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Diffstat (limited to 'lib/sleepy_penguin/splice.rb')
| -rw-r--r-- | lib/sleepy_penguin/splice.rb | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/lib/sleepy_penguin/splice.rb b/lib/sleepy_penguin/splice.rb new file mode 100644 index 0000000..5358ed5 --- /dev/null +++ b/lib/sleepy_penguin/splice.rb @@ -0,0 +1,121 @@ +# -*- encoding: binary -*- + +module SleepyPenguin + # call-seq: + # SleepyPenguin.splice(io_in, io_out, len[, flags [, keywords]) => Integer + # + # Splice +len+ bytes from/to a pipe. Either +io_in+ or +io_out+ + # MUST be a pipe. +io_in+ and +io_out+ may BOTH be pipes as of + # Linux 2.6.31 or later. + # + # +flags+ defaults to zero if unspecified. + # It may be an Integer bitmask, a Symbol, or Array of Symbols + # + # The integer bitmask may any combination of: + # + # * SleepyPenguin::F_MOVE - attempt to move pages instead of copying + # + # * SleepyPenguin::F_NONBLOCK - do not block on pipe I/O (only) + # + # * SleepyPenguin::F_MORE - indicates more data will be sent soon + # + # Symbols may be used as well to specify a single flag: + # + # * :move - corresponds to F_MOVE + # * :nonblock - corresponds to F_NONBLOCK + # * :more - corresponds to F_MORE + # + # Or, an array of any combination of the above symbols. + # + # Keywords: + # + # :off_in and :off_out if non-nil may be used to + # specify an offset for the respective non-pipe file descriptor. + # + # :exception defaults to +true+. Setting it to +false+ + # will return :EAGAIN symbol instead of raising Errno::EAGAIN. + # This will also return +nil+ instead of raising EOFError + # when +io_in+ is at the end. + # + # Raises EOFError when +io_in+ has reached end of file. + # Raises Errno::EAGAIN if the SleepyPenguin::F_NONBLOCK flag is set + # and the pipe has no data to read from or space to write to. May + # also raise Errno::EAGAIN if the non-pipe descriptor has no data + # to read from or space to write to. + # + # As splice never exposes buffers to userspace, it will not take + # into account userspace buffering done by Ruby or stdio. It is + # also not subject to encoding/decoding filters under Ruby 1.9+. + # + # Consider using `exception: false` if +io_out+ is a pipe or if you + # are using non-blocking I/O on both descriptors as it avoids the + # cost of raising common Errno::EAGAIN exceptions. + # + # See manpage for full documentation: + # http://man7.org/linux/man-pages/man2/splice.2.html + def self.splice(io_in, io_out, len, flags = 0, + off_in: nil, off_out: nil, exception: true) + flags = __map_splice_flags(flags) + ret = __splice(io_in, off_in, io_out, off_out, len, flags) + exception ? __map_exc(ret) : ret + end + + # call-seq: + # SleepyPenguin.tee(io_in, io_out, len[, flags[, keywords]) => Integer + # + # Copies up to +len+ bytes of data from +io_in+ to +io_out+. +io_in+ + # and +io_out+ must both refer to pipe descriptors. +io_in+ and +io_out+ + # may not be endpoints of the same pipe. + # + # +flags+ may be zero (the default) or a combination of: + # * SleepyPenguin::F_NONBLOCK + # + # As a shortcut, the `:nonblock` symbol may be used instead. + # + # Other splice-related flags are currently unimplemented in the + # kernel and have no effect. + # + # Returns the number of bytes duplicated if successful. + # Raises EOFError when +io_in+ is closed and emptied. + # Raises Errno::EAGAIN when +io_in+ is empty and/or +io_out+ is full + # and +flags+ specifies non-blocking operation + # + # Keywords: + # + # :exception defaults to +true+. Setting it to +false+ + # will return :EAGAIN symbol instead of raising Errno::EAGAIN. + # This will also return +nil+ instead of raising EOFError + # when +io_in+ is at the end. + # + # Consider using `exception: false` if +io_out+ is a pipe or if you + # are using non-blocking I/O on both descriptors as it avoids the + # cost of raising common Errno::EAGAIN exceptions. + # + # See manpage for full documentation: + # http://man7.org/linux/man-pages/man2/tee.2.html + def self.tee(io_in, io_out, len, flags = 0, exception: true) + flags = __map_splice_flags(flags) + ret = __tee(io_in, io_out, len, flags) + exception ? __map_exc(ret) : ret + end if respond_to?(:__tee) + + @__splice_f_map = { # :nodoc: + :nonblock => F_NONBLOCK, + :more => F_MORE, + :move => F_MOVE + } + + def self.__map_splice_flags(flags) # :nodoc: + onef = @__splice_f_map[flags] and return onef + flags.respond_to?(:inject) ? + flags.inject(0) { |fl, sym| fl |= @__splice_f_map[sym] } : flags + end + + def self.__map_exc(ret) # :nodoc: + case ret + when :EAGAIN then raise Errno::EAGAIN, 'Resource temporarily unavailable' + when nil then raise EOFError, 'end of file reached' + end + ret + end +end |