Add internal metric families. (#914)

- minimal counter, gauge and histogram implementations
- metric family interfaces as defined in libcartographer
- serializable to ROS messages

RFC: https://github.com/googlecartographer/rfcs/pull/26

cartographer_ros/cartographer_ros/metrics/internal/counter.h

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2018 The Cartographer Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef CARTOGRAPHER_ROS_METRICS_INTERNAL_COUNTER_H
+#define CARTOGRAPHER_ROS_METRICS_INTERNAL_COUNTER_H
+
+#include "cartographer/metrics/counter.h"
+#include "cartographer_ros/metrics/internal/gauge.h"
+#include "cartographer_ros_msgs/Metric.h"
+
+namespace cartographer_ros {
+namespace metrics {
+
+class Counter : public ::cartographer::metrics::Counter {
+ public:
+  explicit Counter(const std::map<std::string, std::string>& labels)
+      : gauge_(labels) {}
+
+  void Increment(const double by_value) override { gauge_.Increment(by_value); }
+
+  void Increment() override { gauge_.Increment(); }
+
+  double Value() const { return gauge_.Value(); }
+
+  cartographer_ros_msgs::Metric ToRosMessage() {
+    cartographer_ros_msgs::Metric msg = gauge_.ToRosMessage();
+    msg.type = cartographer_ros_msgs::Metric::TYPE_COUNTER;
+    return msg;
+  }
+
+ private:
+  Gauge gauge_;
+};
+
+}  // namespace metrics
+}  // namespace cartographer_ros
+
+#endif  // CARTOGRAPHER_ROS_METRICS_INTERNAL_COUNTER_H

cartographer_ros/cartographer_ros/metrics/internal/family.cc

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2018 The Cartographer Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "cartographer_ros/metrics/internal/family.h"
+
+#include "cartographer/common/make_unique.h"
+#include "cartographer_ros/metrics/internal/counter.h"
+#include "cartographer_ros/metrics/internal/gauge.h"
+#include "cartographer_ros/metrics/internal/histogram.h"
+
+namespace cartographer_ros {
+namespace metrics {
+
+using BucketBoundaries = ::cartographer::metrics::Histogram::BucketBoundaries;
+
+Counter* CounterFamily::Add(const std::map<std::string, std::string>& labels) {
+  auto wrapper = ::cartographer::common::make_unique<Counter>(labels);
+  auto* ptr = wrapper.get();
+  wrappers_.emplace_back(std::move(wrapper));
+  return ptr;
+}
+
+cartographer_ros_msgs::MetricFamily CounterFamily::ToRosMessage() {
+  cartographer_ros_msgs::MetricFamily family_msg;
+  family_msg.name = name_;
+  family_msg.description = description_;
+  for (const auto& wrapper : wrappers_) {
+    family_msg.metrics.push_back(wrapper->ToRosMessage());
+  }
+  return family_msg;
+}
+
+Gauge* GaugeFamily::Add(const std::map<std::string, std::string>& labels) {
+  auto wrapper = ::cartographer::common::make_unique<Gauge>(labels);
+  auto* ptr = wrapper.get();
+  wrappers_.emplace_back(std::move(wrapper));
+  return ptr;
+}
+
+cartographer_ros_msgs::MetricFamily GaugeFamily::ToRosMessage() {
+  cartographer_ros_msgs::MetricFamily family_msg;
+  family_msg.name = name_;
+  family_msg.description = description_;
+  for (const auto& wrapper : wrappers_) {
+    family_msg.metrics.push_back(wrapper->ToRosMessage());
+  }
+  return family_msg;
+}
+
+Histogram* HistogramFamily::Add(
+    const std::map<std::string, std::string>& labels) {
+  auto wrapper =
+      ::cartographer::common::make_unique<Histogram>(labels, boundaries_);
+  auto* ptr = wrapper.get();
+  wrappers_.emplace_back(std::move(wrapper));
+  return ptr;
+}
+
+cartographer_ros_msgs::MetricFamily HistogramFamily::ToRosMessage() {
+  cartographer_ros_msgs::MetricFamily family_msg;
+  family_msg.name = name_;
+  family_msg.description = description_;
+  for (const auto& wrapper : wrappers_) {
+    family_msg.metrics.push_back(wrapper->ToRosMessage());
+  }
+  return family_msg;
+}
+
+}  // namespace metrics
+}  // namespace cartographer_ros

