feat: AutoSync connected contracts when syncState #333

src/__tests__/integration/basic/pst-auto-sync.test.ts

@@ -0,0 +1,197 @@
+import fs from 'fs';
+
+import ArLocal from 'arlocal';
+import Arweave from 'arweave';
+import { JWKInterface } from 'arweave/node/lib/wallet';
+import path from 'path';
+import { mineBlock } from '../_helpers';
+import { PstState, PstContract } from '../../../contract/PstContract';
+import { Warp } from '../../../core/Warp';
+import { WarpFactory } from '../../../core/WarpFactory';
+import { LoggerFactory } from '../../../logging/LoggerFactory';
+import { DeployPlugin } from "warp-contracts-plugin-deploy";
+
+// note: each tests suit (i.e. file with tests that Jest is running concurrently
+// with another files has to have ArLocal set to a different port!)
+const AR_PORT = 1825;
+
+describe('Testing the Profit Sharing Token', () => {
+  let contractSrc: string;
+
+  let wallet: JWKInterface;
+  let walletAddress: string;
+
+  let initialState: PstState;
+
+  let arweave: Arweave;
+  let arlocal: ArLocal;
+  let warp: Warp;
+  let contractTxId: string;
+  let pst: PstContract;
+
+  const actualFetch = global.fetch
+  let responseData = {
+    sortKey: "",
+    state: {}
+  }
+  let firstSortKey = ''
+  const remoteCalls = {
+    total: 0,
+    measure: function() {
+      const self = this;
+      const start = self.total;
+      return {
+        diff: () => self.total - start
+      }
+    }
+  }
+
+  const localWarp = async function() {
+    if (!arlocal) {
+      arlocal = new ArLocal(AR_PORT, false);
+      await arlocal.start();
+    }
+    return WarpFactory.forLocal(AR_PORT).use(new DeployPlugin());
+  }
+
+  const autoSyncPst = async function() {
+    const autoSyncPst = (await localWarp()).pst(contractTxId);
+    autoSyncPst.setEvaluationOptions({
+      remoteStateSyncEnabled: true
+    })
+    return autoSyncPst;
+  }
+
+  beforeAll(async () => {
+    LoggerFactory.INST.logLevel('error');
+
+    warp = await localWarp();
+    ({ arweave } = warp);
+    ({ jwk: wallet, address: walletAddress } = await warp.generateWallet());
+
+    contractSrc = fs.readFileSync(path.join(__dirname, '../data/token-pst.js'), 'utf8');
+    const stateFromFile: PstState = JSON.parse(fs.readFileSync(path.join(__dirname, '../data/token-pst.json'), 'utf8'));
+
+    initialState = {
+      ...stateFromFile,
+      ...{
+        owner: walletAddress,
+        balances: {
+          ...stateFromFile.balances,
+          [walletAddress]: 555669
+        }
+      }
+    };
+
+    // deploying contract using the new SDK.
+    ({ contractTxId } = await warp.deploy({
+      wallet,
+      initState: JSON.stringify(initialState),
+      src: contractSrc
+    }));
+
+    // connecting to the PST contract
+    pst = warp.pst(contractTxId);
+
+    // connecting wallet to the PST contract
+    pst.connect(wallet);
+
+    await mineBlock(warp);
+
+    jest
+      .spyOn(global, 'fetch')
+      .mockImplementation( async (input: string, init) => {
+        if (input.includes(pst.evaluationOptions().remoteStateSyncSource)) {
+          remoteCalls.total++;
+          return Promise.resolve({ json: () => Promise.resolve(responseData), ok: true, status: 200 }) as Promise<Response>;
+        }
+        return actualFetch(input, init);
+      })
+  });
+
+  afterAll(async () => {
+    await arlocal.stop();
+    jest.restoreAllMocks();
+  });
+
+  it('should read pst state and balance data', async () => {
+    const dreCalls = remoteCalls.measure();
+    const state = await pst.readState();
+    firstSortKey = state.sortKey;
+    responseData.sortKey = state.sortKey;
+    responseData.state = state.cachedValue.state;
+
+    expect(state.cachedValue.state).toEqual(initialState);
+    const syncPst = await autoSyncPst();
+    expect(await syncPst.currentState()).toEqual(initialState);
+
+    expect((await pst.currentBalance('uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M')).balance).toEqual(10000000);
+    expect((await syncPst.currentBalance('uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M')).balance).toEqual(10000000);
+    expect((await pst.currentBalance('33F0QHcb22W7LwWR1iRC8Az1ntZG09XQ03YWuw2ABqA')).balance).toEqual(23111222);
+    expect((await syncPst.currentBalance('33F0QHcb22W7LwWR1iRC8Az1ntZG09XQ03YWuw2ABqA')).balance).toEqual(23111222);
+    expect((await pst.currentBalance(walletAddress)).balance).toEqual(555669);
+    expect((await syncPst.currentBalance(walletAddress)).balance).toEqual(555669);
+    expect(dreCalls.diff()).toEqual(4);
+  });
+
+  it('should properly transfer tokens and ignore remote source', async () => {
+    const dreCalls = remoteCalls.measure();
+    await pst.transfer({
+      target: 'uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M',
+      qty: 100
+    });
+
+    await mineBlock(warp);
+    const state = await pst.readState();
+    responseData.sortKey = state.sortKey;
+    responseData.state = state.cachedValue.state;
+
+    expect((await pst.currentState()).balances[walletAddress]).toEqual(555669 - 100);
+    expect((await pst.currentState()).balances['uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M']).toEqual(10000000 + 100);
+    expect(dreCalls.diff()).toEqual(0);
+  });
+
+  it('should transfer tokens and read state from remote source', async () => {
+    const dreCalls = remoteCalls.measure();
+    await pst.transfer({
+      target: 'uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M',
+      qty: 450
+    });
+
+    await mineBlock(warp);
+
+    expect((await pst.currentState()).balances[walletAddress]).toEqual(555669 - 550);
+    expect((await pst.currentState()).balances['uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M']).toEqual(10000000 + 550);
+
+    const syncPst = await autoSyncPst();
+    expect((await syncPst.currentState()).balances['uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M']).toEqual(10000000 + 100);
+    expect((await syncPst.currentState()).balances[walletAddress]).toEqual(555669 - 100);
+
+    syncPst.setEvaluationOptions({
+      remoteStateSyncEnabled: false
+    })
+    expect((await syncPst.currentState()).balances[walletAddress]).toEqual(555669 - 550);
+    expect((await syncPst.currentState()).balances['uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M']).toEqual(
+      10000000 + 550);
+    expect(dreCalls.diff()).toEqual(2);
+  });
+
+  it('should read pst state for previous sortKey', async () => {
+    const dreCalls = remoteCalls.measure();
+
+    const state = await pst.readState(firstSortKey);
+    expect(state.cachedValue.state.balances['uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M']).toEqual(10000000);
+    expect(state.cachedValue.state.balances['33F0QHcb22W7LwWR1iRC8Az1ntZG09XQ03YWuw2ABqA']).toEqual(23111222);
+
+    expect(state.cachedValue.state).toEqual(initialState);
+    const syncPst = await autoSyncPst();
+
+
+    const syncState = (await syncPst.readState(firstSortKey));
+    expect(await syncState.cachedValue.state).toEqual(initialState);
+    expect(syncState.cachedValue.state.balances['uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M']).toEqual(10000000);
+    expect(syncState.cachedValue.state.balances['33F0QHcb22W7LwWR1iRC8Az1ntZG09XQ03YWuw2ABqA']).toEqual(23111222);
+    expect(dreCalls.diff()).toEqual(1);
+  });
+
+});

