Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://docs.ruby-lang.org/en/master/Tempfile.html below:

class Tempfile - Documentation for Ruby 3.5

A utility class for managing temporary files.

There are two kind of methods of creating a temporary file:

• Tempfile.create (recommended)

• Tempfile.new and Tempfile.open (mostly for backward compatibility, not recommended)

Tempfile.create creates a usual File object. The timing of file deletion is predictable. Also, it supports open-and-unlink technique which removes the temporary file immediately after creation.

Tempfile.new and Tempfile.open creates a Tempfile object. The created file is removed by the GC (finalizer). The timing of file deletion is not predictable.

require 'tempfile'




Tempfile.create {|f|
  f.puts "foo"
  f.rewind
  f.read                
}                       



f = Tempfile.create
f.puts "foo"
f.close
File.unlink(f.path)     


f = Tempfile.create(anonymous: true)

f.path                  
f.puts "foo"
f.rewind
f.read                  
f.close


Tempfile.create(anonymous: true) {|f|
  
  f.path                
  f.puts "foo"
  f.rewind
  f.read                
}


file = Tempfile.new('foo')
file.path      
               
               
file.write("hello world")
file.rewind
file.read      
file.close
file.unlink    

This section does not apply to Tempfile.create because it returns a File object (not a Tempfile object).

When you create a Tempfile object, it will create a temporary file with a unique filename. A Tempfile objects behaves just like a File object, and you can perform all the usual file operations on it: reading data, writing data, changing its permissions, etc. So although this class does not explicitly document all instance methods supported by File, you can in fact call any File instance method on a Tempfile object.

A Tempfile object has a finalizer to remove the temporary file. This means that the temporary file is removed via GC. This can cause several problems:

• Long GC intervals and conservative GC can accumulate temporary files that are not removed.

• Temporary files are not removed if Ruby exits abnormally (such as SIGKILL, SEGV).

There are legacy good practices for Tempfile.new and Tempfile.open as follows.

When a Tempfile object is garbage collected, or when the Ruby interpreter exits, its associated temporary file is automatically deleted. This means that it’s unnecessary to explicitly delete a Tempfile after use, though it’s a good practice to do so: not explicitly deleting unused Tempfiles can potentially leave behind a large number of temp files on the filesystem until they’re garbage collected. The existence of these temp files can make it harder to determine a new Tempfile filename.

Therefore, one should always call unlink or close in an ensure block, like this:

file = Tempfile.new('foo')
begin
   
ensure
   file.close
   file.unlink   
end

Tempfile.create { … } exists for this purpose and is more convenient to use. Note that Tempfile.create returns a File instance instead of a Tempfile, which also avoids the overhead and complications of delegation.

Tempfile.create('foo') do |file|
   
end

On POSIX systems, it’s possible to unlink a file right after creating it, and before closing it. This removes the filesystem entry without closing the file handle, so it ensures that only the processes that already had the file handle open can access the file’s contents. It’s strongly recommended that you do this if you do not want any other processes to be able to read from or write to the Tempfile, and you do not need to know the Tempfile’s filename either.

Also, this guarantees the temporary file is removed even if Ruby exits abnormally. The OS reclaims the storage for the temporary file when the file is closed or the Ruby process exits (normally or abnormally).

For example, a practical use case for unlink-after-creation would be this: you need a large byte buffer that’s too large to comfortably fit in RAM, e.g. when you’re writing a web server and you want to buffer the client’s file upload data.

‘Tempfile.create(anonymous: true)` supports this behavior. It also works on Windows.

Tempfile’s filename picking method is both thread-safe and inter-process-safe: it guarantees that no other threads or processes will pick the same filename.

Tempfile itself however may not be entirely thread-safe. If you access the same Tempfile object from multiple threads then you should protect it with a mutex.

VERSION

The version

def Tempfile.create(basename="", tmpdir=nil, mode: 0, anonymous: false, **options, &block)
  if anonymous
    create_anonymous(basename, tmpdir, mode: mode, **options, &block)
  else
    create_with_filename(basename, tmpdir, mode: mode, **options, &block)
  end
end

Creates a file in the underlying file system; returns a new File object based on that file.

With no block given and no arguments, creates and returns file whose:

• Class is File (not Tempfile).

• Directory is the system temporary directory (system-dependent).

• Generated filename is unique in that directory.

• Permissions are 0600; see File Permissions.

• Mode is 'w+' (read/write mode, positioned at the end).

The temporary file removal depends on the keyword argument anonymous and whether a block is given or not. See the description about the anonymous keyword argument later.

