Add support for jobs & queueables, migrations

- Create migration directives & migrators
- Modify Cache classes to support array manipulation
- Create Redis unit and RedisCache implementation
- Create Queueable base class and Queue class that uses Cache backend

src/support/cache/MemoryCache.ts

@@ -8,7 +8,10 @@ export class MemoryCache extends Cache {
     /** Static collection of in-memory cache items. */
     private static cacheItems: Collection<{key: string, value: string, expires?: Date}> = new Collection<{key: string; value: string, expires?: Date}>()
 
-    public fetch(key: string): Awaitable<string|undefined> {
+    /** Static collection of in-memory arrays. */
+    private static cacheArrays: Collection<{key: string, values: string[]}> = new Collection<{key: string; values: string[]}>()
+
+    public fetch(key: string): string|undefined {
         const now = new Date()
         return MemoryCache.cacheItems
             .where('key', '=', key)
@@ -41,4 +44,41 @@ export class MemoryCache extends Cache {
     public drop(key: string): Awaitable<void> {
         MemoryCache.cacheItems = MemoryCache.cacheItems.where('key', '!=', key)
     }
+
+    public decrement(key: string, amount = 1): Awaitable<number | undefined> {
+        const nextValue = (parseInt(this.fetch(key) ?? '0', 10) ?? 0) - amount
+        this.put(key, String(nextValue))
+        return nextValue
+    }
+
+    public increment(key: string, amount = 1): Awaitable<number | undefined> {
+        const nextValue = (parseInt(this.fetch(key) ?? '0', 10) ?? 0) + amount
+        this.put(key, String(nextValue))
+        return nextValue
+    }
+
+    public pop(key: string): Awaitable<string | undefined> {
+        const value = this.fetch(key)
+        this.drop(key)
+        return value
+    }
+
+    public arrayPop(key: string): Awaitable<string | undefined> {
+        const arr = MemoryCache.cacheArrays.firstWhere('key', '=', key)
+        if ( arr ) {
+            return arr.values.shift()
+        }
+    }
+
+    public arrayPush(key: string, value: string): Awaitable<void> {
+        const arr = MemoryCache.cacheArrays.firstWhere('key', '=', key)
+        if ( arr ) {
+            arr.values.push(value)
+        } else {
+            MemoryCache.cacheArrays.push({
+                key,
+                values: [value],
+            })
+        }
+    }
 }