src/__tests__/integration/basic/pst-kv-auto-sync.test.ts

@@ -0,0 +1,219 @@
+import fs from 'fs';
+
+import ArLocal from 'arlocal';
+import Arweave from 'arweave';
+import { JWKInterface } from 'arweave/node/lib/wallet';
+import path from 'path';
+import { mineBlock } from '../_helpers';
+import { PstState, PstContract } from '../../../contract/PstContract';
+import { Warp } from '../../../core/Warp';
+import { DEFAULT_LEVEL_DB_LOCATION, defaultCacheOptions, WarpFactory } from "../../../core/WarpFactory";
+import { LoggerFactory } from '../../../logging/LoggerFactory';
+import { DeployPlugin } from "warp-contracts-plugin-deploy";
+
+// note: each tests suit (i.e. file with tests that Jest is running concurrently
+// with another files has to have ArLocal set to a different port!)
+const AR_PORT = 1826;
+
+
+describe('Testing the Profit Sharing Token', () => {
+  let contractSrc: string;
+
+  let wallet: JWKInterface;
+  let walletAddress: string;
+
+  let initialState: PstState;
+
+  let arweave: Arweave;
+  let arlocal: ArLocal;
+  let warp: Warp;
+  let contractTxId: string;
+  let pst: PstContract;
+
+  const actualFetch = global.fetch
+  let responseData = {
+    sortKey: "",
+    state: {}
+  }
+  const remoteCalls = {
+    total: 0,
+    measure: function() {
+      const self = this;
+      const start = self.total;
+      return {
+        diff: () => self.total - start
+      }
+    }
+  }
+
+  const localWarp = async function() {
+    if (!arlocal) {
+      arlocal = new ArLocal(AR_PORT, false);
+      await arlocal.start();
+
+      arweave = Arweave.init({
+        host: 'localhost',
+        port: AR_PORT,
+        protocol: 'http'
+      })
+    }
+
+    return WarpFactory.forLocal(AR_PORT, arweave, { ...defaultCacheOptions, inMemory: true }).use(new DeployPlugin());
+  }
+
+  const autoSyncPst = async function() {
+    // const autoSyncPst = warp.pst(contractTxId);
+    const autoSyncPst = (await localWarp()).pst(contractTxId);
+    autoSyncPst.setEvaluationOptions({
+      remoteStateSyncEnabled: true
+    })
+    return autoSyncPst;
+  }
+
+  beforeAll(async () => {
+    LoggerFactory.INST.logLevel('error');
+
+    warp = await localWarp();
+    ({ jwk: wallet, address: walletAddress } = await warp.generateWallet());
+
+    contractSrc = fs.readFileSync(path.join(__dirname, '../data/kv-storage.js'), 'utf8');
+    const stateFromFile: PstState = JSON.parse(fs.readFileSync(path.join(__dirname, '../data/token-pst.json'), 'utf8'));
+
+    initialState = {
+      ...stateFromFile,
+      ...{
+        owner: walletAddress
+      }
+    };
+
+    // deploying contract using the new SDK.
+    ({ contractTxId } = await warp.deploy({
+      wallet,
+      initState: JSON.stringify(initialState),
+      src: contractSrc,
+      evaluationManifest: {
+        evaluationOptions: {
+          useKVStorage: true,
+        }
+      }
+    }));
+
+    pst = warp.pst(contractTxId);
+    pst.connect(wallet);
+
+    await mineBlock(warp);
+
+    jest
+      .spyOn(global, 'fetch')
+      .mockImplementation( async (input: string, init) => {
+        if (input.includes(pst.evaluationOptions().remoteStateSyncSource)) {
+          remoteCalls.total++;
+          return Promise.resolve({ json: () => Promise.resolve(responseData), ok: true, status: 200 }) as Promise<Response>;
+        }
+        return actualFetch(input, init);
+      })
+  });
+
+  afterAll(async () => {
+    await arlocal.stop();
+    jest.restoreAllMocks();
+    fs.rmSync(`${DEFAULT_LEVEL_DB_LOCATION}/kv/ldb/${contractTxId}`, { recursive: true });
+  });
+
+  it('should initialize', async () => {
+    // this is done to "initialize" the state
+    await pst.writeInteraction({
