Stream projected block deltas instead of full data

backend/src/api/mempool-blocks.ts

@@ -1,10 +1,11 @@
 import logger from '../logger';
-import { MempoolBlock, TransactionExtended, MempoolBlockWithTransactions } from '../mempool.interfaces';
+import { MempoolBlock, TransactionExtended, TransactionStripped, MempoolBlockWithTransactions, MempoolBlockDelta } from '../mempool.interfaces';
 import { Common } from './common';
 import config from '../config';
 
 class MempoolBlocks {
   private mempoolBlocks: MempoolBlockWithTransactions[] = [];
+  private mempoolBlockDeltas: MempoolBlockDelta[] = [];
 
   constructor() {}
 
@@ -25,6 +26,10 @@ class MempoolBlocks {
     return this.mempoolBlocks;
   }
 
+  public getMempoolBlockDeltas(): MempoolBlockDelta[] {
+    return this.mempoolBlockDeltas
+  }
+
   public updateMempoolBlocks(memPool: { [txid: string]: TransactionExtended }): void {
     const latestMempool = memPool;
     const memPoolArray: TransactionExtended[] = [];
@@ -66,11 +71,14 @@ class MempoolBlocks {
     const time = end - start;
     logger.debug('Mempool blocks calculated in ' + time / 1000 + ' seconds');
 
-    this.mempoolBlocks = this.calculateMempoolBlocks(memPoolArray);
+    const { blocks, deltas } = this.calculateMempoolBlocks(memPoolArray, this.mempoolBlocks);
+    this.mempoolBlocks = blocks
+    this.mempoolBlockDeltas = deltas
   }
 
-  private calculateMempoolBlocks(transactionsSorted: TransactionExtended[]): MempoolBlockWithTransactions[] {
+  private calculateMempoolBlocks(transactionsSorted: TransactionExtended[], prevBlocks: MempoolBlockWithTransactions[]): { blocks: MempoolBlockWithTransactions[], deltas: MempoolBlockDelta[] } {
     const mempoolBlocks: MempoolBlockWithTransactions[] = [];
+    const mempoolBlockDeltas: MempoolBlockDelta[] = [];
     let blockWeight = 0;
     let blockSize = 0;
     let transactions: TransactionExtended[] = [];
@@ -90,7 +98,39 @@ class MempoolBlocks {
     if (transactions.length) {
       mempoolBlocks.push(this.dataToMempoolBlocks(transactions, blockSize, blockWeight, mempoolBlocks.length));
     }
-    return mempoolBlocks;
+    // Calculate change from previous block states
+    for (let i = 0; i < Math.max(mempoolBlocks.length, prevBlocks.length); i++) {
+      let added: TransactionStripped[] = []
+      let removed: string[] = []
+      if (mempoolBlocks[i] && !prevBlocks[i]) {
+        added = mempoolBlocks[i].transactions
+      } else if (!mempoolBlocks[i] && prevBlocks[i]) {
+        removed = prevBlocks[i].transactions.map(tx => tx.txid)
+      } else if (mempoolBlocks[i] && prevBlocks[i]) {
+        const prevIds = {}
+        const newIds = {}
+        prevBlocks[i].transactions.forEach(tx => {
+          prevIds[tx.txid] = true
+        })
+        mempoolBlocks[i].transactions.forEach(tx => {
+          newIds[tx.txid] = true
+        })
+        prevBlocks[i].transactions.forEach(tx => {
+          if (!newIds[tx.txid]) removed.push(tx.txid)
+        })
+        mempoolBlocks[i].transactions.forEach(tx => {
+          if (!prevIds[tx.txid]) added.push(tx)
+        })
+      }
+      mempoolBlockDeltas.push({
+        added,
+        removed
+      })
+    }
+    return {
+      blocks: mempoolBlocks,
+      deltas: mempoolBlockDeltas
+    }
   }
 
   private dataToMempoolBlocks(transactions: TransactionExtended[],

backend/src/api/websocket-handler.ts

@@ -1,7 +1,6 @@
 import logger from '../logger';
 import * as WebSocket from 'ws';
-import { BlockExtended, TransactionExtended, WebsocketResponse, MempoolBlock,
-  OptimizedStatistic, ILoadingIndicators, IConversionRates } from '../mempool.interfaces';
+import { BlockExtended, TransactionExtended, WebsocketResponse, MempoolBlock, MempoolBlockDelta, OptimizedStatistic, ILoadingIndicators, IConversionRates } from '../mempool.interfaces';
 import blocks from './blocks';
 import memPool from './mempool';
 import backendInfo from './backend-info';
@@ -249,7 +248,7 @@ class WebsocketHandler {
 
     mempoolBlocks.updateMempoolBlocks(newMempool);
     const mBlocks = mempoolBlocks.getMempoolBlocks();
-    const mBlocksWithTransactions = mempoolBlocks.getMempoolBlocksWithTransactions();
+    const mBlockDeltas = mempoolBlocks.getMempoolBlockDeltas();
     const mempoolInfo = memPool.getMempoolInfo();
     const vBytesPerSecond = memPool.getVBytesPerSecond();
     const rbfTransactions = Common.findRbfTransactions(newTransactions, deletedTransactions);
@@ -389,10 +388,10 @@ class WebsocketHandler {
 
       if (client['track-mempool-block'] >= 0) {
         const index = client['track-mempool-block'];
-        if (mBlocksWithTransactions[index]) {
+        if (mBlockDeltas[index]) {
           response['projected-mempool-block'] = {
             index: index,
-            block: mBlocksWithTransactions[index],
+            delta: mBlockDeltas[index],
           };
         }
       }
@@ -409,6 +408,7 @@ class WebsocketHandler {
     }
 
     let mBlocks: undefined | MempoolBlock[];
+    let mBlockDeltas: undefined | MempoolBlockDelta[];
     let matchRate = 0;
     const _memPool = memPool.getMempool();
     const _mempoolBlocks = mempoolBlocks.getMempoolBlocksWithTransactions();
@@ -425,6 +425,7 @@ class WebsocketHandler {
       matchRate = Math.round((matches.length / (txIds.length - 1)) * 100);
       mempoolBlocks.updateMempoolBlocks(_memPool);
       mBlocks = mempoolBlocks.getMempoolBlocks();
+      mBlockDeltas = mempoolBlocks.getMempoolBlockDeltas();
     }
 
     if (block.extras) {
@@ -522,6 +523,16 @@ class WebsocketHandler {
         }
       }
 
+      if (client['track-mempool-block'] >= 0) {
+        const index = client['track-mempool-block'];
+        if (mBlockDeltas && mBlockDeltas[index]) {
+          response['projected-mempool-block'] = {
+            index: index,
+            delta: mBlockDeltas[index],
+          };
+        }
+      }
+
       client.send(JSON.stringify(response));
     });
   }

backend/src/mempool.interfaces.ts

@@ -36,6 +36,11 @@ export interface MempoolBlockWithTransactions extends MempoolBlock {
   transactions: TransactionStripped[];
 }
 
+export interface MempoolBlockDelta {
+  added: TransactionStripped[];
+  removed: string[];
+}
+
 interface VinStrippedToScriptsig {
   scriptsig: string;
 }