Table of Contents

• Scope
• Motivation
• Installation
• Usage
  • Filters
  • Defaults
  • Custom
  • Worker
  • Enumerator
  • Block
  • Mode
  • Check
  • Logger

Scope

This gem is aimed to collect a set of file paths starting by a wildcard rule, filter them by any/all default/custom filters (access time, matching name and size range) and apply a set of actions via a block call.

Motivation

This gem is helpful to purge obsolete files or to promote relevant ones, by calling external services (CDN APIs) and/or local file system actions (copy, move, delete, etc).

Installation

Add this line to your application's Gemfile:

gem "file_scanner"

And then execute:

bundle

Or install it yourself as:

gem install file_scanner

Usage

Filters

The first step is to provide the filters list to select file paths for which the call method is truthy.

Defaults

If you specify no filters the default ones are loaded, selecting files by:

• checking if file is older than 30 days
• checking if file size is within 0KB and 5KB
• checking if file basename matches the specified regexp (if any)

You can update default filters behaviours by passing custom arguments:

a_week_ago = FileScanner::Filters::LastAccess.new(Time.now-7*24*3600)
one_two_mb = FileScanner::Filters::SizeRange.new(min: 1024**2, max: 2*1024**2)
hidden = FileScanner::Filters::MatchingName.new(/^\./)
filters = [a_week_ago, one_two_mb, hidden]

Custom

It is convenient to create custom filters by using Proc instances that satisfy the callable protocol:

filters << ->(file) { File.directory?(file) }

Worker

The second step is to create the Worker instance by providing the path to scan and the list of filters to apply.

Enumerator

The call method of the worker return a lazy enumerator with the filtered elements, sliced by the specified number (default to 1000):

worker = FileScanner::Worker.new(path: "~/Downloads", filters: filters, slice: 35)
p worker.call
=> #<Enumerator::Lazy: ...

Block

To perform actions on each of the sliced paths just pass a block:

worker.call do |slice|
  # perform actions on a slice of at max 35 elements
end

Mode

By default the worker will select paths by applying any of the matching filters: this is it, it suffice just one of the specified filters to be true to grab the path.
In case you want restrict paths selection by all matching filters, just specify the all option:

worker = FileScanner::Worker.new(loader: loader, filters: filters, all: true)
worker.call # will filter by applying all? predicate

Check

By default the worker will scan for both directories and files. In case you want restrict paths selection by files only, just specify the check option:

worker = FileScanner::Worker.new(loader: loader, filters: filters, check: true)
worker.call # will skip directories

Logger

If you dare to trace what the worker is doing (including errors), you can specify a logger to the worker class:

my_logger = Logger.new("my_file.log")
worker = FileScanner::Worker.new(loader: loader, logger: my_logger)
worker.call do |slice|
  fail "Doh!" # will log error to my_file.log and re-raise exception
end

If you want to easily pass the same logger instance to the actions you are performing, it's available as the second argument of the block:

require "fileutils"

worker.call do |slice, logger|
  logger.info { "going to remove #{slice.size} files from disk!" }
  FileUtils.rm_rf(slice)
end