feat: add file-based transaction indexing (gnolang#546)

# Description

This PR introduces file-based transaction indexing. As discussed in
gnolang#275, transaction index parsing should be done as a separate process
from the main node, meaning other services can be instantiated to index
transactions as readers.

The general architecture of the transaction indexers in this PR can be
described with the following image:
<img width="1481" alt="Architecture"
src="https://user-images.githubusercontent.com/16712663/221845299-ff552470-8efc-4134-8c3d-e71e74929acc.png">

Each concrete indexer implementation decides how to handle transaction
events, and where to store them.
Independent processes from the indexers themselves read these events (by
parsing files, logs, executing RPC queries...).

## File Indexer

The `file` transaction indexer that is included in this PR utilizes
`autofile.Group`s to write down transaction events.

Users can now specify to use the file-based indexer with the following
added flags to the `gnoland` command:
- `--tx-indexer-type` - specify the type of indexer (none is default)
- `--tx-indexer-path` - path for the file-based tx indexer

# Changes include

- [ ] Bugfix (non-breaking change that solves an issue)
- [ ] Hotfix (change that solves an urgent issue, and requires immediate
attention)
- [x] New feature (non-breaking change that adds functionality)
- [ ] Breaking change (change that is not backwards-compatible and/or
changes current functionality)

# Checklist (for contributors)

- [x] I have assigned this PR to myself
- [x] I have added at least 1 reviewer
- [x] I have added the relevant labels
- [ ] I have updated the official documentation
- [x] I have added sufficient documentation in code

# Testing

- [x] I have tested this code with the official test suite
- [x] I have tested this code manually

## Manual tests

- Manually executed transactions and verified they were saved to disk.
- Added unit tests that cover all added functionality.

# Additional comments

- [Relevant tendermint2
issue](tendermint/tendermint2#2)
- Resolves gnolang#275 

EDIT:
After comments from @jaekwon, this `Indexer` functionality has been
renamed to `EventStore`, and work on an independent indexer process
(process that can read from the event store) will begin soon that will
offer indexing functionality

cc @ilgooz

gno.land/cmd/gnoland/start.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"errors"
 	"flag"
 	"fmt"
 	"path/filepath"
@@ -17,6 +18,9 @@ import (
 	"github.com/gnolang/gno/tm2/pkg/bft/config"
 	"github.com/gnolang/gno/tm2/pkg/bft/node"
 	"github.com/gnolang/gno/tm2/pkg/bft/privval"
+	"github.com/gnolang/gno/tm2/pkg/bft/state/eventstore/file"
+	"github.com/gnolang/gno/tm2/pkg/bft/state/eventstore/null"
+	eventstorecfg "github.com/gnolang/gno/tm2/pkg/bft/state/eventstore/types"
 	bft "github.com/gnolang/gno/tm2/pkg/bft/types"
 	"github.com/gnolang/gno/tm2/pkg/commands"
 	"github.com/gnolang/gno/tm2/pkg/crypto"
@@ -35,6 +39,9 @@ type startCfg struct {
 	rootDir               string
 	genesisMaxVMCycles    int64
 	config                string
+
+	txEventStoreType string
+	txEventStorePath string
 }
 
 func newStartCmd(io *commands.IO) *commands.Command {
@@ -116,6 +123,29 @@ func (c *startCfg) RegisterFlags(fs *flag.FlagSet) {
 		"",
 		"config file (optional)",
 	)
+
+	fs.StringVar(
+		&c.txEventStoreType,
+		"tx-event-store-type",
+		null.EventStoreType,
+		fmt.Sprintf(
+			"type of transaction event store [%s]",
+			strings.Join(
+				[]string{
+					null.EventStoreType,
+					file.EventStoreType,
+				},
+				", ",
+			),
+		),
+	)
+
+	fs.StringVar(
+		&c.txEventStorePath,
+		"tx-event-store-path",
+		"",
+		fmt.Sprintf("path for the file tx event store (required if event store is '%s')", file.EventStoreType),
+	)
 }
 
 func execStart(c *startCfg, args []string, io *commands.IO) error {
@@ -145,6 +175,14 @@ func execStart(c *startCfg, args []string, io *commands.IO) error {
 		writeGenesisFile(genDoc, genesisFilePath)
 	}
 
+	// Initialize the indexer config
+	txEventStoreCfg, err := getTxEventStoreConfig(c)
+	if err != nil {
+		return fmt.Errorf("unable to parse indexer config, %w", err)
+	}
+
+	cfg.TxEventStore = txEventStoreCfg
+
 	// create application and node.
 	gnoApp, err := gnoland.NewApp(rootDir, c.skipFailingGenesisTxs, logger, c.genesisMaxVMCycles)
 	if err != nil {
@@ -180,6 +218,30 @@ func execStart(c *startCfg, args []string, io *commands.IO) error {
 	select {} // run forever
 }
 
