strip non-essential data from redis cache txs

backend/package-lock.json

@@ -19,6 +19,7 @@
         "maxmind": "~4.3.11",
         "mysql2": "~3.5.2",
         "rust-gbt": "file:./rust-gbt",
+        "redis": "^4.6.6",
         "socks-proxy-agent": "~7.0.0",
         "typescript": "~4.9.3",
         "ws": "~8.13.0"
@@ -1555,6 +1556,64 @@
         "node": ">= 8"
       }
     },
+    "node_modules/@redis/bloom": {
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/@redis/bloom/-/bloom-1.2.0.tgz",
+      "integrity": "sha512-HG2DFjYKbpNmVXsa0keLHp/3leGJz1mjh09f2RLGGLQZzSHpkmZWuwJbAvo3QcRY8p80m5+ZdXZdYOSBLlp7Cg==",
+      "peerDependencies": {
+        "@redis/client": "^1.0.0"
+      }
+    },
+    "node_modules/@redis/client": {
+      "version": "1.5.7",
+      "resolved": "https://registry.npmjs.org/@redis/client/-/client-1.5.7.tgz",
+      "integrity": "sha512-gaOBOuJPjK5fGtxSseaKgSvjiZXQCdLlGg9WYQst+/GRUjmXaiB5kVkeQMRtPc7Q2t93XZcJfBMSwzs/XS9UZw==",
+      "dependencies": {
+        "cluster-key-slot": "1.1.2",
+        "generic-pool": "3.9.0",
+        "yallist": "4.0.0"
+      },
+      "engines": {
+        "node": ">=14"
+      }
+    },
+    "node_modules/@redis/client/node_modules/yallist": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/yallist/-/yallist-4.0.0.tgz",
+      "integrity": "sha512-3wdGidZyq5PB084XLES5TpOSRA3wjXAlIWMhum2kRcv/41Sn2emQ0dycQW4uZXLejwKvg6EsvbdlVL+FYEct7A=="
+    },
+    "node_modules/@redis/graph": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/@redis/graph/-/graph-1.1.0.tgz",
+      "integrity": "sha512-16yZWngxyXPd+MJxeSr0dqh2AIOi8j9yXKcKCwVaKDbH3HTuETpDVPcLujhFYVPtYrngSco31BUcSa9TH31Gqg==",
+      "peerDependencies": {
+        "@redis/client": "^1.0.0"
+      }
+    },
+    "node_modules/@redis/json": {
+      "version": "1.0.4",
+      "resolved": "https://registry.npmjs.org/@redis/json/-/json-1.0.4.tgz",
+      "integrity": "sha512-LUZE2Gdrhg0Rx7AN+cZkb1e6HjoSKaeeW8rYnt89Tly13GBI5eP4CwDVr+MY8BAYfCg4/N15OUrtLoona9uSgw==",
+      "peerDependencies": {
+        "@redis/client": "^1.0.0"
+      }
+    },
+    "node_modules/@redis/search": {
+      "version": "1.1.2",
+      "resolved": "https://registry.npmjs.org/@redis/search/-/search-1.1.2.tgz",
+      "integrity": "sha512-/cMfstG/fOh/SsE+4/BQGeuH/JJloeWuH+qJzM8dbxuWvdWibWAOAHHCZTMPhV3xIlH4/cUEIA8OV5QnYpaVoA==",
+      "peerDependencies": {
+        "@redis/client": "^1.0.0"
+      }
+    },
+    "node_modules/@redis/time-series": {
+      "version": "1.0.4",
+      "resolved": "https://registry.npmjs.org/@redis/time-series/-/time-series-1.0.4.tgz",
+      "integrity": "sha512-ThUIgo2U/g7cCuZavucQTQzA9g9JbDDY2f64u3AbAoz/8vE2lt2U37LamDUVChhaDA3IRT9R6VvJwqnUfTJzng==",
+      "peerDependencies": {
+        "@redis/client": "^1.0.0"
+      }
+    },
     "node_modules/@sinclair/typebox": {
       "version": "0.25.24",
       "resolved": "https://registry.npmjs.org/@sinclair/typebox/-/typebox-0.25.24.tgz",
@@ -2718,6 +2777,14 @@
         "node": ">=12"
       }
     },
+    "node_modules/cluster-key-slot": {
+      "version": "1.1.2",
+      "resolved": "https://registry.npmjs.org/cluster-key-slot/-/cluster-key-slot-1.1.2.tgz",
+      "integrity": "sha512-RMr0FhtfXemyinomL4hrWcYJxmX6deFdCxpJzhDttxgO1+bcCnkk+9drydLVDmAMG7NE6aN/fl4F7ucU/90gAA==",
+      "engines": {
+        "node": ">=0.10.0"
+      }
+    },
     "node_modules/co": {
       "version": "4.6.0",
       "resolved": "https://registry.npmjs.org/co/-/co-4.6.0.tgz",
@@ -3678,6 +3745,14 @@
         "is-property": "^1.0.2"
       }
     },
+    "node_modules/generic-pool": {
+      "version": "3.9.0",
+      "resolved": "https://registry.npmjs.org/generic-pool/-/generic-pool-3.9.0.tgz",
+      "integrity": "sha512-hymDOu5B53XvN4QT9dBmZxPX4CWhBPPLguTZ9MMFeFa/Kg0xWVfylOVNlJji/E7yTZWFd/q9GO5TxDLq156D7g==",
+      "engines": {
+        "node": ">= 4"
+      }
+    },
     "node_modules/gensync": {
       "version": "1.0.0-beta.2",
       "resolved": "https://registry.npmjs.org/gensync/-/gensync-1.0.0-beta.2.tgz",
@@ -6577,6 +6652,19 @@
       "integrity": "sha512-xWGDIW6x921xtzPkhiULtthJHoJvBbF3q26fzloPCK0hsvxtPVelvftw3zjbHWSkR2km9Z+4uxbDDK/6Zw9B8w==",
       "dev": true
     },
+    "node_modules/redis": {
+      "version": "4.6.6",
+      "resolved": "https://registry.npmjs.org/redis/-/redis-4.6.6.tgz",
+      "integrity": "sha512-aLs2fuBFV/VJ28oLBqYykfnhGGkFxvx0HdCEBYdJ99FFbSEMZ7c1nVKwR6ZRv+7bb7JnC0mmCzaqu8frgOYhpA==",
+      "dependencies": {
+        "@redis/bloom": "1.2.0",
+        "@redis/client": "1.5.7",
+        "@redis/graph": "1.1.0",
+        "@redis/json": "1.0.4",
+        "@redis/search": "1.1.2",
+        "@redis/time-series": "1.0.4"
+      }
+    },
     "node_modules/require-directory": {
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/require-directory/-/require-directory-2.1.1.tgz",
@@ -8704,6 +8792,53 @@
         "fastq": "^1.6.0"
       }
     },
+    "@redis/bloom": {
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/@redis/bloom/-/bloom-1.2.0.tgz",
+      "integrity": "sha512-HG2DFjYKbpNmVXsa0keLHp/3leGJz1mjh09f2RLGGLQZzSHpkmZWuwJbAvo3QcRY8p80m5+ZdXZdYOSBLlp7Cg==",
+      "requires": {}
+    },
+    "@redis/client": {
+      "version": "1.5.7",
+      "resolved": "https://registry.npmjs.org/@redis/client/-/client-1.5.7.tgz",
+      "integrity": "sha512-gaOBOuJPjK5fGtxSseaKgSvjiZXQCdLlGg9WYQst+/GRUjmXaiB5kVkeQMRtPc7Q2t93XZcJfBMSwzs/XS9UZw==",
+      "requires": {
+        "cluster-key-slot": "1.1.2",
+        "generic-pool": "3.9.0",
+        "yallist": "4.0.0"
+      },
+      "dependencies": {
+        "yallist": {
+          "version": "4.0.0",
+          "resolved": "https://registry.npmjs.org/yallist/-/yallist-4.0.0.tgz",
+          "integrity": "sha512-3wdGidZyq5PB084XLES5TpOSRA3wjXAlIWMhum2kRcv/41Sn2emQ0dycQW4uZXLejwKvg6EsvbdlVL+FYEct7A=="
+        }
+      }
+    },
+    "@redis/graph": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/@redis/graph/-/graph-1.1.0.tgz",
+      "integrity": "sha512-16yZWngxyXPd+MJxeSr0dqh2AIOi8j9yXKcKCwVaKDbH3HTuETpDVPcLujhFYVPtYrngSco31BUcSa9TH31Gqg==",
+      "requires": {}
+    },
+    "@redis/json": {
+      "version": "1.0.4",
+      "resolved": "https://registry.npmjs.org/@redis/json/-/json-1.0.4.tgz",
+      "integrity": "sha512-LUZE2Gdrhg0Rx7AN+cZkb1e6HjoSKaeeW8rYnt89Tly13GBI5eP4CwDVr+MY8BAYfCg4/N15OUrtLoona9uSgw==",
+      "requires": {}
+    },
+    "@redis/search": {
+      "version": "1.1.2",
+      "resolved": "https://registry.npmjs.org/@redis/search/-/search-1.1.2.tgz",
+      "integrity": "sha512-/cMfstG/fOh/SsE+4/BQGeuH/JJloeWuH+qJzM8dbxuWvdWibWAOAHHCZTMPhV3xIlH4/cUEIA8OV5QnYpaVoA==",
+      "requires": {}
+    },
+    "@redis/time-series": {
+      "version": "1.0.4",
+      "resolved": "https://registry.npmjs.org/@redis/time-series/-/time-series-1.0.4.tgz",
+      "integrity": "sha512-ThUIgo2U/g7cCuZavucQTQzA9g9JbDDY2f64u3AbAoz/8vE2lt2U37LamDUVChhaDA3IRT9R6VvJwqnUfTJzng==",
+      "requires": {}
+    },
     "@sinclair/typebox": {
       "version": "0.25.24",
       "resolved": "https://registry.npmjs.org/@sinclair/typebox/-/typebox-0.25.24.tgz",
@@ -9604,6 +9739,11 @@
         "wrap-ansi": "^7.0.0"
       }
     },
+    "cluster-key-slot": {
+      "version": "1.1.2",
+      "resolved": "https://registry.npmjs.org/cluster-key-slot/-/cluster-key-slot-1.1.2.tgz",
+      "integrity": "sha512-RMr0FhtfXemyinomL4hrWcYJxmX6deFdCxpJzhDttxgO1+bcCnkk+9drydLVDmAMG7NE6aN/fl4F7ucU/90gAA=="
+    },
     "co": {
       "version": "4.6.0",
       "resolved": "https://registry.npmjs.org/co/-/co-4.6.0.tgz",
@@ -10332,6 +10472,11 @@
         "is-property": "^1.0.2"
       }
     },
+    "generic-pool": {
+      "version": "3.9.0",
+      "resolved": "https://registry.npmjs.org/generic-pool/-/generic-pool-3.9.0.tgz",
+      "integrity": "sha512-hymDOu5B53XvN4QT9dBmZxPX4CWhBPPLguTZ9MMFeFa/Kg0xWVfylOVNlJji/E7yTZWFd/q9GO5TxDLq156D7g=="
+    },
     "gensync": {
       "version": "1.0.0-beta.2",
       "resolved": "https://registry.npmjs.org/gensync/-/gensync-1.0.0-beta.2.tgz",
@@ -12454,6 +12599,19 @@
       "integrity": "sha512-xWGDIW6x921xtzPkhiULtthJHoJvBbF3q26fzloPCK0hsvxtPVelvftw3zjbHWSkR2km9Z+4uxbDDK/6Zw9B8w==",
       "dev": true
     },
+    "redis": {
+      "version": "4.6.6",
+      "resolved": "https://registry.npmjs.org/redis/-/redis-4.6.6.tgz",
+      "integrity": "sha512-aLs2fuBFV/VJ28oLBqYykfnhGGkFxvx0HdCEBYdJ99FFbSEMZ7c1nVKwR6ZRv+7bb7JnC0mmCzaqu8frgOYhpA==",
+      "requires": {
+        "@redis/bloom": "1.2.0",
+        "@redis/client": "1.5.7",
+        "@redis/graph": "1.1.0",
+        "@redis/json": "1.0.4",
+        "@redis/search": "1.1.2",
+        "@redis/time-series": "1.0.4"
+      }
+    },
     "require-directory": {
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/require-directory/-/require-directory-2.1.1.tgz",

