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deltas: skip if projected compressed size does not match text size constraint

Description

deltas: skip if projected compressed size does not match text size constraint

If we have a delta, we check constraints against a lower bound estimate of the
resulting compressed delta. We then checks this projected size against the ½ⁿ
size constraints. This allows to exclude potential base candidates before doing
any expensive computation.

This only apply to the intermediate-snapshot case since this constraint only apply to
them.

For some pathological cases of a private repository this step provide a
further performance boost (timing from hg perfrevlogwrite):

before: 3.145906 seconds
after: 3.010646 seconds

Details

Committed
valentin.gatienbaronJan 21 2019, 4:46 PM
Parents
rHG465f2d0df9ae: deltas: accept and skip None return for delta info
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