Some frameworks (e.g. Merb) call seek and rewind on the input stream if it responds to these methods. In case of Phusion Passenger, the input stream is a socket, and altough socket objects respond to seek and rewind, calling these methods will raise an exception. We don’t want this to happen so in AbstractRequestHandler we wrap the client socket into an UnseekableSocket wrapper, which doesn’t respond to these methods.
We used to dynamically undef seek and rewind on sockets, but this blows the Ruby interpreter’s method cache and made things slower. Wrapping a socket is faster despite extra method calls.
Furthermore, all exceptions originating from the wrapped socket will be annotated. One can check whether a certain exception originates from the wrapped socket by calling source_of_exception?
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 44 def self.wrap(socket) return new.wrap(socket) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 94 def addr @socket.addr rescue => e raise annotate(e) end
Already set to binary mode.
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 87 def binmode end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 166 def close @socket.close rescue => e raise annotate(e) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 172 def close_read @socket.close_read rescue => e raise annotate(e) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 178 def close_write @socket.close_write rescue => e raise annotate(e) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 160 def closed? @socket.closed? rescue => e raise annotate(e) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 154 def each(&block) @socket.each(&block) rescue => e raise annotate(e) end
Socket is sync’ed so flushing shouldn’t do anything.
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 83 def flush end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 130 def gets @socket.gets rescue => e raise annotate(e) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 124 def puts(*args) @socket.puts(*args) rescue => e raise annotate(e) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 136 def read(*args) @socket.read(*args) rescue => e raise annotate(e) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 148 def readline @socket.readline rescue => e raise annotate(e) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 142 def readpartial(*args) @socket.readpartial(*args) rescue => e raise annotate(e) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 184 def source_of_exception?(exception) return exception.instance_variable_get(:"@from_unseekable_socket") == @socket.object_id end
Don’t allow disabling of sync.
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 79 def sync=(value) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 90 def to_io self end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 48 def wrap(socket) # Some people report that sometimes their Ruby (MRI/REE) # processes get stuck with 100% CPU usage. Upon further # inspection with strace, it turns out that these Ruby # processes are continuously calling lseek() on a socket, # which of course returns ESPIPE as error. gdb reveals # lseek() is called by fwrite(), which in turn is called # by rb_fwrite(). The affected socket is the # AbstractRequestHandler client socket. # # I inspected the MRI source code and didn't find # anything that would explain this behavior. This makes # me think that it's a glibc bug, but that's very # unlikely. # # The rb_fwrite() implementation takes an entirely # different code path if I set 'sync' to true: it will # skip fwrite() and use write() instead. So here we set # 'sync' to true in the hope that this will work around # the problem. socket.sync = true # There's no need to set the encoding for Ruby 1.9 because # abstract_request_handler.rb is tagged with 'encoding: binary'. @socket = socket return self end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 100 def write(string) @socket.write(string) rescue => e raise annotate(e) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 106 def writev(components) @socket.writev(components) rescue => e raise annotate(e) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 112 def writev2(components, components2) @socket.writev2(components, components2) rescue => e raise annotate(e) end
# File lib/phusion_passenger/utils/unseekable_socket.rb, line 118 def writev3(components, components2, components3) @socket.writev3(components, components2, components3) rescue => e raise annotate(e) end