From 87170247bd237c2bc90eaf94e9333cd0e3201118 Mon Sep 17 00:00:00 2001
From: nymkappa <vialjoris@hotmail.com>
Date: Fri, 11 Feb 2022 20:35:53 +0900
Subject: [PATCH 1/2] Revert "Merge pull request #1240 from
 nymkappa/feature/mempool-sync-threshold"

This reverts commit 2f921f4cc73994cc9ea9c317c8897de0d1881340, reversing
changes made to 877be47e5be03e31b25cc12fbe2ee45be881e5d8.
---
 backend/src/api/mempool.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/backend/src/api/mempool.ts b/backend/src/api/mempool.ts
index 3a389c059..a8b0b461a 100644
--- a/backend/src/api/mempool.ts
+++ b/backend/src/api/mempool.ts
@@ -168,8 +168,7 @@ class Mempool {
     const newTransactionsStripped = newTransactions.map((tx) => Common.stripTransaction(tx));
     this.latestTransactions = newTransactionsStripped.concat(this.latestTransactions).slice(0, 6);
 
-    const syncedThreshold = 0.99; // If we synced 99% of the mempool tx count, consider we're synced
-    if (!this.inSync && Object.keys(this.mempoolCache).length >= transactions.length * syncedThreshold) {
+    if (!this.inSync && transactions.length === Object.keys(this.mempoolCache).length) {
       this.inSync = true;
       logger.notice('The mempool is now in sync!');
       loadingIndicators.setProgress('mempool', 100);

From a88d6d2fca401e94d8e08047d538b94847170f65 Mon Sep 17 00:00:00 2001
From: nymkappa <vialjoris@hotmail.com>
Date: Fri, 11 Feb 2022 21:25:58 +0900
Subject: [PATCH 2/2] Don't wait for 100% mempool sync before starting block
 indexing

---
 backend/src/api/blocks.ts  |  6 +++---
 backend/src/api/mempool.ts | 16 ++++++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/backend/src/api/blocks.ts b/backend/src/api/blocks.ts
index d2487414f..affbf0049 100644
--- a/backend/src/api/blocks.ts
+++ b/backend/src/api/blocks.ts
@@ -61,7 +61,7 @@ class Blocks {
         // optimize here by directly fetching txs in the "outdated" mempool
         transactions.push(mempool[txIds[i]]);
         transactionsFound++;
-      } else if (config.MEMPOOL.BACKEND === 'esplora' || memPool.isInSync() || i === 0) {
+      } else if (config.MEMPOOL.BACKEND === 'esplora' || !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}`);
@@ -175,7 +175,7 @@ class Blocks {
   public async $generateBlockDatabase() {
     if (['mainnet', 'testnet', 'signet'].includes(config.MEMPOOL.NETWORK) === false || // Bitcoin only
       config.MEMPOOL.INDEXING_BLOCKS_AMOUNT === 0 || // Indexing of older blocks must be enabled
-      !memPool.isInSync() || // We sync the mempool first
+      memPool.hasPriority() || // We sync the mempool first
       this.blockIndexingStarted === true || // Indexing must not already be in progress
       config.DATABASE.ENABLED === false
     ) {
@@ -314,7 +314,7 @@ class Blocks {
       if (this.newBlockCallbacks.length) {
         this.newBlockCallbacks.forEach((cb) => cb(blockExtended, txIds, transactions));
       }
-      if (memPool.isInSync()) {
+      if (!memPool.hasPriority()) {
         diskCache.$saveCacheToDisk();
       }
     }
diff --git a/backend/src/api/mempool.ts b/backend/src/api/mempool.ts
index a8b0b461a..64505ba2b 100644
--- a/backend/src/api/mempool.ts
+++ b/backend/src/api/mempool.ts
@@ -13,6 +13,7 @@ class Mempool {
   private static WEBSOCKET_REFRESH_RATE_MS = 10000;
   private static LAZY_DELETE_AFTER_SECONDS = 30;
   private inSync: boolean = false;
+  private mempoolCacheDelta: number = -1;
   private mempoolCache: { [txId: string]: TransactionExtended } = {};
   private mempoolInfo: IBitcoinApi.MempoolInfo = { loaded: false, size: 0, bytes: 0, usage: 0, total_fee: 0,
                                                     maxmempool: 300000000, mempoolminfee: 0.00001000, minrelaytxfee: 0.00001000 };
@@ -32,6 +33,17 @@ class Mempool {
     setInterval(this.deleteExpiredTransactions.bind(this), 20000);
   }
 
+  /**
+   * Return true if we should leave resources available for mempool tx caching
+   */
+  public hasPriority(): boolean {
+    if (this.inSync) {
+      return false;
+    } else {
+      return this.mempoolCacheDelta == -1 || this.mempoolCacheDelta > 25;
+    }
+  }
+
   public isInSync(): boolean {
     return this.inSync;
   }
@@ -100,6 +112,8 @@ class Mempool {
     const diff = transactions.length - currentMempoolSize;
     const newTransactions: TransactionExtended[] = [];
 
+    this.mempoolCacheDelta = Math.abs(diff);
+
     if (!this.inSync) {
       loadingIndicators.setProgress('mempool', Object.keys(this.mempoolCache).length / transactions.length * 100);
     }
@@ -174,6 +188,8 @@ class Mempool {
       loadingIndicators.setProgress('mempool', 100);
     }
 
+    this.mempoolCacheDelta = Math.abs(transactions.length - Object.keys(this.mempoolCache).length);
+
     if (this.mempoolChangedCallback && (hasChange || deletedTransactions.length)) {
       this.mempoolChangedCallback(this.mempoolCache, newTransactions, deletedTransactions);
     }