add small redis client

Author: Felix Robles

package-lock.json

@@ -62,6 +62,7 @@
     "@types/mysql": "^2.15.5",
     "@types/node": "^10.11.3",
     "@types/pg": "^7.4.11",
+    "@types/redis": "^2.8.11",
     "@types/uuid": "^3.4.4",
     "@types/validator": "^9.4.2",
     "axios": "^0.18.0",
@@ -72,6 +73,7 @@
     "lodash": "^4.17.11",
     "mysql": "^2.16.0",
     "pg": "^7.5.0",
+    "redis": "^2.8.0",
     "uuid": "^3.3.2",
     "validator": "^10.8.0"
   },

package.json

@@ -0,0 +1,89 @@
+import { Container } from "inversify"
+import { Logger } from "../../../logging"
+import { ClientOpts, RedisClient, createClient } from "redis"
+import { Process } from "../../../runtime"
+import { promisify } from "util"
+
+export class RedisStore implements Process {
+    private client?: RedisClient
+    private logger?: Logger
+    private healthyState: boolean = false
+
+    constructor(private connectionOptions?: ClientOpts) {}
+
+    public isHealthy(): boolean {
+        return this.healthyState
+    }
+
+    public getClient(): RedisClient {
+        if (this.client === undefined) {
+            throw new Error(
+                "The RedisStore is not currently open and cannot be used. Check that the store has had .startup() called and that the Promise has successfully returned."
+            )
+        }
+
+        return this.client
+    }
+
+    public async startup(container: Container): Promise<void> {
+        if (this.client === undefined) {
+            this.client = createClient(this.connectionOptions)
+
+            // Handle errors and mark the connection as unhealthy
+            this.client.on("error", (err) => {
+                if (container.isBound(Logger)) {
+                    this.logger = container.get(Logger)
+                    this.logger.error("RedisStore encountered an error", err)
+                }
+
+                this.healthyState = false
+            })
+
+            this.client.on("end", (err) => {
+                if (container.isBound(Logger)) {
+                    this.logger = container.get(Logger)
+                    this.logger.error("RedisStore encountered an error", err)
+                }
+
+                this.healthyState = false
+            })
+
+            // listen for the connection to mark it as healthy
+            this.client.on("connect", () => {
+                this.healthyState = true
+            })
+
+            container.bind(RedisStore).toConstantValue(this)
+        } else {
+            throw new Error(
+                "A RedisClient already exists and cannot be reinstated without first being closed. This usually happens from calling startup on an existing Runtime."
+            )
+        }
+    }
+
+    public async shutdown(container: Container): Promise<void> {
+        if (this.client) {
+            container.unbind(RedisStore)
+
+            await promisify(this.client.quit.bind(this.client))()
+
+            // Dereference the pool
+            this.client = undefined
+            this.healthyState = false
+        }
+    }
+
+    public async sendCommand<A, B>(command: string, args?: A): Promise<B> {
+        if (this.client === undefined) {
+            throw new Error(
+                "RedisStore cannot send a command on a closed connection. This usually happens from forgetting to call startup."
+            )
+        }
+
+        let result: B = await promisify(
+            this.client.sendCommand.bind(this.client)
+        )(command, args)
+
+        return result
+    }
+}