29 

    30 ### Index entry key

    31 #

    32 #

    33 #    Internal details

    34 #    ----------------

    35 #

    36 #    A large part of the revlog logic deals with revisions' "index entries", tuple

    37 #    objects that contains the same "items" whatever the revlog version.

    38 #    Different versions will have different ways of storing these items (sometimes

    39 #    not having them at all), but the tuple will always be the same. New fields

    40 #    are usually added at the end to avoid breaking existing code that relies

    41 #    on the existing order. The field are defined as follows:

    42 

    43 #    [0] offset:

    44 #            The byte index of the start of revision data chunk.

    45 #            That value is shifted up by 16 bits. use "offset = field >> 16" to

    46 #            retrieve it.

    47 #

    48 #        flags:

    49 #            A flag field that carries special information or changes the behavior

    50 #            of the revision. (see `REVIDX_*` constants for details)

    51 #            The flag field only occupies the first 16 bits of this field,

    52 #            use "flags = field & 0xFFFF" to retrieve the value.

    53 ENTRY_DATA_OFFSET = 0

    54 

    55 #    [1] compressed length:

    56 #            The size, in bytes, of the chunk on disk

    57 ENTRY_DATA_COMPRESSED_LENGTH = 1

    58 

    59 #    [2] uncompressed length:

    60 #            The size, in bytes, of the full revision once reconstructed.

    61 ENTRY_DATA_UNCOMPRESSED_LENGTH = 2

    62 

    63 #    [3] base rev:

    64 #            Either the base of the revision delta chain (without general

    65 #            delta), or the base of the delta (stored in the data chunk)

    66 #            with general delta.

    67 ENTRY_DELTA_BASE = 3

    68 

    69 #    [4] link rev:

    70 #            Changelog revision number of the changeset introducing this

    71 #            revision.

    72 ENTRY_LINK_REV = 4

    73 

    74 #    [5] parent 1 rev:

    75 #            Revision number of the first parent

    76 ENTRY_PARENT_1 = 5

    77 

    78 #    [6] parent 2 rev:

    79 #            Revision number of the second parent

    80 ENTRY_PARENT_2 = 6

    81 

    82 #    [7] node id:

    83 #            The node id of the current revision

    84 ENTRY_NODE_ID = 7

    85 

    86 #    [8] sidedata offset:

    87 #            The byte index of the start of the revision's side-data chunk.

    88 ENTRY_SIDEDATA_OFFSET = 8

    89 

    90 #    [9] sidedata chunk length:

    91 #            The size, in bytes, of the revision's side-data chunk.

    92 ENTRY_SIDEDATA_COMPRESSED_LENGTH = 9

    93 

    94 #    [10] data compression mode:

    95 #            two bits that detail the way the data chunk is compressed on disk.

    96 #            (see "COMP_MODE_*" constants for details). For revlog version 0 and

    97 #            1 this will always be COMP_MODE_INLINE.

    98 ENTRY_DATA_COMPRESSION_MODE = 10

    99 

   100 #    [11] side-data compression mode:

   101 #            two bits that detail the way the sidedata chunk is compressed on disk.

   102 #            (see "COMP_MODE_*" constants for details)

   103 ENTRY_SIDEDATA_COMPRESSION_MODE = 11