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task.c
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// This file is a part of Julia. License is MIT: https://julialang.org/license
/*
task.c
lightweight processes (symmetric coroutines)
*/
// need this to get the real definition of ucontext_t,
// if we're going to use the ucontext_t implementation there
//#if defined(__APPLE__) && defined(JL_HAVE_UCONTEXT)
//#pragma push_macro("_XOPEN_SOURCE")
//#define _XOPEN_SOURCE
//#include <ucontext.h>
//#pragma pop_macro("_XOPEN_SOURCE")
//#endif
// this is needed for !COPY_STACKS to work on linux
#ifdef _FORTIFY_SOURCE
// disable __longjmp_chk validation so that we can jump between stacks
// (which would normally be invalid to do with setjmp / longjmp)
#pragma push_macro("_FORTIFY_SOURCE")
#undef _FORTIFY_SOURCE
#include <setjmp.h>
#pragma pop_macro("_FORTIFY_SOURCE")
#endif
#include "platform.h"
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <inttypes.h>
#include "julia.h"
#include "julia_internal.h"
#include "threading.h"
#include "julia_assert.h"
#ifdef __cplusplus
extern "C" {
#endif
#if defined(_COMPILER_ASAN_ENABLED_)
static inline void sanitizer_start_switch_fiber(const void* bottom, size_t size) {
__sanitizer_start_switch_fiber(NULL, bottom, size);
}
static inline void sanitizer_finish_switch_fiber(void) {
__sanitizer_finish_switch_fiber(NULL, NULL, NULL);
}
#else
static inline void sanitizer_start_switch_fiber(const void* bottom, size_t size) {}
static inline void sanitizer_finish_switch_fiber(void) {}
#endif
#if defined(_COMPILER_TSAN_ENABLED_)
// must defined as macros, since the function containing them must not return before the longjmp
#define tsan_destroy_ctx(_ptls, _ctx) do { \
jl_ucontext_t *_tsan_macro_ctx = (_ctx); \
if (_tsan_macro_ctx != &(_ptls)->root_task->ctx) { \
__tsan_destroy_fiber(_tsan_macro_ctx->tsan_state); \
} \
_tsan_macro_ctx->tsan_state = NULL; \
} while (0)
#define tsan_switch_to_ctx(_ctx) do { \
jl_ucontext_t *_tsan_macro_ctx = (_ctx); \
__tsan_switch_to_fiber(_tsan_macro_ctx->tsan_state, 0); \
} while (0)
#ifdef COPY_STACKS
#define tsan_destroy_copyctx(_ptls, _ctx) do { \
jl_ucontext_t *_tsan_macro_ctx = (_ctx); \
if (_tsan_macro_ctx != &(_ptls)->root_task->ctx) { \
__tsan_destroy_fiber(_tsan_macro_ctx->tsan_state); \
} \
_tsan_macro_ctx->tsan_state = NULL; \
} while (0)
#define tsan_switch_to_copyctx(_ctx) do { \
struct jl_stack_context_t *_tsan_macro_ctx = (_ctx); \
__tsan_switch_to_fiber(_tsan_macro_ctx->tsan_state, 0); \
} while (0)
#endif
#else
// just do minimal type-checking on the arguments
#define tsan_destroy_ctx(_ptls, _ctx) do { \
jl_ucontext_t *_tsan_macro_ctx = (_ctx); \
(void)_tsan_macro_ctx; \
} while (0)
#define tsan_switch_to_ctx(_ctx) do { \
jl_ucontext_t *_tsan_macro_ctx = (_ctx); \
(void)_tsan_macro_ctx; \
} while (0)
#ifdef COPY_STACKS
#define tsan_destroy_copyctx(_ptls, _ctx) do { \
jl_ucontext_t *_tsan_macro_ctx = (_ctx); \
(void)_tsan_macro_ctx; \
} while (0)
#define tsan_switch_to_copyctx(_ctx) do { \
jl_ucontext_t *_tsan_macro_ctx = (_ctx); \
(void)_tsan_macro_ctx; \
} while (0)
#endif
#endif
// empirically, jl_finish_task needs about 64k stack space to infer/run
// and additionally, gc-stack reserves 64k for the guard pages
#if defined(MINSIGSTKSZ)
#define MINSTKSZ (MINSIGSTKSZ > 131072 ? MINSIGSTKSZ : 131072)
#else
#define MINSTKSZ 131072
#endif
#define ROOT_TASK_STACK_ADJUSTMENT 3000000
