trafficserver Remove intermediate buffer in PluginVC

Removes active/passive buffer intermediate buffer to reduce data transfer latency

removes MIOBuffer and IOBufferReader objects for both transfers
for every write, it reduces transfer_bytes call from 2 to 1

Tests done internally show improvements

Feb 24 '22 00:02 serrislew

Fixed connection timeout issue, ready for testing

Mar 11 '22 23:03 serrislew

CI tests show failed assertion on PVC regression test but...

Tested this locally on Mac, CentOS and Fedora docker image and PVC regression tests passes on all of those machines

Mar 21 '22 16:03 serrislew

In case it's helpful, I reproduced this locally on my Mac using rockylinux:8 like so:

docker pull controller.trafficserver.org/ats/rockylinux:8
docker run --name test_serris_patch -it controller.trafficserver.org/ats/rockylinux:8 /bin/bash

# Now, from within the running container.
cd /var/tmp
git clone https://github.com/serrislew/trafficserver.git
cd trafficserver/
git checkout pluginvc_opt
source /opt/rh/gcc-toolset-11/enable
autoreconf -fiv
./configure --with-openssl=/opt/openssl-quic --enable-experimental-plugins --enable-example-plugins --prefix=/tmp/ats/ --enable-werror --enable-debug --enable-luajit --enable-ccache
make -j4 V=1 Q=
make install
/tmp/ats/bin/traffic_server -K -k -R 1

That triggered this PluginVC assertion:

REGRESSION TEST PVC started
[SDK_API_TSContSchedule] TSContScheduleOnPool : [TestCase1] <<PASS>> { ok }
[SDK_API_TSContDataGet] TSContDataSet : [TestCase1] <<PASS>> { ok }
[SDK_API_TSContDataGet] TSContDataGet : [TestCase1] <<PASS>> { ok }
[SDK_API_TSActionCancel] TSActionCancel : [TestCase1] <<PASS>> { ok }
Fatal: PluginVC.cc:310: failed assertion `!closed`
[Mar 21 20:06:23.089] traffic_crashlo NOTE: crashlog started, target=59214, debug=false syslog=true, uid=65534 euid=0
[Mar 21 20:06:23.090] traffic_crashlo WARNING: failed to initialize management API: [5] Error establishing socket connection.
[Mar 21 20:06:23.090] traffic_crashlo NOTE: logging to 0x2365e60
[Mar 21 20:06:23.090] traffic_crashlo NOTE: readlink failed with Permission denied
[Mar 21 20:06:23.092] traffic_crashlo ERROR: wrote crash log to /tmp/ats/var/log/trafficserver/crash-2022-03-21-200623.log
traffic_server: received signal 6 (Aborted)
traffic_server - STACK TRACE: 
/tmp/ats/bin/traffic_server(_Z19crash_logger_invokeiP9siginfo_tPv+0xc3)[0x82079c]
/lib64/libpthread.so.0(+0x12c20)[0x7f2e3e2c6c20]
/lib64/libc.so.6(gsignal+0x10f)[0x7f2e3d3f337f]
/lib64/libc.so.6(abort+0x127)[0x7f2e3d3dddb5]
/tmp/ats//lib/libtscore.so.10(_Z11ink_warningPKcz+0x0)[0x7f2e3f8cb72c]
/tmp/ats//lib/libtscore.so.10(_Z17ats_base64_encodePKhmPcmPm+0x0)[0x7f2e3f8c70b1]
/tmp/ats/bin/traffic_server(_ZN8PluginVC8reenableEP3VIO+0x3d)[0xb15b7f]
/tmp/ats/bin/traffic_server(_ZN3VIO8reenableEv+0x47)[0x825c7d]
/tmp/ats/bin/traffic_server(_ZN8PluginVC18process_write_sideEv+0xc61)[0xb17273]
/tmp/ats/bin/traffic_server(_ZN8PluginVC12main_handlerEiPv+0x66f)[0xb15515]
/tmp/ats/bin/traffic_server(_ZN12Continuation11handleEventEiPv+0xdd)[0x825a81]
/tmp/ats/bin/traffic_server(_ZN7EThread13process_eventEP5Eventi+0x157)[0xbfc17f]
/tmp/ats/bin/traffic_server(_ZN7EThread13process_queueEP5QueueI5EventNS1_9Link_linkEEPiS5_+0xb2)[0xbfc384]
/tmp/ats/bin/traffic_server(_ZN7EThread15execute_regularEv+0x2dc)[0xbfc746]
/tmp/ats/bin/traffic_server(_ZN7EThread7executeEv+0x107)[0xbfca5d]
/tmp/ats/bin/traffic_server[0xbfb234]
/lib64/libpthread.so.0(+0x817a)[0x7f2e3e2bc17a]
/lib64/libc.so.6(clone+0x43)[0x7f2e3d4b8dc3]
Aborted