class Rightscale::HttpConnection

HttpConnection maintains a persistent HTTP connection to a remote server. Each instance maintains its own unique connection to the HTTP server. HttpConnection makes a best effort to receive a proper HTTP response from the server, although it does not guarantee that this response contains a HTTP Success code.

On low-level errors (TCP/IP errors) HttpConnection invokes a reconnect and retry algorithm. Note that although each HttpConnection object has its own connection to the HTTP server, error handling is shared across all connections to a server. For example, if there are three connections to www.somehttpserver.com, a timeout error on one of those connections will cause all three connections to break and reconnect. A connection will not break and reconnect, however, unless a request becomes active on it within a certain amount of time after the error (as specified by HTTP_CONNECTION_RETRY_DELAY). An idle connection will not break even if other connections to the same server experience errors.

A HttpConnection will retry a request a certain number of times (as defined by HTTP_CONNNECTION_RETRY_COUNT). If all the retries fail, an exception is thrown and all HttpConnections associated with a server enter a probationary period defined by HTTP_CONNECTION_RETRY_DELAY. If the user makes a new request subsequent to entering probation, the request will fail immediately with the same exception thrown on probation entry. This is so that if the HTTP server has gone down, not every subsequent request must wait for a connect timeout before failing. After the probation period expires, the internal state of the HttpConnection is reset and subsequent requests have the full number of potential reconnects and retries available to them.

Constants

HTTP_CONNECTION_OPEN_TIMEOUT

Throw a Timeout::Error if a connection isn’t established within this number of seconds

HTTP_CONNECTION_READ_TIMEOUT

Throw a Timeout::Error if no data have been read on this connnection within this number of seconds

HTTP_CONNECTION_RETRY_COUNT

Number of times to retry the request after encountering the first error

HTTP_CONNECTION_RETRY_DELAY

Length of the post-error probationary period during which all requests will fail

Attributes

http[RW]
logger[RW]
params[RW]
server[RW]

Public Class Methods

blank?(obj) click to toggle source
    # File lib/right_http_connection.rb
422 def self.blank?(obj)
423   case obj
424   when NilClass, FalseClass
425     true
426   when TrueClass, Numeric
427     false
428   when Array, Hash
429     obj.empty?
430   when String
431     obj.empty? || obj.strip.empty?
432   else
433     # "", "   ", nil, [], and {} are blank
434     if obj.respond_to?(:empty?) && obj.respond_to?(:strip)
435       obj.empty? or obj.strip.empty?
436     elsif obj.respond_to?(:empty?)
437       obj.empty?
438     else
439       !obj
440     end
441   end
442 end
new(params={}) click to toggle source

Params hash:

:user_agent => 'www.HostName.com'    # String to report as HTTP User agent
:ca_file    => 'path_to_file'        # A path of a CA certification file in PEM format. The file can contain several CA certificates.
:logger     => Logger object         # If omitted, HttpConnection logs to STDOUT
:exception  => Exception to raise    # The type of exception to raise if a request repeatedly fails. RuntimeError is raised if this parameter is omitted.
:http_connection_retry_count         # by default == Rightscale::HttpConnection.params[:http_connection_retry_count]
:http_connection_open_timeout        # by default == Rightscale::HttpConnection.params[:http_connection_open_timeout]
:http_connection_read_timeout        # by default == Rightscale::HttpConnection.params[:http_connection_read_timeout]
:http_connection_retry_delay         # by default == Rightscale::HttpConnection.params[:http_connection_retry_delay]
    # File lib/right_http_connection.rb
128 def initialize(params={})
129   @params                                = params
130   @params[:http_connection_retry_count]  ||= @@params[:http_connection_retry_count]
131   @params[:http_connection_open_timeout] ||= @@params[:http_connection_open_timeout]
132   @params[:http_connection_read_timeout] ||= @@params[:http_connection_read_timeout]
133   @params[:http_connection_retry_delay]  ||= @@params[:http_connection_retry_delay]
134   @http                                  = nil
135   @server                                = nil
136   @logger                                = get_param(:logger) ||
137       (RAILS_DEFAULT_LOGGER if defined?(RAILS_DEFAULT_LOGGER))
138   unless @logger
139     @logger = Logger.new(STDOUT)
140     @logger.level = Logger::INFO
141   end
142 end
params() click to toggle source

