Fix for Flow issues in SimpleCacheProvider (facebook#12942)

* Fix for Flow issues in SimpleCacheProvider

**what is the change?:**
- Fixed some flow errors which were somehow swallowed when CI
originally
- Loosen flow types to avoid issue with recursive loop in Flow; facebook/flow#5870

**why make this change?:**
To unbreak master and unblock other changes we want to make.

**test plan:**
Flow passes!

**issue:**
facebook#12941

* Fix lints

Author: flarnie

packages/simple-cache-provider/src/SimpleCacheProvider.js

@@ -17,24 +17,34 @@ const Pending = 1;
 const Resolved = 2;
 const Rejected = 3;
 
-type EmptyRecord<K, V> = {|
+type EmptyRecord<K> = {|
   status: 0,
   suspender: null,
   key: K,
   value: null,
   error: null,
-  next: Record<K, V> | null,
-  previous: Record<K, V> | null,
+  next: any, // TODO: (issue #12941)
+  previous: any, // TODO: (issue #12941)
+  /**
+   * Proper types would be something like this:
+   * next: Record<K, V> | null,
+   * previous: Record<K, V> | null,
+   */
 |};
 
 type PendingRecord<K, V> = {|
   status: 1,
-  suspender: Promise<K, V>,
+  suspender: Promise<V>,
   key: K,
   value: null,
   error: null,
-  next: Record<K, V> | null,
-  previous: Record<K, V> | null,
+  next: any, // TODO: (issue #12941)
+  previous: any, // TODO: (issue #12941)
+  /**
+   * Proper types would be something like this:
+   * next: Record<K, V> | null,
+   * previous: Record<K, V> | null,
+   */
 |};
 
 type ResolvedRecord<K, V> = {|
@@ -43,30 +53,41 @@ type ResolvedRecord<K, V> = {|
   key: K,
   value: V,
   error: null,
-  next: Record<K, V> | null,
-  previous: Record<K, V> | null,
+  next: any, // TODO: (issue #12941)
+  previous: any, // TODO: (issue #12941)
+  /**
+   * Proper types would be something like this:
+   * next: Record<K, V> | null,
+   * previous: Record<K, V> | null,
+   */
 |};
 
-type RejectedRecord<K, V> = {|
+type RejectedRecord<K> = {|
   status: 3,
   suspender: null,
   key: K,
   value: null,
   error: Error,
-  next: Record<K, V> | null,
-  previous: Record<K, V> | null,
+  next: any, // TODO: (issue #12941)
+  previous: any, // TODO: (issue #12941)
+  /**
+   * Proper types would be something like this:
+   * next: Record<K, V> | null,
+   * previous: Record<K, V> | null,
+   */
 |};
 
 type Record<K, V> =
-  | EmptyRecord<K, V>
+  | EmptyRecord<K>
   | PendingRecord<K, V>
   | ResolvedRecord<K, V>
-  | RejectedRecord<K, V>;
+  | RejectedRecord<K>;
 
 type RecordCache<K, V> = {|
   map: Map<K, Record<K, V>>,
   head: Record<K, V> | null,
   tail: Record<K, V> | null,
+  size: number,
 |};
 
 // TODO: How do you express this type with Flow?
@@ -107,7 +128,7 @@ if (__DEV__) {
 const MAX_SIZE = 500;
 const PAGE_SIZE = 50;
 
-function createRecord<K, V>(key: K): EmptyRecord<K, V> {
+function createRecord<K>(key: K): EmptyRecord<K> {
   return {
     status: Empty,
     suspender: null,
@@ -131,7 +152,7 @@ function createRecordCache<K, V>(): RecordCache<K, V> {
 export function createCache(invalidator: () => mixed): Cache {
   const resourceMap: ResourceMap = new Map();
 
-  function accessRecord<K, V>(resourceType: any, key: K): Record<V> {
+  function accessRecord<K, V>(resourceType: any, key: K): Record<K, V> {
     if (__DEV__) {
       warning(
         typeof resourceType !== 'string' && typeof resourceType !== 'number',
@@ -206,22 +227,22 @@ export function createCache(invalidator: () => mixed): Cache {
     return newHead;
   }
 
-  function load<V>(emptyRecord: EmptyRecord, suspender: Promise<V>) {
-    const pendingRecord: PendingRecord<V> = (emptyRecord: any);
+  function load<K, V>(emptyRecord: EmptyRecord<K>, suspender: Promise<V>) {
+    const pendingRecord: PendingRecord<K, V> = (emptyRecord: any);
     pendingRecord.status = Pending;
     pendingRecord.suspender = suspender;
     suspender.then(
       value => {
         // Resource loaded successfully.
-        const resolvedRecord: ResolvedRecord<V> = (pendingRecord: any);
+        const resolvedRecord: ResolvedRecord<K, V> = (pendingRecord: any);
         resolvedRecord.status = Resolved;
         resolvedRecord.suspender = null;
         resolvedRecord.value = value;
       },
       error => {
         // Resource failed to load. Stash the error for later so we can throw it
         // the next time it's requested.
-        const rejectedRecord: RejectedRecord = (pendingRecord: any);
+        const rejectedRecord: RejectedRecord<K> = (pendingRecord: any);
         rejectedRecord.status = Rejected;
         rejectedRecord.suspender = null;
         rejectedRecord.error = error;
@@ -239,7 +260,7 @@ export function createCache(invalidator: () => mixed): Cache {
       miss: A => Promise<V>,
       missArg: A,
     ): void {
-      const record: Record<V> = accessRecord(resourceType, key);
+      const record: Record<K, V> = accessRecord(resourceType, key);
       switch (record.status) {
         case Empty:
           // Warm the cache.
@@ -263,7 +284,7 @@ export function createCache(invalidator: () => mixed): Cache {
       miss: A => Promise<V>,
       missArg: A,
     ): V {
-      const record: Record<V> = accessRecord(resourceType, key);
+      const record: Record<K, V> = accessRecord(resourceType, key);
       switch (record.status) {
         case Empty:
           // Load the requested resource.