Class: Rightscale::HttpConnection

Inherits:
Object
  • Object
show all
Defined in:
lib/right_http_connection.rb

Overview

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.

Constant Summary collapse

HTTP_CONNECTION_RETRY_COUNT =

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

3
HTTP_CONNECTION_OPEN_TIMEOUT =

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

5
HTTP_CONNECTION_READ_TIMEOUT =

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

30
HTTP_CONNECTION_RETRY_DELAY =

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

15
@@params =

if a request repeatedly fails. RuntimeError is raised if this parameter is omitted.

{}

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(params = {}) ⇒ HttpConnection

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.



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# File 'lib/right_http_connection.rb', line 126

def initialize(params={})
  @params = params     
  @http   = nil
  @server = nil
  @logger = get_param(:logger) || 
            (RAILS_DEFAULT_LOGGER if defined?(RAILS_DEFAULT_LOGGER)) ||
            Logger.new(STDOUT)
end

Instance Attribute Details

#http ⇒ Object

instance methods



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# File 'lib/right_http_connection.rb', line 113

def http
  @http
end

#logger ⇒ Object

Returns the value of attribute logger.



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# File 'lib/right_http_connection.rb', line 116

def logger
  @logger
end

#params ⇒ Object

see @@params



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# File 'lib/right_http_connection.rb', line 115

def params
  @params
end

#server ⇒ Object

Returns the value of attribute server.



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# File 'lib/right_http_connection.rb', line 114

def server
  @server
end

Class Method Details

.params ⇒ Object

Query the global (class-level) parameters



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# File 'lib/right_http_connection.rb', line 101

def self.params
  @@params
end

.params=(params) ⇒ Object

Set the global (class-level) parameters



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# File 'lib/right_http_connection.rb', line 106

def self.params=(params)
  @@params = params
end

Instance Method Details

#finish(reason = '') ⇒ Object 



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# File 'lib/right_http_connection.rb', line 363

def finish(reason = '')
  if @http && @http.started?
    reason = ", reason: '#{reason}'" unless reason.blank?
    @logger.info("Closing #{@http.use_ssl? ? 'HTTPS' : 'HTTP'} connection to #{@http.address}:#{@http.port}#{reason}")
    @http.finish 
  end
end

#get_param(name) ⇒ Object 



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# File 'lib/right_http_connection.rb', line 135

def get_param(name)
  @params[name] || @@params[name]
end

#local_read_size=(newsize) ⇒ Object

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.



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# File 'lib/right_http_connection.rb', line 163

def local_read_size=(newsize)
  Net::HTTPGenericRequest.local_read_size=(newsize)
end

#local_read_size? ⇒ Boolean

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.

Returns:

  • (Boolean) 


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# File 'lib/right_http_connection.rb', line 156

def local_read_size?
  Net::HTTPGenericRequest.local_read_size?
end

#request(request_params, &block) ⇒ Object

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[:exception] (if specified in new).



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# File 'lib/right_http_connection.rb', line 282

def request(request_params, &block)
  loop do
    # if we are inside a delay between retries: no requests this time!
    if error_count > HTTP_CONNECTION_RETRY_COUNT \
    && error_time + HTTP_CONNECTION_RETRY_DELAY > Time.now
      @logger.warn("#{err_header} re-raising same error: #{banana_message} " +
                  "-- error count: #{error_count}, error age: #{Time.now.to_i - error_time.to_i}")  
      exception = get_param(:exception) || RuntimeError
      raise exception.new(banana_message)
    end
  
    # try to connect server(if connection does not exist) and get response data
    begin
      request_params[:protocol] ||= (request_params[:port] == 443 ? 'https' : 'http')
      # (re)open connection to server if none exists or params has changed
      unless @http          && 
             @http.started? &&
             @server   == request_params[:server] &&
             @port     == request_params[:port]   &&
             @protocol == request_params[:protocol]
        start(request_params)
      end
      
      # get response and return it
      request  = request_params[:request]
      request['User-Agent'] = get_param(:user_agent) || ''

      # Detect if the body is a streamable object like a file or socket.  If so, stream that
      # bad boy.
      if(request.body && request.body.respond_to?(:read))
        body = request.body
        request.content_length = body.respond_to?(:lstat) ? body.lstat.size : body.size 
        request.body_stream = request.body
      end
      response = @http.request(request, &block)
      
      error_reset
      eof_reset
      return response

    # We treat EOF errors and the timeout/network errors differently.  Both
    # are tracked in different statistics blocks.  Note below that EOF
    # errors will sleep for a certain (exponentially increasing) period.
    # Other errors don't sleep because there is already an inherent delay
    # in them; connect and read timeouts (for example) have already
    # 'slept'.  It is still not clear which way we should treat errors
    # like RST and resolution failures.  For now, there is no additional
    # delay for these errors although this may change in the future.
    
    # EOFError means the server closed the connection on us.
    rescue EOFError => e
      @logger.debug("#{err_header} server #{@server} closed connection")
      @http = nil
      
        # if we have waited long enough - raise an exception...
      if raise_on_eof_exception?
        exception = get_param(:exception) || RuntimeError
        @logger.warn("#{err_header} raising #{exception} due to permanent EOF being received from #{@server}, error age: #{Time.now.to_i - eof_time.to_i}")  
        raise exception.new("Permanent EOF is being received from #{@server}.")
      else
          # ... else just sleep a bit before new retry
        sleep(add_eof)
      end 
    rescue Exception => e  # See comment at bottom for the list of errors seen...
      @http = nil
      # if ctrl+c is pressed - we have to reraise exception to terminate proggy 
      if e.is_a?(Interrupt) && !( e.is_a?(Errno::ETIMEDOUT) || e.is_a?(Timeout::Error))
        @logger.debug( "#{err_header} request to server #{@server} interrupted by ctrl-c")
        raise
      elsif e.is_a?(ArgumentError) && e.message.include?('wrong number of arguments (5 for 4)')
        # seems our net_fix patch was overriden...
        exception = get_param(:exception) || RuntimeError
        raise exception.new('incompatible Net::HTTP monkey-patch')
      end
      # oops - we got a banana: log it
      error_add(e.message)
      @logger.warn("#{err_header} request failure count: #{error_count}, exception: #{e.inspect}")
    end
  end
end

#socket_read_size=(newsize) ⇒ Object

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.



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# File 'lib/right_http_connection.rb', line 149

def socket_read_size=(newsize)
  Net::BufferedIO.socket_read_size=(newsize)
end

#socket_read_size? ⇒ Boolean

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.

Returns:

  • (Boolean) 


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# File 'lib/right_http_connection.rb', line 142

def socket_read_size?
  Net::BufferedIO.socket_read_size?
end