optimize requests sent by RemoteImporter with batch rpc calls

lib/remote-importer/remote-importer.js

@@ -260,19 +260,21 @@ class RemoteImporter {
 
       Logger.info(` Got ${scanTx.length} transactions`)
 
-      await util.seriesCall(scanTx, async txid => {
+      // Retrieve the transactions by batches of 100 transactions
+      const txsChunks = util.splitList(scanTx, 100)
       try {
-          const tx = await rpcTxns.getTransaction(txid, false)
+        for (let txsChunk of txsChunks) {
-          if (tx == null) {
+          const txs = await rpcTxns.getTransactions(txsChunk, false)
-            Logger.info(`   got null for ${txid}`)
+          for (let tx of txs) {
-            return null
+            if (tx != null) {
-          }
               ret.transactions.push(tx)
               txids[tx.txid] = true
+            }
+          }
+        }
       } catch(e) {
-          Logger.error(e, `RemoteImporter.xpubScan() : rawTransaction error, txid ${txid}`)
+        Logger.error(e, `RemoteImporter.xpubScan() : getTransactions error`)
       }
-      })
 
       if (gotTransactions) {
         // We must go deeper
@@ -335,15 +337,14 @@ class RemoteImporter {
 
       Logger.info(` Got ${scanTx.length} transactions`)
 
-      // Get transaction s data from bitcoind
+      // Retrieve the transactions by batches of 100 transactions
-      await util.seriesCall(scanTx, async txid => {
+      const txsChunks = util.splitList(scanTx, 100)
-        const tx = await rpcTxns.getTransaction(txid, false)
+      for (let txsChunk of txsChunks) {
-        if (tx == null) {
+        const txs = await rpcTxns.getTransactions(txsChunk, false)
-          Logger.info(`   got null for ${txid}`)
+        for (let tx of txs)
-          return null
+          if (tx != null)
-        }
             txns.push(tx)
-      })
+      }
 
       // Import addresses and transactions into the database
       await db.addAddresses(imported)