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cont.c
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cont.c
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/**********************************************************************
cont.c -
$Author$
created at: Thu May 23 09:03:43 2007
Copyright (C) 2007 Koichi Sasada
**********************************************************************/
#include "ruby/ruby.h"
#include "vm_core.h"
#include "gc.h"
#include "eval_intern.h"
#if ((defined(_WIN32) && _WIN32_WINNT >= 0x0400) || defined(HAVE_SETCONTEXT)) && !defined(__NetBSD__) && !defined(FIBER_USE_NATIVE)
#define FIBER_USE_NATIVE 1
/* FIBER_USE_NATIVE enables Fiber performance improvement using system
* dependent method such as make/setcontext on POSIX system or
* CreateFiber() API on Windows.
* This hack make Fiber context switch faster (x2 or more).
* However, it decrease maximum number of Fiber. For example, on the
* 32bit POSIX OS, ten or twenty thousands Fiber can be created.
*
* Details is reported in the paper "A Fast Fiber Implementation for Ruby 1.9"
* in Proc. of 51th Programming Symposium, pp.21--28 (2010) (in Japanese).
*/
/* On our experience, NetBSD doesn't support using setcontext() and pthread
* simultaneously. This is because pthread_self(), TLS and other information
* are represented by stack pointer (higher bits of stack pointer).
* TODO: check such constraint on configure.
*/
#endif
#ifdef FIBER_USE_NATIVE
#ifndef _WIN32
#include <unistd.h>
#include <sys/mman.h>
#include <ucontext.h>
#endif
#define RB_PAGE_SIZE (pagesize)
#define RB_PAGE_MASK (~(RB_PAGE_SIZE - 1))
static long pagesize;
#define FIBER_MACHINE_STACK_ALLOCATION_SIZE (0x10000 / sizeof(VALUE))
#endif
#define CAPTURE_JUST_VALID_VM_STACK 1
enum context_type {
CONTINUATION_CONTEXT = 0,
FIBER_CONTEXT = 1,
ROOT_FIBER_CONTEXT = 2
};
typedef struct rb_context_struct {
enum context_type type;
VALUE self;
int argc;
VALUE value;
VALUE *vm_stack;
#ifdef CAPTURE_JUST_VALID_VM_STACK
size_t vm_stack_slen; /* length of stack (head of th->stack) */
size_t vm_stack_clen; /* length of control frames (tail of th->stack) */
#endif
VALUE *machine_stack;
VALUE *machine_stack_src;
#ifdef __ia64
VALUE *machine_register_stack;
VALUE *machine_register_stack_src;
int machine_register_stack_size;
#endif
rb_thread_t saved_thread;
rb_jmpbuf_t jmpbuf;
size_t machine_stack_size;
} rb_context_t;
enum fiber_status {
CREATED,
RUNNING,
TERMINATED
};
#if defined(FIBER_USE_NATIVE) && !defined(_WIN32)
#define MAX_MAHINE_STACK_CACHE 10
static int machine_stack_cache_index = 0;
typedef struct machine_stack_cache_struct {
void *ptr;
size_t size;
} machine_stack_cache_t;
static machine_stack_cache_t machine_stack_cache[MAX_MAHINE_STACK_CACHE];
static machine_stack_cache_t terminated_machine_stack;
#endif
typedef struct rb_fiber_struct {
rb_context_t cont;
VALUE prev;
enum fiber_status status;
struct rb_fiber_struct *prev_fiber;
struct rb_fiber_struct *next_fiber;
#ifdef FIBER_USE_NATIVE
#ifdef _WIN32
void *fib_handle;
#else
