Optimize pack readHeader() implementation #1574
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Load pack header length and 15 header entries with single backend request. This eliminates separate header Load() request for most pack files and significantly improves index.New() performance. Signed-off-by: Igor Fedorenko <igor@ifedorenko.com>
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ifedorenko
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Jan 24, 2018
| const maxHeaderSize = 16 * 1024 * 1024 | ||
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| // we require at least one entry in the header, and one blob for a pack file | ||
| var minFileSize = entrySize + crypto.Extension | ||
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| // number of header enries to download as part of header-length request | ||
| var eagerEntries = uint(15) |
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@fd0 This number is based on stats from single 435GB repository (where >98% of all packs have 15 or less header entries, fwiw). Maybe useful to get stats from other repositories, assuming you have access or have interested users who can provide the info.
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| return binary.LittleEndian.Uint32(buf), nil | ||
| } | ||
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| const maxHeaderSize = 16 * 1024 * 1024 | ||
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| // we require at least one entry in the header, and one blob for a pack file | ||
| var minFileSize = entrySize + crypto.Extension |
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Not related to my change, but I believe minFileSize should be 4 bytes longer to account for header length record at the end of the file.
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Optimize pack readHeader() implementation
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What is the purpose of this change? What does it change?
Load pack header length and 15 header entries with single backend
request. This eliminates separate header Load() request for most pack
files and significantly improves index.New() performance.
Was the change discussed in an issue or in the forum before?
See #1567
Checklist
changelog/x.y.zthat describe the changes for our users (template here)gofmton the code in all commits