Class | Rightscale::HttpConnection |
In: |
lib/right_http_connection.rb
|
Parent: | Object |
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.
HTTP_CONNECTION_RETRY_COUNT | = | 3 unless defined?(HTTP_CONNECTION_RETRY_COUNT) | Number of times to retry the request after encountering the first error | |
HTTP_CONNECTION_OPEN_TIMEOUT | = | 5 unless defined?(HTTP_CONNECTION_OPEN_TIMEOUT) | Throw a Timeout::Error if a connection isn‘t established within this number of seconds | |
HTTP_CONNECTION_READ_TIMEOUT | = | 120 unless defined?(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_DELAY | = | 15 unless defined?(HTTP_CONNECTION_RETRY_DELAY) | Length of the post-error probationary period during which all requests will fail |
http | [RW] | |
logger | [RW] | |
params | [RW] | |
server | [RW] |
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. :fail_if_ca_mismatch => Boolean # If ca_file is set and the server certificate doesn't verify, a log line is generated regardless, but normally right_http_connection continues on past the failure. If this is set, fail to connect in that case. Defaults to false. :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. :proxy_host => 'hostname' # hostname of HTTP proxy host to use, default none. :proxy_port => port # port of HTTP proxy host to use, default none. :proxy_username => 'username' # username to use for proxy authentication, default none. :proxy_password => 'password' # password to use for proxy authentication, default none. :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] :raise_on_timeout # do not perform a retry if timeout is received (false by default)
# File lib/right_http_connection.rb, line 138 138: def initialize(params={}) 139: @params = params 140: @params[:http_connection_retry_count] ||= @@params[:http_connection_retry_count] 141: @params[:http_connection_open_timeout] ||= @@params[:http_connection_open_timeout] 142: @params[:http_connection_read_timeout] ||= @@params[:http_connection_read_timeout] 143: @params[:http_connection_retry_delay] ||= @@params[:http_connection_retry_delay] 144: @params[:proxy_host] ||= @@params[:proxy_host] 145: @params[:proxy_port] ||= @@params[:proxy_port] 146: @params[:proxy_username] ||= @@params[:proxy_username] 147: @params[:proxy_password] ||= @@params[:proxy_password] 148: @http = nil 149: @server = nil 150: @logger = get_param(:logger) || 151: (RAILS_DEFAULT_LOGGER if defined?(RAILS_DEFAULT_LOGGER)) || 152: Logger.new(STDOUT) 153: #-------------- 154: # Retry state - Keep track of errors on a per-server basis 155: #-------------- 156: @state = {} # retry state indexed by server: consecutive error count, error time, and error 157: @eof = {} 158: end
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. :fail_if_ca_mismatch => Boolean # If ca_file is set and the server certificate doesn't verify, a log line is generated regardless, but normally right_http_connection continues on past the failure. If this is set, fail to connect in that case. Defaults to false. :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. :proxy_host => 'hostname' # hostname of HTTP proxy host to use, default none. :proxy_port => port # port of HTTP proxy host to use, default none. :proxy_username => 'username' # username to use for proxy authentication, default none. :proxy_password => 'password' # password to use for proxy authentication, default none. :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 :raise_on_timeout # do not perform a retry if timeout is received (false by default)
# File lib/right_http_connection.rb, line 106 106: def self.params 107: @@params 108: end
Set the global (class-level) parameters
# File lib/right_http_connection.rb, line 111 111: def self.params=(params) 112: @@params = params 113: end
# File lib/right_http_connection.rb, line 459 459: def finish(reason = '') 460: if @http && @http.started? 461: reason = ", reason: '#{reason}'" unless reason.empty? 462: @logger.info("Closing #{@http.use_ssl? ? 'HTTPS' : 'HTTP'} connection to #{@http.address}:#{@http.port}#{reason}") 463: @http.finish 464: end 465: end
# File lib/right_http_connection.rb, line 160 160: def get_param(name, custom_options={}) 161: custom_options [name] || @params[name] || @@params[name] 162: end
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, line 188 188: def local_read_size=(newsize) 189: Net::HTTPGenericRequest.local_read_size=(newsize) 190: end
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, line 181 181: def local_read_size? 182: Net::HTTPGenericRequest.local_read_size? 183: end
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 :proxy_host => 'hostname' # hostname of HTTP proxy host to use, default none. :proxy_port => port # port of HTTP proxy host to use, default none. :proxy_username => 'username' # username to use for proxy authentication, default none. :proxy_password => 'password' # password to use for proxy authentication, default none. :raise_on_timeout # do not perform a retry if timeout is received (false by default) :http_connection_retry_count :http_connection_open_timeout :http_connection_read_timeout :http_connection_retry_delay :user_agent :exception
Raises RuntimeError, Interrupt, and params[:exception] (if specified in new).
