gdb.FiberUnwinder Class Reference

Inheritance diagram for gdb.FiberUnwinder:

Public Member Functions
def	set_fiber (cls, fiber)
def	__init__ (self)
def	__call__ (self, pending_frame)

Public Attributes
	fiber_context_ptr

Static Public Attributes
	instance = None

Detailed Description

Definition at line 191 of file gdb.py.

Constructor & Destructor Documentation

def gdb.FiberUnwinder.__init__

(

self

)

Definition at line 203 of file gdb.py.

    def __init__(self):
        super(FiberUnwinder, self).__init__("Fiber unwinder")
        self.fiber_context_ptr = None

Member Function Documentation

def gdb.FiberUnwinder.__call__	(		self,
			pending_frame
	)

Definition at line 207 of file gdb.py.

References folly::gen.dereference, and gdb.FiberUnwinder.fiber_context_ptr.

    def __call__(self, pending_frame):
        if not self.fiber_context_ptr:
            return None

        orig_sp = pending_frame.read_register('rsp')
        orig_pc = pending_frame.read_register('rip')

        void_star_star = gdb.lookup_type('uint64_t').pointer()
        ptr = self.fiber_context_ptr.cast(void_star_star)

        # This code may need to be adjusted to newer versions of boost::context.
        #
        # The easiest way to get these offsets is to first attach to any
        # program which uses folly::fibers and add a break point in
        # boost::context::jump_fcontext. You then need to save information about
        # frame 1 via 'info frame 1' command.
        #
        # After that you need to resume program until fiber switch is complete
        # and expore the contents of saved fiber context via
        # 'x/16gx {fiber pointer}->fiberImpl_.fiberContext_' command.
        # You then need to match those to the following values you've previously
        # observed in the output of 'info frame 1'  command.
        #
        # Value found at "rbp at X" of 'info frame 1' output:
        rbp = (ptr + 6).dereference()
        # Value found at "rip = X" of 'info frame 1' output:
        rip = (ptr + 7).dereference()
        # Value found at "caller of frame at X" of 'info frame 1' output:
        rsp = rbp - 96

        frame_id = FrameId(rsp, orig_pc)
        unwind_info = pending_frame.create_unwind_info(frame_id)
        unwind_info.add_saved_register('rbp', rbp)
        unwind_info.add_saved_register('rsp', rsp)
        unwind_info.add_saved_register('rip', rip)

        self.fiber_context_ptr = None

        FiberUnwinderFrameFilter.set_skip_frame_sp(orig_sp)

        return unwind_info

def gdb.FiberUnwinder.set_fiber	(		cls,
			fiber
	)

Definition at line 195 of file gdb.py.

References fizz::client::test::MockClientStateMachineInstance.instance, fizz::server::test::MockServerStateMachineInstance.instance, fizz::server::test::MockTicketCodec.instance, fizz::test::TestStateMachine.instance, gdb.FiberUnwinderFrameFilter.instance, folly::observer_detail::ObserverManager::Singleton.instance, and gdb.FiberUnwinder.instance.

    def set_fiber(cls, fiber):
        if cls.instance is None:
            cls.instance = FiberUnwinder()
            gdb.unwinder.register_unwinder(None, cls.instance)

        fiber_impl = fiber['fiberImpl_']
        cls.instance.fiber_context_ptr = fiber_impl['fiberContext_']

Member Data Documentation

gdb.FiberUnwinder.fiber_context_ptr

Definition at line 205 of file gdb.py.

Referenced by gdb.FiberUnwinder.__call__().

gdb.FiberUnwinder.instance = None

static

Definition at line 192 of file gdb.py.

Referenced by gdb.FiberUnwinder.set_fiber().

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The documentation for this class was generated from the following file:

• proxygen/folly/folly/fibers/scripts/gdb.py