Class: Fiber

Inherits:
Object show all
Defined in:
mruby/mrbgems/mruby-fiber/src/fiber.c

Instance Method Summary collapse

Constructor Details

#new { ... } ⇒ Object

Creates a fiber, whose execution is suspended until it is explicitly resumed using Fiber#resume method. The code running inside the fiber can give up control by calling Fiber.yield in which case it yields control back to caller (the caller of the Fiber#resume).

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

produces

1
2
resuming dead fiber (FiberError)

The Fiber#resume method accepts an arbitrary number of parameters, if it is the first call to resume then they will be passed as block arguments. Otherwise they will be the return value of the call to Fiber.yield

Example:

fiber = Fiber.new do |first|
  second = Fiber.yield first + 2
end

puts fiber.resume 10
puts fiber.resume 14
puts fiber.resume 18

produces

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14
resuming dead fiber (FiberError)

Yields:

[View source]

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# File 'mruby/mrbgems/mruby-fiber/src/fiber.c', line 66

static mrb_value
fiber_init(mrb_state *mrb, mrb_value self)
{
  static const struct mrb_context mrb_context_zero = { 0 };
  struct RFiber *f = fiber_ptr(self);
  struct mrb_context *c;
  struct RProc *p;
  mrb_callinfo *ci;
  mrb_value blk;
  size_t slen;

  mrb_get_args(mrb, "&!", &blk);

  if (f->cxt) {
    mrb_raise(mrb, E_RUNTIME_ERROR, "cannot initialize twice");
  }
  p = mrb_proc_ptr(blk);
  if (MRB_PROC_CFUNC_P(p)) {
    mrb_raise(mrb, E_FIBER_ERROR, "tried to create Fiber from C defined method");
  }

  c = (struct mrb_context*)mrb_malloc(mrb, sizeof(struct mrb_context));
  *c = mrb_context_zero;
  f->cxt = c;

  /* initialize VM stack */
  slen = FIBER_STACK_INIT_SIZE;
  if (p->body.irep->nregs > slen) {
    slen += p->body.irep->nregs;
  }
  c->stbase = (mrb_value *)mrb_malloc(mrb, slen*sizeof(mrb_value));
  c->stend = c->stbase + slen;

  {
    mrb_value *p = c->stbase;
    mrb_value *pend = c->stend;

    while (p < pend) {
      SET_NIL_VALUE(*p);
      p++;
    }
  }

  /* copy receiver from a block */
  c->stbase[0] = mrb->c->ci->stack[0];

  /* initialize callinfo stack */
  c->cibase = (mrb_callinfo *)mrb_calloc(mrb, FIBER_CI_INIT_SIZE, sizeof(mrb_callinfo));
  c->ciend = c->cibase + FIBER_CI_INIT_SIZE;
  c->ci = c->cibase;

  /* adjust return callinfo */
  ci = c->ci;
  mrb_vm_ci_target_class_set(ci, MRB_PROC_TARGET_CLASS(p));
  mrb_vm_ci_proc_set(ci, p);
  mrb_field_write_barrier(mrb, (struct RBasic*)mrb_obj_ptr(self), (struct RBasic*)p);
  ci->stack = c->stbase;
  ci[1] = ci[0];
  c->ci++;                      /* push dummy callinfo */

  c->fib = f;
  c->status = MRB_FIBER_CREATED;

  return self;
}

Instance Method Details

#== ⇒ Object

[View source]

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# File 'mruby/mrbgems/mruby-fiber/src/fiber.c', line 334

static mrb_value
fiber_eq(mrb_state *mrb, mrb_value self)
{
  mrb_value other = mrb_get_arg1(mrb);

  if (!mrb_fiber_p(other)) {
    return mrb_false_value();
  }
  return mrb_bool_value(fiber_ptr(self) == fiber_ptr(other));
}

#alive? ⇒ Boolean

Returns:

  • (Boolean)

#resume(args, ...) ⇒ Object

Resumes the fiber from the point at which the last Fiber.yield was called, or starts running it if it is the first call to resume. Arguments passed to resume will be the value of the Fiber.yield expression or will be passed as block parameters to the fiber’s block if this is the first resume.

Alternatively, when resume is called it evaluates to the arguments passed to the next Fiber.yield statement inside the fiber’s block or to the block value if it runs to completion without any Fiber.yield

This method cannot be called from C using mrb_funcall(). Use mrb_fiber_resume() function instead.

Returns:

[View source]

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# File 'mruby/mrbgems/mruby-fiber/src/fiber.c', line 298

static mrb_value
fiber_resume(mrb_state *mrb, mrb_value self)
{
  const mrb_value *a;
  mrb_int len;
  mrb_bool vmexec = FALSE;

  fiber_check_cfunc(mrb, mrb->c);
  mrb_get_args(mrb, "*!", &a, &len);
  if (mrb->c->ci->cci > 0) {
    vmexec = TRUE;
  }
  return fiber_switch(mrb, self, len, a, TRUE, vmexec);
}

#transfer(args, ...) ⇒ Object

Transfers control to receiver fiber of the method call. Unlike resume the receiver wouldn’t be pushed to call stack of fibers. Instead it will switch to the call stack of transferring fiber. When resuming a fiber that was transferred to another fiber it would cause double resume error. Though when the fiber is re-transferred and Fiber.yield is called, the fiber would be resumable.

Returns:

[View source]

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# File 'mruby/mrbgems/mruby-fiber/src/fiber.c', line 357

static mrb_value
fiber_transfer(mrb_state *mrb, mrb_value self)
{
  struct mrb_context *c = fiber_check(mrb, self);
  const mrb_value* a;
  mrb_int len;

  fiber_check_cfunc(mrb, mrb->c);
  mrb_get_args(mrb, "*!", &a, &len);

  if (c->status == MRB_FIBER_RESUMED) {
    mrb_raise(mrb, E_FIBER_ERROR, "attempt to transfer to a resuming fiber");
  }

  if (c == mrb->root_c) {
    mrb->c->status = MRB_FIBER_TRANSFERRED;
    fiber_switch_context(mrb, c);
    MARK_CONTEXT_MODIFY(c);
    return fiber_result(mrb, a, len);
  }

  if (c == mrb->c) {
    return fiber_result(mrb, a, len);
  }

  return fiber_switch(mrb, self, len, a, FALSE, FALSE);
}