streamroller [![CodeQL](https://github.com/log4js-node/streamroller/actions/workflows/codeql-analysis.yml/badge.svg)](https://github.com/log4js-node/streamroller/actions/workflows/codeql-analysis.yml) [![Node.js CI](https://github.com/log4js-node/streamroller/actions/workflows/node.js.yml/badge.svg)](https://github.com/log4js-node/streamroller/actions/workflows/node.js.yml)
============

[![NPM](https://nodei.co/npm/streamroller.png?downloads=true&downloadRank=true&stars=true)](https://nodei.co/npm/streamroller/)

node.js file streams that roll over when they reach a maximum size, or a date/time.

```sh
npm install streamroller
```

## usage

```javascript
var rollers = require('streamroller');
var stream = new rollers.RollingFileStream('myfile', 1024, 3);
stream.write("stuff");
stream.end();
```

The streams behave the same as standard node.js streams, except that when certain conditions are met they will rename the current file to a backup and start writing to a new file.

### new RollingFileStream(filename [, maxSize, numBackups, options])
* `filename` \<string\>
* `maxSize` \<integer\> - defaults to `0` - the size in bytes to trigger a rollover. If not specified or 0, then no log rolling will happen.
* `numBackups` \<integer\> - defaults to `1` - the number of old files to keep (excluding the hot file)
* `options` \<Object\>
  * `encoding` \<string\> - defaults to `'utf8'`
  * `mode` \<integer\> - defaults to `0o600` (see [node.js file modes](https://nodejs.org/dist/latest-v12.x/docs/api/fs.html#fs_file_modes))
  * `flags` \<string\> - defaults to `'a'` (see [node.js file flags](https://nodejs.org/dist/latest-v12.x/docs/api/fs.html#fs_file_system_flags))
  * `compress` \<boolean\> - defaults to `false` - compress the backup files using gzip (backup files will have `.gz` extension)
  * `keepFileExt` \<boolean\> - defaults to `false` - preserve the file extension when rotating log files (`file.log` becomes `file.1.log` instead of `file.log.1`).
  * `fileNameSep` \<string\> - defaults to `'.'` - the filename separator when rolling. e.g.: abc.log`.`1 or abc`.`1.log (keepFileExt)

This returns a `WritableStream`. When the current file being written to (given by `filename`) gets up to or larger than `maxSize`, then the current file will be renamed to `filename.1` and a new file will start being written to. Up to `numBackups` of old files are maintained, so if `numBackups` is 3 then there will be 4 files:

     filename
     filename.1
     filename.2
     filename.3

When filename size >= maxSize then:

     filename -> filename.1
     filename.1 -> filename.2
     filename.2 -> filename.3
     filename.3 gets overwritten
     filename is a new file

### new DateRollingFileStream(filename [, pattern, options])
* `filename` \<string\>
* `pattern` \<string\> - defaults to `yyyy-MM-dd` - the date pattern to trigger rolling (see below)
* `options` \<Object\>
  * `encoding` \<string\> - defaults to `'utf8'`
  * `mode` \<integer\> - defaults to `0o600` (see [node.js file modes](https://nodejs.org/dist/latest-v12.x/docs/api/fs.html#fs_file_modes))
  * `flags` \<string\> - defaults to `'a'` (see [node.js file flags](https://nodejs.org/dist/latest-v12.x/docs/api/fs.html#fs_file_system_flags))
  * `compress` \<boolean\> - defaults to `false` - compress the backup files using gzip (backup files will have `.gz` extension)
  * `keepFileExt` \<boolean\> - defaults to `false` - preserve the file extension when rotating log files (`file.log` becomes `file.2017-05-30.log` instead of `file.log.2017-05-30`).
  * `fileNameSep` \<string\> - defaults to `'.'` - the filename separator when rolling. e.g.: abc.log`.`2013-08-30 or abc`.`2013-08-30.log (keepFileExt)
  * `alwaysIncludePattern` \<boolean\> - defaults to `false` - extend the initial file with the pattern
  * `daysToKeep` `numBackups` \<integer\> - defaults to `1` - the number of old files that matches the pattern to keep (excluding the hot file)
  * `maxSize` \<integer\> - defaults to `0` - the size in bytes to trigger a rollover. If not specified or 0, then no log rolling will happen.

This returns a `WritableStream`. When the current time, formatted as `pattern`, changes then the current file will be renamed to `filename.formattedDate` where `formattedDate` is the result of processing the date through the pattern, and a new file will begin to be written. Streamroller uses [date-format](http://github.com/nomiddlename/date-format) to format dates, and the `pattern` should use the date-format format. e.g. with a `pattern` of `"yyyy-MM-dd"`, and assuming today is August 29, 2013 then writing to the stream today will just write to `filename`. At midnight (or more precisely, at the next file write after midnight), `filename` will be renamed to `filename.2013-08-29` and a new `filename` will be created. If `options.alwaysIncludePattern` is true, then the initial file will be `filename.2013-08-29` and no renaming will occur at midnight, but a new file will be written to with the name `filename.2013-08-30`. If `maxSize` is populated, when the current file being written to (given by `filename`) gets up to or larger than `maxSize`, then the current file will be renamed to `filename.pattern.1` and a new file will start being written to. Up to `numBackups` of old files are maintained, so if `numBackups` is 3 then there will be 4 files:

     filename
     filename.20220131.1
     filename.20220131.2
     filename.20220131.3