Query the global (class-level) parameters:

:user_agent => 'www.HostName.com'    # String to report as HTTP User agent
:ca_file    => 'path_to_file'        # Path to a CA certification file in PEM format. The file can contain several CA certificates.  If this parameter isn't set, HTTPS certs won't be verified.
:logger     => Logger object         # If omitted, HttpConnection logs to STDOUT
:exception  => Exception to raise    # The type of exception to raise
                                     # if a request repeatedly fails. RuntimeError is raised if this parameter is omitted.
:http_connection_retry_count         # by default == Rightscale::HttpConnection::HTTP_CONNECTION_RETRY_COUNT
:http_connection_open_timeout        # by default == Rightscale::HttpConnection::HTTP_CONNECTION_OPEN_TIMEOUT
:http_connection_read_timeout        # by default == Rightscale::HttpConnection::HTTP_CONNECTION_READ_TIMEOUT
:http_connection_retry_delay         # by default == Rightscale::HttpConnection::HTTP_CONNECTION_RETRY_DELAY
    # File lib/right_http_connection.rb
101 def self.params
102   @@params
103 end
params=(params) click to toggle source

Set the global (class-level) parameters

    # File lib/right_http_connection.rb
106 def self.params=(params)
107   @@params = params
108 end

Public Instance Methods

close(reason='') click to toggle source
    # File lib/right_http_connection.rb
418 def close(reason='')
419   finish
420 end
finish(reason = '') click to toggle source
    # File lib/right_http_connection.rb
410 def finish(reason = '')
411   if @http && @http.started?
412     reason = ", reason: '#{reason}'" unless self.class.blank?(reason)
413     @logger.debug("Closing #{@http.use_ssl? ? 'HTTPS' : 'HTTP'} connection to #{@http.address}:#{@http.port}#{reason}")
414     @http.finish
415   end
416 end
get_param(name) click to toggle source
    # File lib/right_http_connection.rb
144 def get_param(name)
145   @params[name] || @@params[name]
146 end
local_read_size=(newsize) click to toggle source

Set the maximum size (in bytes) of a single read from local data sources like files. This can be used to tune the performance of, for example, a streaming PUT of a large buffer.

    # File lib/right_http_connection.rb
172 def local_read_size=(newsize)
173   Net::HTTPGenericRequest.local_read_size=(newsize)
174 end
local_read_size?() click to toggle source

Query for the maximum size (in bytes) of a single read from local data sources like files. This is important, for example, in a streaming PUT of a large buffer.

    # File lib/right_http_connection.rb
165 def local_read_size?
166   Net::HTTPGenericRequest.local_read_size?
167 end
request(request_params, &block) click to toggle source

Send HTTP request to server

request_params hash:
:server   => 'www.HostName.com'   # Hostname or IP address of HTTP server
:port     => '80'                 # Port of HTTP server
:protocol => 'https'              # http and https are supported on any port
:request  => 'requeststring'      # Fully-formed HTTP request to make

Raises RuntimeError, Interrupt, and params (if specified in new).