backend/package.json

@@ -47,13 +47,14 @@
     "maxmind": "~4.3.11",
     "mysql2": "~3.5.2",
     "rust-gbt": "file:./rust-gbt",
+    "redis": "^4.6.6",
     "socks-proxy-agent": "~7.0.0",
     "typescript": "~4.9.3",
     "ws": "~8.13.0"
   },
   "devDependencies": {
-    "@babel/core": "^7.21.3",
     "@babel/code-frame": "^7.18.6",
+    "@babel/core": "^7.21.3",
     "@types/compression": "^1.7.2",
     "@types/crypto-js": "^4.1.1",
     "@types/express": "^4.17.17",

backend/src/__fixtures__/mempool-config.template.json

@@ -10,6 +10,7 @@
     "AUTOMATIC_BLOCK_REINDEXING": false,
     "POLL_RATE_MS": 3,
     "CACHE_DIR": "__MEMPOOL_CACHE_DIR__",
+    "CACHE_ENABLED": true,
     "CLEAR_PROTECTION_MINUTES": 4,
     "RECOMMENDED_FEE_PERCENTILE": 5,
     "BLOCK_WEIGHT_UNITS": 6,
@@ -127,5 +128,9 @@
     "AUDIT": false,
     "AUDIT_START_HEIGHT": 774000,
     "SERVERS": []
+  },
+  "REDIS": {
+    "ENABLED": false,
+    "UNIX_SOCKET_PATH": "/tmp/redis.sock"
   }
 }

backend/src/__tests__/config.test.ts

@@ -23,6 +23,7 @@ describe('Mempool Backend Config', () => {
         AUTOMATIC_BLOCK_REINDEXING: false,
         POLL_RATE_MS: 2000,
         CACHE_DIR: './cache',
+        CACHE_ENABLED: true,
         CLEAR_PROTECTION_MINUTES: 20,
         RECOMMENDED_FEE_PERCENTILE: 50,
         BLOCK_WEIGHT_UNITS: 4000000,
@@ -127,6 +128,11 @@ describe('Mempool Backend Config', () => {
         AUDIT_START_HEIGHT: 774000,
         SERVERS: []
       });
+
+      expect(config.REDIS).toStrictEqual({
+        ENABLED: false,
+        UNIX_SOCKET_PATH: ''
+      });
     });
   });
 
