Schedule cached wallets' engine startup behind a limited-concurrency queue

Wallets that emit from walletCache.json no longer race every other
wallet through repo sync, key derivation, and engine creation in the
seconds after login. Their heavy startup work now waits in a per-context
queue (8 at a time), while wallets without a cache bypass the queue
because they cannot emit at all until that work runs, keeping first
login identical to before.

Asking for a wallet moves it to the front of the line: the account's
waitForCurrencyWallet, the internal engine/storage waiters, and
changePaused(false) all bump the wallet's queued startup.

Author: j0ntz

src/core/account/account-api.ts

@@ -31,6 +31,7 @@ import {
 } from '../../types/types'
 import { makeEdgeResult } from '../../util/edgeResult'
 import { base58 } from '../../util/encoding'
+import { bumpEngineQueue } from '../currency/currency-selectors'
 import { saveWalletSettings } from '../currency/wallet/currency-wallet-files'
 import { getPublicWalletInfo } from '../currency/wallet/currency-wallet-pixie'
 import {
@@ -724,6 +725,10 @@ export function makeAccountApi(ai: ApiInput, accountId: string): EdgeAccount {
     },
 
     async waitForCurrencyWallet(walletId: string): Promise<EdgeCurrencyWallet> {
+      // Asking for a wallet is the "the user wants this one" signal,
+      // so move its engine startup to the front of the queue:
+      bumpEngineQueue(ai, walletId)
+
       return await new Promise((resolve, reject) => {
         const check = (): void => {
           const wallet = this.currencyWallets[walletId]

src/core/currency/currency-selectors.ts

@@ -4,6 +4,7 @@ import {
   EdgeTokenMap
 } from '../../types/types'
 import { ApiInput, RootProps } from '../root-pixie'
+import { getEngineScheduler } from './wallet/engine-scheduler'
 
 export function getCurrencyMultiplier(
   currencyInfo: EdgeCurrencyInfo,
@@ -47,6 +48,10 @@ export function waitForCurrencyWallet(
   ai: ApiInput,
   walletId: string
 ): Promise<EdgeCurrencyWallet> {
+  // Asking for a wallet is the "the user wants this one" signal,
+  // so move its engine startup to the front of the queue:
+  bumpEngineQueue(ai, walletId)
+
   const out: Promise<EdgeCurrencyWallet> = ai.waitFor(
     (props: RootProps): EdgeCurrencyWallet | undefined => {
       checkCurrencyWallet(props, walletId)
@@ -59,3 +64,13 @@ export function waitForCurrencyWallet(
   )
   return out
 }
+
+/**
+ * Prioritizes a wallet's engine startup when its startup work is still
+ * waiting in the limited-concurrency queue. Harmless otherwise.
+ */
+export function bumpEngineQueue(ai: ApiInput, walletId: string): void {
+  if (getEngineScheduler(ai.props.io).bump(walletId)) {
+    ai.props.log(`${walletId} engine startup bumped to front of queue`)
+  }
+}

src/core/currency/wallet/currency-wallet-api.ts

@@ -52,6 +52,7 @@ import { RootProps, toApiInput } from '../../root-pixie'
 import { makeLocalDisklet, makeRepoPaths } from '../../storage/repo'
 import { makeStorageWalletApi } from '../../storage/storage-api'
 import {
+  bumpEngineQueue,
   checkCurrencyWallet,
   getCurrencyMultiplier
 } from '../currency-selectors'
@@ -116,6 +117,9 @@ export function makeCurrencyWalletApi(
    * method call instead of a hang.
    */
   function getEngine(): Promise<EdgeCurrencyEngine> {
+    // The caller needs this engine now, so skip the startup queue:
+    bumpEngineQueue(ai, walletId)
+
     return ai.waitFor((props: RootProps): EdgeCurrencyEngine | undefined => {
       checkCurrencyWallet(props, walletId)
       return props.output.currency.wallets[walletId]?.engine
@@ -136,6 +140,10 @@ export function makeCurrencyWalletApi(
    * `addStorageWallet`, so the repo is never coming).
    */
   function getStorage(): Promise<true> {
+    // The repo loads inside the queued startup work, so a caller
+    // waiting on storage wants this wallet at the front too:
+    bumpEngineQueue(ai, walletId)
+
     return ai.waitFor((props: RootProps): true | undefined => {
       if (props.state.storageWallets[walletId] != null) return true
       checkCurrencyWallet(props, walletId)
@@ -314,6 +322,10 @@ export function makeCurrencyWalletApi(
 
     // Running state:
     async changePaused(paused: boolean): Promise<void> {
+      // Un-pausing means the app wants this wallet running,
+      // so align the startup queue with the caller's boot order:
+      if (!paused) bumpEngineQueue(ai, walletId)
+
       input.props.dispatch({
         type: 'CURRENCY_WALLET_CHANGED_PAUSED',
         payload: { walletId: input.props.walletId, paused }