## Description

Refs #2659

Breaking changes in the mempool package:

[mempool] #2659 Mempool now an interface
    old Mempool renamed to CListMempool
    NewMempool renamed to NewCListMempool
    Option renamed to CListOption
    MempoolReactor renamed to Reactor
    NewMempoolReactor renamed to NewReactor
    unexpose TxID method
    TxInfo.PeerID renamed to SenderID
    unexpose MempoolReactor.Mempool

Breaking changes in the state package:

[state] #2659 Mempool interface moved to mempool package
    MockMempool moved to top-level mock package and renamed to Mempool

Non Breaking changes in the node package:

[node] #2659 Add Mempool method, which allows you to access mempool

## Commits

* move Mempool interface into mempool package

Refs #2659

Breaking changes in the mempool package:

- Mempool now an interface
- old Mempool renamed to CListMempool

Breaking changes to state package:

- MockMempool moved to mempool/mock package and renamed to Mempool
- Mempool interface moved to mempool package

* assert CListMempool impl Mempool

* gofmt code

* rename MempoolReactor to Reactor

- combine everything into one interface
- rename TxInfo.PeerID to TxInfo.SenderID
- unexpose MempoolReactor.Mempool

* move mempool mock into top-level mock package

* add a fixme

TxsFront should not be a part of the Mempool interface
because it leaks implementation details. Instead, we need to come up
with general interface for querying the mempool so the MempoolReactor
can fetch and broadcast txs to peers.

* change node#Mempool to return interface

* save commit = new reactor arch

* Revert "save commit = new reactor arch"

This reverts commit 1bfceacd9d.

* require CListMempool in mempool.Reactor

* add two changelog entries

* fixes after my own review

* quote interfaces, structs and functions

* fixes after Ismail's review

* make node's mempool an interface

* make InitWAL/CloseWAL methods a part of Mempool interface

* fix merge conflicts

* make node's mempool an interface

Closes #1798

This is done by making every mempool tx maintain a list of peers who its received the tx from. Instead of using the 20byte peer ID, it instead uses a local map from peerID to uint16 counter, so every peer adds 2 bytes. (Word aligned to probably make it 8 bytes)

This also required resetting the callback function on every CheckTx. This likely has performance ramifications for instruction caching. The actual setting operation isn't costly with the removal of defers in this PR.

* Make the mempool not gossip txs back to peers its received it from

* Fix adversarial memleak

* Don't break interface

* Update changelog

* Forgot to add a mtx

* forgot a mutex

* Update mempool/reactor.go

Co-Authored-By: ValarDragon <ValarDragon@users.noreply.github.com>

* Update mempool/mempool.go

Co-Authored-By: ValarDragon <ValarDragon@users.noreply.github.com>

* Use unknown peer ID

Co-Authored-By: ValarDragon <ValarDragon@users.noreply.github.com>

* fix compilation

* use next wait chan logic when skipping

* Minor fixes

* Add TxInfo

* Add reverse map

* Make activeID's auto-reserve 0

* 0 -> UnknownPeerID

Co-Authored-By: ValarDragon <ValarDragon@users.noreply.github.com>

* Switch to making the normal case set a callback on the reqres object

The recheck case is still done via the global callback, and stats
are also set via global callback

* fix merge conflict

* Addres comments

* Add cache tests

* add cache tests

* minor fixes

* update metrics in reqResCb and reformat code

* goimport -w mempool/reactor.go

* mempool: update memTx senders

I had to introduce txsMap for quick mempoolTx lookups.