cartographer_ros/cartographer_ros/metrics/internal/family.h

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2018 The Cartographer Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef CARTOGRAPHER_ROS_METRICS_INTERNAL_FAMILY_H
+#define CARTOGRAPHER_ROS_METRICS_INTERNAL_FAMILY_H
+
+#include <memory>
+#include <string>
+
+#include "cartographer/metrics/family_factory.h"
+#include "cartographer_ros/metrics/internal/counter.h"
+#include "cartographer_ros/metrics/internal/gauge.h"
+#include "cartographer_ros/metrics/internal/histogram.h"
+#include "cartographer_ros_msgs/MetricFamily.h"
+
+namespace cartographer_ros {
+namespace metrics {
+class CounterFamily
+    : public ::cartographer::metrics::Family<::cartographer::metrics::Counter> {
+ public:
+  CounterFamily(const std::string& name, const std::string& description)
+      : name_(name), description_(description) {}
+  Counter* Add(const std::map<std::string, std::string>& labels) override;
+  cartographer_ros_msgs::MetricFamily ToRosMessage();
+
+ private:
+  std::string name_;
+  std::string description_;
+  std::vector<std::unique_ptr<Counter>> wrappers_;
+};
+
+class GaugeFamily
+    : public ::cartographer::metrics::Family<::cartographer::metrics::Gauge> {
+ public:
+  GaugeFamily(const std::string& name, const std::string& description)
+      : name_(name), description_(description) {}
+  Gauge* Add(const std::map<std::string, std::string>& labels) override;
+
+  cartographer_ros_msgs::MetricFamily ToRosMessage();
+
+ private:
+  std::string name_;
+  std::string description_;
+  std::vector<std::unique_ptr<Gauge>> wrappers_;
+};
+
+class HistogramFamily : public ::cartographer::metrics::Family<
+                            ::cartographer::metrics::Histogram> {
+ public:
+  HistogramFamily(const std::string& name, const std::string& description,
+                  const BucketBoundaries& boundaries)
+      : boundaries_(boundaries) {}
+
+  Histogram* Add(const std::map<std::string, std::string>& labels) override;
+
+  cartographer_ros_msgs::MetricFamily ToRosMessage();
+
+ private:
+  std::string name_;
+  std::string description_;
+  std::vector<std::unique_ptr<Histogram>> wrappers_;
+  const BucketBoundaries boundaries_;
+};
+
+}  // namespace metrics
+}  // namespace cartographer_ros
+
+#endif  // CARTOGRAPHER_ROS_METRICS_INTERNAL_FAMILY_H

cartographer_ros/cartographer_ros/metrics/internal/gauge.h

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2018 The Cartographer Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef CARTOGRAPHER_ROS_METRICS_INTERNAL_GAUGE_H
+#define CARTOGRAPHER_ROS_METRICS_INTERNAL_GAUGE_H
+
+#include <atomic>
+#include <map>
+#include <string>
+
+#include "cartographer/metrics/gauge.h"
+#include "cartographer_ros_msgs/Metric.h"
+
+namespace cartographer_ros {
+namespace metrics {
+
+class Gauge : public ::cartographer::metrics::Gauge {
+ public:
+  explicit Gauge(const std::map<std::string, std::string>& labels)
+      : labels_(labels) {}
+
+  void Decrement(const double by_value) override { Add(-1. * by_value); }
+
+  void Decrement() override { Decrement(1.); }
+
+  void Increment(const double by_value) override { Add(by_value); }
+
+  void Increment() override { Increment(1.); }
+
+  void Set(double value) override {
+    double expected = value_.load();
+    while (!value_.compare_exchange_weak(expected, value)) {
+      ;
+    }
+  }
+  double Value() const { return value_.load(); }
+
+  cartographer_ros_msgs::Metric ToRosMessage() {
+    cartographer_ros_msgs::Metric msg;
+    msg.type = cartographer_ros_msgs::Metric::TYPE_GAUGE;
+    for (const auto& label : labels_) {
+      cartographer_ros_msgs::MetricLabel label_msg;
+      label_msg.key = label.first;
+      label_msg.value = label.second;
+      msg.labels.push_back(label_msg);
+    }
+    msg.value = Value();
+    return msg;
+  }
+
+ private:
+  void Add(const double value) {
+    double current = Value();
+    Set(current + value);
+  }
+
+  const std::map<std::string, std::string> labels_;
+  std::atomic<double> value_{0.};
+};
+
+}  // namespace metrics
+}  // namespace cartographer_ros
+
+#endif  // CARTOGRAPHER_ROS_METRICS_INTERNAL_GAUGE_H

