This is only one part of #2989. We also need to fix the application,
and add rules to consensus to ensure this.

Within every tx in the mempool, we store a 64 bit counter,
as an index for when it was inserted into the mempool.
This counter doesn't really serve any purpose.
It was likely added for debugging at one point,
Removing the counter reclaims memory,
which enables greater mempool sizes / mitigates resources at the same size.

Closes #2835

We should add txs that come in from mempool.Update to the mempool's
cache, so that they never hit a potentially expensive check tx.

Originally posted by @ValarDragon in #2846
https://github.com/tendermint/tendermint/issues/2846#issuecomment-439216656

Refs #2855

- rename filterTxs to removeTxs
- move txsMap into removeTxs func
- rename goodTxs to txsLeft

* use READ lock/unlock in ConsensusState#GetLastHeight

Refs #2721

* do not use defers when there's no need

* fix peer formatting (output its address instead of the pointer)

```
[54310]: E[11-02|11:59:39.851] Connection failed @ sendRoutine              module=p2p peer=0xb78f00 conn=MConn{74.207.236.148:26656} err="pong timeout"
```

https://github.com/tendermint/tendermint/issues/2721#issuecomment-435326581

* panic if peer has no state

https://github.com/tendermint/tendermint/issues/2721#issuecomment-435347165

It's confusing that sometimes we check if peer has a state, but most of
the times we expect it to be there

1. add79700b5/mempool/reactor.go (L138)
2. add79700b5/rpc/core/consensus.go (L196) (edited)

I will change everything to always assume peer has a state and panic
otherwise

that should help identify issues earlier

* abci/localclient: extend lock on app callback

App callback should be protected by lock as well (note this was already
done for InitChainAsync, why not for others???). Otherwise, when we
execute the block, tx might come in and call the callback in the same
time we're updating it in execBlockOnProxyApp => DATA RACE

Fixes #2721

Consensus state is locked

```
goroutine 113333 [semacquire, 309 minutes]:
sync.runtime_SemacquireMutex(0xc00180009c, 0xc0000c7e00)
        /usr/local/go/src/runtime/sema.go:71 +0x3d
sync.(*RWMutex).RLock(0xc001800090)
        /usr/local/go/src/sync/rwmutex.go:50 +0x4e
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).GetRoundState(0xc001800000, 0x0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:218 +0x46
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusReactor).queryMaj23Routine(0xc0017def80, 0x11104a0, 0xc0072488f0, 0xc007248
9c0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/reactor.go:735 +0x16d
created by github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusReactor).AddPeer
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/reactor.go:172 +0x236
```

because localClient is locked

```
goroutine 1899 [semacquire, 309 minutes]:
sync.runtime_SemacquireMutex(0xc00003363c, 0xc0000cb500)
        /usr/local/go/src/runtime/sema.go:71 +0x3d
sync.(*Mutex).Lock(0xc000033638)
        /usr/local/go/src/sync/mutex.go:134 +0xff
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/abci/client.(*localClient).SetResponseCallback(0xc0001fb560, 0xc007868540)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/abci/client/local_client.go:32 +0x33
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/proxy.(*appConnConsensus).SetResponseCallback(0xc00002f750, 0xc007868540)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/proxy/app_conn.go:57 +0x40
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/state.execBlockOnProxyApp(0x1104e20, 0xc002ca0ba0, 0x11092a0, 0xc00002f750, 0xc0001fe960, 0xc000bfc660, 0x110cfe0, 0xc000090330, 0xc9d12, 0xc000d9d5a0, ...)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/state/execution.go:230 +0x1fd
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/state.(*BlockExecutor).ApplyBlock(0xc002c2a230, 0x7, 0x0, 0xc000eae880, 0x6, 0xc002e52c60, 0x16, 0x1f927, 0xc9d12, 0xc000d9d5a0, ...)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/state/execution.go:96 +0x142
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).finalizeCommit(0xc001800000, 0x1f928)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:1339 +0xa3e
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).tryFinalizeCommit(0xc001800000, 0x1f928)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:1270 +0x451
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).enterCommit.func1(0xc001800000, 0x0, 0x1f928)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:1218 +0x90
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).enterCommit(0xc001800000, 0x1f928, 0x0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:1247 +0x6b8
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).addVote(0xc001800000, 0xc003d8dea0, 0xc000cf4cc0, 0x28, 0xf1, 0xc003bc7ad0, 0xc003bc7b10)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:1659 +0xbad
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).tryAddVote(0xc001800000, 0xc003d8dea0, 0xc000cf4cc0, 0x28, 0xf1, 0xf1, 0xf1)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:1517 +0x59
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).handleMsg(0xc001800000, 0xd98200, 0xc0070dbed0, 0xc000cf4cc0, 0x28)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:660 +0x64b
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).receiveRoutine(0xc001800000, 0x0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:617 +0x670
created by github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).OnStart
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:311 +0x132
```

