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"""Dummy Frame object"""

# Copyright (C) PyZMQ Developers
# Distributed under the terms of the Modified BSD License.

import errno
from threading import Event

import zmq
import zmq.error
from zmq.constants import ETERM

from ._cffi import ffi
from ._cffi import lib as C

zmq_gc = None

try:
    from __pypy__.bufferable import bufferable as maybe_bufferable
except ImportError:
    maybe_bufferable = object


def _content(obj):
    """Return content of obj as bytes"""
    if type(obj) is bytes:
        return obj
    if not isinstance(obj, memoryview):
        obj = memoryview(obj)
    return obj.tobytes()


def _check_rc(rc):
    err = C.zmq_errno()
    if rc == -1:
        if err == errno.EINTR:
            raise zmq.error.InterrruptedSystemCall(err)
        elif err == errno.EAGAIN:
            raise zmq.error.Again(errno)
        elif err == ETERM:
            raise zmq.error.ContextTerminated(err)
        else:
            raise zmq.error.ZMQError(err)
    return 0


class Frame(maybe_bufferable):
    _data = None
    tracker = None
    closed = False
    more = False
    _buffer = None
    _bytes = None
    _failed_init = False
    tracker_event = None
    zmq_msg = None

    def __init__(self, data=None, track=False, copy=None, copy_threshold=None):
        self._failed_init = True

        self.zmq_msg = ffi.cast('zmq_msg_t[1]', C.malloc(ffi.sizeof("zmq_msg_t")))

        # self.tracker should start finished
        # except in the case where we are sharing memory with libzmq
        if track:
            self.tracker = zmq._FINISHED_TRACKER

        if isinstance(data, str):
            raise TypeError(
                "Unicode strings are not allowed. Only: bytes, buffer interfaces."
            )

        if data is None:
            rc = C.zmq_msg_init(self.zmq_msg)
            _check_rc(rc)
            self._failed_init = False
            return

        self._data = data
        if type(data) is bytes:
            # avoid unnecessary copy on .bytes access
            self._bytes = data

        self._buffer = memoryview(data)
        c_data = ffi.from_buffer(self._buffer)
        data_len_c = self._buffer.nbytes

        if copy is None:
            if copy_threshold and data_len_c < copy_threshold:
                copy = True
            else:
                copy = False

        if copy:
            # copy message data instead of sharing memory
            rc = C.zmq_msg_init_size(self.zmq_msg, data_len_c)
            _check_rc(rc)
            ffi.buffer(C.zmq_msg_data(self.zmq_msg), data_len_c)[:] = self._buffer
            self._failed_init = False
            return

        # Getting here means that we are doing a true zero-copy Frame,
        # where libzmq and Python are sharing memory.
        # Hook up garbage collection with MessageTracker and zmq_free_fn

        # Event and MessageTracker for monitoring when zmq is done with data:
        if track:
            evt = Event()
            self.tracker_event = evt
            self.tracker = zmq.MessageTracker(evt)
        # create the hint for zmq_free_fn
        # two pointers: the zmq_gc context and a message to be sent to the zmq_gc PULL socket
        # allows libzmq to signal to Python when it is done with Python-owned memory.
        global zmq_gc
        if zmq_gc is None:
            from zmq.utils.garbage import gc as zmq_gc
        # can't use ffi.new because it will be freed at the wrong time!
        hint = ffi.cast("zhint[1]", C.malloc(ffi.sizeof("zhint")))
        hint[0].id = zmq_gc.store(data, self.tracker_event)
        if not zmq_gc._push_mutex:
            zmq_gc._push_mutex = C.mutex_allocate()

        hint[0].mutex = ffi.cast("mutex_t*", zmq_gc._push_mutex)
        hint[0].sock = ffi.cast("void*", zmq_gc._push_socket.underlying)

        # calls zmq_wrap_msg_init_data with the C.free_python_msg callback
        rc = C.zmq_wrap_msg_init_data(
            self.zmq_msg,
            c_data,
            data_len_c,
            hint,
        )
        if rc != 0:
            C.free(hint)
            C.free(self.zmq_msg)
            _check_rc(rc)
        self._failed_init = False

    def __del__(self):
        if not self.closed and not self._failed_init:
            self.close()

    def close(self):
        if self.closed or self._failed_init or self.zmq_msg is None:
            return
        self.closed = True
        rc = C.zmq_msg_close(self.zmq_msg)
        C.free(self.zmq_msg)
        self.zmq_msg = None
        if rc != 0:
            _check_rc(rc)

    def _buffer_from_zmq_msg(self):
        """one-time extract buffer from zmq_msg

        for Frames created by recv
        """
        if self._data is None:
            self._data = ffi.buffer(
                C.zmq_msg_data(self.zmq_msg), C.zmq_msg_size(self.zmq_msg)
            )
        if self._buffer is None:
            self._buffer = memoryview(self._data)

    @property
    def buffer(self):
        if self._buffer is None:
            self._buffer_from_zmq_msg()
        return self._buffer

    @property
    def bytes(self):
        if self._bytes is None:
            self._bytes = self.buffer.tobytes()
        return self._bytes

    def __len__(self):
        return self.buffer.nbytes

    def __eq__(self, other):
        return self.bytes == _content(other)

    def __str__(self):
        return self.bytes.decode()

    @property
    def done(self):
        return self.tracker.done()

    def __buffer__(self, flags):
        return self.buffer

    def __copy__(self):
        """Create a shallow copy of the message.

        This does not copy the contents of the Frame, just the pointer.
        This will increment the 0MQ ref count of the message, but not
        the ref count of the Python object. That is only done once when
        the Python is first turned into a 0MQ message.
        """
        return self.fast_copy()

    def fast_copy(self):
        """Fast shallow copy of the Frame.

        Does not copy underlying data.
        """
        new_msg = Frame()
        # This does not copy the contents, but just increases the ref-count
        # of the zmq_msg by one.
        C.zmq_msg_copy(new_msg.zmq_msg, self.zmq_msg)
        # Copy the ref to underlying data
        new_msg._data = self._data
        new_msg._buffer = self._buffer

        # Frame copies share the tracker and tracker_event
        new_msg.tracker_event = self.tracker_event
        new_msg.tracker = self.tracker

        return new_msg


Message = Frame

__all__ = ['Frame', 'Message']
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