| 1 | # The MIT License (MIT) |
| 2 | # |
| 3 | # Copyright (c) 2017 Philippe Proulx <pproulx@efficios.com> |
| 4 | # |
| 5 | # Permission is hereby granted, free of charge, to any person obtaining a copy |
| 6 | # of this software and associated documentation files (the "Software"), to deal |
| 7 | # in the Software without restriction, including without limitation the rights |
| 8 | # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| 9 | # copies of the Software, and to permit persons to whom the Software is |
| 10 | # furnished to do so, subject to the following conditions: |
| 11 | # |
| 12 | # The above copyright notice and this permission notice shall be included in |
| 13 | # all copies or substantial portions of the Software. |
| 14 | # |
| 15 | # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 16 | # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 17 | # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| 18 | # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 19 | # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| 20 | # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| 21 | # THE SOFTWARE. |
| 22 | |
| 23 | |
| 24 | class _BaseObject: |
| 25 | # Ensure that the object always has _ptr set, even if it throws during |
| 26 | # construction. |
| 27 | |
| 28 | def __new__(cls, *args, **kwargs): |
| 29 | obj = super().__new__(cls) |
| 30 | obj._ptr = None |
| 31 | return obj |
| 32 | |
| 33 | def __init__(self, ptr): |
| 34 | self._ptr = ptr |
| 35 | |
| 36 | @property |
| 37 | def addr(self): |
| 38 | return int(self._ptr) |
| 39 | |
| 40 | def __repr__(self): |
| 41 | return '<{}.{} object @ {}>'.format( |
| 42 | self.__class__.__module__, self.__class__.__name__, hex(self.addr) |
| 43 | ) |
| 44 | |
| 45 | def __copy__(self): |
| 46 | raise NotImplementedError |
| 47 | |
| 48 | def __deepcopy__(self, memo): |
| 49 | raise NotImplementedError |
| 50 | |
| 51 | |
| 52 | # A Python object that is itself not refcounted, but is wholly owned by an |
| 53 | # object that is itself refcounted (a _SharedObject). A Babeltrace unique |
| 54 | # object gets destroyed once its owner gets destroyed (its refcount drops to |
| 55 | # 0). |
| 56 | # |
| 57 | # In the Python bindings, to avoid having to deal with issues with the lifetime |
| 58 | # of unique objects, we make it so acquiring a reference on a unique object |
| 59 | # acquires a reference on its owner. |
| 60 | |
| 61 | |
| 62 | class _UniqueObject(_BaseObject): |
| 63 | |
| 64 | # Create a _UniqueObject. |
| 65 | # |
| 66 | # - ptr: SWIG Object, pointer to the unique object. |
| 67 | # - owner_ptr: SWIG Object, pointer to the owner of the unique |
| 68 | # object. A new reference is acquired. |
| 69 | # - owner_get_ref: Callback to get a reference on the owner |
| 70 | # - owner_put_ref: Callback to put a reference on the owner. |
| 71 | |
| 72 | @classmethod |
| 73 | def _create_from_ptr_and_get_ref(cls, ptr, owner_ptr, owner_get_ref, owner_put_ref): |
| 74 | obj = cls.__new__(cls) |
| 75 | |
| 76 | obj._ptr = ptr |
| 77 | obj._owner_ptr = owner_ptr |
| 78 | obj._owner_get_ref = owner_get_ref |
| 79 | obj._owner_put_ref = owner_put_ref |
| 80 | |
| 81 | obj._owner_get_ref(obj._owner_ptr) |
| 82 | |
| 83 | return obj |
| 84 | |
| 85 | def __del__(self): |
| 86 | self._owner_put_ref(self._owner_ptr) |
| 87 | |
| 88 | |
| 89 | # Python object that owns a reference to a Babeltrace object. |
| 90 | class _SharedObject(_BaseObject): |
| 91 | |
| 92 | # Get a new reference on ptr. |
| 93 | # |
| 94 | # This must be implemented by subclasses to work correctly with a pointer |
| 95 | # of the native type they wrap. |
| 96 | |
| 97 | @staticmethod |
| 98 | def _get_ref(ptr): |
| 99 | raise NotImplementedError |
| 100 | |
| 101 | # Put a reference on ptr. |
| 102 | # |
| 103 | # This must be implemented by subclasses to work correctly with a pointer |
| 104 | # of the native type they wrap. |
| 105 | |
| 106 | @staticmethod |
| 107 | def _put_ref(ptr): |
| 108 | raise NotImplementedError |
| 109 | |
| 110 | # Create a _SharedObject from an existing reference. |
| 111 | # |
| 112 | # This assumes that the caller owns a reference to the Babeltrace object |
| 113 | # and transfers this ownership to the newly created Python object. |
| 114 | |
| 115 | @classmethod |
| 116 | def _create_from_ptr(cls, ptr_owned): |
| 117 | obj = cls.__new__(cls) |
| 118 | obj._ptr = ptr_owned |
| 119 | return obj |
| 120 | |
| 121 | # Like _create_from_ptr, but acquire a new reference rather than |
| 122 | # stealing the caller's reference. |
| 123 | |
| 124 | @classmethod |
| 125 | def _create_from_ptr_and_get_ref(cls, ptr): |
| 126 | obj = cls._create_from_ptr(ptr) |
| 127 | cls._get_ref(obj._ptr) |
| 128 | return obj |
| 129 | |
| 130 | def __del__(self): |
| 131 | self._put_ref(self._ptr) |