Returns a copy of the storage hash for the fiber. The method can only be called on the Fiber.current.
Sets the storage hash for the fiber. This feature is experimental and may change in the future. The method can only be called on the Fiber.current.
You should be careful about using this method as you may inadvertently clear important fiber-storage state. You should mostly prefer to assign specific keys in the storage using Fiber::[]=.
You can also use Fiber.new(storage: nil) to create a fiber with an empty storage.
Example:
while request = request_queue.pop # Reset the per-request state: Fiber.current.storage = nil handle_request(request) end
Returns the current execution stack of the fiber. start, count and end allow to select only parts of the backtrace.
def level3 Fiber.yield end def level2 level3 end def level1 level2 end f = Fiber.new { level1 } # It is empty before the fiber started f.backtrace #=> [] f.resume f.backtrace #=> ["test.rb:2:in `yield'", "test.rb:2:in `level3'", "test.rb:6:in `level2'", "test.rb:10:in `level1'", "test.rb:13:in `block in <main>'"] p f.backtrace(1) # start from the item 1 #=> ["test.rb:2:in `level3'", "test.rb:6:in `level2'", "test.rb:10:in `level1'", "test.rb:13:in `block in <main>'"] p f.backtrace(2, 2) # start from item 2, take 2 #=> ["test.rb:6:in `level2'", "test.rb:10:in `level1'"] p f.backtrace(1..3) # take items from 1 to 3 #=> ["test.rb:2:in `level3'", "test.rb:6:in `level2'", "test.rb:10:in `level1'"] f.resume # It is nil after the fiber is finished f.backtrace #=> nil
Transfer control to another fiber, resuming it from where it last stopped or starting it if it was not resumed before. The calling fiber will be suspended much like in a call to Fiber.yield.
The fiber which receives the transfer call treats it much like a resume call. Arguments passed to transfer are treated like those passed to resume.
The two style of control passing to and from fiber (one is resume and Fiber::yield, another is transfer to and from fiber) can’t be freely mixed.
If the Fiber’s lifecycle had started with transfer, it will never be able to yield or be resumed control passing, only finish or transfer back. (It still can resume other fibers that are allowed to be resumed.)
If the Fiber’s lifecycle had started with resume, it can yield or transfer to another Fiber, but can receive control back only the way compatible with the way it was given away: if it had transferred, it only can be transferred back, and if it had yielded, it only can be resumed back. After that, it again can transfer or yield.
If those rules are broken FiberError is raised.
For an individual Fiber design, yield/resume is easier to use (the Fiber just gives away control, it doesn’t need to think about who the control is given to), while transfer is more flexible for complex cases, allowing to build arbitrary graphs of Fibers dependent on each other.
Example:
manager = nil # For local var to be visible inside worker block # This fiber would be started with transfer # It can't yield, and can't be resumed worker = Fiber.new { |work| puts "Worker: starts" puts "Worker: Performed #{work.inspect}, transferring back" # Fiber.yield # this would raise FiberError: attempt to yield on a not resumed fiber # manager.resume # this would raise FiberError: attempt to resume a resumed fiber (double resume) manager.transfer(work.capitalize) } # This fiber would be started with resume # It can yield or transfer, and can be transferred # back or resumed manager = Fiber.new { puts "Manager: starts" puts "Manager: transferring 'something' to worker" result = worker.transfer('something') puts "Manager: worker returned #{result.inspect}" # worker.resume # this would raise FiberError: attempt to resume a transferring fiber Fiber.yield # this is OK, the fiber transferred from and to, now it can yield puts "Manager: finished" } puts "Starting the manager" manager.resume puts "Resuming the manager" # manager.transfer # this would raise FiberError: attempt to transfer to a yielding fiber manager.resume
produces
Starting the manager Manager: starts Manager: transferring 'something' to worker Worker: starts Worker: Performed "something", transferring back Manager: worker returned "Something" Resuming the manager Manager: finished
Returns whether dirpath is a directory in the underlying file system:
Dir.exist?('/example') # => true Dir.exist?('/nosuch') # => false Dir.exist?('/example/main.rb') # => false
Same as File.directory?.
Returns a File::Stat object for the file at filepath (see File::Stat):
File.stat('t.txt').class # => File::Stat
Like File::stat, but does not follow the last symbolic link; instead, returns a File::Stat object for the link itself.
