Delete pending txs by external mark, store tx IP

- In tx_pool, add a column called `external_delete` that can be set to true
  externally.  Regularly, the coordinator will delete all pending txs with this
  column set to true.  The interval for this action is set via the new config
  parameter `Coordinator.PurgeByExtDelInterval`.
- In tx_pool, add a column for the client ip that sent the transaction.  The
  api fills this value using the ClientIP method from gin.Context, which should
  work even under a reverse-proxy.

db/l2db/l2db.go

@@ -73,24 +73,6 @@ func (l2db *L2DB) GetAccountCreationAuth(addr ethCommon.Address) (*common.Accoun
 	))
 }
 
-// AddTx inserts a tx to the pool
-func (l2db *L2DB) AddTx(tx *PoolL2TxWrite) error {
-	row := l2db.db.QueryRow(
-		"SELECT COUNT(*) FROM tx_pool WHERE state = $1;",
-		common.PoolL2TxStatePending,
-	)
-	var totalTxs uint32
-	if err := row.Scan(&totalTxs); err != nil {
-		return tracerr.Wrap(err)
-	}
-	if totalTxs >= l2db.maxTxs {
-		return tracerr.New(
-			"The pool is at full capacity. More transactions are not accepted currently",
-		)
-	}
-	return tracerr.Wrap(meddler.Insert(l2db.db, "tx_pool", tx))
-}
-
 // UpdateTxsInfo updates the parameter Info of the pool transactions
 func (l2db *L2DB) UpdateTxsInfo(txs []common.PoolL2Tx) error {
 	if len(txs) == 0 {
@@ -354,3 +336,14 @@ func (l2db *L2DB) Purge(currentBatchNum common.BatchNum) (err error) {
 	)
 	return tracerr.Wrap(err)
 }
+
+// PurgeByExternalDelete deletes all pending transactions marked with true in
+// the `external_delete` column.  An external process can set this column to
+// true to instruct the coordinator to delete the tx when possible.
+func (l2db *L2DB) PurgeByExternalDelete() error {
+	_, err := l2db.db.Exec(
+		`DELETE from tx_pool WHERE (external_delete = true AND state = $1);`,
+		common.PoolL2TxStatePending,
+	)
+	return tracerr.Wrap(err)
+}

db/l2db/l2db_test.go

@@ -1,6 +1,7 @@
 package l2db
 
 import (
+	"database/sql"
 	"math"
 	"math/big"
 	"os"
@@ -701,3 +702,56 @@ func TestAddGet(t *testing.T) {
 		assert.Equal(t, txs[i], *dbTx)
 	}
 }
+
+func TestPurgeByExternalDelete(t *testing.T) {
+	err := prepareHistoryDB(historyDB)
+	if err != nil {
+		log.Error("Error prepare historyDB", err)
+	}
+	txs, err := generatePoolL2Txs()
+	assert.NoError(t, err)
+
+	// We will work with 8 txs
+	require.GreaterOrEqual(t, len(txs), 8)
+	txs = txs[:8]
+	for i := range txs {
+		require.NoError(t, l2DB.AddTxTest(&txs[i]))
+	}
+
+	// We will recreate this scenario:
+	// tx index, status , external_delete
+	// 0       , pending, false
+	// 1       , pending, false
+	// 2       , pending, true // will be deleted
+	// 3       , pending, true // will be deleted
+	// 4       , fging  , false
+	// 5       , fging  , false
+	// 6       , fging  , true
+	// 7       , fging  , true
+
+	require.NoError(t, l2DB.StartForging(
+		[]common.TxID{txs[4].TxID, txs[5].TxID, txs[6].TxID, txs[7].TxID},
+		1))
+	_, err = l2DB.db.Exec(
+		`UPDATE tx_pool SET external_delete = true WHERE
+			tx_id IN ($1, $2, $3, $4)
+		;`,
+		txs[2].TxID, txs[3].TxID, txs[6].TxID, txs[7].TxID,
+	)
+	require.NoError(t, err)
+	require.NoError(t, l2DB.PurgeByExternalDelete())
+
+	// Query txs that are have been not deleted
+	for _, i := range []int{0, 1, 4, 5, 6, 7} {
+		txID := txs[i].TxID
+		_, err := l2DB.GetTx(txID)
+		require.NoError(t, err)
+	}
+
+	// Query txs that have been deleted
+	for _, i := range []int{2, 3} {
+		txID := txs[i].TxID
+		_, err := l2DB.GetTx(txID)
+		require.Equal(t, sql.ErrNoRows, tracerr.Unwrap(err))
+	}
+}

db/l2db/views.go

@@ -34,6 +34,7 @@ type PoolL2TxWrite struct {
 	RqFee       *common.FeeSelector    `meddler:"rq_fee"`
 	RqNonce     *common.Nonce          `meddler:"rq_nonce"`
 	Type        common.TxType          `meddler:"tx_type"`
+	ClientIP    string                 `meddler:"client_ip"`
 }
 
 // PoolTxAPI represents a L2 Tx pool with extra metadata used by the API