feat: ADR 040: Implement in-memory DB backend #9952

roysc · 2021-08-17T08:53:41Z

Description

Implements an in-memory backend for the DB interface introduced by #9573 and specified by ADR-040. This expands on the btree-based MemDB from tm-db by using copy-on-write clones to implement versioning.

Resolves: vulcanize#2

Will move out of draft once #9573 is merged and rebased on.

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redundant since dbWriter uses a clone

roysc · 2021-08-23T07:46:56Z

Now that the interface has been merged, this is good to review. This contains MemDB, unit tests, and supporting utilities, which logically fit together but make a large PR, so let me know if it would be better to break the code down further.

alexanderbez

Changes mainly LGTM, great work. Left some small remarks 👍

CHANGELOG.md

db/README.md

db/memdb/db.go

alexanderbez · 2021-08-23T19:38:17Z

db/memdb/db.go

+func (db *MemDB) Versions() (dbm.VersionSet, error) {
+	db.mtx.RLock()
+	defer db.mtx.RUnlock()
+	return db.vmgr, nil


do we not want to return a copy of the map?

It seems we already have a Copy method too.

I opted to make this copy-on-write. Versions is called whenever version history is queried, and if the history becomes large, it could be expensive. So a vmgr is just copied over whenever versions are saved/deleted, and the caller can safely keep the old reference.

vmgr is a pointer, so we don't make any object copy here

db/types.go

alexanderbez · 2021-08-23T19:42:07Z

db/version_manager.go

+	return &vmIterator{ch: ch}
+}
+
+// Count implements VersionSet.


If this type implements an interface, we don't need to add godocs for the sake of adding godocs 👍

Fine with me, I was just following the existing practice

alexanderbez · 2021-08-23T19:47:25Z

db/memdb/iterator.go

+
+// Error implements Iterator.
+func (i *memDBIterator) Error() error {
+	return nil // famous last words


lol, any reason not to track an error? Or can one never happen?

Yeah, there's no error case for this iterator - it's only invalidated when it reaches its end.

ACK. Let's remove // famous last words then

haha sure, that was from the tm-db code.

Co-authored-by: Aleksandr Bezobchuk <[email protected]>

codecov · 2021-08-24T06:40:52Z

Codecov Report

Merging #9952 (3494b38) into master (54b0556) will increase coverage by 0.24%.
The diff coverage is n/a.

❗ Current head 3494b38 differs from pull request most recent head b56dd6e. Consider uploading reports for the commit b56dd6e to get more accurate results

@@            Coverage Diff             @@
##           master    #9952      +/-   ##
==========================================
+ Coverage   63.56%   63.80%   +0.24%     
==========================================
  Files         572      566       -6     
  Lines       53584    53363     -221     
==========================================
- Hits        34058    34047      -11     
+ Misses      17583    17397     -186     
+ Partials     1943     1919      -24

Impacted Files	Coverage Δ
server/mock/tx.go	`63.15% <0.00%> (-1.85%)`	⬇️
x/auth/keeper/grpc_query.go	`57.14% <0.00%> (-0.86%)`	⬇️
types/address.go	`68.69% <0.00%> (ø)`
x/auth/vesting/types/msgs.go	`0.00% <0.00%> (ø)`
x/auth/middleware/index_events.go
x/auth/middleware/run_msgs.go
x/auth/middleware/recovery.go
x/auth/middleware/middleware.go
x/auth/middleware/legacy_router.go
x/auth/middleware/gas.go
... and 18 more

tac0turtle

@robert-zaremba want to review this so we can merge?

alexanderbez · 2021-08-25T18:55:58Z

Let's give @robert-zaremba a day to review. Is that okay?

tac0turtle · 2021-08-26T06:54:15Z

Let's give @robert-zaremba a day to review. Is that okay?

