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introduce usage of thread local storage structure #44

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ba884f0
introduce usage of thread local storage structure
frankeh Feb 4, 2016
b79a638
fix format and content issues
frankeh Feb 5, 2016
e3c1862
disable inlining libdispatch_tsd_init for code efficiency
frankeh Feb 9, 2016
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21 changes: 21 additions & 0 deletions configure.ac
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Original file line number Diff line number Diff line change
Expand Up @@ -101,6 +101,27 @@ AS_IF([test "x$enable_apple_tsd_optimizations" = "xyes"],
[Define to use non-portable pthread TSD optimizations for Mac OS X)])]
)

#
# Enable __thread based TSD on platforms where it is efficient
# Allow override based on command line argument to configure
#
AC_CANONICAL_TARGET
AC_ARG_ENABLE([thread-local-storage],
[AS_HELP_STRING([--enable-thread-local-storage],
[Enable usage of thread local storage via __thread])],,
[case $target_os in
linux*)
enable_thread_local_storage=yes
;;
*)
enable_thread_local_storage=no
esac]
)
AS_IF([test "x$enable_thread_local_storage" = "xyes"],
[AC_DEFINE(DISPATCH_USE_THREAD_LOCAL_STORAGE, 1,
[Enable usage of thread local storage via __thread])]
)

AC_USE_SYSTEM_EXTENSIONS
AM_INIT_AUTOMAKE([foreign no-dependencies subdir-objects])
LT_INIT([disable-static])
Expand Down
8 changes: 2 additions & 6 deletions src/init.c
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,7 @@ void *(*_dispatch_begin_NSAutoReleasePool)(void);
void (*_dispatch_end_NSAutoReleasePool)(void *);
#endif

#if !DISPATCH_USE_DIRECT_TSD
#if !DISPATCH_USE_DIRECT_TSD && !DISPATCH_USE_THREAD_LOCAL_STORAGE
pthread_key_t dispatch_queue_key;
pthread_key_t dispatch_sema4_key;
pthread_key_t dispatch_cache_key;
Expand All @@ -77,7 +77,7 @@ pthread_key_t dispatch_introspection_key;
#elif DISPATCH_PERF_MON
pthread_key_t dispatch_bcounter_key;
#endif
#endif // !DISPATCH_USE_DIRECT_TSD
#endif // !DISPATCH_USE_DIRECT_TSD && !DISPATCH_USE_THREAD_LOCAL_STORAGE

#if VOUCHER_USE_MACH_VOUCHER
dispatch_once_t _voucher_task_mach_voucher_pred;
Expand Down Expand Up @@ -161,10 +161,6 @@ const struct dispatch_tsd_indexes_s dispatch_tsd_indexes = {
.dti_voucher_index = dispatch_voucher_key,
.dti_qos_class_index = dispatch_priority_key,
};
#else // DISPATCH_USE_DIRECT_TSD
#ifndef __LINUX_PORT_HDD__
#error Not implemented on this platform
#endif
#endif // DISPATCH_USE_DIRECT_TSD

// 6618342 Contact the team that owns the Instrument DTrace probe before
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58 changes: 58 additions & 0 deletions src/queue.c
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Expand Up @@ -913,6 +913,60 @@ _dispatch_root_queues_init(void *context DISPATCH_UNUSED)

#define countof(x) (sizeof(x) / sizeof(x[0]))

#if DISPATCH_USE_THREAD_LOCAL_STORAGE
#include <unistd.h>
#include <sys/syscall.h>

#ifdef SYS_gettid
DISPATCH_ALWAYS_INLINE
static inline pid_t
gettid(void)
{
return (pid_t) syscall(SYS_gettid);
}
#else
#error "SYS_gettid unavailable on this system"
#endif

#define _tsd_call_cleanup(k, f) do { \
if (f && tsd->k) ((void(*)(void*))(f))(tsd->k); \
} while (0)
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Style would rather be:

#define _tsd_call_cleanup(k, f)  do { \
        if (f && __dispatch_tsd.k) ((void(*)(void*))(f))(__dispatch_tsd.k); \
    } while (0)

why the cast? it looks gross

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to handle calls like this:
_tsd_call_cleanup(dispatch_io_key, NULL);
in the _libdispatch_thread_cleanup.
One can argue I don't need that anyway, since it will be optimized out (see macro), but
I wanted it there to get some symmetry in the code for TSD and non-TSD code.
If you prefer I don't call the NULL instances of these I can simplify the macro.
Also look at the "dispatch_sema4_key K,V" .. same ugliness there in the code by default"


static void
_libdispatch_tsd_cleanup(void *ctx)
{
struct dispatch_tsd *tsd = (struct dispatch_tsd*) ctx;

_tsd_call_cleanup(dispatch_queue_key, _dispatch_queue_cleanup);
_tsd_call_cleanup(dispatch_voucher_key, _voucher_thread_cleanup);
_tsd_call_cleanup(dispatch_cache_key, _dispatch_cache_cleanup);
_tsd_call_cleanup(dispatch_io_key, NULL);
_tsd_call_cleanup(dispatch_apply_key, NULL);
_tsd_call_cleanup(dispatch_defaultpriority_key, NULL);
_tsd_call_cleanup(dispatch_pthread_root_queue_observer_hooks_key,
NULL);
#if DISPATCH_PERF_MON && !DISPATCH_INTROSPECTION
_tsd_call_cleanup(dispatch_bcounter_key, NULL);
#endif
#if !DISPATCH_USE_OS_SEMAPHORE_CACHE
_tsd_call_cleanup(dispatch_sema4_key,
(void (*)(void *))_dispatch_thread_semaphore_dispose);
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why the cast?

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code take from other case to maintain code symmetry:
e.g.
#if !DISPATCH_USE_OS_SEMAPHORE_CACHE
_dispatch_thread_key_create(&dispatch_sema4_key,
(void (*)(void *))_dispatch_thread_semaphore_dispose);
#endif

#endif
tsd->tid = -1;
tsd->initialized = false;
}

DISPATCH_EXPORT DISPATCH_NOINLINE
void
libdispatch_tsd_init(void)
{
__dispatch_tsd.tid = gettid();
pthread_setspecific(__dispatch_tsd_key, &__dispatch_tsd);
__dispatch_tsd.initialized = true;
}

#endif

DISPATCH_EXPORT DISPATCH_NOTHROW
void
libdispatch_init(void)
Expand Down Expand Up @@ -951,6 +1005,9 @@ libdispatch_init(void)
dispatch_assert(sizeof(struct dispatch_root_queue_context_s) %
DISPATCH_CACHELINE_SIZE == 0);

#if DISPATCH_USE_THREAD_LOCAL_STORAGE
_dispatch_thread_key_create(&__dispatch_tsd_key, _libdispatch_tsd_cleanup);
#else
_dispatch_thread_key_create(&dispatch_queue_key, _dispatch_queue_cleanup);
_dispatch_thread_key_create(&dispatch_voucher_key, _voucher_thread_cleanup);
_dispatch_thread_key_create(&dispatch_cache_key, _dispatch_cache_cleanup);
Expand All @@ -966,6 +1023,7 @@ libdispatch_init(void)
_dispatch_thread_key_create(&dispatch_sema4_key,
(void (*)(void *))_dispatch_thread_semaphore_dispose);
#endif
#endif

#if DISPATCH_USE_RESOLVERS // rdar://problem/8541707
_dispatch_main_q.do_targetq = &_dispatch_root_queues[
Expand Down
8 changes: 7 additions & 1 deletion src/shims/linux_stubs.c
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Expand Up @@ -53,8 +53,9 @@ char* mach_error_string(mach_msg_return_t x) {
void mach_vm_deallocate() { LINUX_PORT_ERROR(); }

mach_port_t pthread_mach_thread_np(void) {
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and you can probably get rid of that guy

return (pid_t)syscall(SYS_gettid);
return (mach_port_t)pthread_self();
}

mach_port_t mach_task_self(void) {
return (mach_port_t)pthread_self();
}
Expand All @@ -72,3 +73,8 @@ unsigned short dispatch_timer__fire_semaphore;
unsigned short dispatch_timer__configure_semaphore;
void (*_dispatch_block_special_invoke)(void*);
struct dispatch_queue_attr_s _dispatch_queue_attr_concurrent;

