Support pausing and resuming scanning (#39)

Author: dguenther

packages/mobile-app/app/(tabs)/contacts.tsx

@@ -1,19 +1,40 @@
 import { Button } from "@ironfish/ui";
 import { View, Text } from "react-native";
-import { wallet } from "../../data/wallet/wallet";
 
-import { Network } from "../../data/constants";
+import { useFacade } from "../../data/facades";
 
 export default function Contacts() {
+  const facade = useFacade();
+
+  const walletStatus = facade.getWalletStatus.useQuery(undefined, {
+    refetchInterval: 1000,
+  });
+
+  const pauseSyncing = facade.pauseSyncing.useMutation();
+  const resumeSyncing = facade.resumeSyncing.useMutation();
+
   return (
     <View>
-      <Text>Contacts</Text>
+      {walletStatus.data && (
+        <>
+          <Text>{`Scan status: ${walletStatus.data.status}`}</Text>
+          <Text>{`Latest known block: ${walletStatus.data.latestKnownBlock}`}</Text>
+        </>
+      )}
+      <Text>{}</Text>
+      <Button
+        onPress={async () => {
+          await resumeSyncing.mutateAsync(undefined);
+        }}
+      >
+        Resume Syncing
+      </Button>
       <Button
-        onPress={() => {
-          wallet.scan(Network.TESTNET);
+        onPress={async () => {
+          await pauseSyncing.mutateAsync(undefined);
         }}
       >
-        Request Blocks
+        Pause Syncing
       </Button>
     </View>
   );

packages/mobile-app/data/blockchain.ts

@@ -122,6 +122,7 @@ class BlockchainClass {
     start: { hash: Uint8Array; sequence: number },
     end: { hash: Uint8Array; sequence: number },
     onBlock: (block: LightBlock) => unknown,
+    abort: AbortSignal,
   ) {
     await this.lockRequest(async () => {
       const manifest = await WalletServerChunksApi.getChunksManifest(network);
@@ -131,6 +132,8 @@ class BlockchainClass {
       let lastHash: null | Uint8Array = null;
 
       const onBlockInner = (block: LightBlock) => {
+        if (abort.aborted) return;
+
         // TODO: Errors thrown here don't propagate
         if (!lastHash && !Uint8ArrayUtils.areEqual(block.hash, start.hash)) {
           console.error(
@@ -170,8 +173,13 @@ class BlockchainClass {
           chunk.range.start <= end.sequence,
       );
       for (const chunk of finalizedChunks) {
+        if (abort.aborted) break;
+
         await WalletServerChunksApi.getChunkBlockAndByteRanges(network, chunk);
+
+        if (abort.aborted) break;
         readPromise = readPromise.then(async () => {
+          if (abort.aborted) return;
           await WalletServerChunksApi.readChunkBlocks(
             network,
             chunk,
@@ -187,14 +195,20 @@ class BlockchainClass {
       const downloadSize = 100;
 
       for (let i = serverStart; i <= lastSequence; i += downloadSize) {
+        if (abort.aborted) break;
+
         const endIndex = Math.min(i + downloadSize - 1, lastSequence);
         console.log("fetching blocks from wallet server", i, endIndex);
         const download = await WalletServerApi.getBlockRange(
           network,
           i,
           endIndex,
         );
+
+        if (abort.aborted) break;
+
         readPromise = readPromise.then(async () => {
+          if (abort.aborted) return;
           await this.readWalletServerBlocks(download, onBlockInner);
         });
       }

packages/mobile-app/data/chainProcessor.ts

@@ -19,21 +19,24 @@ import * as Uint8ArrayUtils from "../utils/uint8Array";
  */
 export class ChainProcessor {
   readonly network: Network;
+  abort: AbortSignal;
   head: Readonly<{ hash: Uint8Array; sequence: number }> | null = null;
   onAdd: (block: LightBlock) => unknown;
   onRemove: (block: LightBlock) => unknown;
 
   constructor(options: {
     network: Network;
+    abort: AbortSignal;
     onAdd: (block: LightBlock) => unknown;
     onRemove: (block: LightBlock) => unknown;
   }) {
     this.network = options.network;
+    this.abort = options.abort;
     this.onAdd = options.onAdd;
     this.onRemove = options.onRemove;
   }
 
-  async update({ signal }: { signal?: AbortSignal } = {}): Promise<{
+  async update(): Promise<{
     hashChanged: boolean;
   }> {
     const oldHash = this.head;
@@ -65,17 +68,26 @@ export class ChainProcessor {
     }
 
     for (const block of result.blocksToRemove) {
+      if (this.abort.aborted)
+        return { hashChanged: !oldHash || this.head.hash !== oldHash.hash };
+
       this.onRemove(block);
       this.head = {
         hash: block.previousBlockHash,
         sequence: block.sequence - 1,
       };
     }
 
-    await Blockchain.iterateTo(this.network, this.head, chainHead, (block) => {
-      this.onAdd(block);
-      this.head = { hash: block.hash, sequence: block.sequence };
-    });
+    await Blockchain.iterateTo(
+      this.network,
+      this.head,
+      chainHead,
+      (block) => {
+        this.onAdd(block);
+        this.head = { hash: block.hash, sequence: block.sequence };
+      },
+      this.abort,
+    );
 
     return { hashChanged: !oldHash || this.head.hash !== oldHash.hash };
   }

packages/mobile-app/data/facades/wallet/demoHandlers.ts

@@ -70,7 +70,7 @@ const ACCOUNTS: Account[] = [
 ];
 
 const WALLET_STATUS: WalletStatus = {
-  status: "SYNCING",
+  status: "SCANNING",
   latestKnownBlock: 523142,
 };
 