#ifdef JL_HAVE_ASYNCIFY
// Switching logic is implemented in JavaScript
#define STATIC_OR_JS JL_DLLEXPORT
#else
#define STATIC_OR_JS static
#endif
static char *jl_alloc_fiber(_jl_ucontext_t *t, size_t *ssize, jl_task_t *owner) JL_NOTSAFEPOINT;
STATIC_OR_JS void jl_set_fiber(jl_ucontext_t *t);
STATIC_OR_JS void jl_swap_fiber(jl_ucontext_t *lastt, jl_ucontext_t *t);
STATIC_OR_JS void jl_start_fiber_swap(jl_ucontext_t *savet, jl_ucontext_t *t);
STATIC_OR_JS void jl_start_fiber_set(jl_ucontext_t *t);
#ifdef ALWAYS_COPY_STACKS
# ifndef COPY_STACKS
# error "ALWAYS_COPY_STACKS requires COPY_STACKS"
# endif
static int always_copy_stacks = 1;
#else
static int always_copy_stacks = 0;
#endif
#ifdef COPY_STACKS
static void memcpy_a16(uint64_t *to, uint64_t *from, size_t nb)
{
memcpy((char*)jl_assume_aligned(to, 16), (char*)jl_assume_aligned(from, 16), nb);
//uint64_t *end = (uint64_t*)((char*)from + nb);
//while (from < end)
// *(to++) = *(from++);
}
static void NOINLINE save_stack(jl_ptls_t ptls, jl_task_t *lastt, jl_task_t **pt)
{
char *frame_addr = (char*)((uintptr_t)jl_get_frame_addr() & ~15);
char *stackbase = (char*)ptls->stackbase;
assert(stackbase > frame_addr);
size_t nb = stackbase - frame_addr;
void *buf;
if (lastt->bufsz < nb) {
buf = (void*)jl_gc_alloc_buf(ptls, nb);
lastt->stkbuf = buf;
lastt->bufsz = nb;
}
else {
buf = lastt->stkbuf;
}
*pt = NULL; // clear the gc-root for the target task before copying the stack for saving
lastt->copy_stack = nb;
lastt->sticky = 1;
memcpy_a16((uint64_t*)buf, (uint64_t*)frame_addr, nb);
// this task's stack could have been modified after
// it was marked by an incremental collection
// move the barrier back instead of walking it again here
jl_gc_wb_back(lastt);
}
static void NOINLINE JL_NORETURN restore_stack(jl_task_t *t, jl_ptls_t ptls, char *p)
{
size_t nb = t->copy_stack;
char *_x = (char*)ptls->stackbase - nb;
if (!p) {
// switch to a stackframe that's beyond the bounds of the last switch
p = _x;
if ((char*)&_x > _x) {
p = (char*)alloca((char*)&_x - _x);
}
restore_stack(t, ptls, p); // pass p to ensure the compiler can't tailcall this or avoid the alloca
}
void *_y = t->stkbuf;
assert(_x != NULL && _y != NULL);
memcpy_a16((uint64_t*)_x, (uint64_t*)_y, nb); // destroys all but the current stackframe
sanitizer_start_switch_fiber(t->stkbuf, t->bufsz);
#if defined(_OS_WINDOWS_)
jl_setcontext(&t->ctx.copy_ctx);
#else
jl_longjmp(t->ctx.copy_ctx.uc_mcontext, 1);
#endif
abort(); // unreachable
}
static void restore_stack2(jl_task_t *t, jl_ptls_t ptls, jl_task_t *lastt)
{
assert(t->copy_stack && !lastt->copy_stack);
size_t nb = t->copy_stack;
char *_x = (char*)ptls->stackbase - nb;
void *_y = t->stkbuf;
assert(_x != NULL && _y != NULL);
memcpy_a16((uint64_t*)_x, (uint64_t*)_y, nb); // destroys all but the current stackframe
#if defined(JL_HAVE_UNW_CONTEXT)
volatile int returns = 0;
int r = unw_getcontext(&lastt->ctx.ctx);
if (++returns == 2) // r is garbage after the first return
return;
if (r != 0 || returns != 1)
abort();
#elif defined(JL_HAVE_ASM) || defined(JL_HAVE_SIGALTSTACK) || defined(_OS_WINDOWS_)
if (jl_setjmp(lastt->ctx.copy_ctx.uc_mcontext, 0))
return;
#else
#error COPY_STACKS is incompatible with this platform
#endif
sanitizer_start_switch_fiber(t->stkbuf, t->bufsz);
tsan_switch_to_copyctx(&t->ctx);
#if defined(_OS_WINDOWS_)
jl_setcontext(&t->ctx.copy_ctx);
#else
jl_longjmp(t->ctx.copy_ctx.uc_mcontext, 1);
#endif
}
#endif