+      function: 'mint',
+      target: 'uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M',
+      qty: 10000000
+    });
+    await mineBlock(warp);
+
+    await pst.writeInteraction({
+      function: 'mint',
+      target: '33F0QHcb22W7LwWR1iRC8Az1ntZG09XQ03YWuw2ABqA',
+      qty: 23111222
+    });
+    await mineBlock(warp);
+
+    await pst.writeInteraction({
+      function: 'mint',
+      target: walletAddress,
+      qty: 555669
+    });
+    await mineBlock(warp);
+  });
+
+  it('should properly transfer tokens and ignore remote source', async () => {
+    const dreCalls = remoteCalls.measure();
+    await pst.transfer({
+      target: 'uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M',
+      qty: 100
+    });
+
+    await mineBlock(warp);
+    const state = await pst.readState();
+    responseData.sortKey = state.sortKey;
+    responseData.state = state.cachedValue.state;
+
+    expect((await pst.currentBalance(walletAddress)).balance).toEqual(555669 - 100);
+    expect((await pst.currentBalance('uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M')).balance).toEqual(10000000 + 100);
+    expect(dreCalls.diff()).toEqual(0);
+  });
+
+  it('should properly transfer tokens and read state from remote source', async () => {
+    const dreCalls = remoteCalls.measure();
+    await pst.transfer({
+      target: 'uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M',
+      qty: 400
+    });
+
+    await mineBlock(warp);
+
+    expect((await pst.currentBalance(walletAddress)).balance).toEqual(555669 - 500);
+    expect((await pst.currentBalance('uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M')).balance).toEqual(10000000 + 500);
+
+    expect(dreCalls.diff()).toEqual(0);
+  });
+
+  it('should properly read storage value', async () => {
+    expect((await pst.getStorageValues([walletAddress])).cachedValue.get(walletAddress)).toEqual(555669 - 500);
+    expect(
+      (await pst.getStorageValues(['uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M'])).cachedValue.get(
+        'uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M'
+      )
+    ).toEqual(10000000 + 500);
+    expect(
+      (await pst.getStorageValues(['33F0QHcb22W7LwWR1iRC8Az1ntZG09XQ03YWuw2ABqA'])).cachedValue.get(
+        '33F0QHcb22W7LwWR1iRC8Az1ntZG09XQ03YWuw2ABqA'
+      )
+    ).toEqual(23111222);
+    expect((await pst.getStorageValues(['foo'])).cachedValue.get('foo')).toBeNull();
+    fs.rmSync(`${DEFAULT_LEVEL_DB_LOCATION}/kv/ldb/${contractTxId}`, { recursive: true });
+  });
+
+  it('should properly calculate kv storage with auto sync', async () => {
+    const dreCalls = remoteCalls.measure();
+
+    const syncPst = await autoSyncPst();
+
+    expect(await syncPst.currentState()).toEqual(initialState);
+    expect((await syncPst.currentBalance(walletAddress)).balance).toEqual(555669 - 500);
+    expect((await syncPst.currentBalance('uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M')).balance).toEqual(10000000 + 500);
+
+    expect((await syncPst.getStorageValues([walletAddress])).cachedValue.get(walletAddress)).toEqual(555669 - 500);
+    expect(
+      (await syncPst.getStorageValues(['uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M'])).cachedValue.get(
+        'uhE-QeYS8i4pmUtnxQyHD7dzXFNaJ9oMK-IM-QPNY6M'
+      )
+    ).toEqual(10000000 + 500);
+    expect(
+      (await syncPst.getStorageValues(['33F0QHcb22W7LwWR1iRC8Az1ntZG09XQ03YWuw2ABqA'])).cachedValue.get(
+        '33F0QHcb22W7LwWR1iRC8Az1ntZG09XQ03YWuw2ABqA'
+      )
+    ).toEqual(23111222);
+    expect((await syncPst.getStorageValues(['foo'])).cachedValue.get('foo')).toBeNull();
+    expect(dreCalls.diff()).toEqual(0);
+  });
+
+});