haha, more than one day is fine as well. It was mainly a ping, not a "needs to be done now"

tac0turtle · 2021-08-31T07:41:57Z

@roysc once the PR is updated to master the bot will merge it

orijbot · 2021-08-31T08:09:48Z

Visit https://dashboard.github.orijtech.com?back=0&pr=9952&remote=false&repo=cosmos%2Fcosmos-sdk to see benchmark details.

odeke-em · 2021-10-07T03:32:07Z

Surprisingly the code from this change is failing tests locally

$ go test
# github.com/cosmos/cosmos-sdk/db/memdb [github.com/cosmos/cosmos-sdk/db/memdb.test]
./db.go:44:23: incompatible type: cannot use (*MemDB)(nil) (value of type *MemDB) as db.DBConnection value
./db_test.go:32:9: incompatible type: cannot use NewDB() (value of type *MemDB) as db.DBConnection value
FAIL	github.com/cosmos/cosmos-sdk/db/memdb [build failed]

roysc force-pushed the roysc/adr-040-db-memdb branch 3 times, most recently from a80c49d to f189a95 Compare August 18, 2021 11:36

roysc changed the title ~~feat: ADR 040: Implement in-memory DB~~ feat: ADR 040: Implement in-memory DB backend Aug 18, 2021

roysc force-pushed the roysc/adr-040-db-memdb branch 2 times, most recently from 9bdcfa2 to 15501e8 Compare August 22, 2021 01:02

roysc marked this pull request as ready for review August 22, 2021 01:03

roysc requested review from aaronc and alexanderbez as code owners August 22, 2021 01:03

changelog entry

9d58b92

roysc marked this pull request as draft August 22, 2021 06:47

roysc added 3 commits August 23, 2021 01:41

KVDB readme

9086cc1

Add dbtest package, test cases

caea36b

Add VersionManager

42306a3

roysc force-pushed the roysc/adr-040-db-memdb branch from 3867290 to 1358c4f Compare August 23, 2021 03:09

Add memdb package

c8cd01d

roysc force-pushed the roysc/adr-040-db-memdb branch from 1358c4f to c8cd01d Compare August 23, 2021 03:50

roysc added 2 commits August 23, 2021 11:56

readme nit

3665e04

fix testcase

e193214

roysc marked this pull request as ready for review August 23, 2021 05:05

clone is not needed here

e17792b

redundant since dbWriter uses a clone

roysc force-pushed the roysc/adr-040-db-memdb branch from 3638b40 to e17792b Compare August 23, 2021 07:21

alexanderbez added the C:Store label Aug 23, 2021

alexanderbez reviewed Aug 23, 2021

View reviewed changes

alexanderbez requested a review from robert-zaremba August 23, 2021 19:48

roysc and others added 2 commits August 24, 2021 13:53

Update CHANGELOG.md

0626049

Co-authored-by: Aleksandr Bezobchuk <[email protected]>

Revise PR

0e04e23

alexanderbez approved these changes Aug 24, 2021

View reviewed changes

robert-zaremba mentioned this pull request Aug 24, 2021

Incorporate tm-db #9092

Closed

4 tasks

clean up

3494b38

tac0turtle approved these changes Aug 25, 2021

View reviewed changes

tac0turtle added the A:automerge Automatically merge PR once all prerequisites pass. label Aug 31, 2021

Merge branch 'master' into roysc/adr-040-db-memdb

b56dd6e

mergify bot merged commit 2c31451 into cosmos:master Aug 31, 2021

roysc deleted the roysc/adr-040-db-memdb branch August 31, 2021 10:33

i-norden mentioned this pull request Sep 7, 2021

ADR-040 Implementation: New DB interface #10094

Closed

8 tasks

odeke-em mentioned this pull request Oct 7, 2021

db/memdb: failing tests and non-compiling code from "cannot use (*MemDB)(nil) (value of type *MemDB) as db.DBConnection value" #10319

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feat: ADR 040: Implement in-memory DB backend #9952

feat: ADR 040: Implement in-memory DB backend #9952

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feat: ADR 040: Implement in-memory DB backend #9952

feat: ADR 040: Implement in-memory DB backend #9952

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