#if DISPATCH_USE_THREAD_LOCAL_STORAGE
__thread struct dispatch_tsd __dispatch_tsd;
pthread_key_t __dispatch_tsd_key;
#endif
56 changes: 55 additions & 1 deletion src/shims/tsd.h
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Expand Up @@ -73,6 +73,56 @@ _dispatch_thread_key_create(const unsigned long *k, void (*d)(void *))
if (!*k || !d) return;
dispatch_assert_zero(pthread_key_init_np((int)*k, d));
}
#elif DISPATCH_USE_THREAD_LOCAL_STORAGE

DISPATCH_TSD_INLINE
static inline void
_dispatch_thread_key_create(pthread_key_t *k, void (*d)(void *))
{
dispatch_assert_zero(pthread_key_create(k, d));
}

struct dispatch_tsd {
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style nits for this struct:

  • spaces/tabs
  • void* dispatch_queue_key -> void *dispatch_queue_key

bool initialized;
pid_t tid;
void *dispatch_queue_key;
void *dispatch_voucher_key;
#if DISPATCH_USE_OS_SEMAPHORE_CACHE
#error "Invalid DISPATCH_USE_OS_SEMAPHORE_CACHE configuration"
#else
void *dispatch_sema4_key;
#endif
void *dispatch_cache_key;
void *dispatch_io_key;
void *dispatch_apply_key;
void *dispatch_defaultpriority_key;
#if DISPATCH_INTROSPECTION
void *dispatch_introspection_key;
#elif DISPATCH_PERF_MON
void *dispatch_bcounter_key;
#endif
void *dispatch_pthread_root_queue_observer_hooks_key;
};

extern __thread struct dispatch_tsd __dispatch_tsd;
extern pthread_key_t __dispatch_tsd_key;
extern void libdispatch_tsd_init(void);

DISPATCH_ALWAYS_INLINE
static inline struct dispatch_tsd *
_dispatch_get_tsd_base(void)
{
if (slowpath(!__dispatch_tsd.initialized)) {
libdispatch_tsd_init();
}
return &__dispatch_tsd;
}

#define _dispatch_thread_getspecific(key) \
(_dispatch_get_tsd_base()->key)
#define _dispatch_thread_setspecific(key, value) \
(void)(_dispatch_get_tsd_base()->key = (value))

#else
extern pthread_key_t dispatch_queue_key;
extern pthread_key_t dispatch_voucher_key;
Expand Down Expand Up @@ -100,7 +150,7 @@ _dispatch_thread_key_create(pthread_key_t *k, void (*d)(void *))
}
#endif

#if DISPATCH_USE_TSD_BASE && !DISPATCH_DEBUG
#if (DISPATCH_USE_TSD_BASE && !DISPATCH_DEBUG) || DISPATCH_USE_THREAD_LOCAL_STORAGE
#else // DISPATCH_USE_TSD_BASE
DISPATCH_TSD_INLINE
static inline void
Expand Down Expand Up @@ -134,6 +184,8 @@ _dispatch_thread_getspecific(pthread_key_t k)
#if DISPATCH_USE_DIRECT_TSD
#define _dispatch_thread_self() ((uintptr_t)_dispatch_thread_getspecific( \
_PTHREAD_TSD_SLOT_PTHREAD_SELF))
#elif DISPATCH_USE_THREAD_LOCAL_STORAGE
#define _dispatch_thread_self() ((uintptr_t)pthread_self())
#else
#define _dispatch_thread_self() ((uintptr_t)pthread_self())
#endif
Expand All @@ -145,6 +197,8 @@ _dispatch_thread_getspecific(pthread_key_t k)
#if DISPATCH_USE_DIRECT_TSD
#define _dispatch_thread_port() ((mach_port_t)_dispatch_thread_getspecific(\
_PTHREAD_TSD_SLOT_MACH_THREAD_SELF))
#elif DISPATCH_USE_THREAD_LOCAL_STORAGE
#define _dispatch_thread_port() ((mach_port_t)(_dispatch_get_tsd_base()->tid))
#else
#define _dispatch_thread_port() (pthread_mach_thread_np(_dispatch_thread_self()))
#endif
Expand Down