This sounds very useful. (We did something hacky with the address to get similar functionality just inside a plugin, this would be much cleaner.) I wonder if it should take some extra optional arguments to allow doing transparent stuff too. (So it would be a complete super-set.)
-William Bardwell ________________________________________ From: Alan M. Carroll [a...@network-geographics.com] Sent: Friday, May 23, 2014 4:39 PM To: dev@trafficserver.apache.org Subject: API proposal TSHttpConnectWithPluginID ========================= Allows the plugin to initiate an http connection. This will tag the HTTP state machine with extra data that can be accessed by the logging interface. Synopsis -------- `#include <ts/ts.h>` .. c:function:: TSVConn TSHttpConnectWithPluginId(sockaddr const *addr, char const* tag, int64_t id) Description ----------- This call attempts to create an HTTP state machine and a virtual connection to that state machine. This is more efficient than using :c:func:`TSNetConnect` because it avoids using the operating system stack via the loopback interface. *addr* This is the network address of the target of the connection. This includes the port which should be stored in the :c:type:`sockaddr` structure. *tag* This is a tag that is passed through to the HTTP state machine. It must be a persistent string that has a lifetime longer than the connection. It is accessible via the log field ``pitag``. This is intended as a class or type identifier that is consistent across all connections for this plugin. In effect, the name of the plugin. This can be ``NULL``. *id* This is a numeric identifier that is passed through to the HTTP state machine. It is accessible via the log field ``piid``. This is intended as a connection identifier and should be distinct for every call to ``TSHttpConnectWithPluginID``. The easist mechanism is to define a plugin global value and increment it for each connection. The value ``0`` is reserved to mean "not set" and can be used as a default if this functionality is not needed. The virtual connection returned as the ``TSCVonn`` is API equivalent to a network virtual connection both to the plugin and to internal mechanisms. Data is read and written to the connection (and thence to the target system) by reading and writing on this virtual connection. The combination of tag and id is intended to enable correlation in log post processing. The tag identifies the connection as related to the plugin and the id can be used in conjuction with plugin generated logs to correlate the log records. This is also intended to be useful for debugging by tagging not just the HTTP state machine but also the connection virtual connections (if of type ``PluginVC``) with correlated data. .. topic:: Example The SPDY plugin uses this to correlate client sessions with SPDY streams. Each client connection is assigned a distinct numeric identifier. This is passed as the *id* to ``TSHttpConnectWithPluginId``. The name is selected to be the NPN string for the client session protocol, e.g. "spdy/3" or "spdy/3.1". Log post processing can then count the number of connections for the various supported protocols and the number of streams / sessions / transactions for each real client connection to Traffic Server.
