add jaeger support, link hot container & req span (#840)

* add jaeger support, link hot container & req span

* adds jaeger support now with FN_JAEGER_URL, there's a simple tutorial in the
operating/metrics.md file now and it's pretty easy to get up and running.
* links a hot request span to a hot container span. when we change this to
sample at a lower ratio we'll need to finagle the hot container span to always
sample or something, otherwise we'll hide that info. at least, since we're
sampling at 100% for now if this is flipped on, can see freeze/unfreeze etc.
if they hit. this is useful for debugging. note that zipkin's exporter does
not follow the link at all, hence jaeger... and they're backed by the Cloud
Empire now (CNCF) so we'll probably use it anyway.

* vendor: add thrift for jaeger

vendor/git.apache.org/thrift.git/lib/cpp/test/SpecializationTest.cpp

@@ -0,0 +1,103 @@
+#define _USE_MATH_DEFINES
+#include <cmath>
+#include <thrift/transport/TTransportUtils.h>
+#include <thrift/protocol/TBinaryProtocol.h>
+#include <gen-cpp/DebugProtoTest_types.h>
+
+using namespace thrift::test::debug;
+using namespace apache::thrift::transport;
+using namespace apache::thrift::protocol;
+
+#define BOOST_TEST_MODULE SpecializationTest
+#include <boost/test/unit_test.hpp>
+
+typedef TBinaryProtocolT<TMemoryBuffer> MyProtocol;
+// typedef TBinaryProtocolT<TTransport> MyProtocol;
+
+BOOST_AUTO_TEST_CASE(test_specialization_1) {
+  OneOfEach ooe;
+  ooe.im_true = true;
+  ooe.im_false = false;
+  ooe.a_bite = 0x7f;
+  ooe.integer16 = 27000;
+  ooe.integer32 = 1 << 24;
+  ooe.integer64 = (uint64_t)6000 * 1000 * 1000;
+  ooe.double_precision = M_PI;
+  ooe.some_characters = "JSON THIS! \"\1";
+  ooe.zomg_unicode = "\xd7\n\a\t";
+  ooe.base64 = "\1\2\3\255";
+
+  Nesting n;
+  n.my_ooe = ooe;
+  n.my_ooe.integer16 = 16;
+  n.my_ooe.integer32 = 32;
+  n.my_ooe.integer64 = 64;
+  n.my_ooe.double_precision = (std::sqrt(5.0) + 1) / 2;
+  n.my_ooe.some_characters = ":R (me going \"rrrr\")";
+  n.my_ooe.zomg_unicode     = "\xd3\x80\xe2\x85\xae\xce\x9d\x20\xd0\x9d\xce"
+                              "\xbf\xe2\x85\xbf\xd0\xbe\xc9\xa1\xd0\xb3\xd0"
+                              "\xb0\xcf\x81\xe2\x84\x8e\x20\xce\x91\x74\x74"
+                              "\xce\xb1\xe2\x85\xbd\xce\xba\xc7\x83\xe2\x80"
+                              "\xbc";
+  n.my_bonk.type = 31337;
+  n.my_bonk.message = "I am a bonk... xor!";
+
+  HolyMoley hm;
+
+  hm.big.push_back(ooe);
+  hm.big.push_back(n.my_ooe);
+  hm.big[0].a_bite = 0x22;
+  hm.big[1].a_bite = 0x33;
+
+  std::vector<std::string> stage1;
+  stage1.push_back("and a one");
+  stage1.push_back("and a two");
+  hm.contain.insert(stage1);
+  stage1.clear();
+  stage1.push_back("then a one, two");
+  stage1.push_back("three!");
+  stage1.push_back("FOUR!!");
+  hm.contain.insert(stage1);
+  stage1.clear();
+  hm.contain.insert(stage1);
+
+  std::vector<Bonk> stage2;
+  hm.bonks["nothing"] = stage2;
+  stage2.resize(stage2.size() + 1);
+  stage2.back().type = 1;
+  stage2.back().message = "Wait.";
+  stage2.resize(stage2.size() + 1);
+  stage2.back().type = 2;
+  stage2.back().message = "What?";
+  hm.bonks["something"] = stage2;
+  stage2.clear();
+  stage2.resize(stage2.size() + 1);
+  stage2.back().type = 3;
+  stage2.back().message = "quoth";
+  stage2.resize(stage2.size() + 1);
+  stage2.back().type = 4;
+  stage2.back().message = "the raven";
+  stage2.resize(stage2.size() + 1);
+  stage2.back().type = 5;
+  stage2.back().message = "nevermore";
+  hm.bonks["poe"] = stage2;
+
+  apache::thrift::stdcxx::shared_ptr<TMemoryBuffer> buffer(new TMemoryBuffer());
+  apache::thrift::stdcxx::shared_ptr<TProtocol> proto(new MyProtocol(buffer));
+
+  ooe.write(proto.get());
+  OneOfEach ooe2;
+  ooe2.read(proto.get());
+
+  BOOST_CHECK(ooe == ooe2);
+
+  hm.write(proto.get());
+  HolyMoley hm2;
+  hm2.read(proto.get());
+
+  BOOST_CHECK(hm == hm2);
+
+  hm2.big[0].a_bite = 0x00;
+
+  BOOST_CHECK(hm != hm2);
+}