Fetch block txs from mempool/electrs in bulk

backend/src/api/bitcoin/bitcoin-api-abstract-factory.ts

@@ -8,6 +8,7 @@ export interface AbstractBitcoinApi {
   $getBlockHeightTip(): Promise<number>;
   $getBlockHashTip(): Promise<string>;
   $getTxIdsForBlock(hash: string): Promise<string[]>;
+  $getTxsForBlock(hash: string): Promise<IEsploraApi.Transaction[]>;
   $getBlockHash(height: number): Promise<string>;
   $getBlockHeader(hash: string): Promise<string>;
   $getBlock(hash: string): Promise<IEsploraApi.Block>;

backend/src/api/bitcoin/bitcoin-api.ts

@@ -81,6 +81,10 @@ class BitcoinApi implements AbstractBitcoinApi {
       .then((rpcBlock: IBitcoinApi.Block) => rpcBlock.tx);
   }
 
+  $getTxsForBlock(hash: string): Promise<IEsploraApi.Transaction[]> {
+    throw new Error('Method getTxsForBlock not supported by the Bitcoin RPC API.');
+  }
+
   $getRawBlock(hash: string): Promise<Buffer> {
     return this.bitcoindClient.getBlock(hash, 0)
       .then((raw: string) => Buffer.from(raw, "hex"));

backend/src/api/bitcoin/esplora-api.ts

@@ -89,6 +89,10 @@ class ElectrsApi implements AbstractBitcoinApi {
     return this.$queryWrapper<string[]>(config.ESPLORA.REST_API_URL + '/block/' + hash + '/txids');
   }
 
+  $getTxsForBlock(hash: string): Promise<IEsploraApi.Transaction[]> {
+    return this.$queryWrapper<IEsploraApi.Transaction[]>(config.ESPLORA.REST_API_URL + '/block/' + hash + '/txs');
+  }
+
   $getBlockHash(height: number): Promise<string> {
     return this.$queryWrapper<string>(config.ESPLORA.REST_API_URL + '/block-height/' + height);
   }

backend/src/api/blocks.ts

@@ -80,22 +80,30 @@ class Blocks {
     quiet: boolean = false,
     addMempoolData: boolean = false,
   ): Promise<TransactionExtended[]> {
-    const transactions: TransactionExtended[] = [];
+    let transactions: TransactionExtended[] = [];
-    if (!txIds) {
-      txIds = await bitcoinApi.$getTxIdsForBlock(blockHash);
-    }
 
     const mempool = memPool.getMempool();
     let transactionsFound = 0;
     let transactionsFetched = 0;
 
+    if (config.MEMPOOL.BACKEND === 'esplora') {
+      const rawTransactions = await bitcoinApi.$getTxsForBlock(blockHash);
+      transactions = rawTransactions.map(tx => transactionUtils.extendTransaction(tx));
+
+      if (!quiet) {
+        logger.debug(`${transactions.length} fetched through backend service.`);
+      }
+    } else {
+      if (!txIds) {
+        txIds = await bitcoinApi.$getTxIdsForBlock(blockHash);
+      }
       for (let i = 0; i < txIds.length; i++) {
         if (mempool[txIds[i]]) {
           // We update blocks before the mempool (index.ts), therefore we can
           // optimize here by directly fetching txs in the "outdated" mempool
           transactions.push(mempool[txIds[i]]);
           transactionsFound++;
-      } else if (config.MEMPOOL.BACKEND === 'esplora' || !memPool.hasPriority() || i === 0) {
+        } else if (!memPool.hasPriority() || i === 0) {
           // Otherwise we fetch the tx data through backend services (esplora, electrum, core rpc...)
           if (!quiet && (i % (Math.round((txIds.length) / 10)) === 0 || i + 1 === txIds.length)) { // Avoid log spam
             logger.debug(`Indexing tx ${i + 1} of ${txIds.length} in block #${blockHeight}`);
@@ -104,16 +112,6 @@ class Blocks {
             const tx = await transactionUtils.$getTransactionExtended(txIds[i], false, false, false, addMempoolData);
             transactions.push(tx);
             transactionsFetched++;
-        } catch (e) {
-          try {
-            if (config.MEMPOOL.BACKEND === 'esplora') {
-              // Try again with core
-              const tx = await transactionUtils.$getTransactionExtended(txIds[i], false, false, true, addMempoolData);
-              transactions.push(tx);
-              transactionsFetched++;
-            } else {
-              throw e;
-            }
           } catch (e) {
             if (i === 0) {
               const msg = `Cannot fetch coinbase tx ${txIds[i]}. Reason: ` + (e instanceof Error ? e.message : e); 
@@ -124,7 +122,6 @@ class Blocks {
             }
           }
         }
-      }
 
         if (onlyCoinbase === true) {
           break; // Fetch the first transaction and exit
@@ -134,6 +131,7 @@ class Blocks {
       if (!quiet) {
         logger.debug(`${transactionsFound} of ${txIds.length} found in mempool. ${transactionsFetched} fetched through backend service.`);
       }
+    }
 
     return transactions;
   }

backend/src/api/transaction-utils.ts

@@ -53,7 +53,7 @@ class TransactionUtils {
     return (await this.$getTransactionExtended(txId, addPrevouts, lazyPrevouts, forceCore, true)) as MempoolTransactionExtended;
   }
 
-  private extendTransaction(transaction: IEsploraApi.Transaction): TransactionExtended {
+  public extendTransaction(transaction: IEsploraApi.Transaction): TransactionExtended {
     // @ts-ignore
     if (transaction.vsize) {
       // @ts-ignore