* feat: more prometheus metrics for monitoring performance (#146) (#175)

* chore: config timeout and connection pool (#150) (#171)

* fix: use line/tm-db instead of tendermint/tm-db

* bump up tm-db, iavl; re-apply #201

* chore: use default db backend among the available ones (#212)

* chore: use default db backend among the available ones

* chore: bump up iavl, tm-db

* feat: concurrent checkTx #213; fix tm-db call

* fix: rename TM to OC

* fix: modify key name; tendermint -> ostracon

* chore: rename tendermint to ostracon

* chore: remove mempool.postCheck (#158) (#217)

* fix: error handling after check tx

* fix: typo

* chore: (mempool) remove postCheck and impl reserve

* chore: fix tests

* chore: revise log (remove checkTx.Code)

* chore: add `CONTRACT` for `mem.proxyAppConn.CheckTxAsync()`

* chore: revise numTxs, txsBytes for `ErrMempoolIsFull` in reserve()

* chore: revise to remove redundant `isFull()`

* fix: remove tx from cache when `app errors` or `failed to reserve`

* Revert "chore: revise to remove redundant `isFull()`"

This reverts commit 55990ec.

* fix: revise to call Begin/EndRecheck even though mem.Size() is 0 (#219)

* fix: revise to call Begin/EndRecheck even though `mem.Size()` is 0

* chore: revise local_client.go

* fix: lint error

* chore: recheckTxs() just return if mem.Size() == 0

* feat: concurrent recheckTx (#163) (#221)

* chore: increase the value of maxPerPage (#223)

* chore: fix the type of consensus_block_interval_seconds from histogram to gauge (#224)

* feat: impl checkTxAsyncReactor() (#168) (#225)

* feat: impl checkTxAsyncReactor() (#168)

* fix: tests

* fix: lint errors

* chore: revise abci.Client, Async() interfaces (#169) (#226)

* chore: revise abci.Client, Async() interfaces

* chore: regen mock w/ mockery 2.7.4

* fix: lint error

* fix: test_race

* mempool.Flush() flushes all txs from mempool so it should get `Lock()` instead of `RLock()`

* chore: remove iavl dependency (#228)

* chore: remove iavl dependency

* chore: fix lint error

* fix: add more fixing for abci.Client, Async()

* feat: revise metric for measuring performance

* build: remove needless build tag `!libsecp256k1` (#246)

The build tag makes disable go implementation of secp256k1.
Cause there is no C implementation, a build error will occur when using tag `libsecp256k1`.

* feat: add duration metrics of gauge type (#256)

* perf: optimize checking the txs size (#264)

* perf: optimize checking the txs size

* ci: add GOPRIVATE to workflows

* test: add a unit test

* fix: fix lint errors

* perf: do not flush wal when receive consensus msgs (#273)

* perf: do not flush wal when receive consensus msgs

* fix: ci failure

* fix: lint failure

* fix: ci-e2e build failure

* fix: bump up tm-db

* fix: missing abci api

* fix: bump up tm-db; use memdb

* test: add test case to raise test coverage

* fix: race error

* fix: race error

* fix: race error

* fix: increase e2e test timeout

* fix: add test case for coverage

* fix: e2e docker file

* fix: apply comments

* fix: a Ostracon to an Ostracon