File.symlink('t.txt', 'symlink') File.stat('symlink').size # => 47 File.lstat('symlink').size # => 5
Truncates the file file_name to be at most integer bytes long. Not available on all platforms.
f = File.new("out", "w") f.write("1234567890") #=> 10 f.close #=> nil File.truncate("out", 5) #=> 0 File.size("out") #=> 5
Like File#stat, but does not follow the last symbolic link; instead, returns a File::Stat object for the link itself:
File.symlink('t.txt', 'symlink') f = File.new('symlink') f.stat.size # => 47 f.lstat.size # => 11
Truncates file to at most integer bytes. The file must be opened for writing. Not available on all platforms.
f = File.new("out", "w") f.syswrite("1234567890") #=> 10 f.truncate(5) #=> 0 f.close() #=> nil File.size("out") #=> 5
Return true if the named file exists.
file_name can be an IO object.
“file exists” means that stat() or fstat() system call is successful.
Returns true if the named file is writable by the effective user and group id of this process. See eaccess(3).
Note that some OS-level security features may cause this to return true even though the file is not writable by the effective user/group.
Returns true if filepath points to a pipe, false otherwise:
File.mkfifo('tmp/fifo') File.pipe?('tmp/fifo') # => true File.pipe?('t.txt') # => false
Returns the list of loaded encodings.
Encoding.list #=> [#<Encoding:ASCII-8BIT>, #<Encoding:UTF-8>, #<Encoding:ISO-2022-JP (dummy)>] Encoding.find("US-ASCII") #=> #<Encoding:US-ASCII> Encoding.list #=> [#<Encoding:ASCII-8BIT>, #<Encoding:UTF-8>, #<Encoding:US-ASCII>, #<Encoding:ISO-2022-JP (dummy)>]
Returns a Digest subclass by name in a thread-safe manner even when on-demand loading is involved.
require 'digest' Digest("MD5") # => Digest::MD5 Digest(:SHA256) # => Digest::SHA256 Digest(:Foo) # => LoadError: library not found for class Digest::Foo -- digest/foo
Returns any backtrace associated with the exception. The backtrace is an array of strings, each containing either “filename:lineNo: in ‘method”’ or “filename:lineNo.”
def a raise "boom" end def b a() end begin b() rescue => detail print detail.backtrace.join("\n") end
produces:
prog.rb:2:in `a' prog.rb:6:in `b' prog.rb:10
In the case no backtrace has been set, nil is returned
ex = StandardError.new ex.backtrace #=> nil
Return the status value associated with this system exit.
Returns the list of Modules nested at the point of call.
module M1 module M2 $a = Module.nesting end end $a #=> [M1::M2, M1] $a[0].name #=> "M1::M2"
In the first form, returns an array of the names of all constants accessible from the point of call. This list includes the names of all modules and classes defined in the global scope.
Module.constants.first(4) # => [:ARGF, :ARGV, :ArgumentError, :Array] Module.constants.include?(:SEEK_SET) # => false class IO Module.constants.include?(:SEEK_SET) # => true end
The second form calls the instance method constants.
Returns a list of modules included/prepended in mod (including mod itself).
module Mod include Math include Comparable prepend Enumerable end Mod.ancestors #=> [Enumerable, Mod, Comparable, Math] Math.ancestors #=> [Math] Enumerable.ancestors #=> [Enumerable]
The first form is equivalent to attr_reader. The second form is equivalent to attr_accessor(name) but deprecated. The last form is equivalent to attr_reader(name) but deprecated. Returns an array of defined method names as symbols.
Returns an array of the names of the constants accessible in mod. This includes the names of constants in any included modules (example at start of section), unless the inherit parameter is set to false.
The implementation makes no guarantees about the order in which the constants are yielded.
IO.constants.include?(:SYNC) #=> true IO.constants(false).include?(:SYNC) #=> false
Also see Module#const_defined?.
With no arguments, sets the default visibility for subsequently defined methods to private. With arguments, sets the named methods to have private visibility. String arguments are converted to symbols. An Array of Symbols and/or Strings is also accepted. If a single argument is passed, it is returned. If no argument is passed, nil is returned. If multiple arguments are passed, the arguments are returned as an array.
module Mod def a() end def b() end private def c() end private :a end Mod.private_instance_methods #=> [:a, :c]
Note that to show a private method on RDoc, use :doc:.
Truncate to the nearest integer (by default), returning the result as a BigDecimal.
BigDecimal('3.14159').truncate #=> 3 BigDecimal('8.7').truncate #=> 8 BigDecimal('-9.9').truncate #=> -9
If n is specified and positive, the fractional part of the result has no more than that many digits.
If n is specified and negative, at least that many digits to the left of the decimal point will be 0 in the result.
BigDecimal('3.14159').truncate(3) #=> 3.141 BigDecimal('13345.234').truncate(-2) #=> 13300.0