quick log rotation (#2432)

Author: sawka

emain/log.ts

@@ -1,13 +1,107 @@
 // Copyright 2025, Command Line Inc.
 // SPDX-License-Identifier: Apache-2.0
 
+import fs from "fs";
 import path from "path";
 import { format } from "util";
 import winston from "winston";
 import { getWaveDataDir, isDev } from "./platform";
 
 const oldConsoleLog = console.log;
 
+function findHighestLogNumber(logsDir: string): number {
+    if (!fs.existsSync(logsDir)) {
+        return 0;
+    }
+    const files = fs.readdirSync(logsDir);
+    let maxNum = 0;
+    for (const file of files) {
+        const match = file.match(/^waveapp\.(\d+)\.log$/);
+        if (match) {
+            const num = parseInt(match[1], 10);
+            if (num > maxNum) {
+                maxNum = num;
+            }
+        }
+    }
+    return maxNum;
+}
+
+function pruneOldLogs(logsDir: string): { pruned: string[]; error: any } {
+    if (!fs.existsSync(logsDir)) {
+        return { pruned: [], error: null };
+    }
+
+    const files = fs.readdirSync(logsDir);
+    const logFiles: { name: string; num: number }[] = [];
+
+    for (const file of files) {
+        const match = file.match(/^waveapp\.(\d+)\.log$/);
+        if (match) {
+            logFiles.push({ name: file, num: parseInt(match[1], 10) });
+        }
+    }
+
+    if (logFiles.length <= 5) {
+        return { pruned: [], error: null };
+    }
+
+    logFiles.sort((a, b) => b.num - a.num);
+    const toDelete = logFiles.slice(5);
+    const pruned: string[] = [];
+    let firstError: any = null;
+
+    for (const logFile of toDelete) {
+        try {
+            fs.unlinkSync(path.join(logsDir, logFile.name));
+            pruned.push(logFile.name);
+        } catch (e) {
+            if (firstError == null) {
+                firstError = e;
+            }
+        }
+    }
+
+    return { pruned, error: firstError };
+}
+
+function rotateLogIfNeeded(): string | null {
+    const waveDataDir = getWaveDataDir();
+    const logFile = path.join(waveDataDir, "waveapp.log");
+    const logsDir = path.join(waveDataDir, "logs");
+
+    if (!fs.existsSync(logsDir)) {
+        fs.mkdirSync(logsDir, { recursive: true });
+    }
+
+    if (!fs.existsSync(logFile)) {
+        return null;
+    }
+
+    const stats = fs.statSync(logFile);
+    if (stats.size > 10 * 1024 * 1024) {
+        const nextNum = findHighestLogNumber(logsDir) + 1;
+        const rotatedPath = path.join(logsDir, `waveapp.${nextNum}.log`);
+        fs.renameSync(logFile, rotatedPath);
+        return rotatedPath;
+    }
+    return null;
+}
+
+let logRotateError: any = null;
+let rotatedPath: string | null = null;
+let prunedFiles: string[] = [];
+let pruneError: any = null;
+try {
+    rotatedPath = rotateLogIfNeeded();
+    const logsDir = path.join(getWaveDataDir(), "logs");
+    const pruneResult = pruneOldLogs(logsDir);
+    prunedFiles = pruneResult.pruned;
+    pruneError = pruneResult.error;
+} catch (e) {
+    logRotateError = e;
+}
+
 const loggerTransports: winston.transport[] = [
     new winston.transports.File({ filename: path.join(getWaveDataDir(), "waveapp.log"), level: "info" }),
 ];
@@ -23,6 +117,7 @@ const loggerConfig = {
     transports: loggerTransports,
 };
 const logger = winston.createLogger(loggerConfig);
+
 function log(...msg: any[]) {
     try {
         logger.info(format(...msg));
@@ -31,4 +126,17 @@ function log(...msg: any[]) {
     }
 }
 
+if (logRotateError != null) {
+    log("error rotating/pruning logs (non-fatal):", logRotateError);
+}
+if (rotatedPath != null) {
+    log("rotated old log file to:", rotatedPath);
+}
+if (prunedFiles.length > 0) {
+    log("pruned old log files:", prunedFiles.join(", "));
+}
+if (pruneError != null) {
+    log("error pruning some log files (non-fatal):", pruneError);
+}
+
 export { log };