Add timeout for fetching tokens (#1644)

* Add timeout for fetching tokens

* Improve timeout util (#1645)

* simplify type without casting

* default delay() return to void

* simplify timeout function logic

* improve timeout types

* use new timeout with automatic rejected Promise detection

* construct cacheKey once only

* throw proper Error

Co-authored-by: Velenir <[email protected]>

src/const.ts

@@ -21,6 +21,7 @@ import { Network } from 'types'
 import { DisabledTokensMaps, TokenOverride, AddressToOverrideMap } from 'types/config'
 
 export const BATCH_TIME_IN_MS = BATCH_TIME * 1000
+export const DEFAULT_TIMEOUT = 5000
 
 export const ZERO_BIG_NUMBER = new BigNumber(0)
 export const ONE_BIG_NUMBER = new BigNumber(1)

src/hooks/useTokenBalances.ts

@@ -7,7 +7,7 @@ import { erc20Api, depositApi } from 'api'
 import useSafeState from './useSafeState'
 import { useWalletConnection } from './useWalletConnection'
 
-import { formatSmart, logDebug, isTokenEnabled } from 'utils'
+import { formatSmart, logDebug, isTokenEnabled, timeout, notEmpty } from 'utils'
 import { TokenBalanceDetails, TokenDetails } from 'types'
 import { WalletInfo } from 'api/wallet/WalletApi'
 import { PendingFlux } from 'api/deposit/DepositApi'
@@ -34,6 +34,7 @@ async function fetchBalancesForToken(
   networkId: number,
 ): Promise<TokenBalanceDetails> {
   const tokenAddress = token.address
+
   const [
     exchangeBalance,
     pendingDeposit,
@@ -83,29 +84,40 @@ async function _getBalances(walletInfo: WalletInfo, tokens: TokenDetails[]): Pro
   const contractAddress = depositApi.getContractAddress(networkId)
   assert(contractAddress, 'No valid contract address found. Stopping.')
 
-  const balancePromises: Promise<TokenBalanceDetails | null>[] = tokens.map((token) =>
-    fetchBalancesForToken(token, userAddress, contractAddress, networkId)
-      .then((balance) => {
-        const cacheKey = constructCacheKey({ token, userAddress, contractAddress, networkId })
+  const balancePromises: Promise<TokenBalanceDetails | null>[] = tokens.map((token) => {
+    const cacheKey = constructCacheKey({ token, userAddress, contractAddress, networkId })
+
+    // timoutPromise == Promise<never>, correctly determined to always throw
+    const timeoutPromise = timeout({
+      timeoutErrorMsg: 'Timeout fetching balances for ' + token.address,
+    })
+
+    const fetchBalancesPromise = fetchBalancesForToken(token, userAddress, contractAddress, networkId).then(
+      (balance) => {
         balanceCache[cacheKey] = balance
         return balance
-      })
-      .catch((e) => {
-        console.error('[useTokenBalances] Error for', token, userAddress, contractAddress, e)
+      },
+    )
 
-        const cacheKey = constructCacheKey({ token, userAddress, contractAddress, networkId })
+    // balancePromise == Promise<TokenBalanceDetails | never> == Promise<TokenBalanceDetails> or throws
+    const balancePromise = Promise.race([fetchBalancesPromise, timeoutPromise])
 
-        const cachedValue = balanceCache[cacheKey]
-        if (cachedValue) {
-          logDebug('Using cached value for', token, userAddress, contractAddress)
-          return cachedValue
-        }
+    return balancePromise.catch((e) => {
+      console.error('[useTokenBalances] Error for', token, userAddress, contractAddress, e)
+      const cachedValue = balanceCache[cacheKey]
+      if (cachedValue) {
+        logDebug('Using cached value for', token, userAddress, contractAddress)
+        return cachedValue
+      }
+
+      return null
+    })
+  })
 
-        return null
-      }),
-  )
   const balances = await Promise.all(balancePromises)
-  return balances.filter(Boolean) as TokenBalanceDetails[]
+
+  // TODO: Would be better to show the errored tokens in error state
+  return balances.filter(notEmpty)
 }
 
 export const useTokenBalances = (passOnParams: Partial<UseTokenListParams> = {}): UseBalanceResult => {

src/utils/miscellaneous.ts

@@ -5,7 +5,7 @@ import { TokenDetails, Unpromise } from 'types'
 import { AssertionError } from 'assert'
 import { AuctionElement, Trade, Order } from 'api/exchange/ExchangeApi'
 import { batchIdToDate } from './time'
-import { ORDER_FILLED_FACTOR, MINIMUM_ALLOWANCE_DECIMALS } from 'const'
+import { ORDER_FILLED_FACTOR, MINIMUM_ALLOWANCE_DECIMALS, DEFAULT_TIMEOUT } from 'const'
 import { TEN, ZERO } from '@gnosis.pm/dex-js'
 
 export function assertNonNull<T>(val: T, message: string): asserts val is NonNullable<T> {
@@ -72,7 +72,8 @@ export function getToken<T extends TokenDetails, K extends keyof T>(
   return token
 }
 
-export const delay = <T>(ms = 100, result?: T): Promise<T> => new Promise((resolve) => setTimeout(resolve, ms, result))
+export const delay = <T = void>(ms = 100, result?: T): Promise<T> =>
+  new Promise((resolve) => setTimeout(resolve, ms, result))
 
 /**
  * Uses images from https://github.com/trustwallet/tokens
@@ -210,3 +211,21 @@ export function notEmpty<TValue>(value: TValue | null | undefined): value is TVa
 }
 
 export const isNonZeroNumber = (value?: string | number): boolean => !!value && !!+value
+
+export interface TimeoutParams<T> {
+  time?: number
+  result?: T
+  timeoutErrorMsg?: string
+}
+
+export function timeout(params: TimeoutParams<undefined>): Promise<never> // never means function throws
+export function timeout<T>(params: TimeoutParams<T extends undefined ? never : T>): Promise<T>
+export async function timeout<T>(params: TimeoutParams<T>): Promise<T | never> {
+  const { time = DEFAULT_TIMEOUT, result, timeoutErrorMsg: timeoutMsg = 'Timeout' } = params
+
+  await delay(time)
+  // provided defined result -- return it
+  if (result !== undefined) return result
+  // no defined result -- throw message
+  throw new Error(timeoutMsg)
+}