Class: EM::File

Inherits:
Object
  • Object
show all
Defined in:
lib/em-files.rb

Overview

Sequenced file reader and writer.

Constant Summary collapse

RWSIZE =

Holds the default size of block operated during one tick.

65536

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(filepath, mode = "r", rwsize = self.class::RWSIZE) ⇒ File

Constructor. If IO object is given instead of filepath, uses it as native one and mode argument is ignored.

Parameters:

  • filepath (String, IO, StringIO) —

    path to file or IO object

  • mode (String) (defaults to: "r") —

    file access mode (see equivalent Ruby method)

  • rwsize (Integer) (defaults to: self.class::RWSIZE) —

    size of block operated during one tick



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# File 'lib/em-files.rb', line 137

def initialize(filepath, mode = "r", rwsize = self.class::RWSIZE)
    @mode = mode
    @rw_len = rwsize
    
    rwsize = self::RWSIZE if rwsize.nil?
    
    # If filepath is directly IO, uses it
    if filepath.io?
        @native = filepath
    else
        @native = ::File::open(filepath, mode)
    end
    
end

Instance Attribute Details

#mode ⇒ String (readonly)

Holds mode of the object.

Returns:

  • (String) 


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# File 'lib/em-files.rb', line 125

def mode
  @mode
end

#native ⇒ IO

Holds file object.

Returns:

  • (IO) 


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# File 'lib/em-files.rb', line 109

def native
  @native
end

#rw_len ⇒ Integer

Indicates block size for operate with in one tick.

Returns:

  • (Integer) 


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# File 'lib/em-files.rb', line 117

def rw_len
  @rw_len
end

Class Method Details

.open(filepath, mode = "r", rwsize = self::RWSIZE, &block) ⇒ File

Opens the file.

In opposite to appropriate Ruby method, “block syntax” is only syntactic sugar, file isn’t closed after return from block because processing is asynchronous so it doesn’t know when is convenient to close the file.

Parameters:

  • filepath (String, IO, StringIO) —

    path to file or IO object

  • mode (String) (defaults to: "r") —

    file access mode (see equivalent Ruby method)

  • rwsize (Integer) (defaults to: self::RWSIZE) —

    size of block operated during one tick

  • block (Proc) —

    syntactic sugar for wrapping File access object

Returns:

  • (File) —

    file access object



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# File 'lib/em-files.rb', line 44

def self.open(filepath, mode = "r", rwsize = self::RWSIZE, &block)   # 64 kilobytes
    rwsize = self::RWSIZE if rwsize.nil?
    
    file = self::new(filepath, mode, rwsize)
    if not block.nil?
        block.call(file)
    end
    
    return file
end

.read(filepath, rwsize = self::RWSIZE, filter = nil, &block) ⇒ Object 



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# File 'lib/em-files.rb', line 68

def self.read(filepath, rwsize = self::RWSIZE, filter = nil, &block)
    rwsize = self::RWSIZE if rwsize.nil?
    self::open(filepath, "rb", rwsize) do |io|
        io.read(nil, filter) do |out|
            io.close()
            block.call(out)
        end
    end
end

.write(filepath, data = "", rwsize = self::RWSIZE, filter = nil, &block) ⇒ Object

Writes data to file and closes it. Writes them in binary mode. If IO object is given instead of filepath, uses it as native one and mode argument is ignored.

Parameters:

  • filepath (String, IO, StringIO) —

    path to file or IO object

  • data (String) (defaults to: "") —

    data for write

  • rwsize (Integer) (defaults to: self::RWSIZE) —

    size of block operated during one tick

  • filter (Proc) (defaults to: nil) —

    filter which for preprocessing each written chunk

  • block (Proc) —

    block called when writing is finished with written bytes size count as parameter



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# File 'lib/em-files.rb', line 92

def self.write(filepath, data = "", rwsize = self::RWSIZE, filter = nil, &block)
    rwsize = self::RWSIZE if rwsize.nil?
    self::open(filepath, "wb", rwsize) do |io|
        io.write(data, filter) do |length|
            io.close()
            block.call(length)
        end
    end
end

Instance Method Details

#close ⇒ Object

Closes the file.



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# File 'lib/em-files.rb', line 295

def close
    @native.close
end

#read(length, &block) ⇒ Object #read(&block) ⇒ Object

Reads data from file.

It will reopen the file if EBADF: Bad file descriptor of File class IO object will occur.

Overloads:

  • #read(length, &block) ⇒ Object

    Reads specified amount of data from file.

    Parameters:

    • length (Integer) —

      length for read from file

    • filter (Proc) —

      filter which for postprocessing each read chunk

    • block (Proc) —

      callback for returning the result

  • #read(&block) ⇒ Object

    Reads whole content of file.

    Parameters:

    • filter (Proc) —

      filter which for processing each block

    • block (Proc) —

      callback for returning the result



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# File 'lib/em-files.rb', line 170

def read(length = nil, filter = nil, &block)
    buffer = ""
    pos = 0
    
    # Arguments
    if length.kind_of? Proc
        filter = length
    end
    
    
    worker = Proc::new do
    
        # Sets length for read
        if not length.nil?
            rlen = length - buffer.length
            if rlen > @rw_len
                rlen = @rw_len
            end
        else
            rlen = @rw_len
        end
        
        # Reads
        begin
            chunk = @native.read(rlen)
            if not filter.nil?
                chunk = filter.call(chunk)
            end
            buffer << chunk
        rescue Errno::EBADF
            if @native.kind_of? ::File
                self.reopen!
                @native.seek(pos)
                redo
            else
                raise
            end
        end
        
        pos = @native.pos
        
        # Returns or continues work
        if @native.eof? or (buffer.length == length)
            if not block.nil?
                block.call(buffer)              # returns result
            end
        else
            EM::next_tick { worker.call() }     # continues work
        end
        
    end
    
    worker.call()
end

#reopen! ⇒ Object

Reopens the file with the original mode.



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# File 'lib/em-files.rb', line 229

def reopen!
    @native = ::File.open(@native.path, @mode)
end

#write(data, filter = nil, &block) ⇒ Object

Writes data to file. Supports writing both strings or copying from another IO object.

It will reopen the file if EBADF: Bad file descriptor of File class IO object will occur on File object.

Parameters:

  • data (String, IO, StringIO) —

    data for write or IO object

  • filter (Proc) (defaults to: nil) —

    filter which for preprocessing each written chunk

  • block (Proc) —

    callback called when finish and for giving back the length of written data



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# File 'lib/em-files.rb', line 247

def write(data, filter = nil, &block)
    pos = 0
    
    if data.io?
        io = data
    else
        io = StringIO::new(data)
    end
    
    worker = Proc::new do
    
        # Writes
        begin
            chunk = io.read(@rw_len)
            if not filter.nil?
                chunk = filter.call(chunk)
            end
            @native.write(chunk)
        rescue Errno::EBADF
            if @native.kind_of? File
                self.reopen!
                @native.seek(pos)
                redo
            else
                raise
            end
        end
    
        pos = @native.pos
        
        # Returns or continues work
        if io.eof?
            if not block.nil?
                block.call(pos)                 # returns result
            end
        else
            EM::next_tick { worker.call() }     # continues work
        end
        
    end
    
    worker.call()
end