/* Rooted by the base module */
static _Atomic(jl_function_t*) task_done_hook_func JL_GLOBALLY_ROOTED = NULL;
void JL_NORETURN jl_finish_task(jl_task_t *t)
{
jl_task_t *ct = jl_current_task;
JL_PROBE_RT_FINISH_TASK(ct);
JL_SIGATOMIC_BEGIN();
if (jl_atomic_load_relaxed(&t->_isexception))
jl_atomic_store_release(&t->_state, JL_TASK_STATE_FAILED);
else
jl_atomic_store_release(&t->_state, JL_TASK_STATE_DONE);
if (t->copy_stack) // early free of stkbuf
t->stkbuf = NULL;
// ensure that state is cleared
ct->ptls->in_finalizer = 0;
ct->ptls->in_pure_callback = 0;
ct->world_age = jl_atomic_load_acquire(&jl_world_counter);
// let the runtime know this task is dead and find a new task to run
jl_function_t *done = jl_atomic_load_relaxed(&task_done_hook_func);
if (done == NULL) {
done = (jl_function_t*)jl_get_global(jl_base_module, jl_symbol("task_done_hook"));
if (done != NULL)
jl_atomic_store_release(&task_done_hook_func, done);
}
if (done != NULL) {
jl_value_t *args[2] = {done, (jl_value_t*)t};
JL_TRY {
jl_apply(args, 2);
}
JL_CATCH {
jl_no_exc_handler(jl_current_exception());
}
}
jl_gc_debug_critical_error();
abort();
}
JL_DLLEXPORT void *jl_task_stack_buffer(jl_task_t *task, size_t *size, int *ptid)
{
size_t off = 0;
#ifndef _OS_WINDOWS_
if (jl_all_tls_states[0]->root_task == task) {
// See jl_init_root_task(). The root task of the main thread
// has its buffer enlarged by an artificial 3000000 bytes, but
// that means that the start of the buffer usually points to
// inaccessible memory. We need to correct for this.
off = ROOT_TASK_STACK_ADJUSTMENT;
}
#endif
jl_ptls_t ptls2 = task->ptls;
*ptid = -1;
if (ptls2) {
*ptid = jl_atomic_load_relaxed(&task->tid);
#ifdef COPY_STACKS
if (task->copy_stack) {
*size = ptls2->stacksize;
return (char *)ptls2->stackbase - *size;
}
#endif
}
*size = task->bufsz - off;
return (void *)((char *)task->stkbuf + off);
}
JL_DLLEXPORT void jl_active_task_stack(jl_task_t *task,
char **active_start, char **active_end,
char **total_start, char **total_end)
{
if (!task->started) {
*total_start = *active_start = 0;
*total_end = *active_end = 0;
return;
}
jl_ptls_t ptls2 = task->ptls;
if (task->copy_stack && ptls2) {
*total_start = *active_start = (char*)ptls2->stackbase - ptls2->stacksize;
*total_end = *active_end = (char*)ptls2->stackbase;
}
else if (task->stkbuf) {
*total_start = *active_start = (char*)task->stkbuf;
#ifndef _OS_WINDOWS_
if (jl_all_tls_states[0]->root_task == task) {
// See jl_init_root_task(). The root task of the main thread
// has its buffer enlarged by an artificial 3000000 bytes, but
// that means that the start of the buffer usually points to
// inaccessible memory. We need to correct for this.
*active_start += ROOT_TASK_STACK_ADJUSTMENT;
*total_start += ROOT_TASK_STACK_ADJUSTMENT;
}
#endif
*total_end = *active_end = (char*)task->stkbuf + task->bufsz;
#ifdef COPY_STACKS
// save_stack stores the stack of an inactive task in stkbuf, and the
// actual number of used bytes in copy_stack.
if (task->copy_stack > 1)
*active_end = (char*)task->stkbuf + task->copy_stack;
#endif
}
else {
// no stack allocated yet
*total_start = *active_start = 0;
*total_end = *active_end = 0;
return;
}
if (task == jl_current_task) {
// scan up to current `sp` for current thread and task
*active_start = (char*)jl_get_frame_addr();
}
}
// Marked noinline so we can consistently skip the associated frame.
// `skip` is number of additional frames to skip.