src/__tests__/unit/evaluation-options.test.ts

@@ -17,6 +17,8 @@ describe('Evaluation options evaluator', () => {
       maxCallDepth: 7,
       maxInteractionEvaluationTimeSeconds: 60,
       mineArLocalBlocks: true,
+      remoteStateSyncEnabled: false,
+      remoteStateSyncSource: "https://dre-1.warp.cc/contract",
       sequencerUrl: 'https://d1o5nlqr4okus2.cloudfront.net/',
       sourceType: SourceType.BOTH,
       stackTrace: {
@@ -54,6 +56,8 @@ describe('Evaluation options evaluator', () => {
       maxCallDepth: 7,
       maxInteractionEvaluationTimeSeconds: 60,
       mineArLocalBlocks: true,
+      remoteStateSyncEnabled: false,
+      remoteStateSyncSource: "https://dre-1.warp.cc/contract",
       sequencerUrl: 'https://d1o5nlqr4okus2.cloudfront.net/',
       sourceType: SourceType.BOTH,
       stackTrace: {
@@ -85,7 +89,8 @@ describe('Evaluation options evaluator', () => {
       maxCallDepth: 5,
       maxInteractionEvaluationTimeSeconds: 60,
       mineArLocalBlocks: true,
-      sequencerUrl: 'https://d1o5nlqr4okus2.cloudfront.net/',
+      remoteStateSyncEnabled: false,
+      remoteStateSyncSource: "https://dre-1.warp.cc/contract",      sequencerUrl: 'https://d1o5nlqr4okus2.cloudfront.net/',
       sourceType: 'both',
       stackTrace: {
         saveState: false

src/contract/Contract.ts

@@ -21,6 +21,18 @@ export interface WriteInteractionResponse {
   originalTxId: string;
 }
 