+// getTxEventStoreConfig constructs an event store config from provided user options
+func getTxEventStoreConfig(c *startCfg) (*eventstorecfg.Config, error) {
+	var cfg *eventstorecfg.Config
+
+	switch c.txEventStoreType {
+	case file.EventStoreType:
+		if c.txEventStorePath == "" {
+			return nil, errors.New("unspecified file transaction indexer path")
+		}
+
+		// Fill out the configuration
+		cfg = &eventstorecfg.Config{
+			EventStoreType: file.EventStoreType,
+			Params: map[string]any{
+				file.Path: c.txEventStorePath,
+			},
+		}
+	default:
+		cfg = eventstorecfg.DefaultEventStoreConfig()
+	}
+
+	return cfg, nil
+}
+
 // Makes a local test genesis doc with local privValidator.
 func makeGenesisDoc(
 	pvPub crypto.PubKey,

tm2/pkg/autofile/group.go

@@ -125,7 +125,11 @@ func (g *Group) OnStart() error {
 // OnStop implements service.Service by stopping the goroutine described above.
 // NOTE: g.Head must be closed separately using Close.
 func (g *Group) OnStop() {
-	g.FlushAndSync()
+	if err := g.FlushAndSync(); err != nil {
+		g.Logger.Error(
+			fmt.Sprintf("unable to gracefully flush data, %s", err.Error()),
+		)
+	}
 }
 
 // Wait blocks until all internal goroutines are finished. Supposed to be
@@ -136,11 +140,20 @@ func (g *Group) Wait() {
 
 // Close closes the head file. The group must be stopped by this moment.
 func (g *Group) Close() {
-	g.FlushAndSync()
+	if err := g.FlushAndSync(); err != nil {
+		g.Logger.Error(
+			fmt.Sprintf("unable to gracefully flush data, %s", err.Error()),
+		)
+	}
 
 	g.mtx.Lock()
-	_ = g.Head.Close()
-	g.mtx.Unlock()
+	defer g.mtx.Unlock()
+
+	if err := g.Head.Close(); err != nil {
+		g.Logger.Error(
+			fmt.Sprintf("unable to gracefully close group head, %s", err.Error()),
+		)
+	}
 }
 
 // HeadSizeLimit returns the current head size limit.

tm2/pkg/bft/config/config.go

@@ -9,6 +9,7 @@ import (
 	cns "github.com/gnolang/gno/tm2/pkg/bft/consensus/config"
 	mem "github.com/gnolang/gno/tm2/pkg/bft/mempool/config"
 	rpc "github.com/gnolang/gno/tm2/pkg/bft/rpc/config"
+	eventstore "github.com/gnolang/gno/tm2/pkg/bft/state/eventstore/types"
 	"github.com/gnolang/gno/tm2/pkg/errors"
 	osm "github.com/gnolang/gno/tm2/pkg/os"
 	p2p "github.com/gnolang/gno/tm2/pkg/p2p/config"
@@ -20,20 +21,22 @@ type Config struct {
 	BaseConfig `toml:",squash"`
 
 	// Options for services
-	RPC       *rpc.RPCConfig       `toml:"rpc"`
-	P2P       *p2p.P2PConfig       `toml:"p2p"`
-	Mempool   *mem.MempoolConfig   `toml:"mempool"`
-	Consensus *cns.ConsensusConfig `toml:"consensus"`
+	RPC          *rpc.RPCConfig       `toml:"rpc"`
+	P2P          *p2p.P2PConfig       `toml:"p2p"`
+	Mempool      *mem.MempoolConfig   `toml:"mempool"`
+	Consensus    *cns.ConsensusConfig `toml:"consensus"`
+	TxEventStore *eventstore.Config   `toml:"tx_event_store"`
 }
 
 // DefaultConfig returns a default configuration for a Tendermint node
 func DefaultConfig() *Config {
 	return &Config{
-		BaseConfig: DefaultBaseConfig(),
-		RPC:        rpc.DefaultRPCConfig(),
-		P2P:        p2p.DefaultP2PConfig(),
-		Mempool:    mem.DefaultMempoolConfig(),
-		Consensus:  cns.DefaultConsensusConfig(),
+		BaseConfig:   DefaultBaseConfig(),
+		RPC:          rpc.DefaultRPCConfig(),
+		P2P:          p2p.DefaultP2PConfig(),
+		Mempool:      mem.DefaultMempoolConfig(),
+		Consensus:    cns.DefaultConsensusConfig(),
+		TxEventStore: eventstore.DefaultEventStoreConfig(),
 	}
 }
 
@@ -68,11 +71,12 @@ func LoadOrMakeConfigWithOptions(root string, options ConfigOptions) (cfg *Confi
 // TestConfig returns a configuration that can be used for testing
 func TestConfig() *Config {
 	return &Config{
-		BaseConfig: TestBaseConfig(),
-		RPC:        rpc.TestRPCConfig(),
-		P2P:        p2p.TestP2PConfig(),
-		Mempool:    mem.TestMempoolConfig(),
-		Consensus:  cns.TestConsensusConfig(),
+		BaseConfig:   TestBaseConfig(),
+		RPC:          rpc.TestRPCConfig(),
+		P2P:          p2p.TestP2PConfig(),
+		Mempool:      mem.TestMempoolConfig(),
+		Consensus:    cns.TestConsensusConfig(),
+		TxEventStore: eventstore.DefaultEventStoreConfig(),
 	}
 }
 
@@ -121,7 +125,7 @@ func (cfg *Config) ValidateBasic() error {
 	return nil
 }
 
-//-----------------------------------------------------------------------------
+// -----------------------------------------------------------------------------
 // BaseConfig
 
 const (