From: Amos Jeffries <squid3@treenet.co.nz>
Date: Tue, 17 Nov 2015 05:58:08 +0000 (-0800)
Subject: Docs: Update ConnStateData and ClientServerContext descriptions
X-Git-Tag: SQUID_4_0_3~5^2~8
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=434fe01480e773c9439314f0c96368d4ed0e3f91;p=thirdparty%2Fsquid.git

Docs: Update ConnStateData and ClientServerContext descriptions
---

diff --git a/src/client_side.h b/src/client_side.h
index dbc082c5bd..6bb81dee53 100644
--- a/src/client_side.h
+++ b/src/client_side.h
@@ -37,24 +37,36 @@ class PortCfg;
 
 /**
  * Badly named.
- * This is in fact the processing context for a single HTTP request.
+ * This is in fact the processing context for a single HTTP transaction.
  *
- * Managing what has been done, and what happens next to the data buffer
- * holding what we hope is an HTTP request.
+ * A context lifetime extends from directly after a request has been parsed
+ * off the client connection buffer, until the last byte of both request
+ * and reply payload (if any) have been written.
  *
- * Parsing is still a mess of global functions done in conjunction with the
- * real socket controller which generated ClientHttpRequest.
- * It also generates one of us and passes us control from there based on
- * the results of the parse.
+ * (NOTE: it is not certain yet if an early reply to a POST/PUT is sent by
+ * the server whether the context will remain in the pipeline until its
+ * request payload has finished being read. It is supposed to, but may not)
  *
- * After that all the request interpretation and adaptation is in our scope.
- * Then finally the reply fetcher is created by this and we get the result
- * back. Which we then have to manage writing of it to the ConnStateData.
+ * Contexts self-register with the Pipeline being managed by the Server
+ * for the connection on which the request was received.
  *
- * The socket level management is done by a ConnStateData which owns us.
+ * When HTTP/1 pipeline is operating there may be multiple transactions using
+ * the clientConnection. Only the back() context may read from the connection,
+ * and only the front() context may write to it. A context which needs to read
+ * or write to the connection but does not meet those criteria must be shifted
+ * to the deferred state.
+ *
+ * When a context is completed the finished() method needs to be called which
+ * will perform all cleanup and deregistration operations. If the reason for
+ * finishing is an error, then notifyIoError() needs to be called prior to
+ * the finished() method.
+ * Alternatively the initiateClose() method can be called to terminate the
+ * whole client connection and all other pending contexts.
+ *
+ * The socket level management is done by a Server which owns us.
  * The scope of this objects control over a socket consists of the data
- * buffer received from ConnStateData with an initially unknown length.
- * When that length is known it sets the end bounary of our acces to the
+ * buffer received from the Server with an initially unknown length.
+ * When that length is known it sets the end boundary of our access to the
  * buffer.
  *
  * The individual processing actions are done by other Jobs which we
@@ -151,19 +163,30 @@ namespace Ssl
 class ServerBump;
 }
 #endif
+
 /**
- * Manages a connection to a client.
+ * Legacy Server code managing a connection to a client.
+ *
+ * NP: presents AsyncJob API but does not operate autonomously as a Job.
+ *     So Must() is not safe to use.
+ *
+ * Multiple requests (up to pipeline_prefetch) can be pipelined.
+ * This object is responsible for managing which one is currently being
+ * fulfilled and what happens to the queue if the current one causes the client
+ * connection to be closed early.
+ *
+ * Act as a manager for the client connection and passes data in buffer to a
+ * Parser relevant to the state (message headers vs body) that is being
+ * processed.
  *
- * Multiple requests (up to pipeline_prefetch) can be pipelined. This object is responsible for managing
- * which one is currently being fulfilled and what happens to the queue if the current one
- * causes the client connection to be closed early.
+ * Performs HTTP message processing to kick off the actual HTTP request
+ * handling objects (ClientSocketContext, ClientHttpRequest, HttpRequest).
  *
- * Act as a manager for the connection and passes data in buffer to the current parser.
- * the parser has ambiguous scope at present due to being made from global functions
- * I believe this object uses the parser to identify boundaries and kick off the
- * actual HTTP request handling objects (ClientSocketContext, ClientHttpRequest, HttpRequest)
+ * Performs SSL-Bump processing for switching between HTTP and HTTPS protocols.
  *
- * If the above can be confirmed accurate we can call this object PipelineManager or similar
+ * To terminate a ConnStateData close() the client Comm::Connection it is
+ * managing, or for graceful half-close use the stopReceiving() or
+ * stopSending() methods.
  */
 class ConnStateData : public Server, public HttpControlMsgSink, public RegisteredRunner
 {