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comparison mercurial/revlog.py @ 47393:7a0ec25d5836

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revlog: move entry documentation alongside new related constants Accessing individual index-entry element is usually done using integer directly. This is presumably for "performance reasons". However as the index entry gain more and more element it seems useful to get the option to use symbolic constant to access item, for both clarify and versatility. We will probably keep using integer for performance critical path, but less critical code may start using them now that they are declared. Differential Revision: https://phab.mercurial-scm.org/D10791
author Pierre-Yves David <pierre-yves.david@octobus.net>
date Sat, 22 May 2021 00:06:22 +0200
parents 33d626910374
children ac60a1366a49
comparison
equal deleted inserted replaced
47392:8089d0fa8400 47393:7a0ec25d5836
308 `concurrencychecker` is an optional function that receives 3 arguments: a 308 `concurrencychecker` is an optional function that receives 3 arguments: a
309 file handle, a filename, and an expected position. It should check whether 309 file handle, a filename, and an expected position. It should check whether
310 the current position in the file handle is valid, and log/warn/fail (by 310 the current position in the file handle is valid, and log/warn/fail (by
311 raising). 311 raising).
312 312
313 313 See mercurial/revlogutils/contants.py for details about the content of an
314 Internal details 314 index entry.
315 ----------------
316
317 A large part of the revlog logic deals with revisions' "index entries", tuple
318 objects that contains the same "items" whatever the revlog version.
319 Different versions will have different ways of storing these items (sometimes
320 not having them at all), but the tuple will always be the same. New fields
321 are usually added at the end to avoid breaking existing code that relies
322 on the existing order. The field are defined as follows:
323
324 [0] offset:
325 The byte index of the start of revision data chunk.
326 That value is shifted up by 16 bits. use "offset = field >> 16" to
327 retrieve it.
328
329 flags:
330 A flag field that carries special information or changes the behavior
331 of the revision. (see `REVIDX_*` constants for details)
332 The flag field only occupies the first 16 bits of this field,
333 use "flags = field & 0xFFFF" to retrieve the value.
334
335 [1] compressed length:
336 The size, in bytes, of the chunk on disk
337
338 [2] uncompressed length:
339 The size, in bytes, of the full revision once reconstructed.
340
341 [3] base rev:
342 Either the base of the revision delta chain (without general
343 delta), or the base of the delta (stored in the data chunk)
344 with general delta.
345
346 [4] link rev:
347 Changelog revision number of the changeset introducing this
348 revision.
349
350 [5] parent 1 rev:
351 Revision number of the first parent
352
353 [6] parent 2 rev:
354 Revision number of the second parent
355
356 [7] node id:
357 The node id of the current revision
358
359 [8] sidedata offset:
360 The byte index of the start of the revision's side-data chunk.
361
362 [9] sidedata chunk length:
363 The size, in bytes, of the revision's side-data chunk.
364
365 [10] data compression mode:
366 two bits that detail the way the data chunk is compressed on disk.
367 (see "COMP_MODE_*" constants for details). For revlog version 0 and
368 1 this will always be COMP_MODE_INLINE.
369
370 [11] side-data compression mode:
371 two bits that detail the way the sidedata chunk is compressed on disk.
372 (see "COMP_MODE_*" constants for details)
373 """ 315 """
374 316
375 _flagserrorclass = error.RevlogError 317 _flagserrorclass = error.RevlogError
376 318
377 def __init__( 319 def __init__(