ucontext_t context;
#endif
#endif
} rb_fiber_t;
static const rb_data_type_t cont_data_type, fiber_data_type;
static VALUE rb_cContinuation;
static VALUE rb_cFiber;
static VALUE rb_eFiberError;
#define GetContPtr(obj, ptr) \
TypedData_Get_Struct(obj, rb_context_t, &cont_data_type, ptr)
#define GetFiberPtr(obj, ptr) do {\
TypedData_Get_Struct(obj, rb_fiber_t, &fiber_data_type, ptr); \
if (!ptr) rb_raise(rb_eFiberError, "uninitialized fiber"); \
} while(0)
NOINLINE(static VALUE cont_capture(volatile int *stat));
void rb_thread_mark(rb_thread_t *th);
#define THREAD_MUST_BE_RUNNING(th) do { \
if (!th->tag) rb_raise(rb_eThreadError, "not running thread"); \
} while (0)
static void
cont_mark(void *ptr)
{
RUBY_MARK_ENTER("cont");
if (ptr) {
rb_context_t *cont = ptr;
rb_gc_mark(cont->value);
rb_thread_mark(&cont->saved_thread);
if (cont->vm_stack) {
#ifdef CAPTURE_JUST_VALID_VM_STACK
rb_gc_mark_locations(cont->vm_stack,
cont->vm_stack + cont->vm_stack_slen + cont->vm_stack_clen);
#else
rb_gc_mark_localtion(cont->vm_stack,
cont->vm_stack, cont->saved_thread.stack_size);
#endif
}
if (cont->machine_stack) {
if (cont->type == CONTINUATION_CONTEXT) {
/* cont */
rb_gc_mark_locations(cont->machine_stack,
cont->machine_stack + cont->machine_stack_size);
}
else {
/* fiber */
rb_thread_t *th;
rb_fiber_t *fib = (rb_fiber_t*)cont;
GetThreadPtr(cont->saved_thread.self, th);
if ((th->fiber != cont->self) && fib->status == RUNNING) {
rb_gc_mark_locations(cont->machine_stack,
cont->machine_stack + cont->machine_stack_size);
}
}
}
#ifdef __ia64
if (cont->machine_register_stack) {
rb_gc_mark_locations(cont->machine_register_stack,
cont->machine_register_stack + cont->machine_register_stack_size);
}
#endif
}
RUBY_MARK_LEAVE("cont");
}
static void
cont_free(void *ptr)
{
RUBY_FREE_ENTER("cont");
if (ptr) {
rb_context_t *cont = ptr;
RUBY_FREE_UNLESS_NULL(cont->saved_thread.stack); fflush(stdout);
#ifdef FIBER_USE_NATIVE
if (cont->type == CONTINUATION_CONTEXT) {
/* cont */
RUBY_FREE_UNLESS_NULL(cont->machine_stack);
}
else {
/* fiber */
#ifdef _WIN32
if (GET_THREAD()->fiber != cont->self && cont->type != ROOT_FIBER_CONTEXT) {
/* don't delete root fiber handle */
rb_fiber_t *fib = (rb_fiber_t*)cont;
if (fib->fib_handle) {
DeleteFiber(fib->fib_handle);
}
}
#else /* not WIN32 */
if (GET_THREAD()->fiber != cont->self) {
rb_fiber_t *fib = (rb_fiber_t*)cont;
if (fib->context.uc_stack.ss_sp) {
if (cont->type == ROOT_FIBER_CONTEXT) {
rb_bug("Illegal root fiber parameter");
}
munmap((void*)fib->context.uc_stack.ss_sp, fib->context.uc_stack.ss_size);
}
}
else {
/* It may reached here when finalize */
/* TODO examine whether it is a bug */
/* rb_bug("cont_free: release self"); */
}
#endif
}
#else /* not FIBER_USE_NATIVE */
RUBY_FREE_UNLESS_NULL(cont->machine_stack);
#endif
#ifdef __ia64
RUBY_FREE_UNLESS_NULL(cont->machine_register_stack);
#endif
RUBY_FREE_UNLESS_NULL(cont->vm_stack);
/* free rb_cont_t or rb_fiber_t */
ruby_xfree(ptr);
}
RUBY_FREE_LEAVE("cont");
}
static size_t
cont_memsize(const void *ptr)
{