* change senders type from []uint16 to sync.Map

Fixes DATA RACE:

```
Read at 0x00c0013fcd3a by goroutine 183:
  github.com/tendermint/tendermint/mempool.(*MempoolReactor).broadcastTxRoutine()
      /go/src/github.com/tendermint/tendermint/mempool/reactor.go:195 +0x3c7

Previous write at 0x00c0013fcd3a by D[2019-02-27|10:10:49.058] Read PacketMsg                               switch=3 peer=35bc1e3558c182927b31987eeff3feb3d58a0fc5@127.0.0.1
:46552 conn=MConn{pipe} packet="PacketMsg{30:2B06579D0A143EB78F3D3299DE8213A51D4E11FB05ACE4D6A14F T:1}"
goroutine 190:
  github.com/tendermint/tendermint/mempool.(*Mempool).CheckTxWithInfo()
      /go/src/github.com/tendermint/tendermint/mempool/mempool.go:387 +0xdc1
  github.com/tendermint/tendermint/mempool.(*MempoolReactor).Receive()
      /go/src/github.com/tendermint/tendermint/mempool/reactor.go:134 +0xb04
  github.com/tendermint/tendermint/p2p.createMConnection.func1()
      /go/src/github.com/tendermint/tendermint/p2p/peer.go:374 +0x25b
  github.com/tendermint/tendermint/p2p/conn.(*MConnection).recvRoutine()
      /go/src/github.com/tendermint/tendermint/p2p/conn/connection.go:599 +0xcce

Goroutine 183 (running) created at:
D[2019-02-27|10:10:49.058] Send                                         switch=2 peer=1efafad5443abeea4b7a8155218e4369525d987e@127.0.0.1:46193 channel=48 conn=MConn{pipe} m
sgBytes=2B06579D0A146194480ADAE00C2836ED7125FEE65C1D9DD51049
  github.com/tendermint/tendermint/mempool.(*MempoolReactor).AddPeer()
      /go/src/github.com/tendermint/tendermint/mempool/reactor.go:105 +0x1b1
  github.com/tendermint/tendermint/p2p.(*Switch).startInitPeer()
      /go/src/github.com/tendermint/tendermint/p2p/switch.go:683 +0x13b
  github.com/tendermint/tendermint/p2p.(*Switch).addPeer()
      /go/src/github.com/tendermint/tendermint/p2p/switch.go:650 +0x585
  github.com/tendermint/tendermint/p2p.(*Switch).addPeerWithConnection()
      /go/src/github.com/tendermint/tendermint/p2p/test_util.go:145 +0x939
  github.com/tendermint/tendermint/p2p.Connect2Switches.func2()
      /go/src/github.com/tendermint/tendermint/p2p/test_util.go:109 +0x50

I[2019-02-27|10:10:49.058] Added good transaction                       validator=0 tx=43B4D1F0F03460BD262835C4AA560DB860CFBBE85BD02386D83DAC38C67B3AD7 res="&{CheckTx:gas_w
anted:1 }" height=0 total=375
Goroutine 190 (running) created at:
  github.com/tendermint/tendermint/p2p/conn.(*MConnection).OnStart()
      /go/src/github.com/tendermint/tendermint/p2p/conn/connection.go:210 +0x313
  github.com/tendermint/tendermint/libs/common.(*BaseService).Start()
      /go/src/github.com/tendermint/tendermint/libs/common/service.go:139 +0x4df
  github.com/tendermint/tendermint/p2p.(*peer).OnStart()
      /go/src/github.com/tendermint/tendermint/p2p/peer.go:179 +0x56
  github.com/tendermint/tendermint/libs/common.(*BaseService).Start()
      /go/src/github.com/tendermint/tendermint/libs/common/service.go:139 +0x4df
  github.com/tendermint/tendermint/p2p.(*peer).Start()
      <autogenerated>:1 +0x43
  github.com/tendermint/tendermint/p2p.(*Switch).startInitPeer()
```

* explain the choice of a map DS for senders

* extract ids pool/mapper to a separate struct

* fix literal copies lock value from senders: sync.Map contains sync.Mutex

* use sync.Map#LoadOrStore instead of Load

* fixes after Ismail's review

* rename resCbNormal to resCbFirstTime

* evidence: NewEvidencePool takes evidenceDB

* evidence: failing TestStoreCommitDuplicate

tendermint/security#35

* GetEvidence -> GetEvidenceInfo

* fix TestStoreCommitDuplicate

* comment in VerifyEvidence

* add check if evidence was already seen
 - modify EventPool interface (EventStore is not known in ApplyBlock):
   - add IsCommitted method to iface
 - add test

* update changelog

* fix TestStoreMark:
 - priority in evidence info gets reset to zero after evidence gets committed

* review comments: simplify EvidencePool.IsCommitted
 - delete obsolete EvidenceStore.IsCommitted

* add simple test for IsCommitted

* update changelog: this is actually breaking (PR number still missing)

* fix TestStoreMark:
 - priority in evidence info gets reset to zero after evidence gets
 committed

* review suggestion: simplify return

Don't add committed evidence to evpool

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

* 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

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

Refs #2035

* #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.

This reverts commit 96a3502

if we call it after, we might receive a "fresh" transaction from
  `broadcast_tx_sync` before old transactions (which were not
  committed).

Refs #1091

```
Commit is called with a lock on the mempool, meaning no calls to CheckTx
can start. However, since CheckTx is called async in the mempool
connection, some CheckTx might have already "sailed", when the lock is
released in the mempool and Commit proceeds.

Then, that spurious CheckTx has not yet "begun" in the ABCI app (stuck
in transport?). Instead, ABCI app manages to start to process the
Commit. Next, the spurious, "sailed" CheckTx happens in the wrong place.
```

uint64 is considered dangerous. the details will follow in a blog post.