cartographer_ros/cartographer_ros/metrics/internal/histogram.cc

@@ -0,0 +1,94 @@
+/*
+ * Copyright 2018 The Cartographer Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "cartographer_ros/metrics/internal/histogram.h"
+
+#include <algorithm>
+#include <numeric>
+
+#include "glog/logging.h"
+
+namespace cartographer_ros {
+namespace metrics {
+
+using BucketBoundaries = ::cartographer::metrics::Histogram::BucketBoundaries;
+
+Histogram::Histogram(const std::map<std::string, std::string>& labels,
+                     const BucketBoundaries& bucket_boundaries)
+    : labels_(labels),
+      bucket_boundaries_(bucket_boundaries),
+      bucket_counts_(bucket_boundaries.size() + 1) {
+  ::cartographer::common::MutexLocker lock(&mutex_);
+  CHECK(std::is_sorted(std::begin(bucket_boundaries_),
+                       std::end(bucket_boundaries_)));
+}
+
+Histogram::Histogram(const BucketBoundaries& bucket_boundaries)
+    : Histogram({}, bucket_boundaries) {}
+
+void Histogram::Observe(double value) {
+  auto bucket_index =
+      std::distance(bucket_boundaries_.begin(),
+                    std::upper_bound(bucket_boundaries_.begin(),
+                                     bucket_boundaries_.end(), value));
+  // TODO: check lock contention and potential for atomic operations.
+  ::cartographer::common::MutexLocker lock(&mutex_);
+  sum_ += value;
+  bucket_counts_[bucket_index] += 1;
+}
+
+std::map<double, double> Histogram::CountsByBucket() {
+  ::cartographer::common::MutexLocker lock(&mutex_);
+  std::map<double, double> counts_by_bucket;
+  // Add the finite buckets.
+  for (size_t i = 0; i < bucket_boundaries_.size(); ++i) {
+    counts_by_bucket[bucket_boundaries_.at(i)] = bucket_counts_.at(i);
+  }
+  // Add the "infinite" bucket.
+  counts_by_bucket[kInfiniteBoundary] = bucket_counts_.back();
+  return counts_by_bucket;
+}
+
+double Histogram::Sum() {
+  ::cartographer::common::MutexLocker lock(&mutex_);
+  return sum_;
+}
+
+double Histogram::CumulativeCount() {
+  ::cartographer::common::MutexLocker lock(&mutex_);
+  return std::accumulate(bucket_counts_.begin(), bucket_counts_.end(), 0.);
+}
+
+cartographer_ros_msgs::Metric Histogram::ToRosMessage() {
+  cartographer_ros_msgs::Metric msg;
+  msg.type = cartographer_ros_msgs::Metric::TYPE_HISTOGRAM;
+  for (const auto& label : labels_) {
+    cartographer_ros_msgs::MetricLabel label_msg;
+    label_msg.key = label.first;
+    label_msg.value = label.second;
+    msg.labels.push_back(label_msg);
+  }
+  for (const auto& bucket : CountsByBucket()) {
+    cartographer_ros_msgs::HistogramBucket bucket_msg;
+    bucket_msg.bucket_boundary = bucket.first;
+    bucket_msg.count = bucket.second;
+    msg.counts_by_bucket.push_back(bucket_msg);
+  }
+  return msg;
+}
+
+}  // namespace metrics
+}  // namespace cartographer_ros