@@ -160,6 +166,8 @@ describe('Mempool Backend Config', () => {
       expect(config.PRICE_DATA_SERVER).toStrictEqual(fixture.PRICE_DATA_SERVER);
 
       expect(config.EXTERNAL_DATA_SERVER).toStrictEqual(fixture.EXTERNAL_DATA_SERVER);
+
+      expect(config.REDIS).toStrictEqual(fixture.REDIS);
     });
   });
 

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

@@ -5,6 +5,7 @@ import { IEsploraApi } from './esplora-api.interface';
 import blocks from '../blocks';
 import mempool from '../mempool';
 import { TransactionExtended } from '../../mempool.interfaces';
+import transactionUtils from '../transaction-utils';
 
 class BitcoinApi implements AbstractBitcoinApi {
   private rawMempoolCache: IBitcoinApi.RawMempool | null = null;
@@ -63,9 +64,16 @@ class BitcoinApi implements AbstractBitcoinApi {
     return Promise.resolve([]);
   }
 
-  $getTransactionHex(txId: string): Promise<string> {
-    return this.$getRawTransaction(txId, true)
-      .then((tx) => tx.hex || '');
+  async $getTransactionHex(txId: string): Promise<string> {
+    const txInMempool = mempool.getMempool()[txId];
+    if (txInMempool && txInMempool.hex) {
+      return txInMempool.hex;
+    }
+
+    return this.bitcoindClient.getRawTransaction(txId, true)
+      .then((transaction: IBitcoinApi.Transaction) => {
+        return transaction.hex;
+      });
   }
 
   $getBlockHeightTip(): Promise<number> {
@@ -209,7 +217,7 @@ class BitcoinApi implements AbstractBitcoinApi {
         scriptpubkey: vout.scriptPubKey.hex,
         scriptpubkey_address: vout.scriptPubKey && vout.scriptPubKey.address ? vout.scriptPubKey.address
           : vout.scriptPubKey.addresses ? vout.scriptPubKey.addresses[0] : '',
-        scriptpubkey_asm: vout.scriptPubKey.asm ? this.convertScriptSigAsm(vout.scriptPubKey.hex) : '',
+        scriptpubkey_asm: vout.scriptPubKey.asm ? transactionUtils.convertScriptSigAsm(vout.scriptPubKey.hex) : '',
         scriptpubkey_type: this.translateScriptPubKeyType(vout.scriptPubKey.type),
       };
     });
@@ -219,7 +227,7 @@ class BitcoinApi implements AbstractBitcoinApi {
         is_coinbase: !!vin.coinbase,
         prevout: null,
         scriptsig: vin.scriptSig && vin.scriptSig.hex || vin.coinbase || '',
-        scriptsig_asm: vin.scriptSig && this.convertScriptSigAsm(vin.scriptSig.hex) || '',
+        scriptsig_asm: vin.scriptSig && transactionUtils.convertScriptSigAsm(vin.scriptSig.hex) || '',
         sequence: vin.sequence,
         txid: vin.txid || '',
         vout: vin.vout || 0,
@@ -291,7 +299,7 @@ class BitcoinApi implements AbstractBitcoinApi {
       }
       const innerTx = await this.$getRawTransaction(vin.txid, false, false);
       vin.prevout = innerTx.vout[vin.vout];
-      this.addInnerScriptsToVin(vin);
+      transactionUtils.addInnerScriptsToVin(vin);
     }
     return transaction;
   }
@@ -330,7 +338,7 @@ class BitcoinApi implements AbstractBitcoinApi {
       }
       const innerTx = await this.$getRawTransaction(transaction.vin[i].txid, false, false);
       transaction.vin[i].prevout = innerTx.vout[transaction.vin[i].vout];
-      this.addInnerScriptsToVin(transaction.vin[i]);
+      transactionUtils.addInnerScriptsToVin(transaction.vin[i]);
       totalIn += innerTx.vout[transaction.vin[i].vout].value;
     }
     if (lazyPrevouts && transaction.vin.length > 12) {
@@ -342,122 +350,6 @@ class BitcoinApi implements AbstractBitcoinApi {
     return transaction;
   }
 
