feat(eds/store): store.GetDAH

[distractedm1nd]

Overview

Closes #1509

Checklist

• New and updated code has appropriate documentation
• New and updated code has new and/or updated testing
• Required CI checks are passing
• Linked issues closed with keywords

[Wondertan]

@distractedm1nd, It seems like we would have to fully access the shard-avoiding cache in GetCar to solve the issue. The Seeker is fine, but it does not work when multiple requests for the same car happen at the same time. Readers must be exclusive. Pretty embarrassing that I didn't catch it earlier.

The optimization using the same mmap file works only for the multiple blockstore accessors because it has internal mutex protection. We can try to make similar synchronization and make the same mmap file work over simultaneous GetCar, but in fact, this would be sequential instead of parallel, though it has only one CAR copy in mem, rather than the amount of requests amount.

The simplest solution right now is just to avoid cache in GetCar and further, we can optimize memory usage by making multiple Readers over the same mmap, rather than multiple Reders with personal mmap

[walldiss]

Nice!

[vgonkivs]

Unit test failed :

=== RUN   TestBlockstore_Operations
(https://github.com/celestiaorg/celestia-node/actions/runs/3731466266/jobs/6329873704#step:4:1267)
    blockstore_test.go:36: 
(https://github.com/celestiaorg/celestia-node/actions/runs/3731466266/jobs/6329873704#step:4:1268)
        	Error Trace:	/home/runner/work/celestia-node/celestia-node/share/eds/blockstore_test.go:36
(https://github.com/celestiaorg/celestia-node/actions/runs/3731466266/jobs/6329873704#step:4:1269)
        	Error:      	Received unexpected error:
(https://github.com/celestiaorg/celestia-node/actions/runs/3731466266/jobs/6329873704#step:4:1270)
        	            	failed to read DAH from car reader: malformed car; header is bigger than util.MaxAllowedSectionSize
(https://github.com/celestiaorg/celestia-node/actions/runs/3731466266/jobs/6329873704#step:4:1271)
        	Test:       	TestBlockstore_Operations

[Wondertan]

Note about updating the ADR

[codecov-commenter]

Codecov Report

Merging #1511 (4478305) into main (e3062d4) will decrease coverage by 0.25%.
The diff coverage is 65.95%.

@@            Coverage Diff             @@
##             main    #1511      +/-   ##
==========================================
- Coverage   55.49%   55.23%   -0.26%     
==========================================
  Files         203      210       +7     
  Lines       12126    12866     +740     
==========================================
+ Hits         6729     7107     +378     
- Misses       4730     5038     +308     
- Partials      667      721      +54     

Impacted Files	Coverage Δ
share/eds/store.go	58.29% <65.21%> (+6.19%)	⬆️
share/eds/blockstore.go	38.77% <100.00%> (ø)
nodebuilder/p2p/genesis.go	0.00% <0.00%> (-33.34%)	⬇️
header/store/init.go	72.72% <0.00%> (-27.28%)	⬇️
nodebuilder/header/constructors.go	54.54% <0.00%> (-20.46%)	⬇️
nodebuilder/share/module.go	58.73% <0.00%> (-18.36%)	⬇️
share/empty.go	86.66% <0.00%> (-13.34%)	⬇️
header/core/exchange.go	31.81% <0.00%> (-9.10%)	⬇️
header/p2p/exchange.go	66.25% <0.00%> (-8.44%)	⬇️
nodebuilder/share/constructors.go	92.10% <0.00%> (-7.90%)	⬇️
... and 41 more

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[vgonkivs]

LGTM 🚀

[Wondertan]

LGTM, a q and a nit

[adlerjohn]

utACK