tx comes in and CheckTx is executed right when we execute the block

```
goroutine 111044 [semacquire, 309 minutes]:
sync.runtime_SemacquireMutex(0xc00003363c, 0x0)
        /usr/local/go/src/runtime/sema.go:71 +0x3d
sync.(*Mutex).Lock(0xc000033638)
        /usr/local/go/src/sync/mutex.go:134 +0xff
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/abci/client.(*localClient).CheckTxAsync(0xc0001fb0e0, 0xc002d94500, 0x13f, 0x280, 0x0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/abci/client/local_client.go:85 +0x47
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/proxy.(*appConnMempool).CheckTxAsync(0xc00002f720, 0xc002d94500, 0x13f, 0x280, 0x1)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/proxy/app_conn.go:114 +0x51
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/mempool.(*Mempool).CheckTx(0xc002d3a320, 0xc002d94500, 0x13f, 0x280, 0xc0072355f0, 0x0, 0x0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/mempool/mempool.go:316 +0x17b
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/core.BroadcastTxSync(0xc002d94500, 0x13f, 0x280, 0x0, 0x0, 0x0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/core/mempool.go:93 +0xb8
reflect.Value.call(0xd85560, 0x10326c0, 0x13, 0xec7b8b, 0x4, 0xc00663f180, 0x1, 0x1, 0xc00663f180, 0xc00663f188, ...)
        /usr/local/go/src/reflect/value.go:447 +0x449
reflect.Value.Call(0xd85560, 0x10326c0, 0x13, 0xc00663f180, 0x1, 0x1, 0x0, 0x0, 0xc005cc9344)
        /usr/local/go/src/reflect/value.go:308 +0xa4
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/lib/server.makeHTTPHandler.func2(0x1102060, 0xc00663f100, 0xc0082d7900)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/lib/server/handlers.go:269 +0x188
net/http.HandlerFunc.ServeHTTP(0xc002c81f20, 0x1102060, 0xc00663f100, 0xc0082d7900)
        /usr/local/go/src/net/http/server.go:1964 +0x44
net/http.(*ServeMux).ServeHTTP(0xc002c81b60, 0x1102060, 0xc00663f100, 0xc0082d7900)
        /usr/local/go/src/net/http/server.go:2361 +0x127
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/lib/server.maxBytesHandler.ServeHTTP(0x10f8a40, 0xc002c81b60, 0xf4240, 0x1102060, 0xc00663f100, 0xc0082d7900)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/lib/server/http_server.go:219 +0xcf
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/lib/server.RecoverAndLogHandler.func1(0x1103220, 0xc00121e620, 0xc0082d7900)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/lib/server/http_server.go:192 +0x394
net/http.HandlerFunc.ServeHTTP(0xc002c06ea0, 0x1103220, 0xc00121e620, 0xc0082d7900)
        /usr/local/go/src/net/http/server.go:1964 +0x44
net/http.serverHandler.ServeHTTP(0xc001a1aa90, 0x1103220, 0xc00121e620, 0xc0082d7900)
        /usr/local/go/src/net/http/server.go:2741 +0xab
net/http.(*conn).serve(0xc00785a3c0, 0x11041a0, 0xc000f844c0)
        /usr/local/go/src/net/http/server.go:1847 +0x646
created by net/http.(*Server).Serve
        /usr/local/go/src/net/http/server.go:2851 +0x2f5
```

* consensus: use read lock in Receive#VoteMessage

* use defer to unlock mutex because application might panic

* use defer in every method of the localClient

* add a changelog entry

* drain channels before Unsubscribe(All)

Read 55362ed766/libs/pubsub/pubsub.go (L13)
for the detailed explanation of the issue.

