fix(scripts): bound source scan file reads

scripts/lib/source-file-scan-cache.mjs

@@ -1,6 +1,7 @@
 import { promises as fs } from "node:fs";
 import path from "node:path";
 
+const DEFAULT_SOURCE_FILE_READ_CONCURRENCY = 32;
 const scanCache = new Map();
 
 function normalizeRepoPath(repoRoot, filePath) {
@@ -34,7 +35,35 @@ async function walkFiles(params, rootDir) {
   return out;
 }
 
+function normalizeConcurrency(value) {
+  if (!Number.isInteger(value) || value < 1) {
+    return DEFAULT_SOURCE_FILE_READ_CONCURRENCY;
+  }
+  return value;
+}
+
+export async function mapWithConcurrency(items, concurrency, mapper) {
+  const out = Array.from({ length: items.length });
+  const workerCount = Math.min(normalizeConcurrency(concurrency), items.length);
+  let nextIndex = 0;
+
+  async function worker() {
+    for (;;) {
+      const index = nextIndex;
+      nextIndex += 1;
+      if (index >= items.length) {
+        return;
+      }
+      out[index] = await mapper(items[index], index);
+    }
+  }
+
+  await Promise.all(Array.from({ length: workerCount }, () => worker()));
+  return out;
+}
+
 export async function collectSourceFileContents(params) {
+  const useCache = !params.readFile;
   const cacheKey = JSON.stringify({
     repoRoot: params.repoRoot,
     scanRoots: params.scanRoots,
@@ -43,9 +72,11 @@ export async function collectSourceFileContents(params) {
       left.localeCompare(right),
     ),
   });
-  const cached = scanCache.get(cacheKey);
-  if (cached) {
-    return await cached;
+  if (useCache) {
+    const cached = scanCache.get(cacheKey);
+    if (cached) {
+      return await cached;
+    }
   }
 
   const promise = (async () => {
@@ -59,22 +90,29 @@ export async function collectSourceFileContents(params) {
         normalizeRepoPath(params.repoRoot, left).localeCompare(
           normalizeRepoPath(params.repoRoot, right),
         ),
-      );
+    );
 
-    return await Promise.all(
-      files.map(async (filePath) => ({
+    const readFile = params.readFile ?? fs.readFile;
+    return await mapWithConcurrency(
+      files,
+      params.maxConcurrentReads,
+      async (filePath) => ({
         filePath,
         relativeFile: normalizeRepoPath(params.repoRoot, filePath),
-        content: await fs.readFile(filePath, "utf8"),
-      })),
+        content: await readFile(filePath, "utf8"),
+      }),
     );
   })();
 
-  scanCache.set(cacheKey, promise);
+  if (useCache) {
+    scanCache.set(cacheKey, promise);
+  }
   try {
     return await promise;
   } catch (error) {
-    scanCache.delete(cacheKey);
+    if (useCache) {
+      scanCache.delete(cacheKey);
+    }
     throw error;
   }
 }