    # File lib/right_http_connection.rb
322 def request(request_params, &block)
323   # We save the offset here so that if we need to retry, we can return the file pointer to its initial position
324   mypos = get_fileptr_offset(request_params)
325   loop do
326     # if we are inside a delay between retries: no requests this time!
327     if error_count > @params[:http_connection_retry_count] &&
328         error_time + @params[:http_connection_retry_delay] > Time.now
329       # store the message (otherwise it will be lost after error_reset and
330       # we will raise an exception with an empty text)
331       banana_message_text = banana_message
332       @logger.warn("#{err_header} re-raising same error: #{banana_message_text} " +
333                        "-- error count: #{error_count}, error age: #{Time.now.to_i - error_time.to_i}")
334       exception = get_param(:exception) || RuntimeError
335       raise exception.new(banana_message_text)
336     end
337 
338     # try to connect server(if connection does not exist) and get response data
339     begin
340       request_params[:protocol] ||= (request_params[:port] == 443 ? 'https' : 'http')
341 
342       request                   = request_params[:request]
343       request['User-Agent']     = get_param(:user_agent) || ''
344 
345       # (re)open connection to server if none exists or params has changed
346       unless @http &&
347           @http.started? &&
348           @server == request_params[:server] &&
349           @port == request_params[:port] &&
350           @protocol == request_params[:protocol]
351         start(request_params)
352       end
353 
354       # Detect if the body is a streamable object like a file or socket.  If so, stream that
355       # bad boy.
356       setup_streaming(request)
357       response = @http.request(request, &block)
358 
359       error_reset
360       eof_reset
361       return response
362 
363       # We treat EOF errors and the timeout/network errors differently.  Both
364       # are tracked in different statistics blocks.  Note below that EOF
365       # errors will sleep for a certain (exponentially increasing) period.
366       # Other errors don't sleep because there is already an inherent delay
367       # in them; connect and read timeouts (for example) have already
368       # 'slept'.  It is still not clear which way we should treat errors
369       # like RST and resolution failures.  For now, there is no additional
370       # delay for these errors although this may change in the future.
371 
372       # EOFError means the server closed the connection on us.
373     rescue EOFError => e
374       @logger.debug("#{err_header} server #{@server} closed connection")
375       @http = nil
376 
377       # if we have waited long enough - raise an exception...
378       if raise_on_eof_exception?
379         exception = get_param(:exception) || RuntimeError
380         @logger.warn("#{err_header} raising #{exception} due to permanent EOF being received from #{@server}, error age: #{Time.now.to_i - eof_time.to_i}")
381         raise exception.new("Permanent EOF is being received from #{@server}.")
382       else
383         # ... else just sleep a bit before new retry
384         sleep(add_eof)
385         # We will be retrying the request, so reset the file pointer
386         reset_fileptr_offset(request, mypos)
387       end
388     rescue Exception => e # See comment at bottom for the list of errors seen...
389       @http = nil
390       # if ctrl+c is pressed - we have to reraise exception to terminate proggy
391       if e.is_a?(Interrupt) && !(e.is_a?(Errno::ETIMEDOUT) || e.is_a?(Timeout::Error))
392         @logger.debug("#{err_header} request to server #{@server} interrupted by ctrl-c")
393         raise
394       elsif e.is_a?(ArgumentError) && e.message.include?('wrong number of arguments (5 for 4)')
395         # seems our net_fix patch was overriden...
396         exception = get_param(:exception) || RuntimeError
397         raise exception.new('incompatible Net::HTTP monkey-patch')
398       end
399       # oops - we got a banana: log it
400       error_add(e.message)
401       @logger.warn("#{err_header} request failure count: #{error_count}, exception: #{e.inspect}")
402 
403       # We will be retrying the request, so reset the file pointer
404       reset_fileptr_offset(request, mypos)
405 
406     end
407   end
408 end
socket_read_size=(newsize) click to toggle source

Set the maximum size (in bytes) of a single read from the underlying socket. For bulk transfer, especially over fast links, this is value is critical to performance.

    # File lib/right_http_connection.rb
158 def socket_read_size=(newsize)
159   Net::BufferedIO.socket_read_size=(newsize)
160 end
socket_read_size?() click to toggle source

Query for the maximum size (in bytes) of a single read from the underlying socket. For bulk transfer, especially over fast links, this is value is critical to performance.

    # File lib/right_http_connection.rb
151 def socket_read_size?
152   Net::BufferedIO.socket_read_size?
153 end