const rb_context_t *cont = ptr;
size_t size = 0;
if (cont) {
size = sizeof(*cont);
if (cont->vm_stack) {
#ifdef CAPTURE_JUST_VALID_VM_STACK
size_t n = (cont->vm_stack_slen + cont->vm_stack_clen);
#else
size_t n = cont->saved_thread.stack_size;
#endif
size += n * sizeof(*cont->vm_stack);
}
if (cont->machine_stack) {
size += cont->machine_stack_size * sizeof(*cont->machine_stack);
}
#ifdef __ia64
if (cont->machine_register_stack) {
size += cont->machine_register_stack_size * sizeof(*cont->machine_register_stack);
}
#endif
}
return size;
}
static void
fiber_mark(void *ptr)
{
RUBY_MARK_ENTER("cont");
if (ptr) {
rb_fiber_t *fib = ptr;
rb_gc_mark(fib->prev);
cont_mark(&fib->cont);
}
RUBY_MARK_LEAVE("cont");
}
static void
fiber_link_join(rb_fiber_t *fib)
{
VALUE current_fibval = rb_fiber_current();
rb_fiber_t *current_fib;
GetFiberPtr(current_fibval, current_fib);
/* join fiber link */
fib->next_fiber = current_fib->next_fiber;
fib->prev_fiber = current_fib;
current_fib->next_fiber->prev_fiber = fib;
current_fib->next_fiber = fib;
}
static void
fiber_link_remove(rb_fiber_t *fib)
{
fib->prev_fiber->next_fiber = fib->next_fiber;
fib->next_fiber->prev_fiber = fib->prev_fiber;
}
static void
fiber_free(void *ptr)
{
RUBY_FREE_ENTER("fiber");
if (ptr) {
rb_fiber_t *fib = ptr;
if (fib->cont.type != ROOT_FIBER_CONTEXT &&
fib->cont.saved_thread.local_storage) {
st_free_table(fib->cont.saved_thread.local_storage);
}
fiber_link_remove(fib);
cont_free(&fib->cont);
}
RUBY_FREE_LEAVE("fiber");
}
static size_t
fiber_memsize(const void *ptr)
{
const rb_fiber_t *fib = ptr;
size_t size = 0;
if (ptr) {
size = sizeof(*fib);
if (fib->cont.type != ROOT_FIBER_CONTEXT) {
size += st_memsize(fib->cont.saved_thread.local_storage);
}
size += cont_memsize(&fib->cont);
}
return size;
}
static void
cont_save_machine_stack(rb_thread_t *th, rb_context_t *cont)
{
size_t size;
rb_thread_t *sth = &cont->saved_thread;
SET_MACHINE_STACK_END(&th->machine_stack_end);
#ifdef __ia64
th->machine_register_stack_end = rb_ia64_bsp();
#endif
if (th->machine_stack_start > th->machine_stack_end) {
size = cont->machine_stack_size = th->machine_stack_start - th->machine_stack_end;
cont->machine_stack_src = th->machine_stack_end;
}
else {
size = cont->machine_stack_size = th->machine_stack_end - th->machine_stack_start;
cont->machine_stack_src = th->machine_stack_start;
}
if (cont->machine_stack) {
REALLOC_N(cont->machine_stack, VALUE, size);
}
else {
cont->machine_stack = ALLOC_N(VALUE, size);
}
FLUSH_REGISTER_WINDOWS;
MEMCPY(cont->machine_stack, cont->machine_stack_src, VALUE, size);
#ifdef __ia64
rb_ia64_flushrs();
size = cont->machine_register_stack_size = th->machine_register_stack_end - th->machine_register_stack_start;
cont->machine_register_stack_src = th->machine_register_stack_start;
if (cont->machine_register_stack) {
REALLOC_N(cont->machine_register_stack, VALUE, size);
}
else {
cont->machine_register_stack = ALLOC_N(VALUE, size);
}
MEMCPY(cont->machine_register_stack, cont->machine_register_stack_src, VALUE, size);
