| khenaidoo | b920354 | 2018-09-17 22:56:37 -0400 | [diff] [blame^] | 1 | # Copyright 2017-present Open Networking Foundation |
| 2 | # |
| 3 | # Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | # you may not use this file except in compliance with the License. |
| 5 | # You may obtain a copy of the License at |
| 6 | # |
| 7 | # http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | # |
| 9 | # Unless required by applicable law or agreed to in writing, software |
| 10 | # distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | # See the License for the specific language governing permissions and |
| 13 | # limitations under the License. |
| 14 | from bitstring import BitArray |
| 15 | import structlog |
| 16 | |
| 17 | log = structlog.get_logger() |
| 18 | |
| 19 | class IndexPool(object): |
| 20 | def __init__(self, max_entries, offset): |
| 21 | self.max_entries = max_entries |
| 22 | self.offset = offset |
| 23 | self.indices = BitArray(self.max_entries) |
| 24 | |
| 25 | def get_next(self): |
| 26 | try: |
| 27 | _pos = self.indices.find('0b0') |
| 28 | self.indices.set(1, _pos) |
| 29 | return self.offset + _pos[0] |
| 30 | except IndexError: |
| 31 | log.info("exception-fail-to-allocate-id-all-bits-in-use") |
| 32 | return None |
| 33 | |
| 34 | def allocate(self, index): |
| 35 | try: |
| 36 | _pos = index - self.offset |
| 37 | if not (0 <= _pos < self.max_entries): |
| 38 | log.info("{}-out-of-range".format(index)) |
| 39 | return None |
| 40 | if self.indices[_pos]: |
| 41 | log.info("{}-is-already-allocated".format(index)) |
| 42 | return None |
| 43 | self.indices.set(1, _pos) |
| 44 | return index |
| 45 | |
| 46 | except IndexError: |
| 47 | return None |
| 48 | |
| 49 | def release(self, index): |
| 50 | index -= self.offset |
| 51 | _pos = (index,) |
| 52 | try: |
| 53 | self.indices.set(0, _pos) |
| 54 | except IndexError: |
| 55 | log.info("bit-position-{}-out-of-range".format(index)) |
| 56 | |
| 57 | #index or multiple indices to set all of them to 1 - need to be a tuple |
| 58 | def pre_allocate(self, index): |
| 59 | if(isinstance(index, tuple)): |
| 60 | _lst = list(index) |
| 61 | for i in range(len(_lst)): |
| 62 | _lst[i] -= self.offset |
| 63 | index = tuple(_lst) |
| 64 | self.indices.set(1, index) |