Example:

f = Tempfile.create     
f.class                 
f.path                  
f.stat.mode.to_s(8)     
f.close
File.exist?(f.path)     
File.unlink(f.path)
File.exist?(f.path)     

Tempfile.create {|f|
  f.puts "foo"
  f.rewind
  f.read                
  f.path                
  File.exist?(f.path)   
}                       

f = Tempfile.create(anonymous: true)

f.path                  
f.puts "foo"
f.rewind
f.read                  
f.close

Tempfile.create(anonymous: true) {|f|
  
  f.path                
  f.puts "foo"
  f.rewind
  f.read                
}

The argument basename, if given, may be one of the following:

• A string: the generated filename begins with basename:

  Tempfile.create('foo') 
  

• An array of two strings [prefix, suffix]: the generated filename begins with prefix and ends with suffix:

  Tempfile.create(%w/foo .jpg/) 
  

With arguments basename and tmpdir, the file is created in the directory tmpdir:

Tempfile.create('foo', '.') 

Keyword arguments mode and options are passed directly to the method File.open:

• The value given for mode must be an integer and may be expressed as the logical OR of constants defined in File::Constants.

• For options, see Open Options.

The keyword argument anonymous specifies when the file is removed.

• anonymous=false (default) without a block: the file is not removed.

• anonymous=false (default) with a block: the file is removed after the block exits.

• anonymous=true without a block: the file is removed before returning.

• anonymous=true with a block: the file is removed before the block is called.

In the first case (anonymous=false without a block), the file is not removed automatically. It should be explicitly closed. It can be used to rename to the desired filename. If the file is not needed, it should be explicitly removed.

The File#path method of the created file object returns the temporary directory with a trailing slash when anonymous is true.

When a block is given, it creates the file as described above, passes it to the block, and returns the block’s value. Before the returning, the file object is closed and the underlying file is removed:

Tempfile.create {|file| file.path } 

Implementation note:

The keyword argument +anonymous=true+ is implemented using FILE_SHARE_DELETE on Windows. O_TMPFILE is used on Linux.

Related: Tempfile.new.

def initialize(basename="", tmpdir=nil, mode: 0, **options)
  warn "Tempfile.new doesn't call the given block.", uplevel: 1 if block_given?

  @unlinked = false
  @mode = mode|File::RDWR|File::CREAT|File::EXCL
  tmpfile = nil
  ::Dir::Tmpname.create(basename, tmpdir, **options) do |tmpname, n, opts|
    opts[:perm] = 0600
    tmpfile = File.open(tmpname, @mode, **opts)
    @opts = opts.freeze
  end

  super(tmpfile)

  @finalizer_manager = FinalizerManager.new(__getobj__.path)
  @finalizer_manager.register(self, __getobj__)
end

Creates a file in the underlying file system; returns a new Tempfile object based on that file.

If possible, consider instead using Tempfile.create, which:

• Avoids the performance cost of delegation, incurred when Tempfile.new calls its superclass DelegateClass(File).

• Does not rely on a finalizer to close and unlink the file, which can be unreliable.

Creates and returns file whose:

• Class is Tempfile (not File, as in Tempfile.create).

• Directory is the system temporary directory (system-dependent).

• Generated filename is unique in that directory.

• Permissions are 0600; see File Permissions.

• Mode is 'w+' (read/write mode, positioned at the end).

The underlying file is removed when the Tempfile object dies and is reclaimed by the garbage collector.

Example:

f = Tempfile.new 
f.class               
f.path                
f.stat.mode.to_s(8)   
File.exist?(f.path)   
File.unlink(f.path)   
File.exist?(f.path)   

Argument basename, if given, may be one of:

• A string: the generated filename begins with basename:

  Tempfile.new('foo') 
  

• An array of two strings [prefix, suffix]: the generated filename begins with prefix and ends with suffix:

  Tempfile.new(%w/foo .jpg/) 
  

With arguments basename and tmpdir, the file is created in directory tmpdir:

Tempfile.new('foo', '.') 

Keyword arguments mode and options are passed directly to method File.open:

• The value given with mode must be an integer, and may be expressed as the logical OR of constants defined in File::Constants.

• For options, see Open Options.

Related: Tempfile.create.

Calls superclass method

def open(*args, **kw)
  tempfile = new(*args, **kw)

  if block_given?
    begin
      yield(tempfile)
    ensure
      tempfile.close
    end
  else
    tempfile
  end
end

Creates a new Tempfile.

This method is not recommended and exists mostly for backward compatibility. Please use Tempfile.create instead, which avoids the cost of delegation, does not rely on a finalizer, and also unlinks the file when given a block.

Tempfile.open is still appropriate if you need the Tempfile to be unlinked by a finalizer and you cannot explicitly know where in the program the Tempfile can be unlinked safely.