We'll need to fix it someday. Make sure to keep an eye on
https://github.com/tendermint/tendermint/blob/master/docs/architecture/adr-033-pubsub.md

* retry instead of panic when peer has no state in reactors other than consensus

in /dump_consensus_state RPC endpoint, skip a peer with no state

* rpc/core/mempool: simplify error messages

* rpc/core/mempool: use time.After instead of timer

also, do not log DeliverTx result (to be consistent with other memthods)

* unlock before calling the callback in reqRes#SetCallback

* fix amino overhead computation for Tx:

- also count the fieldnum / typ3
- add method to compute overhead per Tx
- slightly clarify comment on MaxAminoOverheadForBlock
- add tests

* fix TestReapMaxBytesMaxGas according to amino overhead

* fix TestMempoolFilters according to amino overhead

* address review comments:

 - add a note about fieldNum = 1
 - add forgotten godoc comment

* fix and use sm.TxPreCheck

* fix test

* remove print statement

This is a follow-up from https://github.com/tendermint/tendermint/pull/2724

Closes #2761

* only invoke InitWAL/CloseWAL if WalPath is not empty

Closes #2717

* panic if WAL is not initialized when calling CloseWAL

* add a changelog entry

* mempool: ErrPreCheck and more log info

* change Pre/PostCheckFunc to return errors

also, continue execution when checking txs in mempool_test if
err=PreCheckErr

* Add additional metrics
Continues addressing https://github.com/cosmos/cosmos-sdk/issues/2169.
* Add nop metrics to fix NPE
* Tweak buckets, code review
* Update buckets
* Update docs with new metrics
* Code review updates

* remove some XXX

* config: remove Mempool.RecheckEmpty

* docs: remove recheck_empty

This change doubles the speed of the mempool's reaping.
Before:

BenchmarkReap-8   	    5000	    365390 ns/op	  122887 B/op

After:

BenchmarkReap-8   	   10000	    158274 ns/op	  122882 B/op

* Add additional metrics to p2p and consensus
Partially addresses https://github.com/cosmos/cosmos-sdk/issues/2169.
* WIP
* Updates from code review
* Updates from code review
* Add instrumentation namespace to configuration
* Fix test failure
* Updates from code review
* Add quotes
* Add atomic load
* Use storeint64
* Use addInt64 in writePacketMsgTo

* mempool: update some comments

* make build_c

* docs: notes about databases and WAL files

* docs: determinism. closes #1279

* docs: small note about query paths. closes #2090

* docs: gas

* docs: abci consensus params

This also refactors the prior mempool to filter to be known as
"precheck filter" and this new filter is called "postcheck filter"

This PR also fixes a bug where the precheck filter previously didn't
account for the amino overhead, which could a maliciously sized tx to
halt blocks from getting any txs in them.

* Move maxGas outside of function definition to avoid race condition
* Type filter funcs and make public
* Use helper method for post check
* Remove superfluous Filter suffix
* Move default pre/post checks into package
* Fix broken references
* Fix typos
* Expand on examples for checks

* follow up to removing some consensus params Refs #2382
* change args type to int64 in state#makeParams
* make valsCount and evidenceCount ints again
* MaxEvidenceBytesPerBlock: include magic number in godoc
* [spec] creating a proposal
* test state#TxFilter
* panic if MaxDataBytes is less than 0
* fixes after review
* use amino#UvarintSize to calculate overhead
0c74291f3b/encoder.go (L85-L90)
* avoid cyclic imports
* you can do better Go, come on
* remove testdouble package