+export interface DREContractStatusResponse<State> {
+  status: string;
+  contractTxId: string;
+  state: State;
+  validity: Record<string, boolean>;
+  errorMessages: Record<string, string>;
+  sortKey: string;
+  timestamp: string;
+  signature: string;
+  stateHash: string;
+}
+
 export type WarpOptions = {
   vrf?: boolean;
   disableBundling?: boolean;

src/contract/EvaluationOptionsEvaluator.ts

@@ -104,6 +104,8 @@ export class EvaluationOptionsEvaluator {
     walletBalanceUrl: () => this.rootOptions['walletBalanceUrl'],
     mineArLocalBlocks: () => this.rootOptions['mineArLocalBlocks'],
     cacheEveryNInteractions: () => this.rootOptions['cacheEveryNInteractions'],
+    remoteStateSyncEnabled: () => this.rootOptions['remoteStateSyncEnabled'],
+    remoteStateSyncSource: () => this.rootOptions['remoteStateSyncSource'],
     useKVStorage: (foreignOptions) => foreignOptions['useKVStorage']
   };
 

src/contract/HandlerBasedContract.ts

@@ -20,7 +20,14 @@ import { LoggerFactory } from '../logging/LoggerFactory';
 import { Evolve } from '../plugins/Evolve';
 import { ArweaveWrapper } from '../utils/ArweaveWrapper';
 import { sleep } from '../utils/utils';
-import { BenchmarkStats, Contract, InnerCallData, WriteInteractionOptions, WriteInteractionResponse } from './Contract';
+import {
+  BenchmarkStats,
+  Contract,
+  DREContractStatusResponse,
+  InnerCallData,
+  WriteInteractionOptions,
+  WriteInteractionResponse
+} from './Contract';
 import { ArTransfer, ArWallet, emptyTransfer, Tags } from './deploy/CreateContract';
 import { InnerWritesEvaluator } from './InnerWritesEvaluator';
 import { generateMockVrf } from '../utils/vrf';
@@ -58,6 +65,7 @@ export class HandlerBasedContract<State> implements Contract<State> {
   private _children: HandlerBasedContract<unknown>[] = [];
 
   private _uncommittedStates = new Map<string, EvalStateResult<unknown>>();
+  private _dreStates = new Map<string, SortKeyCacheResult<EvalStateResult<State>>>();
 
   private readonly mutex = new Mutex();
 
@@ -471,13 +479,14 @@ export class HandlerBasedContract<State> implements Contract<State> {
     const { definitionLoader, interactionsLoader, stateEvaluator } = this.warp;
 
     const benchmark = Benchmark.measure();
-    const cachedState = await stateEvaluator.latestAvailableState<State>(contractTxId, upToSortKey);
+    let cachedState = await stateEvaluator.latestAvailableState<State>(contractTxId, upToSortKey);
 
     this.logger.debug('cache lookup', benchmark.elapsed());
     benchmark.reset();
 
     const evolvedSrcTxId = Evolve.evolvedSrcTxId(cachedState?.cachedValue?.state);
-    let handler, contractDefinition, sortedInteractions, contractEvaluationOptions;
+    let handler, contractDefinition, contractEvaluationOptions, remoteState;
+    let sortedInteractions = interactions || [];
 
     this.logger.debug('Cached state', cachedState, upToSortKey);
 
@@ -502,22 +511,29 @@ export class HandlerBasedContract<State> implements Contract<State> {
       contractDefinition = await definitionLoader.load<State>(contractTxId, evolvedSrcTxId);
       contractEvaluationOptions = this.resolveEvaluationOptions(contractDefinition.manifest?.evaluationOptions);
 
