feat: io.Reader factory for ShardAccessor
#155
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raulk
reviewed
Apr 3, 2023
accessor.go
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| if sa.mmapr == nil { | ||
| if f, ok := sa.data.(*os.File); ok { | ||
| if mmapr, err := mmap.Open(f.Name()); err != nil { | ||
| log.Warnf("failed to mmap reader of type %T: %s; using reader as-is", sa.data, err) | ||
| } else { | ||
| sa.mmapr = mmapr | ||
| } | ||
| } | ||
| } |
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Let's extract this logic to a tryMmap() method (and document it requires the lock to be held) and refactor the Blockstore() method to use that?
accessor.go
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| if sa.mmapr != nil { | ||
| return sa.mmapr.ReadAt(p, 0) | ||
| } |
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Would move this above since we expect it to be the most common path when a shard gets reused.
accessor.go
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| if sa.mmapr != nil { | ||
| r = sa.mmapr | ||
| } else if f, ok := sa.data.(*os.File); ok { |
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Let's extract the mmap logic; then make this method short-circuit for more readable and idiomatic code.
|
Crossposting my review celestiaorg#2 (comment) also cc @raulk |
distractedm1nd
changed the title
io.Reader for ShardAccessorio.Reader factory for ShardAccessor
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At celestia-node, we don't only use
ShardAccessor's Blockstore to serve individual blocks, but also use the underlying mount to stream the CAR file to other full nodes. We do this by adding aReader() io.Readermethod toShardAccessorthat creates independent mmap-backed (when possible) readers. We would love to upstream it to avoid maintaining a fork.