# File lib/right_http_connection.rb, line 358 358: def request(request_params, &block) 359: current_params = @params.merge(request_params) 360: exception = get_param(:exception, current_params) || RuntimeError 361: 362: # We save the offset here so that if we need to retry, we can return the file pointer to its initial position 363: mypos = get_fileptr_offset(current_params) 364: loop do 365: current_params[:protocol] ||= (current_params[:port] == 443 ? 'https' : 'http') 366: # (re)open connection to server if none exists or params has changed 367: same_server_as_before = @server == current_params[:server] && 368: @port == current_params[:port] && 369: @protocol == current_params[:protocol] 370: 371: # if we are inside a delay between retries: no requests this time! 372: # (skip this step if the endpoint has changed) 373: if error_count > current_params[:http_connection_retry_count] && 374: error_time + current_params[:http_connection_retry_delay] > Time.now && 375: same_server_as_before 376: 377: # store the message (otherwise it will be lost after error_reset and 378: # we will raise an exception with an empty text) 379: banana_message_text = banana_message 380: @logger.warn("#{err_header} re-raising same error: #{banana_message_text} " + 381: "-- error count: #{error_count}, error age: #{Time.now.to_i - error_time.to_i}") 382: raise exception.new(banana_message_text) 383: end 384: 385: # try to connect server(if connection does not exist) and get response data 386: begin 387: request = current_params[:request] 388: request['User-Agent'] = get_param(:user_agent, current_params) || '' 389: unless @http && 390: @http.started? && 391: same_server_as_before 392: start(current_params) 393: end 394: 395: # Detect if the body is a streamable object like a file or socket. If so, stream that 396: # bad boy. 397: setup_streaming(request) 398: # update READ_TIMEOUT value (it can be passed with request_params hash) 399: @http.read_timeout = get_param(:http_connection_read_timeout, current_params) 400: response = @http.request(request, &block) 401: 402: error_reset 403: eof_reset 404: return response 405: 406: # We treat EOF errors and the timeout/network errors differently. Both 407: # are tracked in different statistics blocks. Note below that EOF 408: # errors will sleep for a certain (exponentially increasing) period. 409: # Other errors don't sleep because there is already an inherent delay 410: # in them; connect and read timeouts (for example) have already 411: # 'slept'. It is still not clear which way we should treat errors 412: # like RST and resolution failures. For now, there is no additional 413: # delay for these errors although this may change in the future. 414: 415: # EOFError means the server closed the connection on us. 416: rescue EOFError => e 417: @logger.debug("#{err_header} server #{@server} closed connection") 418: @http = nil 419: 420: # if we have waited long enough - raise an exception... 421: if raise_on_eof_exception? 422: @logger.warn("#{err_header} raising #{exception} due to permanent EOF being received from #{@server}, error age: #{Time.now.to_i - eof_time.to_i}") 423: raise exception.new("Permanent EOF is being received from #{@server}.") 424: else 425: # ... else just sleep a bit before new retry 426: sleep(add_eof) 427: # We will be retrying the request, so reset the file pointer 428: reset_fileptr_offset(request, mypos) 429: end 430: rescue Exception => e # See comment at bottom for the list of errors seen... 431: @http = nil 432: timeout_exception = e.is_a?(Errno::ETIMEDOUT) || e.is_a?(Timeout::Error) 433: # Omit retries if it was explicitly requested 434: if current_params[:raise_on_timeout] && timeout_exception 435: # #6481: 436: # ... When creating a resource in EC2 (instance, volume, snapshot, etc) it is undetermined what happened if the call times out. 437: # The resource may or may not have been created in EC2. Retrying the call may cause multiple resources to be created... 438: raise e 439: end 440: # if ctrl+c is pressed - we have to reraise exception to terminate proggy 441: if e.is_a?(Interrupt) && !timeout_exception 442: @logger.debug( "#{err_header} request to server #{@server} interrupted by ctrl-c") 443: raise 444: elsif e.is_a?(ArgumentError) && e.message.include?('wrong number of arguments (5 for 4)') 445: # seems our net_fix patch was overriden... 446: raise exception.new('incompatible Net::HTTP monkey-patch') 447: end 448: # oops - we got a banana: log it 449: error_add(e.message) 450: @logger.warn("#{err_header} request failure count: #{error_count}, exception: #{e.inspect}") 451: 452: # We will be retrying the request, so reset the file pointer 453: reset_fileptr_offset(request, mypos) 454: 455: end 456: end 457: end
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, line 174 174: def socket_read_size=(newsize) 175: Net::BufferedIO.socket_read_size=(newsize) 176: end