#endif
sth->machine_stack_start = sth->machine_stack_end = 0;
#ifdef __ia64
sth->machine_register_stack_start = sth->machine_register_stack_end = 0;
#endif
}
static const rb_data_type_t cont_data_type = {
"continuation",
{cont_mark, cont_free, cont_memsize,},
};
static void
cont_init(rb_context_t *cont, rb_thread_t *th)
{
/* save thread context */
cont->saved_thread = *th;
cont->saved_thread.local_storage = 0;
}
static rb_context_t *
cont_new(VALUE klass)
{
rb_context_t *cont;
volatile VALUE contval;
rb_thread_t *th = GET_THREAD();
THREAD_MUST_BE_RUNNING(th);
contval = TypedData_Make_Struct(klass, rb_context_t, &cont_data_type, cont);
cont->self = contval;
cont_init(cont, th);
return cont;
}
void rb_vm_stack_to_heap(rb_thread_t *th);
static VALUE
cont_capture(volatile int *stat)
{
rb_context_t *cont;
rb_thread_t *th = GET_THREAD(), *sth;
volatile VALUE contval;
THREAD_MUST_BE_RUNNING(th);
rb_vm_stack_to_heap(th);
cont = cont_new(rb_cContinuation);
contval = cont->self;
sth = &cont->saved_thread;
#ifdef CAPTURE_JUST_VALID_VM_STACK
cont->vm_stack_slen = th->cfp->sp + th->mark_stack_len - th->stack;
cont->vm_stack_clen = th->stack + th->stack_size - (VALUE*)th->cfp;
cont->vm_stack = ALLOC_N(VALUE, cont->vm_stack_slen + cont->vm_stack_clen);
MEMCPY(cont->vm_stack, th->stack, VALUE, cont->vm_stack_slen);
MEMCPY(cont->vm_stack + cont->vm_stack_slen, (VALUE*)th->cfp, VALUE, cont->vm_stack_clen);
#else
cont->vm_stack = ALLOC_N(VALUE, th->stack_size);
MEMCPY(cont->vm_stack, th->stack, VALUE, th->stack_size);
#endif
sth->stack = 0;
cont_save_machine_stack(th, cont);
if (ruby_setjmp(cont->jmpbuf)) {
VALUE value;
value = cont->value;
if (cont->argc == -1) rb_exc_raise(value);
cont->value = Qnil;
*stat = 1;
return value;
}
else {
*stat = 0;
return cont->self;
}
}
static void
cont_restore_thread(rb_context_t *cont)
{
rb_thread_t *th = GET_THREAD(), *sth = &cont->saved_thread;
/* restore thread context */
if (cont->type == CONTINUATION_CONTEXT) {
/* continuation */
VALUE fib;
th->fiber = sth->fiber;
fib = th->fiber ? th->fiber : th->root_fiber;
if (fib) {
rb_fiber_t *fcont;
GetFiberPtr(fib, fcont);
th->stack_size = fcont->cont.saved_thread.stack_size;
th->stack = fcont->cont.saved_thread.stack;
}
#ifdef CAPTURE_JUST_VALID_VM_STACK
MEMCPY(th->stack, cont->vm_stack, VALUE, cont->vm_stack_slen);
MEMCPY(th->stack + sth->stack_size - cont->vm_stack_clen,
cont->vm_stack + cont->vm_stack_slen, VALUE, cont->vm_stack_clen);
#else
MEMCPY(th->stack, cont->vm_stack, VALUE, sth->stack_size);
#endif
}
else {
/* fiber */
th->stack = sth->stack;
th->stack_size = sth->stack_size;
th->local_storage = sth->local_storage;
th->fiber = cont->self;
}
th->cfp = sth->cfp;
th->safe_level = sth->safe_level;
th->raised_flag = sth->raised_flag;
th->state = sth->state;
th->status = sth->status;
th->tag = sth->tag;
th->protect_tag = sth->protect_tag;
th->errinfo = sth->errinfo;
th->first_proc = sth->first_proc;
}
#ifdef FIBER_USE_NATIVE
#ifdef _WIN32
static void
fiber_set_stack_location(void)
{
rb_thread_t *th = GET_THREAD();