-  private convertScriptSigAsm(hex: string): string {
-    const buf = Buffer.from(hex, 'hex');
-
-    const b: string[] = [];
-
-    let i = 0;
-    while (i < buf.length) {
-      const op = buf[i];
-      if (op >= 0x01 && op <= 0x4e) {
-        i++;
-        let push: number;
-        if (op === 0x4c) {
-          push = buf.readUInt8(i);
-          b.push('OP_PUSHDATA1');
-          i += 1;
-        } else if (op === 0x4d) {
-          push = buf.readUInt16LE(i);
-          b.push('OP_PUSHDATA2');
-          i += 2;
-        } else if (op === 0x4e) {
-          push = buf.readUInt32LE(i);
-          b.push('OP_PUSHDATA4');
-          i += 4;
-        } else {
-          push = op;
-          b.push('OP_PUSHBYTES_' + push);
-        }
-
-        const data = buf.slice(i, i + push);
-        if (data.length !== push) {
-          break;
-        }
-
-        b.push(data.toString('hex'));
-        i += data.length;
-      } else {
-        if (op === 0x00) {
-          b.push('OP_0');
-        } else if (op === 0x4f) {
-          b.push('OP_PUSHNUM_NEG1');
-        } else if (op === 0xb1) {
-          b.push('OP_CLTV');
-        } else if (op === 0xb2) {
-          b.push('OP_CSV');
-        } else if (op === 0xba) {
-          b.push('OP_CHECKSIGADD');
-        } else {
-          const opcode = bitcoinjs.script.toASM([ op ]);
-          if (opcode && op < 0xfd) {
-            if (/^OP_(\d+)$/.test(opcode)) {
-              b.push(opcode.replace(/^OP_(\d+)$/, 'OP_PUSHNUM_$1'));
-            } else {
-              b.push(opcode);
-            }
-          } else {
-            b.push('OP_RETURN_' + op);
-          }
-        }
-        i += 1;
-      }
-    }
-
-    return b.join(' ');
-  }
-
-  private addInnerScriptsToVin(vin: IEsploraApi.Vin): void {
-    if (!vin.prevout) {
-      return;
-    }
-
-    if (vin.prevout.scriptpubkey_type === 'p2sh') {
-      const redeemScript = vin.scriptsig_asm.split(' ').reverse()[0];
-      vin.inner_redeemscript_asm = this.convertScriptSigAsm(redeemScript);
-      if (vin.witness && vin.witness.length > 2) {
-        const witnessScript = vin.witness[vin.witness.length - 1];
-        vin.inner_witnessscript_asm = this.convertScriptSigAsm(witnessScript);
-      }
-    }
-
-    if (vin.prevout.scriptpubkey_type === 'v0_p2wsh' && vin.witness) {
-      const witnessScript = vin.witness[vin.witness.length - 1];
-      vin.inner_witnessscript_asm = this.convertScriptSigAsm(witnessScript);
-    }
-
-    if (vin.prevout.scriptpubkey_type === 'v1_p2tr' && vin.witness) {
-      const witnessScript = this.witnessToP2TRScript(vin.witness);
-      if (witnessScript !== null) {
-        vin.inner_witnessscript_asm = this.convertScriptSigAsm(witnessScript);
-      }
-    }
-  }
-
-  /**
-   * This function must only be called when we know the witness we are parsing
-   * is a taproot witness.
-   * @param witness An array of hex strings that represents the witness stack of
-   *                the input.
-   * @returns null if the witness is not a script spend, and the hex string of
-   *          the script item if it is a script spend.
-   */
-  private witnessToP2TRScript(witness: string[]): string | null {
-    if (witness.length < 2) return null;
-    // Note: see BIP341 for parsing details of witness stack
-
-    // If there are at least two witness elements, and the first byte of the
-    // last element is 0x50, this last element is called annex a and
-    // is removed from the witness stack.
-    const hasAnnex = witness[witness.length - 1].substring(0, 2) === '50';
-    // If there are at least two witness elements left, script path spending is used.
-    // Call the second-to-last stack element s, the script.
-    // (Note: this phrasing from BIP341 assumes we've *removed* the annex from the stack)
-    if (hasAnnex && witness.length < 3) return null;
-    const positionOfScript = hasAnnex ? witness.length - 3 : witness.length - 2;
-    return witness[positionOfScript];
-  }
-
 }
 
 export default BitcoinApi;

backend/src/api/blocks.ts

@@ -26,6 +26,8 @@ import PricesRepository from '../repositories/PricesRepository';
 import priceUpdater from '../tasks/price-updater';
 import chainTips from './chain-tips';
 import websocketHandler from './websocket-handler';
+import redisCache from './redis-cache';
+import rbfCache from './rbf-cache';
 
 class Blocks {
   private blocks: BlockExtended[] = [];
@@ -783,10 +785,18 @@ class Blocks {
       if (this.newBlockCallbacks.length) {
         this.newBlockCallbacks.forEach((cb) => cb(blockExtended, txIds, transactions));
       }
-      if (!memPool.hasPriority() && (block.height % config.MEMPOOL.DISK_CACHE_BLOCK_INTERVAL === 0)) {
+      if (config.MEMPOOL.CACHE_ENABLED && !memPool.hasPriority() && (block.height % config.MEMPOOL.DISK_CACHE_BLOCK_INTERVAL === 0)) {
         diskCache.$saveCacheToDisk();
       }
 
+      // Update Redis cache
+      if (config.REDIS.ENABLED) {
+        await redisCache.$updateBlocks(this.blocks);
+        await redisCache.$updateBlockSummaries(this.blockSummaries);
+        await redisCache.$removeTransactions(txIds);
+        await rbfCache.updateCache();
+      }
+
       handledBlocks++;
     }
 

backend/src/api/disk-cache.ts

@@ -29,7 +29,7 @@ class DiskCache {
   };
 
   constructor() {
-    if (!cluster.isPrimary) {
+    if (!cluster.isPrimary || !config.MEMPOOL.CACHE_ENABLED) {
       return;
     }
     process.on('SIGINT', (e) => {
@@ -39,7 +39,7 @@ class DiskCache {
   }
 
   async $saveCacheToDisk(sync: boolean = false): Promise<void> {
-    if (!cluster.isPrimary) {
+    if (!cluster.isPrimary || !config.MEMPOOL.CACHE_ENABLED) {
       return;
     }
     if (this.isWritingCache) {
@@ -175,7 +175,7 @@ class DiskCache {
   }
 
   async $loadMempoolCache(): Promise<void> {
-    if (!fs.existsSync(DiskCache.FILE_NAME)) {
+    if (!config.MEMPOOL.CACHE_ENABLED || !fs.existsSync(DiskCache.FILE_NAME)) {
       return;
     }
     try {

backend/src/api/mempool.ts

@@ -9,7 +9,7 @@ import loadingIndicators from './loading-indicators';
 import bitcoinClient from './bitcoin/bitcoin-client';
 import bitcoinSecondClient from './bitcoin/bitcoin-second-client';
 import rbfCache from './rbf-cache';
-import { IEsploraApi } from './bitcoin/esplora-api.interface';
+import redisCache from './redis-cache';
 
 class Mempool {
   private inSync: boolean = false;
@@ -86,6 +86,10 @@ class Mempool {
   public async $setMempool(mempoolData: { [txId: string]: MempoolTransactionExtended }) {
     this.mempoolCache = mempoolData;
     let count = 0;
+    const redisTimer = Date.now();
+    if (config.MEMPOOL.CACHE_ENABLED && config.REDIS.ENABLED) {
+      logger.debug(`Migrating ${Object.keys(this.mempoolCache).length} transactions from disk cache to Redis cache`);
+    }
     for (const txid of Object.keys(this.mempoolCache)) {
       if (!this.mempoolCache[txid].sigops || this.mempoolCache[txid].effectiveFeePerVsize == null) {
         this.mempoolCache[txid] = transactionUtils.extendMempoolTransaction(this.mempoolCache[txid]);
@@ -94,6 +98,13 @@ class Mempool {
         this.mempoolCache[txid].order = transactionUtils.txidToOrdering(txid);
       }
       count++;
+      if (config.MEMPOOL.CACHE_ENABLED && config.REDIS.ENABLED) {
+        await redisCache.$addTransaction(this.mempoolCache[txid]);
+      }
+    }
+    if (config.MEMPOOL.CACHE_ENABLED && config.REDIS.ENABLED) {
+      await redisCache.$flushTransactions();
+      logger.debug(`Finished migrating cache transactions in ${((Date.now() - redisTimer) / 1000).toFixed(2)} seconds`);
     }
     if (this.mempoolChangedCallback) {
       this.mempoolChangedCallback(this.mempoolCache, [], []);
@@ -138,8 +149,8 @@ class Mempool {
         logger.err('failed to fetch bulk mempool transactions from esplora');
       }
     }
-    return newTransactions;
     logger.info(`Done inserting loaded mempool transactions into local cache`);
+    return newTransactions;
   }
 
