Remove Congestion Control Feature

This feature has been gathering dust.  I don't beleive anyone is using the
feature, and the feedback I received is that it doesn't really work.

doc/admin-guide/configuration/cache-basics.en.rst

@@ -639,38 +639,6 @@ To alter the limit on the number of alternates:
 
 #. Run the command :option:`traffic_ctl config reload` to apply the configuration changes.
 
-.. _using-congestion-control:
-
-Using Congestion Control
-========================
-
-The *Congestion Control* option enables you to configure Traffic
-Server to stop forwarding HTTP requests to origin servers when they
-become congested. Traffic Server then sends the client a message to
-retry the congested origin server later.
-
-To enable this option:
-
-#. Set :ts:cv:`proxy.config.http.congestion_control.enabled` to ``1`` in
-   :file:`records.config`. ::
-
-        CONFIG proxy.config.http.congestion_control.enabled INT 1
-
-#. Create rules in :file:`congestion.config` to specify:
-
-   -  Which origin servers Traffic Server tracks for congestion.
-
-   -  The timeouts Traffic Server uses, depending on whether a server is
-      congested.
-
-   -  The page Traffic Server sends to the client when a server becomes
-      congested.
-
-   -  Whether Traffic Server tracks the origin servers by IP address or by
-      hostname.
-
-#. Run the command :option:`traffic_ctl config reload` to apply the configuration changes.
-
 .. _transaction-buffering-control:
 
 Using Transaction Buffering Control

doc/admin-guide/files/index.en.rst

@@ -26,7 +26,6 @@ Configuration Files
    :hidden:
 
    cache.config.en
-   congestion.config.en
    hosting.config.en
    ip_allow.config.en
    log_hosts.config.en
@@ -47,10 +46,6 @@ Configuration Files
    Defines if, how, and for what durations |TS| caches objects, based on
    destinations, clients, URL components, and more.
 
-:doc:`congestion.config.en`
-   Defines network conditions under which clients will receive retry messages
-   instead of |TS| contacting origin servers.
-
 :doc:`hosting.config.en`
    Allows |TS| administrators to assign cache volumes to specific origin
    servers or domains.

doc/admin-guide/files/records.config.en.rst

@@ -1533,12 +1533,6 @@ Origin Server Connect Attempts
 Congestion Control
 ==================
 
-.. ts:cv:: CONFIG proxy.config.http.congestion_control.enabled INT 0
-
-   Enables (``1``) or disables (``0``) the Congestion Control option, which configures Traffic Server to stop forwarding
-   HTTP requests to origin servers when they become congested. Traffic Server sends the client a message to retry the
-   congested origin server later. Refer to :ref:`using-congestion-control`.
-
 .. ts:cv:: CONFIG proxy.config.http.flow_control.enabled INT 0
    :overridable:
 

mgmt/RecordsConfig.cc

@@ -300,40 +300,6 @@ static const RecordElement RecordsConfig[] =
   {RECT_CONFIG, "proxy.config.alarm.script_runtime", RECD_INT, "5", RECU_DYNAMIC, RR_NULL, RECC_INT, "[0-300]", RECA_NULL}
   ,
 
-  //####################################################################
-  //# congestion control
-  //####################################################################
-  {RECT_CONFIG, "proxy.config.http.congestion_control.enabled", RECD_INT, "0", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.localtime", RECD_INT, "0", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.filename", RECD_STRING, "congestion.config", RECU_DYNAMIC, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.default.max_connection_failures", RECD_INT, "5", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.default.fail_window", RECD_INT, "120", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.default.proxy_retry_interval", RECD_INT, "10", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.default.client_wait_interval", RECD_INT, "300", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.default.wait_interval_alpha", RECD_INT, "30", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.default.live_os_conn_timeout", RECD_INT, "60", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.default.live_os_conn_retries", RECD_INT, "2", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.default.dead_os_conn_timeout", RECD_INT, "15", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.default.dead_os_conn_retries", RECD_INT, "1", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.default.max_connection", RECD_INT, "-1", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.default.error_page", RECD_STRING, "congestion#retryAfter", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-  {RECT_CONFIG, "proxy.config.http.congestion_control.default.congestion_scheme", RECD_STRING, "per_ip", RECU_NULL, RR_NULL, RECC_NULL, nullptr, RECA_NULL}
-  ,
-
   //        ###########
   //        # Parsing #
   //        ###########

proxy/ControlMatcher.cc

@@ -45,7 +45,6 @@
 #include "P_Net.h"
 #include "P_Cache.h"
 #include "P_SplitDNS.h"
-#include "congest/Congestion.h"
 
 /****************************************************************
  *   Place all template instantiations at the bottom of the file
@@ -1004,10 +1003,3 @@ template class HostMatcher<CacheControlRecord, CacheControlResult>;
 template class RegexMatcher<CacheControlRecord, CacheControlResult>;
 template class UrlMatcher<CacheControlRecord, CacheControlResult>;
 template class IpMatcher<CacheControlRecord, CacheControlResult>;
-
-template class ControlMatcher<CongestionControlRecord, CongestionControlRule>;
-template class HostMatcher<CongestionControlRecord, CongestionControlRule>;
-template class HostRegexMatcher<CongestionControlRecord, CongestionControlRule>;
-template class RegexMatcher<CongestionControlRecord, CongestionControlRule>;
-template class UrlMatcher<CongestionControlRecord, CongestionControlRule>;
-template class IpMatcher<CongestionControlRecord, CongestionControlRule>;

proxy/Main.cc

@@ -88,7 +88,6 @@ extern "C" int plock(int);
 #include "Plugin.h"
 #include "DiagsConfig.h"
 #include "CoreUtils.h"
-#include "congest/Congestion.h"
 #include "RemapProcessor.h"
 #include "I_Tasks.h"
 #include "InkAPIInternal.h"
@@ -1840,7 +1839,6 @@ main(int /* argc ATS_UNUSED */, const char **argv)
     remapProcessor.start(num_remap_threads, stacksize);
     RecProcessStart();
     initCacheControl();
-    initCongestionControl();
     IpAllow::startup();
     ParentConfig::startup();
 #ifdef SPLIT_DNS

proxy/Makefile.am

@@ -19,7 +19,7 @@
 include $(top_srcdir)/build/tidy.mk
 
 # Note that hdrs is targeted from ../Makefile.am
-SUBDIRS = congest http http2 logging config
+SUBDIRS = http http2 logging config
 noinst_LIBRARIES =
 bin_PROGRAMS = \
   traffic_server \
@@ -181,7 +181,6 @@ traffic_server_LDADD = \
   http/libhttp.a \
   http2/libhttp2.a \
   http/remap/libhttp_remap.a \
-  congest/libCongestionControl.a \
   logging/liblogging.a \
   logging/liblogcollation.a \
   hdrs/libhdrs.a  \