Closes #2399

* Make mempool aware of MaxGas requirement

* update spec

* Add tests

* Switch GasWanted from kv store to persistent kv store

* Fix typo in test name

* switch back to using kvstore, not persistent kv store

* ReapMaxTxs: return all txs if max is negative

this mirrors ReapMaxBytes behavior

See https://github.com/tendermint/tendermint/pull/2184#discussion_r214439950

* increase MaxAminoOverheadForBlock

tested with:

```
func TestMaxAminoOverheadForBlock(t *testing.T) {

        maxChainID := ""
        for i := 0; i < MaxChainIDLen; i++ {
                maxChainID += "𠜎"
        }

        h := Header{
                ChainID:            maxChainID,
                Height:             10,
                Time:               time.Now().UTC(),
                NumTxs:             100,
                TotalTxs:           200,
                LastBlockID:        makeBlockID(make([]byte, 20), 300, make([]byte, 20)),
                LastCommitHash:     tmhash.Sum([]byte("last_commit_hash")),
                DataHash:           tmhash.Sum([]byte("data_hash")),
                ValidatorsHash:     tmhash.Sum([]byte("validators_hash")),
                NextValidatorsHash: tmhash.Sum([]byte("next_validators_hash")),
                ConsensusHash:      tmhash.Sum([]byte("consensus_hash")),
                AppHash:            tmhash.Sum([]byte("app_hash")),
                LastResultsHash:    tmhash.Sum([]byte("last_results_hash")),
                EvidenceHash:       tmhash.Sum([]byte("evidence_hash")),
                ProposerAddress:    tmhash.Sum([]byte("proposer_address")),
        }
        b := Block{
                Header:     h,
                Data:       Data{Txs: makeTxs(10000, 100)},
                Evidence:   EvidenceData{},
                LastCommit: &Commit{},
        }

        bz, err := cdc.MarshalBinary(b)
        require.NoError(t, err)

        assert.Equal(t, MaxHeaderBytes+MaxAminoOverheadForBlock-2, len(bz)-1000000-20000-1)
}
```

* fix MaxYYY constants calculation

by using math.MaxInt64

See https://github.com/tendermint/tendermint/pull/2184#discussion_r214444244

* pass mempool filter as an option

See https://github.com/tendermint/tendermint/pull/2184#discussion_r214445869

* fixes after Dev's comments

See ADR 020: Limiting txs size inside a block docs/architecture/adr-020-block-size.md

Refs #2035

* mempool: Store txs by hash inside of cache

This allows for large cachesizes, without fear of the memory
consumption growing rapidly.

* (squash this) rename hashedTx -> txHash

* mempool: Keep cache hashmap and linked list in sync

This removes bugs with the linked list being full, but hashmap empty

* address PR comments

* switch clist back to list

* libs: Remove usage of custom Fmt, in favor of fmt.Sprintf

Closes #2193

* Fix bug that was masked by custom Fmt!

This PR changes ABCI time format from int64 (Unix seconds) to WKT (WellKnownType) google.protobuf.Timestamp.

Refs #1857

Reasons:

better precision
standard DT for proto

* update Gopkg.lock
* [makefile] remove extra grep
    - go list excludes vendor by default now
* proto3 timestamp
* [docs/abci-spec] note about serialisation format
* make time non-nullable

* #1920 try to fix race condition on proposal height for published txs

- related to create_empty_blocks=false
- published height for accepted tx can be wrong (too low)
- use the actual mempool height + 1 for the proposal
- expose Height() on mempool

* #1920 add initial test for mempool.Height()

- not sure how to test the lock
- can the mutex reference be of type Locker?
-- this way, we can use a "mock" of the mutex to test triggering

* #1920 use the ConsensusState height in favor of mempool

- gets rid of indirections
- doesn't need any "+1" magic

* #1920 cosmetic

- if we use cs.Height, it's enough to evaluate right before propose

* #1920 cleanup TODO and non-needed code

* #1920 add changelog entry

This reverts commit d02c5d1e30.

Refs #646

Fixes #1762#issuecomment-398940107

This reverts commit 96a3502

- move prometheus metrics into internal packages
- *Option structs
- misc. format changes

to better handle zero cache size

* updateToState exits early if the state isn't new, which happens after
* fast syncing. This results in not sending a NewRoundStep message. The mempool
* reactor depends on PeerState, which is updated by NewRoundStep
* messages. If the peer never sends a NewRoundStep, the mempool reactor
* will think they're behind, and never forward transactions. Note this
* only happens when `create_empty_blocks = false`, because otherwise
* peers will move through the consensus state and send a NewRoundStep
* for a new step soon anyways. Simple fix is just to send the
* NewRoundStep message during updateToState even if exit early

no longer relevant, I guess. since ABCI only defines 0 (success) code.