Using caching service from cdpType

packages/dai-plugin-mcd/contracts/addresses/kovan.json

@@ -68,8 +68,7 @@
   "MCD_JOIN_KNC_A": "0xE42427325A0e4c8e194692FfbcACD92C2C381598",
   "MCD_FLIP_KNC_A": "0xf14Ec3538C86A31bBf576979783a8F6dbF16d571",
 
-  "MCD_FLIP_PSM_USDC_A": "0x481d4eb969a821B6A8137D9c352aA7a7cBc4C8F2"
+  "MCD_FLIP_PSM_USDC_A": "0x481d4eb969a821B6A8137D9c352aA7a7cBc4C8F2",
   "MCD_JOIN_PSM_USDC_A": "0xaf774866c4b165b88c558C7891290698cf7Ed6B5",
-  "PSM_USDC_A": "0xAfB79e262B7A07666161B95992934eB0AE230Fb4",
-
+  "PSM_USDC_A": "0xAfB79e262B7A07666161B95992934eB0AE230Fb4"
 }

packages/dai-plugin-mcd/contracts/addresses/mainnet.json

@@ -75,5 +75,4 @@
   "MCD_JOIN_PSM_USDC_A": "0xc2FB16712AD538EbcBabB00DfAC5fa511A4cc657",
   "MCD_FLIP_PSM_USDC_A": "0x481d4eb969a821B6A8137D9c352aA7a7cBc4C8F2",
   "PSM_USDC_A": "0xE13eF5966031A50A8df9D7612366a56e3BB36CB1"
-
 }

packages/dai-plugin-mcd/src/CdpType.js

@@ -6,13 +6,13 @@ import * as math from './math';
 
 export default class CdpType {
   constructor(
-    cdpTypeService,
+    typeService,
     { currency, ilk, decimals },
     options = { prefetch: true }
   ) {
     assert(currency && ilk, 'currency and ilk are required');
-    this._cdpTypeService = cdpTypeService;
-    this._systemData = cdpTypeService.get(ServiceRoles.SYSTEM_DATA);
+    this._cdpTypeService = typeService;
+    this._systemData = typeService.get(ServiceRoles.SYSTEM_DATA);
     this._web3Service = this._systemData.get('smartContract').get('web3');
     this.currency = currency;
     this.decimals = decimals || 18;
@@ -90,7 +90,7 @@ export default class CdpType {
     return this._prefetchPromise;
   }
 
-  async reset() {
+  reset() {
     this._prefetchPromise = null;
     this.cache = {};
   }

packages/dai-plugin-mcd/src/PsmType.js

@@ -1,20 +1,24 @@
 import assert from 'assert';
-import { stringToBytes } from './utils';
+import CdpType from './CdpType';
 
 export default class PsmType {
   constructor(
     psmTypeService,
     { currency, ilk, decimals },
-    options = { prefect: true }
+    options = { prefetch: true }
   ) {
     assert(currency && ilk, 'currency and ilk are required');
 
     this._psmTypeService = psmTypeService;
+    this._cdpType = new CdpType(
+      this._psmTypeService,
+      { currency, ilk, decimals },
+      options
+    );
     this.currency = currency;
     this.decimals = decimals;
     this.ilk = ilk;
-    this._ilkBytes = stringToBytes(this.ilk);
-    this.cache = {};
+    this._cache = {};
     if (options.prefetch) this.prefetch();
   }
 
@@ -26,17 +30,27 @@ export default class PsmType {
     return null;
   }
 
-  prefetch() {
-    return null;
+  async prefetch() {
+    if (!this._prefetchPromise) {
+      this._prefetchPromise = Promise.all([this._cdpType.prefetch()]);
+    }
+    return this._prefetchPromise;
+  }
+
+  reset() {
+    this._cdpType.reset();
+    this._cache = {};
   }
 
-  async reset() {
-    this._prefetchPromise = null;
-    this.cache = {};
+  cache() {
+    return {
+      ...this._cache,
+      ...this._cdpType.cache
+    };
   }
 
   _getCached(name) {
-    assert(this.cache[name], `${name} is not cached`);
-    return this.cache[name];
+    assert(this.cache()[name], `${name} is not cached`);
+    return this.cache()[name];
   }
 }

packages/dai-plugin-mcd/src/PsmTypeService.js

@@ -1,12 +1,13 @@
+import assert from 'assert';
+
 import { PublicService } from '@makerdao/services-core';
 import { ServiceRoles } from './constants';
 import PsmType from './PsmType';
-
-const { PSM_TYPE } = ServiceRoles;
+const { PSM_TYPE, SYSTEM_DATA } = ServiceRoles;
 
 export default class PsmService extends PublicService {
   constructor(name = PSM_TYPE) {
-    super(name);
+    super(name, [SYSTEM_DATA]);
     this.reset = this.resetAllPsmTypes;
   }
 
@@ -18,7 +19,26 @@ export default class PsmService extends PublicService {
   }
 
   async connect() {
-    if (this.settings.prefetch) await this.prefetchAllCdpTypes();
+    if (this.settings.prefetch) await this.prefetchAllPsmTypes();
+  }
+
+  getPsmType(currency, ilk) {
+    const types = this.psmTypes.filter(
+      t =>
+        (!currency || t.currency.symbol === currency.symbol) &&
+        (!ilk || ilk === t.ilk)
+    );
+    if (types.length === 1) return types[0];
+
+    const label = [
+      currency && `currency ${currency.symbol}`,
+      ilk && `ilk ${ilk}`
+    ]
+      .filter(x => x)
+      .join(', ');
+
+    assert(types.length <= 1, `${label} matches more than one psm type`);
+    assert(types.length > 0, `${label} matches no psm type`);
   }
 
   async prefetchAllPsmTypes() {

packages/dai-plugin-mcd/src/index.js

@@ -12,7 +12,7 @@ import SavingsService from './SavingsService';
 import CdpTypeService from './CdpTypeService';
 import AuctionService from './AuctionService';
 import SystemDataService from './SystemDataService';
-import PsmService from './PsmService';
+import PsmTypeService from './PsmTypeService';
 
 import { ServiceRoles as ServiceRoles_ } from './constants';
 import BigNumber from 'bignumber.js';
@@ -167,7 +167,7 @@ export const McdPlugin = {
       [SAVINGS]: SavingsService,
       [AUCTION]: AuctionService,
       [SYSTEM_DATA]: SystemDataService,
-      [PSM_TYPE]: [PsmService, { psmTypes, prefetch }]
+      [PSM_TYPE]: [PsmTypeService, { psmTypes, prefetch }]
     };
   }
 };