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Make the locale mutex a general semaphore
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Future commits will use this new capability, and in Configurations where
no locale locking is currently necessary.
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@khwilliamson
khwilliamson committed Apr 16, 2021
1 parent af01cef commit 961e641
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Showing 6 changed files with 90 additions and 31 deletions.
1 change: 1 addition & 0 deletions embedvar.h
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Expand Up @@ -190,6 +190,7 @@
#define PL_laststatval (vTHX->Ilaststatval)
#define PL_laststype (vTHX->Ilaststype)
#define PL_lc_numeric_mutex_depth (vTHX->Ilc_numeric_mutex_depth)
#define PL_locale_mutex_depth (vTHX->Ilocale_mutex_depth)
#define PL_localizing (vTHX->Ilocalizing)
#define PL_localpatches (vTHX->Ilocalpatches)
#define PL_lockhook (vTHX->Ilockhook)
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3 changes: 3 additions & 0 deletions intrpvar.h
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Expand Up @@ -367,6 +367,9 @@ PERLVAR(I, utf8locale, bool) /* utf8 locale detected */
PERLVAR(I, in_utf8_CTYPE_locale, bool)
PERLVAR(I, in_utf8_COLLATE_locale, bool)
PERLVAR(I, in_utf8_turkic_locale, bool)
#if defined(USE_LOCALE) && defined(USE_LOCALE_THREADS)
PERLVARI(I, locale_mutex_depth, int, 0) /* Emulate general semaphore */
#endif
#if defined(USE_ITHREADS) && ! defined(USE_THREAD_SAFE_LOCALE)
PERLVARI(I, lc_numeric_mutex_depth, int, 0) /* Emulate general semaphore */
#endif
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7 changes: 7 additions & 0 deletions locale.c
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Expand Up @@ -414,7 +414,14 @@ Perl_force_locale_unlock()

dTHX;

/* If recursively locked, clear all at once */
if (PL_locale_mutex_depth > 1) {
PL_locale_mutex_depth = 1;
}

if (PL_locale_mutex_depth > 0) {
LOCALE_UNLOCK_;
}

#endif

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1 change: 1 addition & 0 deletions makedef.pl
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Expand Up @@ -375,6 +375,7 @@ sub readvar {
PL_env_mutex
PL_hints_mutex
PL_locale_mutex
PL_locale_mutex_depth
PL_lc_numeric_mutex
PL_lc_numeric_mutex_depth
PL_my_ctx_mutex
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105 changes: 74 additions & 31 deletions perl.h
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Expand Up @@ -6651,17 +6651,74 @@ the plain locale pragma without a parameter (S<C<use locale>>) is in effect.
#define locale_panic_(m) Perl_locale_panic((m), __FILE__, __LINE__, errno)

/* Locale/thread synchronization macros. */
#if ( defined(USE_LOCALE) \
&& defined(USE_LOCALE_THREADS) \
&& ( ! defined(USE_THREAD_SAFE_LOCALE) \
|| ( defined(HAS_LOCALECONV) \
&& ( ! defined(HAS_LOCALECONV_L) \
|| defined(TS_W32_BROKEN_LOCALECONV))) \
|| ( defined(HAS_NL_LANGINFO) \
&& ! defined(HAS_THREAD_SAFE_NL_LANGINFO_L)) \
|| (defined(HAS_MBLEN) && ! defined(HAS_MBRLEN)) \
|| (defined(HAS_MBTOWC) && ! defined(HAS_MBRTOWC)) \
|| (defined(HAS_WCTOMB) && ! defined(HAS_WCRTOMB))))
#if ! defined(USE_LOCALE) || ! defined(USE_LOCALE_THREADS)
# define LOCALE_LOCK_(cond) NOOP
# define LOCALE_UNLOCK_ NOOP
# define LOCALE_INIT
# define LOCALE_TERM

#else /* Below: Threaded, and locales are supported */

/* A locale mutex is required on all such threaded builds.
*
* This mutex simulates a general (or recursive) semaphore. The current
* thread will lock the mutex if the per-thread variable is zero, and then
* increments that variable. Each corresponding UNLOCK decrements the
* variable until it is 0, at which point it actually unlocks the mutex.
* Since the variable is per-thread, initialized to 0, there is no race
* with other threads.
*
* The single argument is a condition to test for, and if true, to panic.
* Call it with the constant 0 to suppress the check.
*
* Clang improperly gives warnings for this, if not silenced:
* https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#conditional-locks
*/
# define LOCALE_LOCK_(cond_to_panic_if_already_locked) \
STMT_START { \
CLANG_DIAG_IGNORE(-Wthread-safety) \
if (LIKELY(PL_locale_mutex_depth <= 0)) { \
DEBUG_Lv(PerlIO_printf(Perl_debug_log, \
"%s: %d: locking locale; depth=1\n", \
__FILE__, __LINE__)); \
MUTEX_LOCK(&PL_locale_mutex); \
PL_locale_mutex_depth = 1; \
} \
else { \
PL_locale_mutex_depth++; \
DEBUG_Lv(PerlIO_printf(Perl_debug_log, \
"%s: %d: avoided locking locale; new depth=%d\n", \
__FILE__, __LINE__, PL_locale_mutex_depth)); \
if (cond_to_panic_if_already_locked) { \
locale_panic_("Trying to lock locale incompatibly: " \
STRINGIFY(cond_to_panic_if_already_locked)); \
} \
} \
CLANG_DIAG_RESTORE \
} STMT_END