   public async $updateMemPoolInfo() {
@@ -208,6 +219,11 @@ class Mempool {
       logger.info(`Missing ${transactions.length - currentMempoolSize} mempool transactions, attempting to reload in bulk from esplora`);
       try {
         newTransactions = await this.$reloadMempool(transactions.length);
+        if (config.REDIS.ENABLED) {
+          for (const tx of newTransactions) {
+            await redisCache.$addTransaction(tx);
+          }
+        }
         loaded = true;
       } catch (e) {
         logger.err('failed to load mempool in bulk from esplora, falling back to fetching individual transactions');
@@ -230,6 +246,10 @@ class Mempool {
             }
             hasChange = true;
             newTransactions.push(transaction);
+
+            if (config.REDIS.ENABLED) {
+              await redisCache.$addTransaction(transaction);
+            }
           } catch (e: any) {
             if (config.MEMPOOL.BACKEND === 'esplora' && e.response?.status === 404) {
               this.missingTxCount++;
@@ -318,6 +338,13 @@ class Mempool {
       loadingIndicators.setProgress('mempool', 100);
     }
 
+    // Update Redis cache
+    if (config.REDIS.ENABLED) {
+      await redisCache.$flushTransactions();
+      await redisCache.$removeTransactions(deletedTransactions.map(tx => tx.txid));
+      await rbfCache.updateCache();
+    }
+
     const end = new Date().getTime();
     const time = end - start;
     logger.debug(`Mempool updated in ${time / 1000} seconds. New size: ${Object.keys(this.mempoolCache).length} (${diff > 0 ? '+' + diff : diff})`);

backend/src/api/rbf-cache.ts

@@ -1,15 +1,17 @@
+import config from "../config";
 import logger from "../logger";
 import { MempoolTransactionExtended, TransactionStripped } from "../mempool.interfaces";
 import bitcoinApi from './bitcoin/bitcoin-api-factory';
 import { Common } from "./common";
+import redisCache from "./redis-cache";
 
-interface RbfTransaction extends TransactionStripped {
+export interface RbfTransaction extends TransactionStripped {
   rbf?: boolean;
   mined?: boolean;
   fullRbf?: boolean;
 }
 
-interface RbfTree {
+export interface RbfTree {
   tx: RbfTransaction;
   time: number;
   interval?: number;
@@ -28,6 +30,19 @@ export interface ReplacementInfo {
   newVsize: number;
 }
 
+enum CacheOp {
+  Remove = 0,
+  Add = 1,
+  Change = 2,
+}
+
+interface CacheEvent {
+  op: CacheOp;
+  type: 'tx' | 'tree' | 'exp';
+  txid: string,
+  value?: any,
+}
+
 class RbfCache {
   private replacedBy: Map<string, string> = new Map();
   private replaces: Map<string, string[]> = new Map();
@@ -36,11 +51,43 @@ class RbfCache {
   private treeMap: Map<string, string> = new Map(); // map of txids to sequence ids
   private txs: Map<string, MempoolTransactionExtended> = new Map();
   private expiring: Map<string, number> = new Map();
+  private cacheQueue: CacheEvent[] = [];
 
   constructor() {
     setInterval(this.cleanup.bind(this), 1000 * 60 * 10);
   }
 
+  private addTx(txid: string, tx: MempoolTransactionExtended): void {
+    this.txs.set(txid, tx);
+    this.cacheQueue.push({ op: CacheOp.Add, type: 'tx', txid });
+  }
+
+  private addTree(txid: string, tree: RbfTree): void {
+    this.rbfTrees.set(txid, tree);
+    this.dirtyTrees.add(txid);
+    this.cacheQueue.push({ op: CacheOp.Add, type: 'tree', txid });
+  }
+
+  private addExpiration(txid: string, expiry: number): void {
+    this.expiring.set(txid, expiry);
+    this.cacheQueue.push({ op: CacheOp.Add, type: 'exp', txid, value: expiry });
+  }
+
+  private removeTx(txid: string): void {
+    this.txs.delete(txid);
+    this.cacheQueue.push({ op: CacheOp.Remove, type: 'tx', txid });
+  }
+
+  private removeTree(txid: string): void {
+    this.rbfTrees.delete(txid);
+    this.cacheQueue.push({ op: CacheOp.Remove, type: 'tree', txid });
+  }
+
+  private removeExpiration(txid: string): void {
+    this.expiring.delete(txid);
+    this.cacheQueue.push({ op: CacheOp.Remove, type: 'exp', txid });
+  }
+
   public add(replaced: MempoolTransactionExtended[], newTxExtended: MempoolTransactionExtended): void {
     if (!newTxExtended || !replaced?.length || this.txs.has(newTxExtended.txid)) {
       return;
@@ -49,7 +96,7 @@ class RbfCache {
     const newTx = Common.stripTransaction(newTxExtended) as RbfTransaction;
     const newTime = newTxExtended.firstSeen || (Date.now() / 1000);
     newTx.rbf = newTxExtended.vin.some((v) => v.sequence < 0xfffffffe);
-    this.txs.set(newTx.txid, newTxExtended);
+    this.addTx(newTx.txid, newTxExtended);
 
     // maintain rbf trees
     let txFullRbf = false;
@@ -66,7 +113,7 @@ class RbfCache {
         const treeId = this.treeMap.get(replacedTx.txid);
         if (treeId) {
           const tree = this.rbfTrees.get(treeId);
-          this.rbfTrees.delete(treeId);
+          this.removeTree(treeId);
           if (tree) {
             tree.interval = newTime - tree?.time;
             replacedTrees.push(tree);
@@ -83,7 +130,7 @@ class RbfCache {
           replaces: [],
         });
         treeFullRbf = treeFullRbf || !replacedTx.rbf;
-        this.txs.set(replacedTx.txid, replacedTxExtended);
+        this.addTx(replacedTx.txid, replacedTxExtended);
       }
     }
     newTx.fullRbf = txFullRbf;
@@ -94,10 +141,9 @@ class RbfCache {
       fullRbf: treeFullRbf,
       replaces: replacedTrees
     };
-    this.rbfTrees.set(treeId, newTree);
+    this.addTree(treeId, newTree);
     this.updateTreeMap(treeId, newTree);
     this.replaces.set(newTx.txid, replacedTrees.map(tree => tree.tx.txid));
-    this.dirtyTrees.add(treeId);
   }
 
   public getReplacedBy(txId: string): string | undefined {
@@ -173,6 +219,7 @@ class RbfCache {
         this.setTreeMined(tree, txid);
         tree.mined = true;
         this.dirtyTrees.add(treeId);
+        this.cacheQueue.push({ op: CacheOp.Change, type: 'tree', txid: treeId });
       }
     }
     this.evict(txid);
@@ -181,7 +228,8 @@ class RbfCache {
   // flag a transaction as removed from the mempool
   public evict(txid: string, fast: boolean = false): void {
     if (this.txs.has(txid) && (fast || !this.expiring.has(txid))) {
-      this.expiring.set(txid, fast ? Date.now() + (1000 * 60 * 10) : Date.now() + (1000 * 86400)); // 24 hours
+      const expiryTime = fast ? Date.now() + (1000 * 60 * 10) : Date.now() + (1000 * 86400); // 24 hours
+      this.addExpiration(txid, expiryTime);
     }
   }
 
