Fiber

Returns the current fiber. You need to require 'fiber' before using this method. If you are not running in the context of a fiber this method will return the root fiber.

 
               static VALUE
rb_fiber_s_current(VALUE klass)
{
    return rb_fiber_current();
}
            

Yields control back to the context that resumed the fiber, passing along any arguments that were passed to it. The fiber will resume processing at this point when resume is called next. Any arguments passed to the next resume will be the value that this ::yield expression evaluates to.

 
               static VALUE
rb_fiber_s_yield(int argc, VALUE *argv, VALUE klass)
{
    return rb_fiber_yield_kw(argc, argv, PASS_KW_SPLAT);
}
            

Returns true if the fiber can still be resumed (or transferred to). After finishing execution of the fiber block this method will always return false. You need to require 'fiber' before using this method.

 
               VALUE
rb_fiber_alive_p(VALUE fiber_value)
{
    return FIBER_TERMINATED_P(fiber_ptr(fiber_value)) ? Qfalse : Qtrue;
}
            

Raises an exception in the fiber at the point at which the last ::yield was called, or at the start if neither resume nor raise were called before.

With no arguments, raises a RuntimeError. With a single String argument, raises a RuntimeError with the string as a message. Otherwise, the first parameter should be the name of an Exception class (or an object that returns an Exception object when sent an exception message). The optional second parameter sets the message associated with the exception, and the third parameter is an array of callback information. Exceptions are caught by the rescue clause of begin...end blocks.

 
               static VALUE
rb_fiber_raise(int argc, VALUE *argv, VALUE fiber)
{
    VALUE exc = rb_make_exception(argc, argv);
    return rb_fiber_resume_kw(fiber, -1, &exc, RB_NO_KEYWORDS);
}
            

Resumes the fiber from the point at which the last ::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 ::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 ::yield statement inside the fiber’s block or to the block value if it runs to completion without any ::yield

 
               static VALUE
rb_fiber_m_resume(int argc, VALUE *argv, VALUE fiber)
{
    return rb_fiber_resume_kw(fiber, argc, argv, PASS_KW_SPLAT);
}
            

Returns fiber information string.

 
               static VALUE
fiber_to_s(VALUE fiber_value)
{
    const rb_fiber_t *fiber = fiber_ptr(fiber_value);
    const rb_proc_t *proc;
    char status_info[0x20];

    if (fiber->transferred) {
        snprintf(status_info, 0x20, " (%s, transferred)", fiber_status_name(fiber->status));
    }
    else {
        snprintf(status_info, 0x20, " (%s)", fiber_status_name(fiber->status));
    }

    if (!rb_obj_is_proc(fiber->first_proc)) {
        VALUE str = rb_any_to_s(fiber_value);
        strlcat(status_info, ">", sizeof(status_info));
        rb_str_set_len(str, RSTRING_LEN(str)-1);
        rb_str_cat_cstr(str, status_info);
        return str;
    }
    GetProcPtr(fiber->first_proc, proc);
    return rb_block_to_s(fiber_value, &proc->block, status_info);
}
            

Transfer control to another fiber, resuming it from where it last stopped or starting it if it was not resumed before. The calling fiber will be suspended much like in a call to ::yield. You need to require 'fiber' before using this method.

The fiber which receives the transfer call is treats it much like a resume call. Arguments passed to transfer are treated like those passed to resume.

You cannot call resume on a fiber that has been transferred to. If you call transfer on a fiber, and later call resume on the the fiber, a FiberError will be raised. Once you call transfer on a fiber, the only way to resume processing the fiber is to call transfer on it again.

Example:

fiber1 = Fiber.new do
  puts "In Fiber 1"
  Fiber.yield
  puts "In Fiber 1 again"
end

fiber2 = Fiber.new do
  puts "In Fiber 2"
  fiber1.transfer
  puts "Never see this message"
end

fiber3 = Fiber.new do
  puts "In Fiber 3"
end

fiber2.resume
fiber3.resume
fiber1.resume rescue (p $!)
fiber1.transfer

produces

In Fiber 2
In Fiber 1
In Fiber 3
#<FiberError: cannot resume transferred Fiber>
In Fiber 1 again

 
               static VALUE
rb_fiber_m_transfer(int argc, VALUE *argv, VALUE fiber_value)
{
    rb_fiber_t *fiber = fiber_ptr(fiber_value);
    fiber->transferred = 1;
    return fiber_switch(fiber, argc, argv, 0, PASS_KW_SPLAT);
}