-      sortedInteractions = interactions
-        ? interactions
-        : await interactionsLoader.load(
-            contractTxId,
-            cachedState?.sortKey,
-            this.getToSortKey(upToSortKey),
-            contractEvaluationOptions
-          );
+      if (contractEvaluationOptions.remoteStateSyncEnabled && !contractEvaluationOptions.useKVStorage) {
+        remoteState = await this.getRemoteContractState(contractTxId);
+        cachedState = await this.maybeSyncStateWithRemoteSource(remoteState, upToSortKey, cachedState);
+      }
 
-      // (2) ...but we still need to return only interactions up to original "upToSortKey"
+      if (!remoteState && sortedInteractions.length == 0) {
+        sortedInteractions = await interactionsLoader.load(
+          contractTxId,
+          cachedState?.sortKey,
+          this.getToSortKey(upToSortKey),
+          contractEvaluationOptions
+        );
+      }
+
+      // we still need to return only interactions up to original "upToSortKey"
       if (cachedState?.sortKey) {
         sortedInteractions = sortedInteractions.filter((i) => i.sortKey.localeCompare(cachedState?.sortKey) > 0);
       }
+
       if (upToSortKey) {
         sortedInteractions = sortedInteractions.filter((i) => i.sortKey.localeCompare(upToSortKey) <= 0);
       }
+
       this.logger.debug('contract and interactions load', benchmark.elapsed());
       if (this.isRoot() && sortedInteractions.length) {
         // note: if the root contract has zero interactions, it still should be safe
@@ -563,6 +579,29 @@ export class HandlerBasedContract<State> implements Contract<State> {
     return this.getRootEoEvaluator().forForeignContract(rootManifestEvalOptions);
   }
 
+  private async getRemoteContractState(contractId: string): Promise<SortKeyCacheResult<EvalStateResult<State>>> {
+    if (this.hasDreState(contractId)) {
+      return this.getDreState(contractId);
+    } else {
+      const dreResponse = await this.fetchRemoteContractState(contractId);
+      if (dreResponse != null) {
+        return this.setDREState(contractId, dreResponse);
+      }
+      return null;
+    }
+  }
+
+  private async fetchRemoteContractState(contractId: string): Promise<DREContractStatusResponse<State> | null> {
+    return this.warpFetchWrapper
+      .fetch(`${this._evaluationOptions.remoteStateSyncSource}?id=${contractId}&events=false`)
+      .then((res) => {
+        return res.ok ? res.json() : Promise.reject(res);
+      })
+      .catch((error) => {
+        throw new Error(`Unable to read contract state from DRE. ${error.status}. ${error.body?.message}`);
+      });
+  }
+
   private getToSortKey(upToSortKey?: string) {
     if (this._parentContract?.rootSortKey) {
       if (!upToSortKey) {
@@ -599,6 +638,7 @@ export class HandlerBasedContract<State> implements Contract<State> {
       this.warp.interactionsLoader.clearCache();
       this._children = [];
       this._uncommittedStates = new Map();
+      this._dreStates = new Map();
     }
   }
 
@@ -820,7 +860,7 @@ export class HandlerBasedContract<State> implements Contract<State> {
         throw new Error(`Unable to retrieve state. ${error.status}: ${error.body?.message}`);
       });
 
-    await stateEvaluator.syncState(this._contractTxId, response.sortKey, response.state, response.validity);
+    await stateEvaluator.syncState<State>(this._contractTxId, response.sortKey, response.state, response.validity);
 
     return this;
   }
@@ -900,6 +940,55 @@ export class HandlerBasedContract<State> implements Contract<State> {
     }
   }
 