NOINLINE static void record_backtrace(jl_ptls_t ptls, int skip) JL_NOTSAFEPOINT
{
// storing bt_size in ptls ensures roots in bt_data will be found
ptls->bt_size = rec_backtrace(ptls->bt_data, JL_MAX_BT_SIZE, skip + 1);
}
JL_DLLEXPORT void jl_set_next_task(jl_task_t *task) JL_NOTSAFEPOINT
{
jl_current_task->ptls->next_task = task;
}
JL_DLLEXPORT jl_task_t *jl_get_next_task(void) JL_NOTSAFEPOINT
{
jl_task_t *ct = jl_current_task;
if (ct->ptls->next_task)
return ct->ptls->next_task;
return ct;
}
#ifdef _COMPILER_TSAN_ENABLED_
const char tsan_state_corruption[] = "TSAN state corrupted. Exiting HARD!\n";
#endif
static void ctx_switch(jl_task_t *lastt)
{
jl_ptls_t ptls = lastt->ptls;
jl_task_t **pt = &ptls->next_task;
jl_task_t *t = *pt;
assert(t != lastt);
// none of these locks should be held across a task switch
assert(ptls->locks.len == 0);
#ifdef _COMPILER_TSAN_ENABLED_
if (lastt->ctx.tsan_state != __tsan_get_current_fiber()) {
// Something went really wrong - don't even assume that we can
// use assert/abort which involve lots of signal handling that
// looks at the tsan state.
write(STDERR_FILENO, tsan_state_corruption, sizeof(tsan_state_corruption) - 1);
_exit(1);
}
#endif
int killed = jl_atomic_load_relaxed(&lastt->_state) != JL_TASK_STATE_RUNNABLE;
if (!t->started && !t->copy_stack) {
// may need to allocate the stack
if (t->stkbuf == NULL) {
t->stkbuf = jl_alloc_fiber(&t->ctx.ctx, &t->bufsz, t);
if (t->stkbuf == NULL) {
#ifdef COPY_STACKS
// fall back to stack copying if mmap fails
t->copy_stack = 1;
t->sticky = 1;
t->bufsz = 0;
if (always_copy_stacks)
memcpy(&t->ctx.copy_ctx, &ptls->copy_stack_ctx, sizeof(t->ctx.copy_ctx));
else
memcpy(&t->ctx.ctx, &ptls->base_ctx, sizeof(t->ctx.ctx));
#else
jl_throw(jl_memory_exception);
#endif
}
}
}
if (killed) {
*pt = NULL; // can't fail after here: clear the gc-root for the target task now
lastt->gcstack = NULL;
if (!lastt->copy_stack && lastt->stkbuf) {
// early free of stkbuf back to the pool
jl_release_task_stack(ptls, lastt);
}
}
else {
#ifdef COPY_STACKS
if (lastt->copy_stack) { // save the old copy-stack
save_stack(ptls, lastt, pt); // allocates (gc-safepoint, and can also fail)
if (jl_setjmp(lastt->ctx.copy_ctx.uc_mcontext, 0)) {
sanitizer_finish_switch_fiber();
// TODO: mutex unlock the thread we just switched from
return;
}
}
else
#endif
*pt = NULL; // can't fail after here: clear the gc-root for the target task now
}
// set up global state for new task and clear global state for old task
t->ptls = ptls;
jl_atomic_store_relaxed(&ptls->current_task, t);
JL_GC_PROMISE_ROOTED(t);
jl_signal_fence();
jl_set_pgcstack(&t->gcstack);
jl_signal_fence();
lastt->ptls = NULL;
#ifdef MIGRATE_TASKS
ptls->previous_task = lastt;
#endif
if (t->started) {
#ifdef COPY_STACKS
if (t->copy_stack) {
if (!killed && !lastt->copy_stack)
restore_stack2(t, ptls, lastt);
else {
tsan_switch_to_copyctx(&t->ctx);
if (killed)
tsan_destroy_copyctx(ptls, &lastt->ctx);
if (lastt->copy_stack) {
restore_stack(t, ptls, NULL); // (doesn't return)
}
else {
restore_stack(t, ptls, (char*)1); // (doesn't return)
}
}
}
else
#endif
{
sanitizer_start_switch_fiber(t->stkbuf, t->bufsz);
if (killed) {
tsan_switch_to_ctx(&t->ctx);
tsan_destroy_ctx(ptls, &lastt->ctx);
jl_set_fiber(&t->ctx); // (doesn't return)
abort(); // unreachable
}
else {
if (lastt->copy_stack) {
// Resume at the jl_setjmp earlier in this function,
// don't do a full task swap
tsan_switch_to_ctx(&t->ctx);
jl_set_fiber(&t->ctx); // (doesn't return)
}
else {
jl_swap_fiber(&lastt->ctx, &t->ctx);
}
}
}
}
else {
