initial commit

app/lib/persist.ts

@@ -0,0 +1,60 @@
+import type { DumpColumns } from './dump-parse'
+
+const DB = 'pdx'
+const STORE = 'dumps'
+const VERSION = 1
+
+export interface CachedDump {
+  key: string
+  label: string
+  bytes: number
+  parsedAt: number
+  cols: DumpColumns
+}
+
+let conn: Promise<IDBDatabase> | null = null
+
+function open(): Promise<IDBDatabase> {
+  if (conn) return conn
+  conn = new Promise((resolve, reject) => {
+    const req = indexedDB.open(DB, VERSION)
+    req.onupgradeneeded = () => {
+      if (!req.result.objectStoreNames.contains(STORE)) {
+        req.result.createObjectStore(STORE, { keyPath: 'key' })
+      }
+    }
+    req.onsuccess = () => resolve(req.result)
+    req.onerror = () => {
+      conn = null
+      reject(req.error)
+    }
+  })
+  return conn
+}
+
+function tx<T>(mode: IDBTransactionMode, fn: (s: IDBObjectStore) => IDBRequest<T>): Promise<T> {
+  return open().then(
+    (db) =>
+      new Promise<T>((resolve, reject) => {
+        const req = fn(db.transaction(STORE, mode).objectStore(STORE))
+        req.onsuccess = () => resolve(req.result)
+        req.onerror = () => reject(req.error)
+      }),
+  )
+}
+
+/**
+ * Identity for a dump. Size plus a sparse byte sample: reading 60 MB to hash it properly costs more than re-parsing, and two dumps that agree on size and 64 spread samples are the same dump for our purposes.
+ */
+export function fingerprint(name: string, buf: Uint8Array): string {
+  let h = 0x811c9dc5
+  const step = Math.max(1, Math.floor(buf.length / 64))
+  for (let i = 0; i < buf.length; i += step) h = Math.imul(h ^ buf[i], 0x01000193)
+  return `${name}:${buf.length}:${(h >>> 0).toString(16)}`
+}
+
+/** Typed arrays survive structured clone, so there is no serialisation step. */
+export const saveDump = (d: CachedDump) => tx('readwrite', (s) => s.put(d))
+export const loadDump = (key: string) => tx<CachedDump | undefined>('readonly', (s) => s.get(key))
+export const listDumps = () => tx<CachedDump[]>('readonly', (s) => s.getAll())
+export const dropDump = (key: string) => tx('readwrite', (s) => s.delete(key))