@@ -202,11 +250,11 @@ class RbfCache {
     const now = Date.now();
     for (const txid of this.expiring.keys()) {
       if ((this.expiring.get(txid) || 0) < now) {
-        this.expiring.delete(txid);
+        this.removeExpiration(txid);
         this.remove(txid);
       }
     }
-    logger.debug(`rbf cache contains ${this.txs.size} txs, ${this.expiring.size} due to expire`);
+    logger.debug(`rbf cache contains ${this.txs.size} txs, ${this.rbfTrees.size} trees, ${this.expiring.size} due to expire`);
   }
 
   // remove a transaction & all previous versions from the cache
@@ -216,14 +264,14 @@ class RbfCache {
       const replaces = this.replaces.get(txid);
       this.replaces.delete(txid);
       this.treeMap.delete(txid);
-      this.txs.delete(txid);
-      this.expiring.delete(txid);
+      this.removeTx(txid);
+      this.removeExpiration(txid);
       for (const tx of (replaces || [])) {
         // recursively remove prior versions from the cache
         this.replacedBy.delete(tx);
         // if this is the id of a tree, remove that too
         if (this.treeMap.get(tx) === tx) {
-          this.rbfTrees.delete(tx);
+          this.removeTree(tx);
         }
         this.remove(tx);
       }
@@ -255,6 +303,33 @@ class RbfCache {
     }
   }
 
+  public async updateCache(): Promise<void> {
+    if (!config.REDIS.ENABLED) {
+      return;
+    }
+    // Update the Redis cache by replaying queued events
+    for (const e of this.cacheQueue) {
+      if (e.op === CacheOp.Add || e.op === CacheOp.Change) {
+        let value = e.value;
+          switch(e.type) {
+            case 'tx': {
+              value = this.txs.get(e.txid);
+            } break;
+            case 'tree': {
+              const tree = this.rbfTrees.get(e.txid);
+              value = tree ? this.exportTree(tree) : null;
+            } break;
+          }
+          if (value != null) {
+            await redisCache.$setRbfEntry(e.type, e.txid, value);
+          }
+      } else if (e.op === CacheOp.Remove) {
+        await redisCache.$removeRbfEntry(e.type, e.txid);
+      }
+    }
+    this.cacheQueue = [];
+  }
+
   public dump(): any {
     const trees = Array.from(this.rbfTrees.values()).map((tree: RbfTree) => { return this.exportTree(tree); });
 
@@ -360,8 +435,7 @@ class RbfCache {
     };
     this.treeMap.set(txid, root);
     if (root === txid) {
-      this.rbfTrees.set(root, tree);
-      this.dirtyTrees.add(root);
+      this.addTree(root, tree);
     }
     return tree;
   }

