1 files changed, 60 insertions, 0 deletions
diff --git a/deno/base/log.ts b/deno/base/log.ts
new file mode 100644
index 0000000..940f569
--- /dev/null
+++ b/deno/base/log.ts
@@ -0,0 +1,60 @@
+import { join } from "@std/path";
+
+import { toFileNameString } from "./lib.ts";
+
+export interface ExternalLogStream extends Disposable {
+  stream: WritableStream;
+}
+
+export class LogFileProvider {
+  #directory: string;
+
+  constructor(directory: string) {
+    this.#directory = directory;
+    Deno.mkdirSync(directory, { recursive: true });
+  }
+
+  async createExternalLogStream(
+    name: string,
+    options?: {
+      noTime?: boolean;
+    },
+  ): Promise<ExternalLogStream> {
+    if (name.includes("/")) {
+      throw new Error(`External log stream's name (${name}) contains '/'.`);
+    }
+
+    const logPath = join(
+      this.#directory,
+      options?.noTime === true
+        ? name
+        : `${name}-${toFileNameString(new Date())}`,
+    );
+
+    const file = await Deno.open(logPath, {
+      read: false,
+      write: true,
+      append: true,
+      create: true,
+    });
+    return {
+      stream: file.writable,
+      [Symbol.dispose]: file[Symbol.dispose].bind(file),
+    };
+  }
+
+  async createExternalLogStreamsForProgram(
+    program: string,
+  ): Promise<{ stdout: WritableStream; stderr: WritableStream } & Disposable> {
+    const stdout = await this.createExternalLogStream(`${program}-stdout`);
+    const stderr = await this.createExternalLogStream(`${program}-stderr`);
+    return {
+      stdout: stdout.stream,
+      stderr: stderr.stream,
+      [Symbol.dispose]: () => {
+        stdout[Symbol.dispose]();
+        stderr[Symbol.dispose]();
+      },
+    };
+  }
+}