+  private async maybeSyncStateWithRemoteSource(
+    remoteState: SortKeyCacheResult<EvalStateResult<State>>,
+    upToSortKey: string,
+    cachedState: SortKeyCacheResult<EvalStateResult<State>>
+  ): Promise<SortKeyCacheResult<EvalStateResult<State>>> {
+    const { stateEvaluator } = this.warp;
+    if (this.isStateHigherThanAndUpTo(remoteState, cachedState?.sortKey, upToSortKey)) {
+      return await stateEvaluator.syncState<State>(
+        this._contractTxId,
+        remoteState.sortKey,
+        remoteState.cachedValue.state,
+        remoteState.cachedValue.validity
+      );
+    }
+    return cachedState;
+  }
+
+  private isStateHigherThanAndUpTo(
+    remoteState: SortKeyCacheResult<EvalStateResult<State>>,
+    fromSortKey: string,
+    upToSortKey: string
+  ) {
+    return (
+      remoteState &&
+      (!upToSortKey || upToSortKey >= remoteState.sortKey) &&
+      (!fromSortKey || remoteState.sortKey > fromSortKey)
+    );
+  }
+
+  setDREState(
+    contractTxId: string,
+    result: DREContractStatusResponse<State>
+  ): SortKeyCacheResult<EvalStateResult<State>> {
+    const dreCachedState = new SortKeyCacheResult(
+      result.sortKey,
+      new EvalStateResult(result.state, {}, result.errorMessages)
+    );
+    this.getRoot()._dreStates.set(contractTxId, dreCachedState);
+    return dreCachedState;
+  }
+
+  getDreState(contractTxId: string): SortKeyCacheResult<EvalStateResult<State>> {
+    return this.getRoot()._dreStates.get(contractTxId) as SortKeyCacheResult<EvalStateResult<State>>;
+  }
+
+  hasDreState(contractTxId: string): boolean {
+    return this.getRoot()._dreStates.has(contractTxId);
+  }
+
   private getRoot(): HandlerBasedContract<unknown> {
     let result: Contract = this;
     while (!result.isRoot()) {

src/core/modules/StateEvaluator.ts

@@ -68,7 +68,12 @@ export interface StateEvaluator {
   /**
    * allows to syncState with an external state source (like Warp Distributed Execution Network)
    */
-  syncState(contractTxId: string, sortKey: string, state: unknown, validity: Record<string, boolean>): Promise<void>;
+  syncState<State>(
+    contractTxId: string,
+    sortKey: string,
+    state: State,
+    validity: Record<string, boolean>
+  ): Promise<SortKeyCacheResult<EvalStateResult<State>>>;
 
   internalWriteState<State>(
     contractTxId: string,
@@ -142,6 +147,10 @@ export class DefaultEvaluationOptions implements EvaluationOptions {
   cacheEveryNInteractions = -1;
 
   useKVStorage = false;
+
+  remoteStateSyncEnabled = false;
+
+  remoteStateSyncSource = 'https://dre-1.warp.cc/contract';
 }
 
 // an interface for the contract EvaluationOptions - can be used to change the behaviour of some features.
@@ -226,4 +235,10 @@ export interface EvaluationOptions {
 
   // whether a separate key-value storage should be used for the contract
   useKVStorage: boolean;
+
+  // whether contract state should be acquired from remote source, e.g. D.R.E.
+  remoteStateSyncEnabled: boolean;
+
+  // remote source for fetching most recent contract state, only applicable if remoteStateSyncEnabled is set to true
+  remoteStateSyncSource: string;
 }

src/core/modules/impl/CacheableStateEvaluator.ts

@@ -187,14 +187,15 @@ export class CacheableStateEvaluator extends DefaultStateEvaluator {
     await this.cache.put(new CacheKey(contractTxId, transaction.sortKey), stateToCache);
   }
 
-  async syncState(
+  async syncState<State>(
     contractTxId: string,
     sortKey: string,
-    state: unknown,
+    state: State,
     validity: Record<string, boolean>
-  ): Promise<void> {
+  ): Promise<SortKeyCacheResult<EvalStateResult<State>>> {
     const stateToCache = new EvalStateResult(state, validity, {});
     await this.cache.put(new CacheKey(contractTxId, sortKey), stateToCache);
+    return new SortKeyCacheResult(sortKey, stateToCache);
   }
 
   // eslint-disable-next-line @typescript-eslint/no-explicit-any

src/core/modules/impl/DefaultStateEvaluator.ts

@@ -392,12 +392,12 @@ export abstract class DefaultStateEvaluator implements StateEvaluator {
     state: EvalStateResult<State>
   ): Promise<void>;
 
-  abstract syncState(
+  abstract syncState<State>(
     contractTxId: string,
     sortKey: string,
-    state: unknown,
+    state: State,
     validity: Record<string, boolean>
-  ): Promise<void>;
+  ): Promise<SortKeyCacheResult<EvalStateResult<State>>>;
 
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   abstract dumpCache(): Promise<any>;