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| author | Sascha Schumann <sas@php.net> | 2001-09-21 13:38:44 +0000 |
|---|---|---|
| committer | Sascha Schumann <sas@php.net> | 2001-09-21 13:38:44 +0000 |
| commit | 9002e37e4e25cf751d675612bdde48316c1a0613 (patch) | |
| tree | 9ac38f3f3d5b26c6147cf9f8a48114f9df80756d /ext/standard/lcg.c | |
| parent | 78fb121a61f5b940308ad33ab8db66c685b0ecba (diff) | |
| download | php-git-9002e37e4e25cf751d675612bdde48316c1a0613.tar.gz | |
Always seed the LCG from the request-init hook, otherwise the seed
would be shared among the threads which is quite pointless. Also
use a function of the current time as one factor.
Use gettimeofday() instead of time(), because it is faster on some
operating systems.
Diffstat (limited to 'ext/standard/lcg.c')
| -rw-r--r-- | ext/standard/lcg.c | 39 |
1 files changed, 28 insertions, 11 deletions
diff --git a/ext/standard/lcg.c b/ext/standard/lcg.c index 91863d0a48..a76725ec38 100644 --- a/ext/standard/lcg.c +++ b/ext/standard/lcg.c @@ -25,11 +25,14 @@ #include <unistd.h> #endif +#if HAVE_SYS_TIME_H +#include <sys/time.h> +#endif + #ifdef ZTS int lcg_globals_id; #else static php_lcg_globals lcg_globals; -static int php_lcg_initialized = 0; #endif @@ -46,7 +49,7 @@ static int php_lcg_initialized = 0; #define MODMULT(a, b, c, m, s) q = s/a;s=b*(s-a*q)-c*q;if(s<0)s+=m -double php_combined_lcg(TSRMLS_D) +PHPAPI double php_combined_lcg(TSRMLS_D) { php_int32 q; php_int32 z; @@ -55,39 +58,53 @@ double php_combined_lcg(TSRMLS_D) MODMULT(52774, 40692, 3791, 2147483399L, LCG(s2)); z = LCG(s1) - LCG(s2); - if(z < 1) { + if (z < 1) { z += 2147483562; } return z * 4.656613e-10; } -static void lcg_init_globals(php_lcg_globals *lcg_globals_p TSRMLS_DC) +static void lcg_seed(TSRMLS_D) { - LCG(s1) = 1; + struct timeval tv; + + if (gettimeofday(&tv, NULL) == 0) { + LCG(s1) = tv.tv_sec ^ (~tv.tv_usec); + } else { + LCG(s1) = 1; + } #ifdef ZTS LCG(s2) = (long) tsrm_thread_id(); #else LCG(s2) = (long) getpid(); #endif + + LCG(seeded) = 1; +} + +static void lcg_init_globals(php_lcg_globals *lcg_globals_p TSRMLS_DC) +{ + LCG(seeded) = 0; } -#ifdef ZTS PHP_MINIT_FUNCTION(lcg) { +#ifdef ZTS ts_allocate_id(&lcg_globals_id, sizeof(php_lcg_globals), (ts_allocate_ctor) lcg_init_globals, NULL); +#else + lcg_init_globals(&lcg_globals); +#endif return SUCCESS; } -#else + PHP_RINIT_FUNCTION(lcg) { - if (!php_lcg_initialized) { - lcg_init_globals(&lcg_globals TSRMLS_CC); - php_lcg_initialized = 1; + if (!LCG(seeded)) { + lcg_seed(TSRMLS_C); } return SUCCESS; } -#endif /* {{{ proto double lcg_value() Returns a value from the combined linear congruential generator */ |