Matthew Dawson df2c03a6a4 repository/master_index: Optimize Index.Lookup() ... When looking up a blob in the master index, with several indexes present in the master index, a significant amount of time is spent generating errors for each failed lookup. However, these errors are often used to check if a blob is present, but the contents are not inspected making the overhead of the error not useful. Instead, change Index.Lookup (and Index.LookupSize) to instead return a boolean denoting if the blob was found instead of an error. Also change all the calls to these functions to handle the new function signature. benchmark old ns/op new ns/op delta BenchmarkMasterIndexLookupSingleIndex-6 820 897 +9.39% BenchmarkMasterIndexLookupMultipleIndex-6 12821 2001 -84.39% BenchmarkMasterIndexLookupSingleIndexUnknown-6 5378 492 -90.85% BenchmarkMasterIndexLookupMultipleIndexUnknown-6 17026 1649 -90.31% benchmark old allocs new allocs delta BenchmarkMasterIndexLookupSingleIndex-6 9 9 +0.00% BenchmarkMasterIndexLookupMultipleIndex-6 59 19 -67.80% BenchmarkMasterIndexLookupSingleIndexUnknown-6 22 6 -72.73% BenchmarkMasterIndexLookupMultipleIndexUnknown-6 72 16 -77.78% benchmark old bytes new bytes delta BenchmarkMasterIndexLookupSingleIndex-6 160 160 +0.00% BenchmarkMasterIndexLookupMultipleIndex-6 3200 240 -92.50% BenchmarkMasterIndexLookupSingleIndexUnknown-6 1232 48 -96.10% BenchmarkMasterIndexLookupMultipleIndexUnknown-6 4272 128 -97.00%		2018-01-23 22:25:56 -05:00
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restic	repository/master_index: Optimize Index.Lookup()	2018-01-23 22:25:56 -05:00