backend/src/api/redis-cache.ts

@@ -0,0 +1,253 @@
+import { createClient } from 'redis';
+import memPool from './mempool';
+import blocks from './blocks';
+import logger from '../logger';
+import config from '../config';
+import { BlockExtended, BlockSummary, MempoolTransactionExtended } from '../mempool.interfaces';
+import rbfCache from './rbf-cache';
+import transactionUtils from './transaction-utils';
+
+enum NetworkDB {
+  mainnet = 0,
+  testnet,
+  signet,
+  liquid,
+  liquidtestnet,
+}
+
+class RedisCache {
+  private client;
+  private connected = false;
+  private schemaVersion = 1;
+
+  private cacheQueue: MempoolTransactionExtended[] = [];
+  private txFlushLimit: number = 10000;
+
+  constructor() {
+    if (config.REDIS.ENABLED) {
+      const redisConfig = {
+        socket: {
+          path: config.REDIS.UNIX_SOCKET_PATH
+        },
+        database: NetworkDB[config.MEMPOOL.NETWORK],
+      };
+      this.client = createClient(redisConfig);
+      this.client.on('error', (e) => {
+        logger.err(`Error in Redis client: ${e instanceof Error ? e.message : e}`);
+      });
+      this.$ensureConnected();
+      this.client.exists('mempool:0').then((mempoolExists) => {
+        if (!mempoolExists) {
+          for (let i = 0; i < 16; i++) {
+            this.client.json.set(`mempool:${i.toString(16)}`, '$', {});
+          }
+        }
+      });
+    }
+  }
+
+  private async $ensureConnected(): Promise<void> {
+    if (!this.connected && config.REDIS.ENABLED) {
+      return this.client.connect().then(async () => {
+        this.connected = true;
+        logger.info(`Redis client connected`);
+        const version = await this.client.get('schema_version');
+        if (version !== this.schemaVersion) {
+          // schema changed
+          // perform migrations or flush DB if necessary
+          logger.info(`Redis schema version changed from ${version} to ${this.schemaVersion}`);
+          await this.client.set('schema_version', this.schemaVersion);
+        }
+      });
+    }
+  }
+
+  async $updateBlocks(blocks: BlockExtended[]) {
+    try {
+      await this.$ensureConnected();
+      await this.client.json.set('blocks', '$', blocks);
+    } catch (e) {
+      logger.warn(`Failed to update blocks in Redis cache: ${e instanceof Error ? e.message : e}`);
+    }
+  }
+
+  async $updateBlockSummaries(summaries: BlockSummary[]) {
+    try {
+      await this.$ensureConnected();
+      await this.client.json.set('block-summaries', '$', summaries);
+    } catch (e) {
+      logger.warn(`Failed to update blocks in Redis cache: ${e instanceof Error ? e.message : e}`);
+    }
+  }
+
+  async $addTransaction(tx: MempoolTransactionExtended) {
+    this.cacheQueue.push(tx);
+    if (this.cacheQueue.length >= this.txFlushLimit) {
+      await this.$flushTransactions();
+    }
+  }
+
+  async $flushTransactions() {
+    const success = await this.$addTransactions(this.cacheQueue);
+    if (success) {
+      logger.info(`Flushed ${this.cacheQueue.length} transactions to Redis cache`);
+      this.cacheQueue = [];
+    } else {
+      logger.err(`Failed to flush ${this.cacheQueue.length} transactions to Redis cache`);
+    }
+  }
+
+  private async $addTransactions(newTransactions: MempoolTransactionExtended[]): Promise<boolean> {
+    try {
+      await this.$ensureConnected();
+      await Promise.all(newTransactions.map(tx => {
+        const minified: any = { ...tx };
+        delete minified.hex;
+        for (const vin of minified.vin) {
+          delete vin.inner_redeemscript_asm;
+          delete vin.inner_witnessscript_asm;
+          delete vin.scriptsig_asm;
+        }
+        for (const vout of minified.vout) {
+          delete vout.scriptpubkey_asm;
+        }
+        return this.client.json.set(`mempool:${tx.txid.slice(0,1)}`, tx.txid, minified);
+      }));
+      return true;
+    } catch (e) {
+      logger.warn(`Failed to add ${newTransactions.length} transactions to Redis cache: ${e instanceof Error ? e.message : e}`);
+      return false;
+    }
+  }
+
+  async $removeTransactions(transactions: string[]) {
+    try {
+      await this.$ensureConnected();
+      await Promise.all(transactions.map(txid => {
+        return this.client.json.del(`mempool:${txid.slice(0,1)}`, txid);
+      }));
+    } catch (e) {
+      logger.warn(`Failed to remove ${transactions.length} transactions from Redis cache: ${e instanceof Error ? e.message : e}`);
+    }
+  }
+
+  async $setRbfEntry(type: string, txid: string, value: any): Promise<void> {
+    try {
+      await this.$ensureConnected();
+      await this.client.json.set(`rbf:${type}:${txid}`, '$', value);
+    } catch (e) {
+      logger.warn(`Failed to set RBF ${type} in Redis cache: ${e instanceof Error ? e.message : e}`);
+    }
+  }
+
+  async $removeRbfEntry(type: string, txid: string): Promise<void> {
+    try {
+      await this.$ensureConnected();
+      await this.client.del(`rbf:${type}:${txid}`);
+    } catch (e) {
+      logger.warn(`Failed to remove RBF ${type} from Redis cache: ${e instanceof Error ? e.message : e}`);
+    }
+  }
+
+  async $getBlocks(): Promise<BlockExtended[]> {
+    try {
+      await this.$ensureConnected();
+      return this.client.json.get('blocks');
+    } catch (e) {
+      logger.warn(`Failed to retrieve blocks from Redis cache: ${e instanceof Error ? e.message : e}`);
+      return [];
+    }
+  }
+
+  async $getBlockSummaries(): Promise<BlockSummary[]> {
+    try {
+      await this.$ensureConnected();
+      return this.client.json.get('block-summaries');
+    } catch (e) {
+      logger.warn(`Failed to retrieve blocks from Redis cache: ${e instanceof Error ? e.message : e}`);
+      return [];
+    }
+  }
+
+  async $getMempool(): Promise<{ [txid: string]: MempoolTransactionExtended }> {
+    const start = Date.now();
+    let mempool = {};
+    try {
+      await this.$ensureConnected();
+      for (let i = 0; i < 16; i++) {
+        const shard = await this.client.json.get(`mempool:${i.toString(16)}`);
+        logger.info(`Loaded ${Object.keys(shard).length} transactions from redis cache ${i.toString(16)}`);
+        mempool = Object.assign(mempool, shard);
+      }
+      logger.info(`Total ${Object.keys(mempool).length} transactions loaded from redis cache `);
+      logger.info(`Loaded redis cache in ${Date.now() - start} ms`);
+      return mempool || {};
+    } catch (e) {
+      logger.warn(`Failed to retrieve mempool from Redis cache: ${e instanceof Error ? e.message : e}`);
+    }
+    return {};
+  }
+
+  async $getRbfEntries(type: string): Promise<any[]> {
+    try {
+      await this.$ensureConnected();
+      const keys = await this.client.keys(`rbf:${type}:*`);
+      const promises: Promise<MempoolTransactionExtended[]>[] = [];
+      for (let i = 0; i < keys.length; i += 10000) {
+        const keySlice = keys.slice(i, i + 10000);
+        if (!keySlice.length) {
+          continue;
+        }
+        promises.push(this.client.json.mGet(keySlice, '$').then(chunk => chunk?.length ? chunk.flat().map((v, i) => [keySlice[i].slice(`rbf:${type}:`.length), v]) : [] ));
+      }
+      const entries = await Promise.all(promises);
+      return entries.flat();
+    } catch (e) {
+      logger.warn(`Failed to retrieve Rbf ${type}s from Redis cache: ${e instanceof Error ? e.message : e}`);
+      return [];
+    }
+  }
+
+  async $loadCache() {
+    logger.info('Restoring mempool and blocks data from Redis cache');
+    // Load block data
+    const loadedBlocks = await this.$getBlocks();
+    const loadedBlockSummaries = await this.$getBlockSummaries();
+    // Load mempool
+    const loadedMempool = await this.$getMempool();
+    this.inflateLoadedTxs(loadedMempool);
+    // Load rbf data
+    const rbfTxs = await this.$getRbfEntries('tx');
+    const rbfTrees = await this.$getRbfEntries('tree');
+    const rbfExpirations = await this.$getRbfEntries('exp');
+
+    // Set loaded data
+    blocks.setBlocks(loadedBlocks || []);
+    blocks.setBlockSummaries(loadedBlockSummaries || []);
+    await memPool.$setMempool(loadedMempool);
+    await rbfCache.load({
+      txs: rbfTxs,
+      trees: rbfTrees.map(loadedTree => loadedTree[1]),
+      expiring: rbfExpirations,
+    });
+  }
+
+  private inflateLoadedTxs(mempool: { [txid: string]: MempoolTransactionExtended }) {
+    for (const tx of Object.values(mempool)) {
+      for (const vin of tx.vin) {
+        if (vin.scriptsig) {
+          vin.scriptsig_asm = transactionUtils.convertScriptSigAsm(vin.scriptsig);
+          transactionUtils.addInnerScriptsToVin(vin);
+        }
+      }
+      for (const vout of tx.vout) {
+        if (vout.scriptpubkey) {
+          vout.scriptpubkey_asm = transactionUtils.convertScriptSigAsm(vout.scriptpubkey);
+        }
+      }
+    }
+  }
+
+}
+
+export default new RedisCache();