@@ -293,7 +293,7 @@ export const walletDemoHandlers = f.facade<WalletHandlers>({
     },
   ),
   resumeSyncing: f.handler.mutation(async () => {
-    WALLET_STATUS.status = "SYNCING";
+    WALLET_STATUS.status = "SCANNING";
   }),
   sendTransaction: f.handler.mutation(
     async (args: {

packages/mobile-app/data/facades/wallet/handlers.ts

@@ -18,6 +18,7 @@ import {
   LanguageUtils,
   TransactionStatus,
 } from "@ironfish/sdk";
+import { WalletServerApi } from "../../api/walletServer";
 
 export const walletHandlers = f.facade<WalletHandlers>({
   createAccount: f.handler.mutation(
@@ -276,8 +277,8 @@ export const walletHandlers = f.facade<WalletHandlers>({
     },
   ),
   getWalletStatus: f.handler.query(async (): Promise<WalletStatus> => {
-    // TODO: Implement getWalletStatus
-    return { status: "PAUSED", latestKnownBlock: 0 };
+    const block = await WalletServerApi.getLatestBlock(Network.TESTNET);
+    return { status: wallet.scanState.type, latestKnownBlock: block.sequence };
   }),
   importAccount: f.handler.mutation(
     async ({
@@ -312,7 +313,9 @@ export const walletHandlers = f.facade<WalletHandlers>({
       };
     },
   ),
-  pauseSyncing: f.handler.mutation(async () => {}),
+  pauseSyncing: f.handler.mutation(async () => {
+    wallet.pauseScan();
+  }),
   removeAccount: f.handler.mutation(async ({ name }: { name: string }) => {
     await wallet.removeAccount(name);
   }),
@@ -321,7 +324,9 @@ export const walletHandlers = f.facade<WalletHandlers>({
       await wallet.renameAccount(name, newName);
     },
   ),
-  resumeSyncing: f.handler.mutation(async () => {}),
+  resumeSyncing: f.handler.mutation(async () => {
+    wallet.scan(Network.TESTNET);
+  }),
   sendTransaction: f.handler.mutation(
     async (args: {
       accountName: string;

packages/mobile-app/data/facades/wallet/types.ts

@@ -84,7 +84,7 @@ export type Burn = {
 };
 
 export type WalletStatus = {
-  status: "SYNCING" | "PAUSED";
+  status: "SCANNING" | "PAUSED" | "IDLE";
   latestKnownBlock: number;
 };
 

packages/mobile-app/data/wallet/wallet.ts

@@ -16,6 +16,13 @@ import { WalletServerApi } from "../api/walletServer";
 
 type StartedState = { type: "STARTED"; db: WalletDb };
 type WalletState = { type: "STOPPED" } | { type: "LOADING" } | StartedState;
+type ScanState =
+  // Not scanning, and a scan can be started
+  | { type: "IDLE" }
+  // Not scanning, and a scan cannot be started
+  | { type: "PAUSED" }
+  // Scanning
+  | { type: "SCANNING"; abort: AbortController };
 
 function assertStarted(state: WalletState): asserts state is StartedState {
   if (state.type !== "STARTED") {
@@ -25,6 +32,7 @@ function assertStarted(state: WalletState): asserts state is StartedState {
 
 class Wallet {
   state: WalletState = { type: "STOPPED" };
+  scanState: ScanState = { type: "IDLE" };
 
   async start() {
     if (this.state.type !== "STOPPED") {
@@ -376,14 +384,18 @@ class Wallet {
   async scan(network: Network): Promise<boolean> {
     assertStarted(this.state);
 
+    if (this.scanState.type === "SCANNING") {
+      return false;
+    }
+    const abort = new AbortController();
+    this.scanState = { type: "SCANNING", abort };
+
     const cache = new WriteCache(this.state.db, network);
 
     let blockProcess = Promise.resolve();
     let performanceTimer = performance.now();
     let finished = false;
 
-    // todo: lock scanning
-
     const dbAccounts = await this.state.db.getAccounts();
     let accounts = dbAccounts.map((account) => {
       return {
@@ -410,8 +422,13 @@ class Wallet {
 
     const chainProcessor = new ChainProcessor({
       network,
+      abort: abort.signal,
       onAdd: (block) => {
         blockProcess = blockProcess.then(async () => {
+          if (abort.signal.aborted) {
+            return;
+          }
+
           assertStarted(this.state);
 
           const prevHash = block.previousBlockHash;
@@ -546,6 +563,10 @@ class Wallet {
       },
       onRemove: (block) => {
         blockProcess = blockProcess.then(() => {
+          if (abort.signal.aborted) {
+            return;
+          }
+
           console.log(`Removing block ${block.sequence}`);
 
           for (const account of accounts) {
@@ -585,11 +606,24 @@ class Wallet {
       finished = true;
       clearTimeout(saveLoopTimeout);
       await saveLoop();
+      if (this.scanState.abort.signal.aborted) {
+        this.scanState = this.scanState = this.scanState.abort.signal.aborted
+          ? { type: "PAUSED" }
+          : { type: "IDLE" };
+      }
       console.log(`finished in ${performance.now() - performanceTimer}ms`);
     }
 
     return hashChanged;
   }
+
+  pauseScan() {
+    if (this.scanState.type === "SCANNING") {
+      this.scanState.abort.abort();
+    } else if (this.scanState.type === "IDLE") {
+      this.scanState = { type: "PAUSED" };
+    }
+  }
 }
 
 export const wallet = new Wallet();