Allow serving API only via new cli command

- Add new command to the cli/node: `serveapi` that alows serving the API just
  by connecting to the PostgreSQL database.  The mode flag should me passed in
  order to select whether we are connecting to a synchronizer database or a
  coordinator database.  If `coord` is chosen as mode, the coordinator
  endpoints can be activated in order to allow inserting l2txs and
  authorizations into the L2DB.

Summary of the implementation details
- New SQL table with 3 columns (plus `item_id` pk).  The table only contains a
  single row with `item_id` = 1.  Columns:
    - state: historydb.StateAPI in JSON.  This is the struct that is served via
      the `/state` API endpoint.  The node will periodically update this struct
      and store it int he DB.  The api server will query it from the DB to
      serve it.
    - config: historydb.NodeConfig in JSON.  This struct contains node
      configuration parameters that the API needs to be aware of.  It's updated
      once every time the node starts.
    - constants: historydb.Constants in JSON.  This struct contains all the
      hermez network constants gathered via the ethereum client by the node.
      It's written once every time the node starts.
- The HistoryDB contains methods to get and update each one of these columns
  individually.
- The HistoryDB contains all methods that query the DB and prepare objects that
  will appear in the StateAPI endpoint.
- The configuration used in for the `serveapi` cli/node command is defined in
  `config.APIServer`, and is a subset of `node.Config` in order to allow
  reusing the same configuration file of the node if desired.
- A new object is introduced in the api: `StateAPIUpdater`, which contains all
  the necessary information to update the StateAPI in the DB periodically by
  the node.

- Moved the types `SCConsts`, `SCVariables` and `SCVariablesPtr` from
  `syncrhonizer` to `common` for convenience.

coordinator/coordinator.go

@@ -145,8 +145,8 @@ type Coordinator struct {
 	pipelineNum       int       // Pipeline sequential number.  The first pipeline is 1
 	pipelineFromBatch fromBatch // batch from which we started the pipeline
 	provers           []prover.Client
-	consts            synchronizer.SCConsts
-	vars              synchronizer.SCVariables
+	consts            common.SCConsts
+	vars              common.SCVariables
 	stats             synchronizer.Stats
 	started           bool
 
@@ -186,8 +186,8 @@ func NewCoordinator(cfg Config,
 	batchBuilder *batchbuilder.BatchBuilder,
 	serverProofs []prover.Client,
 	ethClient eth.ClientInterface,
-	scConsts *synchronizer.SCConsts,
-	initSCVars *synchronizer.SCVariables,
+	scConsts *common.SCConsts,
+	initSCVars *common.SCVariables,
 ) (*Coordinator, error) {
 	// nolint reason: hardcoded `1.0`, by design the percentage can't be over 100%
 	if cfg.L1BatchTimeoutPerc >= 1.0 { //nolint:gomnd
@@ -276,13 +276,13 @@ type MsgSyncBlock struct {
 	Batches []common.BatchData
 	// Vars contains each Smart Contract variables if they are updated, or
 	// nil if they haven't changed.
-	Vars synchronizer.SCVariablesPtr
+	Vars common.SCVariablesPtr
 }
 
 // MsgSyncReorg indicates a reorg
 type MsgSyncReorg struct {
 	Stats synchronizer.Stats
-	Vars  synchronizer.SCVariablesPtr
+	Vars  common.SCVariablesPtr
 }
 
 // MsgStopPipeline indicates a signal to reset the pipeline
@@ -301,7 +301,7 @@ func (c *Coordinator) SendMsg(ctx context.Context, msg interface{}) {
 	}
 }
 
-func updateSCVars(vars *synchronizer.SCVariables, update synchronizer.SCVariablesPtr) {
+func updateSCVars(vars *common.SCVariables, update common.SCVariablesPtr) {
 	if update.Rollup != nil {
 		vars.Rollup = *update.Rollup
 	}
@@ -313,7 +313,7 @@ func updateSCVars(vars *synchronizer.SCVariables, update synchronizer.SCVariable
 	}
 }
 
-func (c *Coordinator) syncSCVars(vars synchronizer.SCVariablesPtr) {
+func (c *Coordinator) syncSCVars(vars common.SCVariablesPtr) {
 	updateSCVars(&c.vars, vars)
 }
 

coordinator/coordinator_test.go

@@ -188,12 +188,12 @@ func newTestCoordinator(t *testing.T, forgerAddr ethCommon.Address, ethClient *t
 		&prover.MockClient{Delay: 400 * time.Millisecond},
 	}
 
-	scConsts := &synchronizer.SCConsts{
+	scConsts := &common.SCConsts{
 		Rollup:   *ethClientSetup.RollupConstants,
 		Auction:  *ethClientSetup.AuctionConstants,
 		WDelayer: *ethClientSetup.WDelayerConstants,
 	}
-	initSCVars := &synchronizer.SCVariables{
+	initSCVars := &common.SCVariables{
 		Rollup:   *ethClientSetup.RollupVariables,
 		Auction:  *ethClientSetup.AuctionVariables,
 		WDelayer: *ethClientSetup.WDelayerVariables,
@@ -529,7 +529,7 @@ func TestCoordinatorStress(t *testing.T) {
 				coord.SendMsg(ctx, MsgSyncBlock{
 					Stats:   *stats,
 					Batches: blockData.Rollup.Batches,
-					Vars: synchronizer.SCVariablesPtr{
+					Vars: common.SCVariablesPtr{
 						Rollup:   blockData.Rollup.Vars,
 						Auction:  blockData.Auction.Vars,
 						WDelayer: blockData.WDelayer.Vars,

coordinator/pipeline.go

@@ -22,7 +22,7 @@ import (
 
 type statsVars struct {
 	Stats synchronizer.Stats
-	Vars  synchronizer.SCVariablesPtr
+	Vars  common.SCVariablesPtr
 }
 
 type state struct {
@@ -36,7 +36,7 @@ type state struct {
 type Pipeline struct {
 	num    int
 	cfg    Config
-	consts synchronizer.SCConsts
+	consts common.SCConsts
 
