git/list[1] front-page[2] threads[3] people[4] search[5] about
 

Re: [PATCH 3/6] connected: refactor iterator to return next object ID directly

From
Junio C Hamano <gitster@pobox.com>
Date
Aug 20, 2021, 17:43 UTC
Message-ID
<xmqqmtpcui4v.fsf@gitster.g>
In-Reply-To
<ffb5da19-937e-fba6-10f8-3993ca5ff0ef@gmail.com>
Derrick Stolee <stolee@gmail.com> writes:
Show 18 quoted lines
> On 8/20/2021 6:08 AM, Patrick Steinhardt wrote:
>> The object ID iterator used by the connectivity checks returns the next
>> object ID via an out-parameter and then uses a return code to indicate
>> whether an item was found. This is a bit roundabout: instead of a
>> separate error code, we can just retrun the next object ID directly and
>> use `NULL` pointers as indicator that the iterator got no items left.
>> Furthermore, this avoids a copy of the object ID.
>> 
>> Refactor the iterator and all its implementations to return object IDs
>> directly. While I was honestly hoping for a small speedup given that we
>> can now avoid a copy, both versions perform the same. Still, the end
>> result is easier to understand and thus it makes sense to keep this
>> refactoring regardless.
>
> It's too bad about the lack of measurable performance gains, but the
> new code _is_ doing less, it's just not enough.
>
> I agree that the new code organization is better.

The only potential downside I can think of is the loss of ability to convey the reason why it failed to return one by adding new return codes from the function, which I do not immediately see all that useful future extension anyway, so I agree that "we find what we found, or NULL if we don't find" is much straight-forward and easier to understand.

Nicely done.
Thanks.
Previous: Derrick StoleeNext: René Scharfe
Message 11 of 48 in “Speed up mirror-fetches with many refs”
  1. 0/6 Speed up mirror-fetches with many refsPatrick Steinhardt, Aug 20, 2021
  2. 1/6 fetch: speed up lookup of want refs via commit-graphPatrick Steinhardt, Aug 20, 2021
  3. Derrick StoleeAug 20, 2021
  4. Junio C HamanoAug 20, 2021
  5. Patrick SteinhardtAug 23, 2021
  6. Derrick StoleeAug 25, 2021
  7. 2/6 fetch: avoid unpacking headers in object existence checkPatrick Steinhardt, Aug 20, 2021
  8. Ævar Arnfjörð BjarmasonAug 25, 2021
  9. 3/6 connected: refactor iterator to return next object ID directlyPatrick Steinhardt, Aug 20, 2021
  10. Derrick StoleeAug 20, 2021
  11. Junio C HamanoAug 20, 2021
  12. René ScharfeAug 20, 2021
  13. Patrick SteinhardtAug 23, 2021
  14. 4/6 fetch-pack: optimize loading of refs via commit graphPatrick Steinhardt, Aug 20, 2021
  15. Derrick StoleeAug 20, 2021
  16. 5/6 fetch: refactor fetch refs to be more extendablePatrick Steinhardt, Aug 20, 2021
  17. Derrick StoleeAug 20, 2021
  18. 6/6 fetch: avoid second connectivity check if we already have all objectsPatrick Steinhardt, Aug 20, 2021
  19. Derrick StoleeAug 20, 2021
  20. Patrick SteinhardtAug 23, 2021
  21. Derrick StoleeAug 20, 2021
  22. Junio C HamanoAug 21, 2021
  23. 0/7 Speed up mirror-fetches with many refsPatrick Steinhardt, Aug 24, 2021
  24. 1/7 fetch: speed up lookup of want refs via commit-graphPatrick Steinhardt, Aug 24, 2021
  25. Derrick StoleeAug 25, 2021
  26. 2/7 fetch: avoid unpacking headers in object existence checkPatrick Steinhardt, Aug 24, 2021
  27. 3/7 connected: refactor iterator to return next object ID directlyPatrick Steinhardt, Aug 24, 2021
  28. 4/7 fetch-pack: optimize loading of refs via commit graphPatrick Steinhardt, Aug 24, 2021
  29. 5/7 fetch: refactor fetch refs to be more extendablePatrick Steinhardt, Aug 24, 2021
  30. Derrick StoleeAug 25, 2021
  31. Patrick SteinhardtSep 1, 2021
  32. 7/7 fetch: avoid second connectivity check if we already have all objectsPatrick Steinhardt, Aug 24, 2021
  33. 6/7 fetch: merge fetching and consuming refsPatrick Steinhardt, Aug 24, 2021
  34. Derrick StoleeAug 25, 2021
  35. Patrick SteinhardtSep 1, 2021
  36. Junio C HamanoAug 24, 2021
  37. Patrick SteinhardtAug 25, 2021
  38. Derrick StoleeAug 25, 2021
  39. 0/7 Speed up mirror-fetches with many refsPatrick Steinhardt, Sep 1, 2021
  40. 1/7 fetch: speed up lookup of want refs via commit-graphPatrick Steinhardt, Sep 1, 2021
  41. 2/7 fetch: avoid unpacking headers in object existence checkPatrick Steinhardt, Sep 1, 2021
  42. 3/7 connected: refactor iterator to return next object ID directlyPatrick Steinhardt, Sep 1, 2021
  43. 4/7 fetch-pack: optimize loading of refs via commit graphPatrick Steinhardt, Sep 1, 2021
  44. 5/7 fetch: refactor fetch refs to be more extendablePatrick Steinhardt, Sep 1, 2021
  45. 6/7 fetch: merge fetching and consuming refsPatrick Steinhardt, Sep 1, 2021
  46. 7/7 fetch: avoid second connectivity check if we already have all objectsPatrick Steinhardt, Sep 1, 2021
  47. Junio C HamanoSep 1, 2021
  48. Junio C HamanoSep 8, 2021

Read the whole thread, see it on lore, or plain text.

$ cat FOOTERMessages come from the public archive at lore.kernel.org/git, fetched every hour. The front page is chosen and written each morning by an AI editor and can be wrong; the threads themselves are the record. About and API. For agents: an MCP server at https://gitlist.dev/mcp, and any thread, story or person page as Markdown by adding .md to its URL (or sending Accept: text/markdown). Details in /llms.txt.