sanitizer_start_switch_fiber(t->stkbuf, t->bufsz);
if (t->copy_stack && always_copy_stacks) {
tsan_switch_to_ctx(&t->ctx);
if (killed) {
tsan_destroy_ctx(ptls, &lastt->ctx);
}
#ifdef COPY_STACKS
#if defined(_OS_WINDOWS_)
jl_setcontext(&t->ctx.copy_ctx);
#else
jl_longjmp(t->ctx.copy_ctx.uc_mcontext, 1);
#endif
#endif
abort(); // unreachable
}
else {
if (killed) {
tsan_switch_to_ctx(&t->ctx);
tsan_destroy_ctx(ptls, &lastt->ctx);
jl_start_fiber_set(&t->ctx); // (doesn't return)
abort();
}
else if (lastt->copy_stack) {
// Resume at the jl_setjmp earlier in this function
tsan_switch_to_ctx(&t->ctx);
jl_start_fiber_set(&t->ctx); // (doesn't return)
abort();
}
else {
jl_start_fiber_swap(&lastt->ctx, &t->ctx);
}
}
}
sanitizer_finish_switch_fiber();
}
JL_DLLEXPORT void jl_switch(void)
{
jl_task_t *ct = jl_current_task;
jl_ptls_t ptls = ct->ptls;
jl_task_t *t = ptls->next_task;
if (t == ct) {
return;
}
if (t->started && t->stkbuf == NULL)
jl_error("attempt to switch to exited task");
if (ptls->in_finalizer)
jl_error("task switch not allowed from inside gc finalizer");
if (ptls->in_pure_callback)
jl_error("task switch not allowed from inside staged nor pure functions");
if (!jl_set_task_tid(t, jl_atomic_load_relaxed(&ct->tid))) // manually yielding to a task
jl_error("cannot switch to task running on another thread");
JL_PROBE_RT_PAUSE_TASK(ct);
// Store old values on the stack and reset
sig_atomic_t defer_signal = ptls->defer_signal;
int8_t gc_state = jl_gc_unsafe_enter(ptls);
int finalizers_inhibited = ptls->finalizers_inhibited;
ptls->finalizers_inhibited = 0;
#ifdef ENABLE_TIMINGS
jl_timing_block_t *blk = ptls->timing_stack;
if (blk)
jl_timing_block_stop(blk);
ptls->timing_stack = NULL;
#endif
ctx_switch(ct);
#ifdef MIGRATE_TASKS
ptls = ct->ptls;
t = ptls->previous_task;
ptls->previous_task = NULL;
assert(t != ct);
assert(jl_atomic_load_relaxed(&t->tid) == ptls->tid);
if (!t->sticky && !t->copy_stack)
jl_atomic_store_release(&t->tid, -1);
#else
assert(ptls == ct->ptls);
#endif
// Pop old values back off the stack
assert(ct == jl_current_task &&
0 != ct->ptls &&
0 == ptls->finalizers_inhibited);
ptls->finalizers_inhibited = finalizers_inhibited;
#ifdef ENABLE_TIMINGS
assert(ptls->timing_stack == NULL);
ptls->timing_stack = blk;
if (blk)
jl_timing_block_start(blk);
#else
(void)ct;
#endif
jl_gc_unsafe_leave(ptls, gc_state);
sig_atomic_t other_defer_signal = ptls->defer_signal;
ptls->defer_signal = defer_signal;
if (other_defer_signal && !defer_signal)
jl_sigint_safepoint(ptls);
JL_PROBE_RT_RUN_TASK(ct);
}
JL_DLLEXPORT void jl_switchto(jl_task_t **pt)
{
jl_set_next_task(*pt);
jl_switch();
}
JL_DLLEXPORT JL_NORETURN void jl_no_exc_handler(jl_value_t *e)
{
// NULL exception objects are used when rethrowing. we don't have a handler to process
// the exception stack, so at least report the exception at the top of the stack.
if (!e)
e = jl_current_exception();
jl_printf((JL_STREAM*)STDERR_FILENO, "fatal: error thrown and no exception handler available.\n");
jl_static_show((JL_STREAM*)STDERR_FILENO, e);
jl_printf((JL_STREAM*)STDERR_FILENO, "\n");
jlbacktrace(); // written to STDERR_FILENO
jl_exit(1);
}
// yield to exception handler
static void JL_NORETURN throw_internal(jl_task_t *ct, jl_value_t *exception JL_MAYBE_UNROOTED)
{
assert(!jl_get_safe_restore());
jl_ptls_t ptls = ct->ptls;
ptls->io_wait = 0;
JL_GC_PUSH1(&exception);
jl_gc_unsafe_enter(ptls);
if (exception) {
// The temporary ptls->bt_data is rooted by special purpose code in the
// GC. This exists only for the purpose of preserving bt_data until we
// set ptls->bt_size=0 below.