VALUE *ptr;
SET_MACHINE_STACK_END(&ptr);
th->machine_stack_start = (void*)(((VALUE)ptr & RB_PAGE_MASK) + STACK_UPPER((void *)&ptr, 0, RB_PAGE_SIZE));
}
static VOID CALLBACK
fiber_entry(void *arg)
{
fiber_set_stack_location();
rb_fiber_start();
}
#else
static VALUE*
fiber_machine_stack_alloc(size_t size)
{
VALUE *ptr;
if (machine_stack_cache_index > 0) {
if (machine_stack_cache[machine_stack_cache_index - 1].size == (size / sizeof(VALUE))) {
ptr = machine_stack_cache[machine_stack_cache_index - 1].ptr;
machine_stack_cache_index--;
machine_stack_cache[machine_stack_cache_index].ptr = NULL;
machine_stack_cache[machine_stack_cache_index].size = 0;
}
else{
/* TODO handle multiple machine stack size */
rb_bug("machine_stack_cache size is not canonicalized");
}
}
else {
STACK_GROW_DIR_DETECTION;
ptr = (VALUE*)mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
if (ptr == (VALUE*)(SIGNED_VALUE)-1) {
rb_raise(rb_eFiberError, "can't alloc machine stack to fiber");
}
if (mprotect(ptr + STACK_DIR_UPPER((size - RB_PAGE_SIZE) / sizeof(VALUE), 0),
RB_PAGE_SIZE, PROT_READ | PROT_WRITE) < 0) {
rb_raise(rb_eFiberError, "mprotect failed");
}
}
return ptr;
}
#endif
static void
fiber_initialize_machine_stack_context(rb_fiber_t *fib, size_t size)
{
rb_thread_t *sth = &fib->cont.saved_thread;
#ifdef _WIN32
fib->fib_handle = CreateFiberEx(size - 1, size, 0, fiber_entry, NULL);
if (!fib->fib_handle) {
/* try to release unnecessary fibers & retry to create */
rb_gc();
fib->fib_handle = CreateFiberEx(size - 1, size, 0, fiber_entry, NULL);
if (!fib->fib_handle) {
rb_raise(rb_eFiberError, "can't create fiber");
}
}
#else /* not WIN32 */
ucontext_t *context = &fib->context;
VALUE *ptr;
STACK_GROW_DIR_DETECTION;
getcontext(context);
ptr = fiber_machine_stack_alloc(size);
context->uc_link = NULL;
context->uc_stack.ss_sp = (char *)ptr;
context->uc_stack.ss_size = size;
makecontext(context, rb_fiber_start, 0);
sth->machine_stack_start = ptr + STACK_DIR_UPPER(0, size / sizeof(VALUE));
#endif
sth->machine_stack_maxsize = size;
#ifdef __ia64
sth->machine_register_stack_maxsize = sth->machine_stack_maxsize;
#endif
}
NOINLINE(static void fiber_setcontext(rb_fiber_t *newfib, rb_fiber_t *oldfib));
static void
fiber_setcontext(rb_fiber_t *newfib, rb_fiber_t *oldfib)
{
rb_thread_t *th = GET_THREAD(), *sth = &newfib->cont.saved_thread;
if (newfib->status != RUNNING) {
fiber_initialize_machine_stack_context(newfib, FIBER_MACHINE_STACK_ALLOCATION_SIZE * sizeof(VALUE));
}
/* restore thread context */
cont_restore_thread(&newfib->cont);
th->machine_stack_maxsize = sth->machine_stack_maxsize;
if (sth->machine_stack_end && (newfib != oldfib)) {
rb_bug("fiber_setcontext: sth->machine_stack_end has non zero value");
}
/* save oldfib's machine stack */
if (oldfib->status != TERMINATED) {
STACK_GROW_DIR_DETECTION;
SET_MACHINE_STACK_END(&th->machine_stack_end);
if (STACK_DIR_UPPER(0, 1)) {
oldfib->cont.machine_stack_size = th->machine_stack_start - th->machine_stack_end;
oldfib->cont.machine_stack = th->machine_stack_end;
