abci: remove lock protecting calls to the application interface (#7984)

Closes #7073

As part of the 0.36 cycle we've discussed and decided to remove the mutex in tendermint that protects the ABCI application. First, applications should be able to be responsible for their own concurrency control, and can make more fine-grained decisions about concurrent use than tendermint ever could. Second, I've observed in recent weeks as we've been making this change that the mutex wasn't applied particularly consistently in many cases (e.g. multiple "local" connections to the application had multiple locks, etc.) so this will give more consistent experiences across ABCI execution environments, and simplifies the tendermint ABCI handling code.

abci/client/grpc_client.go

@@ -91,14 +91,18 @@ RETRY_LOOP:
 }
 
 func (cli *grpcClient) OnStop() {
+	cli.mtx.Lock()
+	defer cli.mtx.Unlock()
+
 	if cli.conn != nil {
-		cli.conn.Close()
+		cli.err = cli.conn.Close()
 	}
 }
 
 func (cli *grpcClient) Error() error {
 	cli.mtx.Lock()
 	defer cli.mtx.Unlock()
+
 	return cli.err
 }
 

abci/client/local_client.go

@@ -2,7 +2,6 @@ package abciclient
 
 import (
 	"context"
-	"sync"
 
 	types "github.com/tendermint/tendermint/abci/types"
 	"github.com/tendermint/tendermint/libs/log"
@@ -15,8 +14,6 @@ import (
 // RPC endpoint), but defers are used everywhere for the sake of consistency.
 type localClient struct {
 	service.BaseService
-
-	mtx sync.Mutex
 	types.Application
 }
 
@@ -47,113 +44,71 @@ func (app *localClient) Echo(_ context.Context, msg string) (*types.ResponseEcho
 }
 
 func (app *localClient) Info(ctx context.Context, req types.RequestInfo) (*types.ResponseInfo, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.Info(req)
 	return &res, nil
 }
 
 func (app *localClient) CheckTx(_ context.Context, req types.RequestCheckTx) (*types.ResponseCheckTx, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.CheckTx(req)
 	return &res, nil
 }
 
 func (app *localClient) Query(_ context.Context, req types.RequestQuery) (*types.ResponseQuery, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.Query(req)
 	return &res, nil
 }
 
 func (app *localClient) Commit(ctx context.Context) (*types.ResponseCommit, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.Commit()
 	return &res, nil
 }
 
 func (app *localClient) InitChain(_ context.Context, req types.RequestInitChain) (*types.ResponseInitChain, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.InitChain(req)
 	return &res, nil
 }
 
 func (app *localClient) ListSnapshots(_ context.Context, req types.RequestListSnapshots) (*types.ResponseListSnapshots, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.ListSnapshots(req)
 	return &res, nil
 }
 
 func (app *localClient) OfferSnapshot(_ context.Context, req types.RequestOfferSnapshot) (*types.ResponseOfferSnapshot, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.OfferSnapshot(req)
 	return &res, nil
 }
 
 func (app *localClient) LoadSnapshotChunk(_ context.Context, req types.RequestLoadSnapshotChunk) (*types.ResponseLoadSnapshotChunk, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.LoadSnapshotChunk(req)
 	return &res, nil
 }
 
 func (app *localClient) ApplySnapshotChunk(_ context.Context, req types.RequestApplySnapshotChunk) (*types.ResponseApplySnapshotChunk, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.ApplySnapshotChunk(req)
 	return &res, nil
 }
 
 func (app *localClient) PrepareProposal(_ context.Context, req types.RequestPrepareProposal) (*types.ResponsePrepareProposal, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.PrepareProposal(req)
 	return &res, nil
 }
 
 func (app *localClient) ProcessProposal(_ context.Context, req types.RequestProcessProposal) (*types.ResponseProcessProposal, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.ProcessProposal(req)
 	return &res, nil
 }
 
 func (app *localClient) ExtendVote(_ context.Context, req types.RequestExtendVote) (*types.ResponseExtendVote, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.ExtendVote(req)
 	return &res, nil
 }
 
 func (app *localClient) VerifyVoteExtension(_ context.Context, req types.RequestVerifyVoteExtension) (*types.ResponseVerifyVoteExtension, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.VerifyVoteExtension(req)
 	return &res, nil
 }
 
 func (app *localClient) FinalizeBlock(_ context.Context, req types.RequestFinalizeBlock) (*types.ResponseFinalizeBlock, error) {
-	app.mtx.Lock()
-	defer app.mtx.Unlock()
-
 	res := app.Application.FinalizeBlock(req)
 	return &res, nil
 }