 	// state
 	state         state
@@ -57,7 +57,7 @@ type Pipeline struct {
 	purger                *Purger
 
 	stats       synchronizer.Stats
-	vars        synchronizer.SCVariables
+	vars        common.SCVariables
 	statsVarsCh chan statsVars
 
 	ctx    context.Context
@@ -90,7 +90,7 @@ func NewPipeline(ctx context.Context,
 	coord *Coordinator,
 	txManager *TxManager,
 	provers []prover.Client,
-	scConsts *synchronizer.SCConsts,
+	scConsts *common.SCConsts,
 ) (*Pipeline, error) {
 	proversPool := NewProversPool(len(provers))
 	proversPoolSize := 0
@@ -125,7 +125,7 @@ func NewPipeline(ctx context.Context,
 
 // SetSyncStatsVars is a thread safe method to sets the synchronizer Stats
 func (p *Pipeline) SetSyncStatsVars(ctx context.Context, stats *synchronizer.Stats,
-	vars *synchronizer.SCVariablesPtr) {
+	vars *common.SCVariablesPtr) {
 	select {
 	case p.statsVarsCh <- statsVars{Stats: *stats, Vars: *vars}:
 	case <-ctx.Done():
@@ -134,7 +134,7 @@ func (p *Pipeline) SetSyncStatsVars(ctx context.Context, stats *synchronizer.Sta
 
 // reset pipeline state
 func (p *Pipeline) reset(batchNum common.BatchNum,
-	stats *synchronizer.Stats, vars *synchronizer.SCVariables) error {
+	stats *synchronizer.Stats, vars *common.SCVariables) error {
 	p.state = state{
 		batchNum:                     batchNum,
 		lastForgeL1TxsNum:            stats.Sync.LastForgeL1TxsNum,
@@ -195,7 +195,7 @@ func (p *Pipeline) reset(batchNum common.BatchNum,
 	return nil
 }
 
-func (p *Pipeline) syncSCVars(vars synchronizer.SCVariablesPtr) {
+func (p *Pipeline) syncSCVars(vars common.SCVariablesPtr) {
 	updateSCVars(&p.vars, vars)
 }
 
@@ -256,7 +256,7 @@ func (p *Pipeline) handleForgeBatch(ctx context.Context,
 
 // Start the forging pipeline
 func (p *Pipeline) Start(batchNum common.BatchNum,
-	stats *synchronizer.Stats, vars *synchronizer.SCVariables) error {
+	stats *synchronizer.Stats, vars *common.SCVariables) error {
 	if p.started {
 		log.Fatal("Pipeline already started")
 	}

coordinator/pipeline_test.go

@@ -206,11 +206,7 @@ PoolTransfer(0) User2-User3: 300 (126)
 		require.NoError(t, err)
 	}
 
-	err = pipeline.reset(batchNum, syncStats, &synchronizer.SCVariables{
-		Rollup:   *syncSCVars.Rollup,
-		Auction:  *syncSCVars.Auction,
-		WDelayer: *syncSCVars.WDelayer,
-	})
+	err = pipeline.reset(batchNum, syncStats, syncSCVars)
 	require.NoError(t, err)
 	// Sanity check
 	sdbAccounts, err := pipeline.txSelector.LocalAccountsDB().TestGetAccounts()

coordinator/txmanager.go

@@ -31,10 +31,10 @@ type TxManager struct {
 	batchCh   chan *BatchInfo
 	chainID   *big.Int
 	account   accounts.Account
-	consts    synchronizer.SCConsts
+	consts    common.SCConsts
 
 	stats       synchronizer.Stats
-	vars        synchronizer.SCVariables
+	vars        common.SCVariables
 	statsVarsCh chan statsVars
 
 	discardPipelineCh chan int // int refers to the pipelineNum
@@ -55,7 +55,7 @@ type TxManager struct {
 
 // NewTxManager creates a new TxManager
 func NewTxManager(ctx context.Context, cfg *Config, ethClient eth.ClientInterface, l2DB *l2db.L2DB,
-	coord *Coordinator, scConsts *synchronizer.SCConsts, initSCVars *synchronizer.SCVariables) (
+	coord *Coordinator, scConsts *common.SCConsts, initSCVars *common.SCVariables) (
 	*TxManager, error) {
 	chainID, err := ethClient.EthChainID()
 	if err != nil {
@@ -104,7 +104,7 @@ func (t *TxManager) AddBatch(ctx context.Context, batchInfo *BatchInfo) {
 
 // SetSyncStatsVars is a thread safe method to sets the synchronizer Stats
 func (t *TxManager) SetSyncStatsVars(ctx context.Context, stats *synchronizer.Stats,
-	vars *synchronizer.SCVariablesPtr) {
+	vars *common.SCVariablesPtr) {
 	select {
 	case t.statsVarsCh <- statsVars{Stats: *stats, Vars: *vars}:
 	case <-ctx.Done():
@@ -120,7 +120,7 @@ func (t *TxManager) DiscardPipeline(ctx context.Context, pipelineNum int) {
 	}
 }
 
-func (t *TxManager) syncSCVars(vars synchronizer.SCVariablesPtr) {
+func (t *TxManager) syncSCVars(vars common.SCVariablesPtr) {
 	updateSCVars(&t.vars, vars)
 }