jl_push_excstack(&ct->excstack, exception,
ptls->bt_data, ptls->bt_size);
ptls->bt_size = 0;
}
assert(ct->excstack && ct->excstack->top);
jl_handler_t *eh = ct->eh;
if (eh != NULL) {
#ifdef ENABLE_TIMINGS
jl_timing_block_t *cur_block = ptls->timing_stack;
while (cur_block && eh->timing_stack != cur_block) {
cur_block = jl_pop_timing_block(cur_block);
}
assert(cur_block == eh->timing_stack);
#endif
jl_longjmp(eh->eh_ctx, 1);
}
else {
jl_no_exc_handler(exception);
}
assert(0);
}
// record backtrace and raise an error
JL_DLLEXPORT void jl_throw(jl_value_t *e JL_MAYBE_UNROOTED)
{
assert(e != NULL);
jl_jmp_buf *safe_restore = jl_get_safe_restore();
if (safe_restore)
jl_longjmp(*safe_restore, 1);
jl_task_t *ct = jl_get_current_task();
if (ct == NULL) // During startup
jl_no_exc_handler(e);
JL_GC_PROMISE_ROOTED(ct);
record_backtrace(ct->ptls, 1);
throw_internal(ct, e);
}
// rethrow with current excstack state
JL_DLLEXPORT void jl_rethrow(void)
{
jl_task_t *ct = jl_current_task;
jl_excstack_t *excstack = ct->excstack;
if (!excstack || excstack->top == 0)
jl_error("rethrow() not allowed outside a catch block");
throw_internal(ct, NULL);
}
// Special case throw for errors detected inside signal handlers. This is not
// (cannot be) called directly in the signal handler itself, but is returned to
// after the signal handler exits.
JL_DLLEXPORT void JL_NORETURN jl_sig_throw(void)
{
CFI_NORETURN
jl_jmp_buf *safe_restore = jl_get_safe_restore();
if (safe_restore)
jl_longjmp(*safe_restore, 1);
jl_task_t *ct = jl_current_task;
jl_ptls_t ptls = ct->ptls;
jl_value_t *e = ptls->sig_exception;
ptls->sig_exception = NULL;
throw_internal(ct, e);
}
JL_DLLEXPORT void jl_rethrow_other(jl_value_t *e JL_MAYBE_UNROOTED)
{
// TODO: Should uses of `rethrow(exc)` be replaced with a normal throw, now
// that exception stacks allow root cause analysis?
jl_task_t *ct = jl_current_task;
jl_excstack_t *excstack = ct->excstack;
if (!excstack || excstack->top == 0)
jl_error("rethrow(exc) not allowed outside a catch block");
// overwrite exception on top of stack. see jl_excstack_exception
jl_excstack_raw(excstack)[excstack->top-1].jlvalue = e;
JL_GC_PROMISE_ROOTED(e);
throw_internal(ct, NULL);
}
/* This is xoshiro256++ 1.0, used for tasklocal random number generation in Julia.
This implementation is intended for embedders and internal use by the runtime, and is
based on the reference implementation at https://prng.di.unimi.it
Credits go to David Blackman and Sebastiano Vigna for coming up with this PRNG.
They described xoshiro256++ in "Scrambled Linear Pseudorandom Number Generators",
ACM Trans. Math. Softw., 2021.
There is a pure Julia implementation in stdlib that tends to be faster when used from
within Julia, due to inlining and more agressive architecture-specific optimizations.
*/
JL_DLLEXPORT uint64_t jl_tasklocal_genrandom(jl_task_t *task) JL_NOTSAFEPOINT
{
uint64_t s0 = task->rngState0;
uint64_t s1 = task->rngState1;
uint64_t s2 = task->rngState2;
uint64_t s3 = task->rngState3;
uint64_t t = s1 << 17;
uint64_t tmp = s0 + s3;
uint64_t res = ((tmp << 23) | (tmp >> 41)) + s0;
s2 ^= s0;
s3 ^= s1;
s1 ^= s2;
s0 ^= s3;
s2 ^= t;
s3 = (s3 << 45) | (s3 >> 19);
task->rngState0 = s0;
task->rngState1 = s1;
task->rngState2 = s2;
task->rngState3 = s3;
return res;
}
void rng_split(jl_task_t *from, jl_task_t *to) JL_NOTSAFEPOINT
{
/* TODO: consider a less ad-hoc construction
Ideally we could just use the output of the random stream to seed the initial
state of the child. Out of an overabundance of caution we multiply with
effectively random coefficients, to break possible self-interactions.
It is not the goal to mix bits -- we work under the assumption that the
source is well-seeded, and its output looks effectively random.
However, xoshiro has never been studied in the mode where we seed the
initial state with the output of another xoshiro instance.