}
else {
oldfib->cont.machine_stack_size = th->machine_stack_end - th->machine_stack_start;
oldfib->cont.machine_stack = th->machine_stack_start;
}
}
/* exchange machine_stack_start between oldfib and newfib */
oldfib->cont.saved_thread.machine_stack_start = th->machine_stack_start;
th->machine_stack_start = sth->machine_stack_start;
/* oldfib->machine_stack_end should be NULL */
oldfib->cont.saved_thread.machine_stack_end = 0;
#ifndef _WIN32
if (!newfib->context.uc_stack.ss_sp && th->root_fiber != newfib->cont.self) {
rb_bug("non_root_fiber->context.uc_stac.ss_sp should not be NULL");
}
#endif
/* swap machine context */
#ifdef _WIN32
SwitchToFiber(newfib->fib_handle);
#else
swapcontext(&oldfib->context, &newfib->context);
#endif
}
#endif
NOINLINE(NORETURN(static void cont_restore_1(rb_context_t *)));
static void
cont_restore_1(rb_context_t *cont)
{
cont_restore_thread(cont);
/* restore machine stack */
#ifdef _M_AMD64
{
/* workaround for x64 SEH */
jmp_buf buf;
setjmp(buf);
((_JUMP_BUFFER*)(&cont->jmpbuf))->Frame =
((_JUMP_BUFFER*)(&buf))->Frame;
}
#endif
if (cont->machine_stack_src) {
FLUSH_REGISTER_WINDOWS;
MEMCPY(cont->machine_stack_src, cont->machine_stack,
VALUE, cont->machine_stack_size);
}
#ifdef __ia64
if (cont->machine_register_stack_src) {
MEMCPY(cont->machine_register_stack_src, cont->machine_register_stack,
VALUE, cont->machine_register_stack_size);
}
#endif
ruby_longjmp(cont->jmpbuf, 1);
}
NORETURN(NOINLINE(static void cont_restore_0(rb_context_t *, VALUE *)));
#ifdef __ia64
#define C(a) rse_##a##0, rse_##a##1, rse_##a##2, rse_##a##3, rse_##a##4
#define E(a) rse_##a##0= rse_##a##1= rse_##a##2= rse_##a##3= rse_##a##4
static volatile int C(a), C(b), C(c), C(d), C(e);
static volatile int C(f), C(g), C(h), C(i), C(j);
static volatile int C(k), C(l), C(m), C(n), C(o);
static volatile int C(p), C(q), C(r), C(s), C(t);
#if 0
{/* the above lines make cc-mode.el confused so much */}
#endif
int rb_dummy_false = 0;
NORETURN(NOINLINE(static void register_stack_extend(rb_context_t *, VALUE *, VALUE *)));
static void
register_stack_extend(rb_context_t *cont, VALUE *vp, VALUE *curr_bsp)
{
if (rb_dummy_false) {
/* use registers as much as possible */
E(a) = E(b) = E(c) = E(d) = E(e) =
E(f) = E(g) = E(h) = E(i) = E(j) =
E(k) = E(l) = E(m) = E(n) = E(o) =
E(p) = E(q) = E(r) = E(s) = E(t) = 0;
E(a) = E(b) = E(c) = E(d) = E(e) =
E(f) = E(g) = E(h) = E(i) = E(j) =
E(k) = E(l) = E(m) = E(n) = E(o) =
E(p) = E(q) = E(r) = E(s) = E(t) = 0;
}
if (curr_bsp < cont->machine_register_stack_src+cont->machine_register_stack_size) {
register_stack_extend(cont, vp, (VALUE*)rb_ia64_bsp());
}
cont_restore_0(cont, vp);
}
#undef C
#undef E
#endif
static void
cont_restore_0(rb_context_t *cont, VALUE *addr_in_prev_frame)
{
if (cont->machine_stack_src) {
#ifdef HAVE_ALLOCA
#define STACK_PAD_SIZE 1
#else
#define STACK_PAD_SIZE 1024
#endif
VALUE space[STACK_PAD_SIZE];
#if !STACK_GROW_DIRECTION
if (addr_in_prev_frame > &space[0]) {
/* Stack grows downward */
#endif
#if STACK_GROW_DIRECTION <= 0