backend/src/api/transaction-utils.ts

@@ -170,6 +170,122 @@ class TransactionUtils {
       16
     );
   }
+
+  public addInnerScriptsToVin(vin: IEsploraApi.Vin): void {
+    if (!vin.prevout) {
+      return;
+    }
+
+    if (vin.prevout.scriptpubkey_type === 'p2sh') {
+      const redeemScript = vin.scriptsig_asm.split(' ').reverse()[0];
+      vin.inner_redeemscript_asm = this.convertScriptSigAsm(redeemScript);
+      if (vin.witness && vin.witness.length > 2) {
+        const witnessScript = vin.witness[vin.witness.length - 1];
+        vin.inner_witnessscript_asm = this.convertScriptSigAsm(witnessScript);
+      }
+    }
+
+    if (vin.prevout.scriptpubkey_type === 'v0_p2wsh' && vin.witness) {
+      const witnessScript = vin.witness[vin.witness.length - 1];
+      vin.inner_witnessscript_asm = this.convertScriptSigAsm(witnessScript);
+    }
+
+    if (vin.prevout.scriptpubkey_type === 'v1_p2tr' && vin.witness) {
+      const witnessScript = this.witnessToP2TRScript(vin.witness);
+      if (witnessScript !== null) {
+        vin.inner_witnessscript_asm = this.convertScriptSigAsm(witnessScript);
+      }
+    }
+  }
+
+  public convertScriptSigAsm(hex: string): string {
+    const buf = Buffer.from(hex, 'hex');
+
+    const b: string[] = [];
+
+    let i = 0;
+    while (i < buf.length) {
+      const op = buf[i];
+      if (op >= 0x01 && op <= 0x4e) {
+        i++;
+        let push: number;
+        if (op === 0x4c) {
+          push = buf.readUInt8(i);
+          b.push('OP_PUSHDATA1');
+          i += 1;
+        } else if (op === 0x4d) {
+          push = buf.readUInt16LE(i);
+          b.push('OP_PUSHDATA2');
+          i += 2;
+        } else if (op === 0x4e) {
+          push = buf.readUInt32LE(i);
+          b.push('OP_PUSHDATA4');
+          i += 4;
+        } else {
+          push = op;
+          b.push('OP_PUSHBYTES_' + push);
+        }
+
+        const data = buf.slice(i, i + push);
+        if (data.length !== push) {
+          break;
+        }
+
+        b.push(data.toString('hex'));
+        i += data.length;
+      } else {
+        if (op === 0x00) {
+          b.push('OP_0');
+        } else if (op === 0x4f) {
+          b.push('OP_PUSHNUM_NEG1');
+        } else if (op === 0xb1) {
+          b.push('OP_CLTV');
+        } else if (op === 0xb2) {
+          b.push('OP_CSV');
+        } else if (op === 0xba) {
+          b.push('OP_CHECKSIGADD');
+        } else {
+          const opcode = bitcoinjs.script.toASM([ op ]);
+          if (opcode && op < 0xfd) {
+            if (/^OP_(\d+)$/.test(opcode)) {
+              b.push(opcode.replace(/^OP_(\d+)$/, 'OP_PUSHNUM_$1'));
+            } else {
+              b.push(opcode);
+            }
+          } else {
+            b.push('OP_RETURN_' + op);
+          }
+        }
+        i += 1;
+      }
+    }
+
+    return b.join(' ');
+  }
+
+  /**
+   * This function must only be called when we know the witness we are parsing
+   * is a taproot witness.
+   * @param witness An array of hex strings that represents the witness stack of
+   *                the input.
+   * @returns null if the witness is not a script spend, and the hex string of
+   *          the script item if it is a script spend.
+   */
+  public witnessToP2TRScript(witness: string[]): string | null {
+    if (witness.length < 2) return null;
+    // Note: see BIP341 for parsing details of witness stack
+
+    // If there are at least two witness elements, and the first byte of the
+    // last element is 0x50, this last element is called annex a and
+    // is removed from the witness stack.
+    const hasAnnex = witness[witness.length - 1].substring(0, 2) === '50';
+    // If there are at least two witness elements left, script path spending is used.
+    // Call the second-to-last stack element s, the script.
+    // (Note: this phrasing from BIP341 assumes we've *removed* the annex from the stack)
+    if (hasAnnex && witness.length < 3) return null;
+    const positionOfScript = hasAnnex ? witness.length - 3 : witness.length - 2;
+    return witness[positionOfScript];
+  }
 }
 
 export default new TransactionUtils();

backend/src/config.ts

@@ -12,6 +12,7 @@ interface IConfig {
     API_URL_PREFIX: string;
     POLL_RATE_MS: number;
     CACHE_DIR: string;
+    CACHE_ENABLED: boolean;
     CLEAR_PROTECTION_MINUTES: number;
     RECOMMENDED_FEE_PERCENTILE: number;
     BLOCK_WEIGHT_UNITS: number;
@@ -137,7 +138,11 @@ interface IConfig {
     AUDIT: boolean;
     AUDIT_START_HEIGHT: number;
     SERVERS: string[];
-  }
+  },
+  REDIS: {
+    ENABLED: boolean;
+    UNIX_SOCKET_PATH: string;
+  },
 }
 
 const defaults: IConfig = {
@@ -150,6 +155,7 @@ const defaults: IConfig = {
     'API_URL_PREFIX': '/api/v1/',
     'POLL_RATE_MS': 2000,
     'CACHE_DIR': './cache',
+    'CACHE_ENABLED': true,
     'CLEAR_PROTECTION_MINUTES': 20,
     'RECOMMENDED_FEE_PERCENTILE': 50,
     'BLOCK_WEIGHT_UNITS': 4000000,
@@ -275,7 +281,11 @@ const defaults: IConfig = {
     'AUDIT': false,
     'AUDIT_START_HEIGHT': 774000,
     'SERVERS': [],
-  }
+  },
+  'REDIS': {
+    'ENABLED': false,
+    'UNIX_SOCKET_PATH': '',
+  },
 };
 
 class Config implements IConfig {
@@ -296,6 +306,7 @@ class Config implements IConfig {
   EXTERNAL_DATA_SERVER: IConfig['EXTERNAL_DATA_SERVER'];
   MAXMIND: IConfig['MAXMIND'];
   REPLICATION: IConfig['REPLICATION'];
+  REDIS: IConfig['REDIS'];
 
   constructor() {
     const configs = this.merge(configFromFile, defaults);
@@ -316,6 +327,7 @@ class Config implements IConfig {
     this.EXTERNAL_DATA_SERVER = configs.EXTERNAL_DATA_SERVER;
     this.MAXMIND = configs.MAXMIND;
     this.REPLICATION = configs.REPLICATION;
+    this.REDIS = configs.REDIS;
   }
 
   merge = (...objects: object[]): IConfig => {

backend/src/index.ts

@@ -41,6 +41,7 @@ import chainTips from './api/chain-tips';
 import { AxiosError } from 'axios';
 import v8 from 'v8';
 import { formatBytes, getBytesUnit } from './utils/format';
+import redisCache from './api/redis-cache';
 
 class Server {
   private wss: WebSocket.Server | undefined;
@@ -122,7 +123,11 @@ class Server {
     await poolsUpdater.updatePoolsJson(); // Needs to be done before loading the disk cache because we sometimes wipe it
     await syncAssets.syncAssets$();
     if (config.MEMPOOL.ENABLED) {
-      await diskCache.$loadMempoolCache();
+      if (config.MEMPOOL.CACHE_ENABLED) {
+        await diskCache.$loadMempoolCache();
+      } else if (config.REDIS.ENABLED) {
+        await redisCache.$loadCache();
+      }
     }
 
     if (config.STATISTICS.ENABLED && config.DATABASE.ENABLED && cluster.isPrimary) {