Constants have nothing up their sleeve:
0x02011ce34bce797f == hash(UInt(1))|0x01
0x5a94851fb48a6e05 == hash(UInt(2))|0x01
0x3688cf5d48899fa7 == hash(UInt(3))|0x01
0x867b4bb4c42e5661 == hash(UInt(4))|0x01
*/
to->rngState0 = 0x02011ce34bce797f * jl_tasklocal_genrandom(from);
to->rngState1 = 0x5a94851fb48a6e05 * jl_tasklocal_genrandom(from);
to->rngState2 = 0x3688cf5d48899fa7 * jl_tasklocal_genrandom(from);
to->rngState3 = 0x867b4bb4c42e5661 * jl_tasklocal_genrandom(from);
}
JL_DLLEXPORT jl_task_t *jl_new_task(jl_function_t *start, jl_value_t *completion_future, size_t ssize)
{
jl_task_t *ct = jl_current_task;
jl_task_t *t = (jl_task_t*)jl_gc_alloc(ct->ptls, sizeof(jl_task_t), jl_task_type);
JL_PROBE_RT_NEW_TASK(ct, t);
t->copy_stack = 0;
if (ssize == 0) {
// stack size unspecified; use default
if (always_copy_stacks) {
t->copy_stack = 1;
t->bufsz = 0;
}
else {
t->bufsz = JL_STACK_SIZE;
}
t->stkbuf = NULL;
}
else {
// user requested dedicated stack of a certain size
if (ssize < MINSTKSZ)
ssize = MINSTKSZ;
t->bufsz = ssize;
t->stkbuf = jl_alloc_fiber(&t->ctx.ctx, &t->bufsz, t);
if (t->stkbuf == NULL)
jl_throw(jl_memory_exception);
}
t->next = jl_nothing;
t->queue = jl_nothing;
t->tls = jl_nothing;
jl_atomic_store_relaxed(&t->_state, JL_TASK_STATE_RUNNABLE);
t->start = start;
t->result = jl_nothing;
t->donenotify = completion_future;
jl_atomic_store_relaxed(&t->_isexception, 0);
// Inherit logger state from parent task
t->logstate = ct->logstate;
// Fork task-local random state from parent
rng_split(ct, t);
// there is no active exception handler available on this stack yet
t->eh = NULL;
t->sticky = 1;
t->gcstack = NULL;
t->excstack = NULL;
t->started = 0;
t->prio = -1;
jl_atomic_store_relaxed(&t->tid, t->copy_stack ? jl_atomic_load_relaxed(&ct->tid) : -1); // copy_stacks are always pinned since they can't be moved
t->ptls = NULL;
t->world_age = ct->world_age;
#ifdef COPY_STACKS
if (!t->copy_stack) {
#if defined(JL_DEBUG_BUILD)
memset(&t->ctx, 0, sizeof(t->ctx));
#endif
}
else {
if (always_copy_stacks)
memcpy(&t->ctx.copy_ctx, &ct->ptls->copy_stack_ctx, sizeof(t->ctx.copy_ctx));
else
memcpy(&t->ctx.ctx, &ct->ptls->base_ctx, sizeof(t->ctx.ctx));
}
#endif
#ifdef _COMPILER_TSAN_ENABLED_
t->ctx.tsan_state = __tsan_create_fiber(0);
#endif
return t;
}
// a version of jl_current_task safe for unmanaged threads
JL_DLLEXPORT jl_task_t *jl_get_current_task(void)
{
jl_gcframe_t **pgcstack = jl_get_pgcstack();
return pgcstack == NULL ? NULL : container_of(pgcstack, jl_task_t, gcstack);
}
#ifdef JL_HAVE_ASYNCIFY
JL_DLLEXPORT jl_ucontext_t *task_ctx_ptr(jl_task_t *t)
{
return &t->ctx.ctx;
}
JL_DLLEXPORT jl_value_t *jl_get_root_task(void)
{
jl_task_t *ct = jl_current_task;
return (jl_value_t*)ct->ptls->root_task;
}
JL_DLLEXPORT void jl_task_wait()
{
static jl_function_t *wait_func = NULL;
if (!wait_func) {
wait_func = (jl_function_t*)jl_get_global(jl_base_module, jl_symbol("wait"));
}
jl_task_t *ct = jl_current_task;
size_t last_age = ct->world_age;
ct->world_age = jl_get_world_counter();
jl_apply(&wait_func, 1);
ct->world_age = last_age;
}
JL_DLLEXPORT void jl_schedule_task(jl_task_t *task)
{
static jl_function_t *sched_func = NULL;
if (!sched_func) {
