From 63ad32e0542dee298d2065a369affcab86ecc468 Mon Sep 17 00:00:00 2001
From: Ben Allfree <ben@benallfree.com>
Date: Sun, 18 Jun 2023 06:13:56 -0700
Subject: [PATCH] enh: SqliteService async serialization enhancements

---
 .../services/SqliteService/SqliteService.ts   | 64 +++++++++++--------
 .../src/util/serialAsyncExecutionGuard.ts     | 26 ++++++++
 2 files changed, 65 insertions(+), 25 deletions(-)
 create mode 100644 packages/daemon/src/util/serialAsyncExecutionGuard.ts

diff --git a/packages/daemon/src/services/SqliteService/SqliteService.ts b/packages/daemon/src/services/SqliteService/SqliteService.ts
index 18489fa9..b2efa58e 100644
--- a/packages/daemon/src/services/SqliteService/SqliteService.ts
+++ b/packages/daemon/src/services/SqliteService/SqliteService.ts
@@ -4,10 +4,10 @@ import {
   mkSingleton,
   SingletonBaseConfig,
 } from '@pockethost/common'
-import Bottleneck from 'bottleneck'
 import { Database as SqliteDatabase, open } from 'sqlite'
 import { Database } from 'sqlite3'
 import { JsonObject } from 'type-fest'
+import { serialAsyncExecutionGuard } from '../../util/serialAsyncExecutionGuard'
 
 export type SqliteUnsubscribe = () => void
 export type SqliteChangeHandler<TRecord extends JsonObject> = (
@@ -35,21 +35,25 @@ export type SqliteService = ReturnType<typeof sqliteService>
 export const sqliteService = mkSingleton((config: SqliteServiceConfig) => {
   const { logger } = config
   const { dbg, trace } = logger.create(`sqliteService`)
-  const connections: { [_: string]: Promise<SqliteServiceApi> } = {}
+  const connections: { [_: string]: SqliteServiceApi } = {}
 
   const cm = createCleanupManager()
 
-  const limiter = new Bottleneck({ maxConcurrent: 1 })
+  /*
+  This function 
+  */
+  const _unsafe_getDatabase = async (
+    filename: string
+  ): Promise<SqliteServiceApi> => {
+    const _dbLogger = logger.create(`SqliteService`)
+    _dbLogger.breadcrumb(filename)
+    const { dbg, error, abort } = _dbLogger
 
-  const getDatabase = async (filename: string): Promise<SqliteServiceApi> => {
-    const _dbLogger = logger.create(`${filename}`)
-    const { dbg } = _dbLogger
-
-    trace(`Fetching database for ${filename}`, connections)
+    trace(`Fetching database`, connections)
     if (!connections[filename]) {
-      dbg(`${filename} is not yet opened`)
+      dbg(`Not yet opened`)
 
-      connections[filename] = new Promise<SqliteServiceApi>(async (resolve) => {
+      const api = await (async () => {
         const db = await open({ filename, driver: Database })
         dbg(`Database opened`)
         db.db.addListener(
@@ -60,20 +64,23 @@ export const sqliteService = mkSingleton((config: SqliteServiceConfig) => {
             table: string,
             rowId: number
           ) => {
-            dbg(`Got a raw change event`, { eventType, database, table, rowId })
+            trace(`Got a raw change event`, {
+              eventType,
+              database,
+              table,
+              rowId,
+            })
             if (eventType === 'delete') return // Not supported
 
-            await limiter.schedule(async () => {
-              const record = await db.get(
-                `select * from ${table} where rowid = '${rowId}'`
-              )
-              const e: SqliteChangeEvent<any> = {
-                table,
-                action: eventType,
-                record,
-              }
-              fireChange(e)
-            })
+            const record = await db.get(
+              `select * from ${table} where rowid = '${rowId}'`
+            )
+            const e: SqliteChangeEvent<any> = {
+              table,
+              action: eventType,
+              record,
+            }
+            fireChange(e)
           }
         )
 
@@ -92,15 +99,22 @@ export const sqliteService = mkSingleton((config: SqliteServiceConfig) => {
           exec: db.exec.bind(db),
           subscribe: onChange,
         }
-        resolve(api)
-      })
+        return api
+      })().catch(error)
+      if (!api) {
+        throw new Error(`Unable to connect to SQLite`)
+      }
+      connections[filename] = api
     }
     return connections[filename]!
   }
+  const getDatabase = serialAsyncExecutionGuard(
+    _unsafe_getDatabase,
+    (fileName) => fileName
+  )
 
   const shutdown = async () => {
     dbg(`Shutting down sqlite service`)
-    await limiter.stop()
     await cm.shutdown()
   }
   return {
diff --git a/packages/daemon/src/util/serialAsyncExecutionGuard.ts b/packages/daemon/src/util/serialAsyncExecutionGuard.ts
new file mode 100644
index 00000000..b5a1cb5f
--- /dev/null
+++ b/packages/daemon/src/util/serialAsyncExecutionGuard.ts
@@ -0,0 +1,26 @@
+import { logger } from '@pockethost/common'
+import { uniqueId } from '@s-libs/micro-dash'
+import Bottleneck from 'bottleneck'
+import { SetReturnType } from 'type-fest'
+
+const limiters: { [lane: string]: Bottleneck } = {}
+export const serialAsyncExecutionGuard = <
+  T extends (...args: any[]) => Promise<any>
+>(
+  cb: T,
+  lane?: SetReturnType<T, string>
+): T => {
+  const uuid = uniqueId()
+  const _lane = lane || (() => uuid)
+  const wrapper = (...args: Parameters<T>) => {
+    const { dbg } = logger()
+    const key = _lane(...args)
+    if (!limiters[key]) {
+      dbg(`New singleton limiter with key ${key}`)
+      limiters[key] = new Bottleneck({ maxConcurrent: 1 })
+    }
+    const limiter = limiters[key]!
+    return limiter.schedule(() => cb(...args)) as unknown as ReturnType<T>
+  }
+  return wrapper as unknown as T
+}