't. It's expected that spins_per_delay will - * converge to the minimum value on a uniprocessor and to the maximum - * value on a multiprocessor. - * - * Note: spins_per_delay is local within our current process. We want to - * average these observations across multiple backends, since it's - * relatively rare for this function to even get entered, and so a single - * backend might not live long enough to converge on a good value. That - * is handled by the two routines below. - */ - if (cur_delay == 0) - { - /* we never had to delay */ - if (spins_per_delay < MAX_SPINS_PER_DELAY) - spins_per_delay = Min(spins_per_delay + 100, MAX_SPINS_PER_DELAY); - } - else - { - if (spins_per_delay > MIN_SPINS_PER_DELAY) - spins_per_delay = Max(spins_per_delay - 1, MIN_SPINS_PER_DELAY); - } -} - - -#if 0 /* -- APC doesn't use the set_spins_per_delay or update_spins_per_delay -- */ -/* - * Set local copy of spins_per_delay during backend startup. - * - * NB: this has to be pretty fast as it is called while holding a spinlock - */ -void -set_spins_per_delay(int shared_spins_per_delay) -{ - spins_per_delay = shared_spins_per_delay; -} - -/* - * Update shared estimate of spins_per_delay during backend exit. - * - * NB: this has to be pretty fast as it is called while holding a spinlock - */ -int -update_spins_per_delay(int shared_spins_per_delay) -{ - /* - * We use an exponential moving average with a relatively slow adaption - * rate, so that noise in any one backend's result won't affect the shared - * value too much. As long as both inputs are within the allowed range, - * the result must be too, so we need not worry about clamping the result. - * - * We deliberately truncate rather than rounding; this is so that single - * adjustments inside a backend can affect the shared estimate (see the - * asymmetric adjustment rules above). - */ - return (shared_spins_per_delay * 15 + spins_per_delay) / 16; -} -#endif - -/* - * Various TAS implementations that cannot live in s_lock.h as no inline - * definition exists (yet). - * In the future, get rid of tas.[cso] and fold it into this file. - * - * If you change something here, you will likely need to modify s_lock.h too, - * because the definitions for these are split between this file and s_lock.h. - */ - - -#ifdef HAVE_SPINLOCKS /* skip spinlocks if requested */ - - -#if defined(__GNUC__) - -/* - * All the gcc flavors that are not inlined - */ - - -/* - * Note: all the if-tests here probably ought to be testing gcc version - * rather than platform, but I don't have adequate info to know what to - * write. Ideally we'd flush all this in favor of the inline version. - */ -#if defined(__m68k__) && !defined(__linux__) -/* really means: extern int tas(slock_t* **lock); */ -static void -tas_dummy() -{ - __asm__ __volatile__( -#if defined(__NetBSD__) && defined(__ELF__) -/* no underscore for label and % for registers */ - "\ -.global tas \n\ -tas: \n\ - movel %sp@(0x4),%a0 \n\ - tas %a0@ \n\ - beq _success \n\ - moveq #-128,%d0 \n\ - rts \n\ -_success: \n\ - moveq #0,%d0 \n\ - rts \n" -#else - "\ -.global _tas \n\ -_tas: \n\ - movel sp@(0x4),a0 \n\ - tas a0@ \n\ - beq _success \n\ - moveq #-128,d0 \n\ - rts \n\ -_success: \n\ - moveq #0,d0 \n\ - rts \n" -#endif /* __NetBSD__ && __ELF__ */ - ); -} -#endif /* __m68k__ && !__linux__ */ -#else /* not __GNUC__ */ - -/* - * All non gcc - */ - - -#if defined(sun3) -static void -tas_dummy() /* really means: extern int tas(slock_t - * *lock); */ -{ - 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 */ -#endif /* not __GNUC__ */ -#endif /* HAVE_SPINLOCKS */ - - - -/*****************************************************************************/ -#if defined(S_LOCK_TEST) - -/* - * test program for verifying a port's spinlock support. - */ - -struct test_lock_struct -{ - char pad1; - slock_t lock; - char pad2; -}; - -volatile struct test_lock_struct test_lock; - -int -main() -{ - srandom((unsigned int) time(NULL)); - - test_lock.pad1 = test_lock.pad2 = 0x44; - - S_INIT_LOCK(&test_lock.lock); - - if (test_lock.pad1 != 0x44 || test_lock.pad2 != 0x44) - { - printf("S_LOCK_TEST: failed, declared datatype is wrong size\n"); - return 1; - } - - if (!S_LOCK_FREE(&test_lock.lock)) - { - printf("S_LOCK_TEST: failed, lock not initialized\n"); - return 1; - } - - S_LOCK(&test_lock.lock); - - if (test_lock.pad1 != 0x44 || test_lock.pad2 != 0x44) - { - printf("S_LOCK_TEST: failed, declared datatype is wrong size\n"); - return 1; - } - - if (S_LOCK_FREE(&test_lock.lock)) - { - printf("S_LOCK_TEST: failed, lock not locked\n"); - return 1; - } - - S_UNLOCK(&test_lock.lock); - - if (test_lock.pad1 != 0x44 || test_lock.pad2 != 0x44) - { - printf("S_LOCK_TEST: failed, declared datatype is wrong size\n"); - return 1; - } - - if (!S_LOCK_FREE(&test_lock.lock)) - { - printf("S_LOCK_TEST: failed, lock not unlocked\n"); - return 1; - } - - S_LOCK(&test_lock.lock); - - if (test_lock.pad1 != 0x44 || test_lock.pad2 != 0x44) - { - printf("S_LOCK_TEST: failed, declared datatype is wrong size\n"); - return 1; - } - - if (S_LOCK_FREE(&test_lock.lock)) - { - printf("S_LOCK_TEST: failed, lock not re-locked\n"); - return 1; - } - - printf("S_LOCK_TEST: this will print %d stars and then\n", NUM_DELAYS); - printf(" exit with a 'stuck spinlock' message\n"); - printf(" if S_LOCK() and TAS() are working.\n"); - fflush(stdout); - - s_lock(&test_lock.lock, __FILE__, __LINE__); - - printf("S_LOCK_TEST: failed, lock not locked\n"); - return 1; -} - -#endif /* S_LOCK_TEST */ - -#endif /* APC_SPIN_LOCKS */