sched_func = (jl_function_t*)jl_get_global(jl_base_module, jl_symbol("schedule"));
}
jl_task_t *ct = jl_current_task;
size_t last_age = ct->world_age;
ct->world_age = jl_get_world_counter();
jl_value_t *args[] = {(jl_value_t*)sched_func, (jl_value_t*)task};
jl_apply(args, 2);
ct->world_age = last_age;
}
#endif
// Do one-time initializations for task system
void jl_init_tasks(void) JL_GC_DISABLED
{
char *acs = getenv("JULIA_COPY_STACKS");
if (acs) {
if (!strcmp(acs, "1") || !strcmp(acs, "yes"))
always_copy_stacks = 1;
else if (!strcmp(acs, "0") || !strcmp(acs, "no"))
always_copy_stacks = 0;
else {
jl_safe_printf("invalid JULIA_COPY_STACKS value: %s\n", acs);
exit(1);
}
}
#ifndef COPY_STACKS
if (always_copy_stacks) {
jl_safe_printf("Julia built without COPY_STACKS support");
exit(1);
}
#endif
}
STATIC_OR_JS void NOINLINE JL_NORETURN start_task(void)
{
CFI_NORETURN
// this runs the first time we switch to a task
sanitizer_finish_switch_fiber();
#ifdef __clang_gcanalyzer__
jl_task_t *ct = jl_get_current_task();
JL_GC_PROMISE_ROOTED(ct);
#else
jl_task_t *ct = jl_current_task;
#endif
jl_ptls_t ptls = ct->ptls;
jl_value_t *res;
assert(ptls->finalizers_inhibited == 0);
#ifdef MIGRATE_TASKS
jl_task_t *pt = ptls->previous_task;
ptls->previous_task = NULL;
if (!pt->sticky && !pt->copy_stack)
jl_atomic_store_release(&pt->tid, -1);
#endif
ct->started = 1;
JL_PROBE_RT_START_TASK(ct);
if (jl_atomic_load_relaxed(&ct->_isexception)) {
record_backtrace(ptls, 0);
jl_push_excstack(&ct->excstack, ct->result,
ptls->bt_data, ptls->bt_size);
res = ct->result;
}
else {
JL_TRY {
if (ptls->defer_signal) {
ptls->defer_signal = 0;
jl_sigint_safepoint(ptls);
}
JL_TIMING(ROOT);
res = jl_apply(&ct->start, 1);
}
JL_CATCH {
res = jl_current_exception();
jl_atomic_store_relaxed(&ct->_isexception, 1);
goto skip_pop_exception;
}
skip_pop_exception:;
}
ct->result = res;
jl_gc_wb(ct, ct->result);
jl_finish_task(ct);
jl_gc_debug_critical_error();
abort();
}
#if defined(JL_HAVE_UCONTEXT)
#ifdef _OS_WINDOWS_
#define setcontext jl_setcontext
#define swapcontext jl_swapcontext
#define makecontext jl_makecontext
#endif
static char *jl_alloc_fiber(_jl_ucontext_t *t, size_t *ssize, jl_task_t *owner) JL_NOTSAFEPOINT
{
#ifndef _OS_WINDOWS_
int r = getcontext(t);
if (r != 0)
jl_error("getcontext failed");
#endif
void *stk = jl_malloc_stack(ssize, owner);
if (stk == NULL)
return NULL;
t->uc_stack.ss_sp = stk;
t->uc_stack.ss_size = *ssize;
#ifdef _OS_WINDOWS_
makecontext(t, &start_task);
#else
t->uc_link = NULL;
makecontext(t, &start_task, 0);
#endif
return (char*)stk;
}
static void jl_start_fiber_set(jl_ucontext_t *t)
{
setcontext(&t->ctx);
}
static void jl_start_fiber_swap(jl_ucontext_t *lastt, jl_ucontext_t *t)
{
assert(lastt);
tsan_switch_to_ctx(t);
swapcontext(&lastt->ctx, &t->ctx);
}
static void jl_swap_fiber(jl_ucontext_t *lastt, jl_ucontext_t *t)
{
tsan_switch_to_ctx(t);
swapcontext(&lastt->ctx, &t->ctx);
}
static void jl_set_fiber(jl_ucontext_t *t)
{
setcontext(&t->ctx);
}
#endif
#if defined(JL_HAVE_UNW_CONTEXT) || defined(JL_HAVE_ASM)
static char *jl_alloc_fiber(_jl_ucontext_t *t, size_t *ssize, jl_task_t *owner)
{
char *stkbuf = (char*)jl_malloc_stack(ssize, owner);
if (stkbuf == NULL)
return NULL;