perf(stats): use compressed incremental snapshot transfers (#241)

src/core/services/stats-sync/transfer-cache.test.ts

@@ -0,0 +1,59 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+import { createTransferCache, transferCacheKey } from './transfer-cache';
+
+test('transfer cache isolates peers and active transfers while replacing previous snapshots', () => {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), 'subminer-cache-test-'));
+  try {
+    const cacheDir = path.join(root, 'cache');
+    const cache = createTransferCache(cacheDir);
+    const key = transferCacheKey('peer');
+    const first = path.join(root, 'first');
+    fs.mkdirSync(path.join(first, 'incoming'), { recursive: true });
+    const incoming = path.join(first, 'incoming', 'snapshot.sqlite');
+    fs.writeFileSync(incoming, 'first received snapshot');
+    cache.remember(key, first);
+    const second = path.join(root, 'second');
+    cache.seed(key, second);
+    fs.writeFileSync(incoming, 'next received snapshot');
+    cache.remember(key, first);
+    assert.equal(
+      fs.readFileSync(path.join(second, 'incoming', 'snapshot.sqlite'), 'utf8'),
+      'first received snapshot',
+    );
+    const third = path.join(root, 'third');
+    cache.seed(key, third);
+    assert.equal(
+      fs.readFileSync(path.join(third, 'incoming', 'snapshot.sqlite'), 'utf8'),
+      'next received snapshot',
+    );
+    assert.deepEqual(fs.readdirSync(cacheDir), [`${key}.sqlite`]);
+    const other = path.join(root, 'other');
+    cache.seed(transferCacheKey('other peer'), other);
+    assert.equal(fs.existsSync(path.join(other, 'incoming', 'snapshot.sqlite')), false);
+    assert.throws(() => cache.seed('../outside', other), /Invalid/);
+    assert.throws(() => cache.remember('../outside', first), /Invalid/);
+  } finally {
+    fs.rmSync(root, { recursive: true, force: true });
+  }
+});
+
+test('unavailable cache storage and missing incoming snapshots do not prevent sync', () => {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), 'subminer-cache-test-'));
+  try {
+    const unavailable = path.join(root, 'file');
+    fs.writeFileSync(unavailable, 'not a directory');
+    const cache = createTransferCache(unavailable);
+    const key = transferCacheKey('peer');
+    const temp = path.join(root, 'transfer');
+    assert.doesNotThrow(() => cache.seed(key, temp));
+    assert.doesNotThrow(() => cache.remember(key, temp));
+    fs.writeFileSync(path.join(temp, 'incoming', 'snapshot.sqlite'), 'received');
+    assert.doesNotThrow(() => cache.remember(key, temp));
+  } finally {
+    fs.rmSync(root, { recursive: true, force: true });
+  }
+});