Class: File
- Defined in:
- activesupport/lib/active_support/core_ext/file/path.rb,
activesupport/lib/active_support/core_ext/file/atomic.rb
Class Method Summary collapse
-
.atomic_write(file_name, temp_dir = Dir.tmpdir) {|temp_file| ... } ⇒ Object
Write to a file atomically.
Class Method Details
.atomic_write(file_name, temp_dir = Dir.tmpdir) {|temp_file| ... } ⇒ Object
Write to a file atomically. Useful for situations where you don’t want other processes or threads to see half-written files.
File.atomic_write("important.file") do |file|
file.write("hello")
end
If your temp directory is not on the same filesystem as the file you’re trying to write, you can provide a different temporary directory.
File.atomic_write("/data/something.important", "/data/tmp") do |file|
file.write("hello")
end
15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 |
# File 'activesupport/lib/active_support/core_ext/file/atomic.rb', line 15 def self.atomic_write(file_name, temp_dir = Dir.tmpdir) require 'tempfile' unless defined?(Tempfile) require 'fileutils' unless defined?(FileUtils) temp_file = Tempfile.new(basename(file_name), temp_dir) temp_file.binmode yield temp_file temp_file.close begin # Get original file permissions old_stat = stat(file_name) rescue Errno::ENOENT # No old permissions, write a temp file to determine the defaults check_name = join(dirname(file_name), ".permissions_check.#{Thread.current.object_id}.#{Process.pid}.#{rand(1000000)}") open(check_name, "w") { } old_stat = stat(check_name) unlink(check_name) end # Overwrite original file with temp file FileUtils.mv(temp_file.path, file_name) # Set correct permissions on new file chown(old_stat.uid, old_stat.gid, file_name) chmod(old_stat.mode, file_name) end |