diff options
| -rw-r--r-- | ChangeLog | 5 | ||||
| -rwxr-xr-x[-rw-r--r--] | lib/tempfile.rb | 201 |
2 files changed, 180 insertions, 26 deletions
@@ -1,3 +1,8 @@ +Wed Aug 26 21:49:23 2009 NARUSE, Yui <naruse@ruby-lang.org> + + * lib/tempfile.rb: add documents from Hongli Lai's fork. + cf [ruby-core:25131]. + Wed Aug 26 19:51:13 2009 NARUSE, Yui <naruse@ruby-lang.org> * tool/mkconfig.rb (program_transform_name): fix for multiple trans diff --git a/lib/tempfile.rb b/lib/tempfile.rb index 34d036fd6a..8b111f48ae 100644..100755 --- a/lib/tempfile.rb +++ b/lib/tempfile.rb @@ -8,27 +8,129 @@ require 'delegate' require 'tmpdir' require 'thread' -# A class for managing temporary files. This library is written to be -# thread safe. +# A utility class for managing temporary files. 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. +# +# == Synopsis +# +# require 'tempfile' +# +# file = Tempfile.new('foo') +# file.path # => A unique filename in the OS's temp directory, +# # e.g.: "/tmp/foo.24722.0" +# # This filename contains 'foo' in its basename. +# file.write("hello world") +# file.rewind +# file.read # => "hello world" +# file.close +# file.unlink # deletes the temp file +# +# == Good practices +# +# === Explicit close +# +# When a Tempfile object is garbage collected, or when the Ruby interpreter +# exits, its associated temporary file is automatically deleted. This means +# that's it's unnecessary to explicitly delete a Tempfile after use, though +# it's good practice to do so: not explicitly deleting unused Tempfiles can +# potentially leave behind large amounts of tempfiles on the filesystem +# until they're garbage collected. The existance 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 +# ...do something with file... +# ensure +# file.close +# file.unlink # deletes the temp file +# end +# +# === Unlink after creation +# +# 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. +# +# 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. +# +# Please refer to #unlink for more information and a code example. +# +# == Minor notes +# +# 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. class Tempfile < DelegateClass(File) MAX_TRY = 10 # :nodoc: @@cleanlist = [] @@lock = Mutex.new - # Creates a temporary file of mode 0600 in the temporary directory, - # opens it with mode "w+", and returns a Tempfile object which - # represents the created temporary file. A Tempfile object can be - # treated just like a normal File object. + # call-seq: + # new(basename, [tmpdir = Dir.tmpdir], [options]) # - # The basename parameter is used to determine the name of a - # temporary file. If an Array is given, the first element is used - # as prefix string and the second as suffix string, respectively. - # Otherwise it is treated as prefix string. + # Creates a temporary file with permissions 0600 (= only readable and + # writable by the owner) and opens it with mode "w+". # - # If tmpdir is omitted, the temporary directory is determined by - # Dir::tmpdir provided by 'tmpdir.rb'. - # When $SAFE > 0 and the given tmpdir is tainted, it uses - # /tmp. (Note that ENV values are tainted by default) + # The +basename+ parameter is used to determine the name of the + # temporary file. You can either pass a String or an Array with + # 2 String elements. In the former form, the temporary file's base + # name will begin with the given string. In the latter form, + # the temporary file's base name will begin with the array's first + # element, and end with the second element. For example: + # + # file = Tempfile.new('hello') + # file.path # => something like: "/tmp/foo2843-8392-92849382--0" + # + # # Use the Array form to enforce an extension in the filename: + # file = Tempfile.new(['hello', '.jpg']) + # file.path # => something like: "/tmp/foo2843-8392-92849382--0.jpg" + # + # The temporary file will be placed in the directory as specified + # by the +tmpdir+ parameter. By default, this is +Dir.tmpdir+. + # When $SAFE > 0 and the given +tmpdir+ is tainted, it uses + # '/tmp' as the temporary directory. Please note that ENV values + # are tainted by default, and +Dir.tmpdir+'s return value might + # come from environment variables (e.g. <tt>$TMPDIR</tt>). + # + # file = Tempfile.new('hello', '/home/aisaka') + # file.path # => something like: "/home/aisaka/foo2843-8392-92849382--0" + # + # You can also pass an options hash. Under the hood, Tempfile creates + # the temporary file using +File.open+. These options will be passed to + # +File.open+. This is mostly useful for specifying encoding + # options, e.g.: + # + # Tempfile.new('hello', '/home/aisaka', :encoding => 'ascii-8bit') + # + # # You can also omit the 'tmpdir' parameter: + # Tempfile.new('hello', :encoding => 'ascii-8bit') + # + # === Exceptions + # + # Under rare circumstances, this constructor can raise an instance of + # Tempfile::CreationError. This could happen if a large number + # of threads or processes are simultaneously trying to create temp files + # and stepping on each others' toes. If Tempfile.new cannot find + # a unique filename within a limited number of tries, then it will raise + # this exception. def initialize(basename, *rest) # I wish keyword argument settled soon. if opts = Hash.try_convert(rest[-1]) @@ -108,8 +210,9 @@ class Tempfile < DelegateClass(File) end protected :_close - #Closes the file. If the optional flag is true, unlinks the file - # after closing. + # 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. @@ -121,18 +224,47 @@ class Tempfile < DelegateClass(File) end end - # Closes and unlinks the file. - # Has the same effect as called <tt>close(true)</tt>. + # Closes and unlinks (deletes) the file. Has the same effect as called + # <tt>close(true)</tt>. def close! _close unlink ObjectSpace.undefine_finalizer(self) end - # Unlinks the file. On UNIX-like systems, it is often a good idea - # to unlink a temporary file immediately after creating and opening - # it, because it leaves other programs zero chance to access the - # file. + # 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 + # ...do something with file... + # ensure + # file.close + # file.unlink # deletes the temp file + # end + # + # === Unlink-before-close + # + # 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 # On Windows this silently fails. + # begin + # ... do something with file ... + # ensure + # file.close! # Closes the file handle. If the file wasn't unlinked + # # because #unlink failed, then this method will attempt + # # to do so again. + # end def unlink # keep this order for thread safeness return unless @tmpname @@ -190,11 +322,28 @@ class Tempfile < DelegateClass(File) } end - # If no block is given, this is a synonym for new(). + # Creates a new Tempfile. + # + # 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 said object as argument. The Tempfile + # oject will be automatically closed after the block terminates. + # The call returns the value of the block. + # + # In any case, all arguments (+*args+) will be passed to Tempfile.new. # - # If a block is given, it will be passed tempfile as an argument, - # and the tempfile will automatically be closed when the block - # terminates. The call returns the value of the block. + # Tempfile.open('foo', '/home/temp') do |f| + # ... do something with f ... + # end + # + # # Equivalent: + # f = Tempfile.open('foo', '/home/temp') + # begin + # ... do something with f ... + # ensure + # f.close + # end def open(*args) tempfile = new(*args) |