Throw exception on invalid sampling rate (fix #149) (#168)

Signed-off-by: FR-MUREX-COM\mchaikhadouaihy <[email protected]>

Author: mdouaihy

src/jaegertracing/samplers/Config.h

@@ -122,6 +122,7 @@ class Config {
                 oss << "Invalid parameter for probabilistic sampler: " << _param
                     << ", expecting value between 0 and 1";
                 logger.error(oss.str());
+                throw std::invalid_argument("Probabilistic sampling rate should be in the interval [0, 1].");
                 return std::unique_ptr<Sampler>();
             }
         }

src/jaegertracing/samplers/SamplerTest.cpp

@@ -20,6 +20,7 @@
 
 #include "jaegertracing/Constants.h"
 #include "jaegertracing/Tag.h"
+#include "jaegertracing/samplers/Config.h"
 #include "jaegertracing/samplers/AdaptiveSampler.h"
 #include "jaegertracing/samplers/ConstSampler.h"
 #include "jaegertracing/samplers/GuaranteedThroughputProbabilisticSampler.h"
@@ -149,6 +150,26 @@ TEST(Sampler, testProbabilisticSamplerPerformance)
     std::cout << "Sampled: " << count << " rate=" << rate << '\n';
 }
 
+TEST(Sampler, testProbabilisticSamplerInvalidRate)
+{
+    Config samplerConfig1(kSamplerTypeProbabilistic,
+                          1.1,
+                          "",
+                          0,
+                          samplers::Config::Clock::duration());
+    Config samplerConfig2(kSamplerTypeProbabilistic,
+                          -0.1,
+                          "",
+                          0,
+                          samplers::Config::Clock::duration());
+    auto logger = logging::nullLogger();
+    auto metrics = metrics::Metrics::makeNullMetrics();
+    ASSERT_THROW(samplerConfig1.makeSampler("test-service", *logger, *metrics),
+                 std::invalid_argument);
+    ASSERT_THROW(samplerConfig2.makeSampler("test-service", *logger, *metrics),
+                 std::invalid_argument);
+}
+
 TEST(Sampler, testRateLimitingSampler)
 {
     {