From 19ff047a791d1abe27b044c716cd34b77ed17ab7 Mon Sep 17 00:00:00 2001
From: Wolfgang Hess <whess@lyft.com>
Date: Fri, 12 Jan 2018 18:54:41 +0100
Subject: [PATCH] Allow FixedRatioSampler to drop all data. (#817)

This is useful to disable loop closure by setting
constraint_builder.sampling_ratio = 0.
---
 cartographer/common/fixed_ratio_sampler.cc      | 3 ++-
 cartographer/common/fixed_ratio_sampler_test.cc | 8 +++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/cartographer/common/fixed_ratio_sampler.cc b/cartographer/common/fixed_ratio_sampler.cc
index ec164e0..690854d 100644
--- a/cartographer/common/fixed_ratio_sampler.cc
+++ b/cartographer/common/fixed_ratio_sampler.cc
@@ -22,7 +22,8 @@ namespace cartographer {
 namespace common {
 
 FixedRatioSampler::FixedRatioSampler(const double ratio) : ratio_(ratio) {
-  CHECK_GT(ratio, 0.);
+  CHECK_GE(ratio, 0.);
+  LOG_IF(WARNING, ratio == 0.) << "FixedRatioSampler is dropping all data.";
   CHECK_LE(ratio, 1.);
 }
 
diff --git a/cartographer/common/fixed_ratio_sampler_test.cc b/cartographer/common/fixed_ratio_sampler_test.cc
index fdcfdc5..ccd716f 100644
--- a/cartographer/common/fixed_ratio_sampler_test.cc
+++ b/cartographer/common/fixed_ratio_sampler_test.cc
@@ -29,8 +29,14 @@ TEST(FixedRatioSamplerTest, AlwaysTrue) {
   }
 }
 
+TEST(FixedRatioSamplerTest, AlwaysFalse) {
+  FixedRatioSampler fixed_ratio_sampler(0.);
+  for (int i = 0; i < 100; ++i) {
+    EXPECT_FALSE(fixed_ratio_sampler.Pulse());
+  }
+}
+
 TEST(FixedRatioSamplerTest, NonSensicalRatio) {
-  EXPECT_DEATH(FixedRatioSampler(0.), "ratio");
   EXPECT_DEATH(FixedRatioSampler(2.), "ratio");
   EXPECT_DEATH(FixedRatioSampler(-0.1), "ratio");
 }