volatile VALUE *const end = cont->machine_stack_src;
if (&space[0] > end) {
# ifdef HAVE_ALLOCA
volatile VALUE *sp = ALLOCA_N(VALUE, &space[0] - end);
(void)sp;
# else
cont_restore_0(cont, &space[0]);
# endif
}
#endif
#if !STACK_GROW_DIRECTION
}
else {
/* Stack grows upward */
#endif
#if STACK_GROW_DIRECTION >= 0
volatile VALUE *const end = cont->machine_stack_src + cont->machine_stack_size;
if (&space[STACK_PAD_SIZE] < end) {
# ifdef HAVE_ALLOCA
volatile VALUE *sp = ALLOCA_N(VALUE, end - &space[STACK_PAD_SIZE]);
(void)sp;
# else
cont_restore_0(cont, &space[STACK_PAD_SIZE-1]);
# endif
}
#endif
#if !STACK_GROW_DIRECTION
}
#endif
}
cont_restore_1(cont);
}
#ifdef __ia64
#define cont_restore_0(cont, vp) register_stack_extend(cont, vp, (VALUE*)rb_ia64_bsp());
#endif
/*
* Document-class: Continuation
*
* Continuation objects are generated by
* <code>Kernel#callcc</code>. They hold a return address and execution
* context, allowing a nonlocal return to the end of the
* <code>callcc</code> block from anywhere within a program.
* Continuations are somewhat analogous to a structured version of C's
* <code>setjmp/longjmp</code> (although they contain more state, so
* you might consider them closer to threads).
*
* For instance:
*
* arr = [ "Freddie", "Herbie", "Ron", "Max", "Ringo" ]
* callcc{|$cc|}
* puts(message = arr.shift)
* $cc.call unless message =~ /Max/
*
* <em>produces:</em>
*
* Freddie
* Herbie
* Ron
* Max
*
* This (somewhat contrived) example allows the inner loop to abandon
* processing early:
*
* callcc {|cont|
* for i in 0..4
* print "\n#{i}: "
* for j in i*5...(i+1)*5
* cont.call() if j == 17
* printf "%3d", j
* end
* end
* }
* print "\n"
*
* <em>produces:</em>
*
* 0: 0 1 2 3 4
* 1: 5 6 7 8 9
* 2: 10 11 12 13 14
* 3: 15 16
*/
/*
* call-seq:
* callcc {|cont| block } -> obj
*
* Generates a <code>Continuation</code> object, which it passes to the
* associated block. Performing a <em>cont</em><code>.call</code> will
* cause the <code>callcc</code> to return (as will falling through the
* end of the block). The value returned by the <code>callcc</code> is
* the value of the block, or the value passed to
* <em>cont</em><code>.call</code>. See class <code>Continuation</code>
* for more details. Also see <code>Kernel::throw</code> for
* an alternative mechanism for unwinding a call stack.
*/
static VALUE
rb_callcc(VALUE self)
{
volatile int called;
volatile VALUE val = cont_capture(&called);
if (called) {
return val;
}
else {
return rb_yield(val);
}
}
static VALUE
make_passing_arg(int argc, VALUE *argv)
{
switch(argc) {
case 0:
return Qnil;
case 1:
return argv[0];
default:
return rb_ary_new4(argc, argv);
}
}
/*
* call-seq:
* cont.call(args, ...)
* cont[args, ...]
*
* Invokes the continuation. The program continues from the end of the
* <code>callcc</code> block. If no arguments are given, the original
* <code>callcc</code> returns <code>nil</code>. If one argument is
* given, <code>callcc</code> returns it. Otherwise, an array
* containing <i>args</i> is returned.
