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1 | 1 | # state.py - writing and reading state files in Mercurial |
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2 | 2 | # |
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3 | 3 | # Copyright 2018 Pulkit Goyal <pulkitmgoyal@gmail.com> |
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4 | 4 | # |
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5 | 5 | # This software may be used and distributed according to the terms of the |
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6 | 6 | # GNU General Public License version 2 or any later version. |
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7 | 7 | |
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8 | 8 | """ |
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9 | 9 | This file contains class to wrap the state for commands and other |
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10 | 10 | related logic. |
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11 | 11 | |
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12 | 12 | All the data related to the command state is stored as dictionary in the object. |
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13 | 13 | The class has methods using which the data can be stored to disk in a file under |
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14 | 14 | .hg/ directory. |
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15 | 15 | |
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16 | 16 | We store the data on disk in cbor, for which we use the third party cbor library |
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17 | 17 | to serialize and deserialize data. |
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18 | 18 | """ |
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19 | 19 | |
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20 | 20 | from __future__ import absolute_import |
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21 | 21 | |
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22 | 22 | from .thirdparty import cbor |
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23 | 23 | |
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24 | 24 | from . import ( |
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25 | 25 | error, |
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26 | 26 | util, |
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27 | 27 | ) |
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28 | 28 | |
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29 | 29 | class cmdstate(object): |
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30 | 30 | """a wrapper class to store the state of commands like `rebase`, `graft`, |
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31 | 31 | `histedit`, `shelve` etc. Extensions can also use this to write state files. |
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32 | 32 | |
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33 | 33 | All the data for the state is stored in the form of key-value pairs in a |
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34 | 34 | dictionary. |
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35 | 35 | |
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36 | 36 | The class object can write all the data to a file in .hg/ directory and |
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37 | 37 | can populate the object data reading that file. |
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38 | 38 | |
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39 | 39 | Uses cbor to serialize and deserialize data while writing and reading from |
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40 | 40 | disk. |
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41 | 41 | """ |
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42 | 42 | |
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43 | 43 | def __init__(self, repo, fname, opts=None): |
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44 | 44 | """ repo is the repo object |
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45 | 45 | fname is the file name in which data should be stored in .hg directory |
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46 | 46 | opts is a dictionary of data of the statefile |
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47 | 47 | """ |
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48 | 48 | self._repo = repo |
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49 | 49 | self.fname = fname |
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50 | 50 | |
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51 | 51 | def read(self): |
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52 | 52 | """read the existing state file and return a dict of data stored""" |
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53 | 53 | return self._read() |
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54 | 54 | |
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55 | 55 | def save(self, version, data): |
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56 | 56 | """write all the state data stored to .hg/<filename> file |
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57 | 57 | |
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58 | 58 | we use third-party library cbor to serialize data to write in the file. |
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59 | 59 | """ |
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60 | 60 | if not isinstance(version, int): |
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61 | 61 | raise error.ProgrammingError("version of state file should be" |
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62 | 62 | " an integer") |
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63 | 63 | |
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64 | 64 | with self._repo.vfs(self.fname, 'wb', atomictemp=True) as fp: |
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65 |
fp.write('%d\n' % |
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65 | fp.write('%d\n' % version) | |
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66 | 66 | cbor.dump(self.opts, fp, canonical=True) |
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67 | 67 | |
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68 | 68 | def _read(self): |
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69 | 69 | """reads the state file and returns a dictionary which contain |
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70 | 70 | data in the same format as it was before storing""" |
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71 | 71 | with self._repo.vfs(self.fname, 'rb') as fp: |
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72 | 72 | try: |
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73 | 73 | version = int(fp.readline()) |
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74 | 74 | except ValueError: |
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75 | 75 | raise error.ProgrammingError("unknown version of state file" |
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76 | 76 | " found") |
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77 | 77 | return cbor.load(fp) |
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78 | 78 | |
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79 | 79 | def delete(self): |
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80 | 80 | """drop the state file if exists""" |
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81 | 81 | util.unlinkpath(self._repo.vfs.join(self.fname), ignoremissing=True) |
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82 | 82 | |
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83 | 83 | def exists(self): |
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84 | 84 | """check whether the state file exists or not""" |
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85 | 85 | return self._repo.vfs.exists(self.fname) |
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