Merge branch 'bracz-direct-hub-router' into bracz-direct-hub-app

* bracz-direct-hub-router: (35 commits)
  High-performance hub component for dealing with many sockets and high throughput (#760)
  Fix test build.
  Fixed comment and adds a todo.
  Remove unnecessary log.
  Fix comments and reduce unnecessary log level.
  FIx comments.
  Fix build of esp8266 train implementation.
  Removes unnecessary includes that might not exist on an embedded compiler.
  Fix compilation of TempFile under esp8266.
  Add libatomic to esp8266 nonos target.
  Fix compile errors in time_client app.
  Fixes in file memory space: (#786)
  Change startup state to stopped. (#784)
  Fixes write code for spiflash. (#782)
  Handles bus passive in TivaCan. (#781)
  Update libify to support IDF export with symlinks (#770)
  Fix esp32 select race conditions. (#780)
  Latency test with maximum stats and custom process evaluation (#773)
  Fix compiler warnings in openmrn when using new GCC's. (#772)
  Upintegrate changes from the OpenMRNIDF repository (#771)
  ...

applications/hub_test/Makefile

@@ -0,0 +1,3 @@
+SUBDIRS = targets
+-include config.mk
+include $(OPENMRNPATH)/etc/recurse.mk

applications/hub_test/README.md

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+Hub throughput testing application {#hub_test_application}
+==================================
+
+[TOC]
+
+# Goal
+
+The purpose of Hub testing is to verify an OpenLCB link or bus for qualitative
+and quantitative performance characteristics. These are as follows.
+
+Qualitative:
+- The link has to be lossless.
+- There is only limited reordering allowed within the link.
+- There has to be proper throttling for ingress of packets to the link.
+
+Quantitative:
+- What is the maximum throughut of packets that can be accepted on the link.
+- What is the round-trip-time of the link.
+- What is the jitter on the timing of the packet round-trips.
+
+For hubs, a relevant question is also how do these metrics change as the number
+of clients on the hub are increased.
+
+## Testing methodology
+
+The application contains a load generator, and a receiver. For a given test,
+one generator and one or more receivers have to be attached to the same bus.
+
+The generator supplies a given load to the bus. This load may be a fixes
+traffic, or the maximum traffic that the bus is willing to accept.
+
+The receiver watches for the traffic coming from the generator, verifies the
+qualitative attributes, and measures the quantitative attributes. Statistics
+about this are printed to the screen.
+
+

applications/hub_test/config.mk

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+../default_config.mk

applications/hub_test/subdirs

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+SUBDIRS = \
+

applications/hub_test/targets/Makefile

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+SUBDIRS = \
+          linux.x86 \
+
+include $(OPENMRNPATH)/etc/recurse.mk

applications/hub_test/targets/linux.x86/.gitignore

@@ -0,0 +1 @@
+hub_test

applications/hub_test/targets/linux.x86/Makefile

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+-include ../../config.mk
+include $(OPENMRNPATH)/etc/prog.mk