*
* callcc {|cont| cont.call } #=> nil
* callcc {|cont| cont.call 1 } #=> 1
* callcc {|cont| cont.call 1, 2, 3 } #=> [1, 2, 3]
*/
static VALUE
rb_cont_call(int argc, VALUE *argv, VALUE contval)
{
rb_context_t *cont;
rb_thread_t *th = GET_THREAD();
GetContPtr(contval, cont);
if (cont->saved_thread.self != th->self) {
rb_raise(rb_eRuntimeError, "continuation called across threads");
}
if (cont->saved_thread.protect_tag != th->protect_tag) {
rb_raise(rb_eRuntimeError, "continuation called across stack rewinding barrier");
}
if (cont->saved_thread.fiber) {
rb_fiber_t *fcont;
GetFiberPtr(cont->saved_thread.fiber, fcont);
if (th->fiber != cont->saved_thread.fiber) {
rb_raise(rb_eRuntimeError, "continuation called across fiber");
}
}
cont->argc = argc;
cont->value = make_passing_arg(argc, argv);
cont_restore_0(cont, &contval);
return Qnil; /* unreachable */
}
/*********/
/* fiber */
/*********/
/*
* Document-class: Fiber
*
* Fibers are primitives for implementing light weight cooperative
* concurrency in Ruby. Basically they are a means of creating code blocks
* that can be paused and resumed, much like threads. The main difference
* is that they are never preempted and that the scheduling must be done by
* the programmer and not the VM.
*
* As opposed to other stackless light weight concurrency models, each fiber
* comes with a small 4KB stack. This enables the fiber to be paused from deeply
* nested function calls within the fiber block.
*
* When a fiber is created it will not run automatically. Rather it must be
* be explicitly asked to run using the <code>Fiber#resume</code> method.
* The code running inside the fiber can give up control by calling
* <code>Fiber.yield</code> in which case it yields control back to caller
* (the caller of the <code>Fiber#resume</code>).
*
* Upon yielding or termination the Fiber returns the value of the last
* executed expression
*
* For instance:
*
* fiber = Fiber.new do
* Fiber.yield 1
* 2
* end
*
* puts fiber.resume
* puts fiber.resume
* puts fiber.resume
*
* <em>produces</em>
*
* 1
* 2
* FiberError: dead fiber called
*
* The <code>Fiber#resume</code> method accepts an arbitrary number of
* parameters, if it is the first call to <code>resume</code> then they
* will be passed as block arguments. Otherwise they will be the return
* value of the call to <code>Fiber.yield</code>
*
* Example:
*
* fiber = Fiber.new do |first|
* second = Fiber.yield first + 2
* end
*
* puts fiber.resume 10
* puts fiber.resume 14
* puts fiber.resume 18
*
* <em>produces</em>
*
* 12
* 14
* FiberError: dead fiber called
*
*/
#define FIBER_VM_STACK_SIZE (4 * 1024)
static const rb_data_type_t fiber_data_type = {
"fiber",
{fiber_mark, fiber_free, fiber_memsize,},
};
static VALUE
fiber_alloc(VALUE klass)
{
return TypedData_Wrap_Struct(klass, &fiber_data_type, 0);
}
static rb_fiber_t*
fiber_t_alloc(VALUE fibval)
{
rb_fiber_t *fib;
rb_thread_t *th = GET_THREAD();
THREAD_MUST_BE_RUNNING(th);
fib = ALLOC(rb_fiber_t);
memset(fib, 0, sizeof(rb_fiber_t));
fib->cont.self = fibval;
fib->cont.type = FIBER_CONTEXT;
cont_init(&fib->cont, th);
fib->prev = Qnil;
fib->status = CREATED;
DATA_PTR(fibval) = fib;
return fib;
}
static VALUE
fiber_init(VALUE fibval, VALUE proc)
{
rb_fiber_t *fib = fiber_t_alloc(fibval);
rb_context_t *cont = &fib->cont;
rb_thread_t *th = &cont->saved_thread;
/* initialize cont */
cont->vm_stack = 0;
th->stack = 0;
th->stack_size = 0;
fiber_link_join(fib);
/*cont->machine_stack, th->machine_stack_start and th->machine_stack_end should be NULL*/
/*because it may happen GC at th->stack allocation*/