class IO # other IO methods are defined in io.c # call-seq: # ios.read_nonblock(maxlen [, options]) -> string # ios.read_nonblock(maxlen, outbuf [, options]) -> outbuf # # Reads at most maxlen bytes from ios using # the read(2) system call after O_NONBLOCK is set for # the underlying file descriptor. # # If the optional outbuf argument is present, # it must reference a String, which will receive the data. # The outbuf will contain only the received data after the method call # even if it is not empty at the beginning. # # read_nonblock just calls the read(2) system call. # It causes all errors the read(2) system call causes: Errno::EWOULDBLOCK, Errno::EINTR, etc. # The caller should care such errors. # # If the exception is Errno::EWOULDBLOCK or Errno::EAGAIN, # it is extended by IO::WaitReadable. # So IO::WaitReadable can be used to rescue the exceptions for retrying # read_nonblock. # # read_nonblock causes EOFError on EOF. # # On some platforms, such as Windows, non-blocking mode is not supported # on IO objects other than sockets. In such cases, Errno::EBADF will # be raised. # # If the read byte buffer is not empty, # read_nonblock reads from the buffer like readpartial. # In this case, the read(2) system call is not called. # # When read_nonblock raises an exception kind of IO::WaitReadable, # read_nonblock should not be called # until io is readable for avoiding busy loop. # This can be done as follows. # # # emulates blocking read (readpartial). # begin # result = io.read_nonblock(maxlen) # rescue IO::WaitReadable # IO.select([io]) # retry # end # # Although IO#read_nonblock doesn't raise IO::WaitWritable. # OpenSSL::Buffering#read_nonblock can raise IO::WaitWritable. # If IO and SSL should be used polymorphically, # IO::WaitWritable should be rescued too. # See the document of OpenSSL::Buffering#read_nonblock for sample code. # # Note that this method is identical to readpartial # except the non-blocking flag is set. # # By specifying a keyword argument _exception_ to +false+, you can indicate # that read_nonblock should not raise an IO::WaitReadable exception, but # return the symbol +:wait_readable+ instead. At EOF, it will return nil # instead of raising EOFError. def read_nonblock(len, buf = nil, exception: true) Primitive.io_read_nonblock(len, buf, exception) end # call-seq: # ios.write_nonblock(string) -> integer # ios.write_nonblock(string [, options]) -> integer # # Writes the given string to ios using # the write(2) system call after O_NONBLOCK is set for # the underlying file descriptor. # # It returns the number of bytes written. # # write_nonblock just calls the write(2) system call. # It causes all errors the write(2) system call causes: Errno::EWOULDBLOCK, Errno::EINTR, etc. # The result may also be smaller than string.length (partial write). # The caller should care such errors and partial write. # # If the exception is Errno::EWOULDBLOCK or Errno::EAGAIN, # it is extended by IO::WaitWritable. # So IO::WaitWritable can be used to rescue the exceptions for retrying write_nonblock. # # # Creates a pipe. # r, w = IO.pipe # # # write_nonblock writes only 65536 bytes and return 65536. # # (The pipe size is 65536 bytes on this environment.) # s = "a" * 100000 # p w.write_nonblock(s) #=> 65536 # # # write_nonblock cannot write a byte and raise EWOULDBLOCK (EAGAIN). # p w.write_nonblock("b") # Resource temporarily unavailable (Errno::EAGAIN) # # If the write buffer is not empty, it is flushed at first. # # When write_nonblock raises an exception kind of IO::WaitWritable, # write_nonblock should not be called # until io is writable for avoiding busy loop. # This can be done as follows. # # begin # result = io.write_nonblock(string) # rescue IO::WaitWritable, Errno::EINTR # IO.select(nil, [io]) # retry # end # # Note that this doesn't guarantee to write all data in string. # The length written is reported as result and it should be checked later. # # On some platforms such as Windows, write_nonblock is not supported # according to the kind of the IO object. # In such cases, write_nonblock raises Errno::EBADF. # # By specifying a keyword argument _exception_ to +false+, you can indicate # that write_nonblock should not raise an IO::WaitWritable exception, but # return the symbol +:wait_writable+ instead. def write_nonblock(buf, exception: true) Primitive.io_write_nonblock(buf, exception) end # call-seq: # readline(sep = $/, chomp: false) -> string # readline(limit, chomp: false) -> string # readline(sep, limit, chomp: false) -> string # # Reads a line as with IO#gets, but raises EOFError if already at end-of-stream. # # Optional keyword argument +chomp+ specifies whether line separators # are to be omitted. def readline(sep = $/, limit = nil, chomp: false) Primitive.io_readline(sep, limit, chomp) end end