# define LOCALE_UNLOCK_ \
STMT_START { \
if (LIKELY(PL_locale_mutex_depth == 1)) { \
DEBUG_Lv(PerlIO_printf(Perl_debug_log, \
"%s: %d: unlocking locale; depth=0, was %d\n", \
__FILE__, __LINE__, PL_locale_mutex_depth )); \
PL_locale_mutex_depth = 0; \
MUTEX_UNLOCK(&PL_locale_mutex); \
} \
else if (PL_locale_mutex_depth <= 0) { \
DEBUG_L(PerlIO_printf(Perl_debug_log, \
"%s: %d: ignored attempt to unlock already" \
" unlocked locale; depth unchanged at %d\n", \
__FILE__, __LINE__, PL_locale_mutex_depth)); \
} \
else { \
PL_locale_mutex_depth--; \
DEBUG_Lv(PerlIO_printf(Perl_debug_log, \
"%s: %d: avoided unlocking locale; new depth=%d\n", \
__FILE__, __LINE__, PL_locale_mutex_depth)); \
} \
} STMT_END

# ifndef USE_POSIX_2008_LOCALE
# define LOCALE_TERM_POSIX_2008_ NOOP
Expand Down Expand Up @@ -6705,8 +6762,6 @@ the plain locale pragma without a parameter (S<C<use locale>>) is in effect.
/* The whole expression just above was complemented, so here we have no need
* for thread synchronization, most likely it would be that this isn't a
* threaded build. */
# define LOCALE_INIT
# define LOCALE_TERM
# define LC_NUMERIC_LOCK(cond) NOOP
# define LC_NUMERIC_UNLOCK NOOP
# define LOCALECONV_LOCK NOOP
Expand Down Expand Up @@ -6753,18 +6808,6 @@ the plain locale pragma without a parameter (S<C<use locale>>) is in effect.
* will be called frequently, and the locked interval should be short, and
* modern platforms will have reentrant versions (which don't lock) for
* almost all of them, so khw thinks a single mutex should suffice. */
# define LOCALE_LOCK_ \
STMT_START { \
DEBUG_Lv(PerlIO_printf(Perl_debug_log, \
"%s: %d: locking locale\n", __FILE__, __LINE__)); \
MUTEX_LOCK(&PL_locale_mutex); \
} STMT_END
# define LOCALE_UNLOCK_ \
STMT_START { \
DEBUG_Lv(PerlIO_printf(Perl_debug_log, \
"%s: %d: unlocking locale\n", __FILE__, __LINE__)); \
MUTEX_UNLOCK(&PL_locale_mutex); \
} STMT_END

/* We do define a different macro for each case; then if we want to have
* separate mutexes for some of them, the only changes needed are here.
Expand All @@ -6773,24 +6816,24 @@ the plain locale pragma without a parameter (S<C<use locale>>) is in effect.
# if defined(HAS_LOCALECONV) && ( ! defined(USE_POSIX_2008_LOCALE) \
|| ! defined(HAS_LOCALECONV_L) \
|| defined(TS_W32_BROKEN_LOCALECONV))
# define LOCALECONV_LOCK LOCALE_LOCK_
# define LOCALECONV_LOCK LOCALE_LOCK_(0)
# define LOCALECONV_UNLOCK LOCALE_UNLOCK_
# endif
# if defined(HAS_NL_LANGINFO) && ( ! defined(HAS_THREAD_SAFE_NL_LANGINFO_L) \
|| ! defined(USE_POSIX_2008_LOCALE))
# define NL_LANGINFO_LOCK LOCALE_LOCK_
# define NL_LANGINFO_LOCK LOCALE_LOCK_(0)
# define NL_LANGINFO_UNLOCK LOCALE_UNLOCK_
# endif
# if defined(HAS_MBLEN) && ! defined(HAS_MBRLEN)
# define MBLEN_LOCK_ LOCALE_LOCK_
# define MBLEN_LOCK_ LOCALE_LOCK_(0)
# define MBLEN_UNLOCK_ LOCALE_UNLOCK_
# endif
# if defined(HAS_MBTOWC) && ! defined(HAS_MBRTOWC)
# define MBTOWC_LOCK_ LOCALE_LOCK_
# define MBTOWC_LOCK_ LOCALE_LOCK_(0)
# define MBTOWC_UNLOCK_ LOCALE_UNLOCK_
# endif
# if defined(HAS_WCTOMB) && ! defined(HAS_WCRTOMB)
# define WCTOMB_LOCK_ LOCALE_LOCK_
# define WCTOMB_LOCK_ LOCALE_LOCK_(0)
# define WCTOMB_UNLOCK_ LOCALE_UNLOCK_
# endif
# if defined(USE_THREAD_SAFE_LOCALE)
Expand All @@ -6807,7 +6850,7 @@ the plain locale pragma without a parameter (S<C<use locale>>) is in effect.
# define SETLOCALE_LOCK NOOP
# define SETLOCALE_UNLOCK NOOP
# else
# define SETLOCALE_LOCK LOCALE_LOCK_
# define SETLOCALE_LOCK LOCALE_LOCK_(0)
# define SETLOCALE_UNLOCK LOCALE_UNLOCK_

/* On platforms without per-thread locales, when another thread can switch
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4 changes: 4 additions & 0 deletions sv.c
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Expand Up @@ -15341,6 +15341,10 @@ perl_clone_using(PerlInterpreter *proto_perl, UV flags,
PL_utf8locale = proto_perl->Iutf8locale;
PL_in_utf8_CTYPE_locale = proto_perl->Iin_utf8_CTYPE_locale;
PL_in_utf8_COLLATE_locale = proto_perl->Iin_utf8_COLLATE_locale;
#if defined(USE_LOCALE) && defined(USE_LOCALE_THREADS)
assert(PL_locale_mutex_depth <= 0);
PL_locale_mutex_depth = 0;
#endif
#if defined(USE_ITHREADS) && ! defined(USE_THREAD_SAFE_LOCALE)
PL_lc_numeric_mutex_depth = 0;
#endif
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