Merge pull request #12 from depot/global-connection

Author: jacobwgillespie

Diff for: README.md

@@ -102,6 +102,24 @@ function inflate(field, value) {
 }
 ```
 
+#### Experimental: `useSharedConnection`
+
+As of version 1.3.0, `PlanetScaleDialect` supports using a shared `@planetscale/database` connection for all non-transaction queries, to improve query performance. This option is not enabled by default, but can be enabled by setting the `useSharedConnection` option to `true`. Transaction queries will always run using their own connection.
+
+This is an experimental feature, and may be removed in a future version.
+
+```typescript
+import {Kysely} from 'kysely'
+import {PlanetScaleDialect} from 'kysely-planetscale'
+
+const db = new Kysely<Database>({
+  dialect: new PlanetScaleDialect({
+    url: process.env.DATABASE_URL,
+    useSharedConnection: true,
+  }),
+})
+```
+
 ## License
 
 MIT License, see `LICENSE`.

Diff for: src/index.ts

@@ -20,7 +20,14 @@ import {
  *
  * @see https://github.com/planetscale/database-js#usage
  */
-export interface PlanetScaleDialectConfig extends Config {}
+export interface PlanetScaleDialectConfig extends Config {
+  /**
+   * Use a single `@planetscale/database` connection for all non-transaction queries.
+   *
+   * @default false
+   */
+  useSharedConnection?: boolean
+}
 
 /**
  * PlanetScale dialect that uses the [PlanetScale Serverless Driver for JavaScript][0].
@@ -99,14 +106,19 @@ class PlanetScaleDriver implements Driver {
   async destroy(): Promise<void> {}
 }
 
+const sharedConnections = new WeakMap<PlanetScaleDialectConfig, Connection>()
+
 class PlanetScaleConnection implements DatabaseConnection {
   #config: PlanetScaleDialectConfig
   #conn: Connection
   #transactionClient?: PlanetScaleConnection
 
-  constructor(config: PlanetScaleDialectConfig) {
+  constructor(config: PlanetScaleDialectConfig, isForTransaction = false) {
     this.#config = config
-    this.#conn = connect({cast: inflateDates, ...config})
+    const useSharedConnection = config.useSharedConnection && !isForTransaction
+    const sharedConnection = useSharedConnection ? sharedConnections.get(config) : undefined
+    this.#conn = sharedConnection ?? connect({cast: inflateDates, ...config})
+    if (useSharedConnection) sharedConnections.set(config, this.#conn)
   }
 
   async executeQuery<O>(compiledQuery: CompiledQuery): Promise<QueryResult<O>> {
@@ -138,7 +150,7 @@ class PlanetScaleConnection implements DatabaseConnection {
   }
 
   async beginTransaction() {
-    this.#transactionClient = this.#transactionClient ?? new PlanetScaleConnection(this.#config)
+    this.#transactionClient = this.#transactionClient ?? new PlanetScaleConnection(this.#config, true)
     await this.#transactionClient.#conn.execute('BEGIN')
   }