If no block is given, this is a synonym for Tempfile.new.

If a block is given, then a Tempfile object will be constructed, and the block is run with the Tempfile object as argument. The Tempfile object will be automatically closed after the block terminates. However, the file will not be unlinked and needs to be manually unlinked with Tempfile#close! or Tempfile#unlink. The finalizer will try to unlink but should not be relied upon as it can keep the file on the disk much longer than intended. For instance, on CRuby, finalizers can be delayed due to conservative stack scanning and references left in unused memory.

The call returns the value of the block.

In any case, all arguments (*args) will be passed to Tempfile.new.

Tempfile.open('foo', '/home/temp') do |f|
   
end


f = Tempfile.open('foo', '/home/temp')
begin
   
ensure
   f.close
end

        def create_anonymous(basename="", tmpdir=nil, mode: 0, **options, &block)
  tmpfile = nil
  tmpdir = Dir.tmpdir() if tmpdir.nil?
  if defined?(File::TMPFILE) 
    begin
      tmpfile = File.open(tmpdir, File::RDWR | File::TMPFILE, 0600)
    rescue Errno::EISDIR, Errno::ENOENT, Errno::EOPNOTSUPP
      
      
    end
  end
  if tmpfile.nil?
    mode |= File::SHARE_DELETE | File::BINARY 
    tmpfile = create_with_filename(basename, tmpdir, mode: mode, **options)
    File.unlink(tmpfile.path)
    tmppath = tmpfile.path
  end
  path = File.join(tmpdir, '')
  unless tmppath == path
    
    tmpfile.autoclose = false
    tmpfile = File.new(tmpfile.fileno, mode: File::RDWR, path: path)
    PathAttr.set_path(tmpfile, path) if defined?(PathAttr)
  end
  if block
    begin
      yield tmpfile
    ensure
      tmpfile.close
    end
  else
    tmpfile
  end
end

        def create_with_filename(basename="", tmpdir=nil, mode: 0, **options)
  tmpfile = nil
  Dir::Tmpname.create(basename, tmpdir, **options) do |tmpname, n, opts|
    mode |= File::RDWR|File::CREAT|File::EXCL
    opts[:perm] = 0600
    tmpfile = File.open(tmpname, mode, **opts)
  end
  if block_given?
    begin
      yield tmpfile
    ensure
      unless tmpfile.closed?
        if File.identical?(tmpfile, tmpfile.path)
          unlinked = File.unlink tmpfile.path rescue nil
        end
        tmpfile.close
      end
      unless unlinked
        begin
          File.unlink tmpfile.path
        rescue Errno::ENOENT
        end
      end
    end
  else
    tmpfile
  end
end

def close(unlink_now=false)
  _close
  unlink if unlink_now
end

Closes the file. If unlink_now is true, then the file will be unlinked (deleted) after closing. Of course, you can choose to later call unlink if you do not unlink it now.

If you don’t explicitly unlink the temporary file, the removal will be delayed until the object is finalized.

def close!
  close(true)
end

Closes and unlinks (deletes) the file. Has the same effect as called close(true).

def open
  _close

  mode = @mode & ~(File::CREAT|File::EXCL)
  __setobj__(File.open(__getobj__.path, mode, **@opts))

  @finalizer_manager.register(self, __getobj__)

  __getobj__
end

Opens or reopens the file with mode “r+”.

def path
  @unlinked ? nil : __getobj__.path
end

Returns the full path name of the temporary file. This will be nil if unlink has been called.

def size
  if !__getobj__.closed?
    __getobj__.size 
  else
    File.size(__getobj__.path)
  end
end

Returns the size of the temporary file. As a side effect, the IO buffer is flushed before determining the size.

def unlink
  return if @unlinked
  begin
    File.unlink(__getobj__.path)
  rescue Errno::ENOENT
  rescue Errno::EACCES
    
    return
  end

  @finalizer_manager.unlinked = true

  @unlinked = true
end

Unlinks (deletes) the file from the filesystem. One should always unlink the file after using it, as is explained in the “Explicit close” good practice section in the Tempfile overview:

file = Tempfile.new('foo')
begin
   
ensure
   file.close
   file.unlink   
end

On POSIX systems it’s possible to unlink a file before closing it. This practice is explained in detail in the Tempfile overview (section “Unlink after creation”); please refer there for more information.

However, unlink-before-close may not be supported on non-POSIX operating systems. Microsoft Windows is the most notable case: unlinking a non-closed file will result in an error, which this method will silently ignore. If you want to practice unlink-before-close whenever possible, then you should write code like this:

file = Tempfile.new('foo')
file.unlink   
begin
   
ensure
   file.close!   
                 
                 
end

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4