cartographer_ros/cartographer_ros/metrics/internal/histogram.h

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2018 The Cartographer Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef CARTOGRAPHER_ROS_METRICS_INTERNAL_HISTOGRAM_H
+#define CARTOGRAPHER_ROS_METRICS_INTERNAL_HISTOGRAM_H
+
+#include <map>
+#include <vector>
+
+#include "cartographer/common/mutex.h"
+#include "cartographer/metrics/histogram.h"
+#include "cartographer_ros_msgs/Metric.h"
+
+namespace cartographer_ros {
+namespace metrics {
+
+constexpr double kInfiniteBoundary = std::numeric_limits<double>::infinity();
+
+using BucketBoundaries = ::cartographer::metrics::Histogram::BucketBoundaries;
+
+class Histogram : public ::cartographer::metrics::Histogram {
+ public:
+  explicit Histogram(const std::map<std::string, std::string>& labels,
+                     const BucketBoundaries& bucket_boundaries);
+
+  explicit Histogram(const BucketBoundaries& bucket_boundaries);
+
+  void Observe(double value) override;
+
+  std::map<double, double> CountsByBucket();
+
+  double Sum();
+
+  double CumulativeCount();
+
+  cartographer_ros_msgs::Metric ToRosMessage();
+
+ private:
+  cartographer::common::Mutex mutex_;
+  const std::map<std::string, std::string> labels_;
+  const BucketBoundaries bucket_boundaries_;
+  std::vector<double> bucket_counts_ GUARDED_BY(mutex_);
+  double sum_ GUARDED_BY(mutex_);
+};
+
+}  // namespace metrics
+}  // namespace cartographer_ros
+
+#endif  // CARTOGRAPHER_ROS_METRICS_INTERNAL_HISTOGRAM_H

cartographer_ros/cartographer_ros/metrics/internal/metrics_test.cc

@@ -0,0 +1,104 @@
+/*
+ * Copyright 2018 The Cartographer Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <algorithm>
+#include <array>
+#include <numeric>
+
+#include "cartographer/metrics/histogram.h"
+#include "cartographer_ros/metrics/internal/counter.h"
+#include "cartographer_ros/metrics/internal/gauge.h"
+#include "cartographer_ros/metrics/internal/histogram.h"
+#include "gtest/gtest.h"
+
+namespace cartographer_ros {
+namespace metrics {
+
+TEST(Metrics, GaugeTest) {
+  Gauge gauge({});
+  EXPECT_EQ(gauge.Value(), 0.);
+  gauge.Increment(1.2);
+  EXPECT_EQ(gauge.Value(), 1.2);
+  gauge.Increment();
+  EXPECT_EQ(gauge.Value(), 2.2);
+  gauge.Decrement(2.2);
+  EXPECT_EQ(gauge.Value(), 0.);
+  gauge.Decrement();
+  EXPECT_EQ(gauge.Value(), -1.);
+}
+
+TEST(Metrics, CounterTest) {
+  Counter counter({});
+  EXPECT_EQ(counter.Value(), 0.);
+  counter.Increment(1.2);
+  EXPECT_EQ(counter.Value(), 1.2);
+  counter.Increment(0.8);
+  EXPECT_EQ(counter.Value(), 2.);
+  counter.Increment();
+  EXPECT_EQ(counter.Value(), 3.);
+}
+
+TEST(Metrics, HistogramFixedWidthTest) {
+  auto boundaries = ::cartographer::metrics::Histogram::FixedWidth(1, 3);
+  Histogram histogram(boundaries);
+
+  // Observe some values that fit in finite buckets.
+  std::array<double, 3> values = {{0., 2, 2.5}};
+  for (const auto& value : values) {
+    histogram.Observe(value);
+  }
+  //     1     2     3    inf
+  //  1  |  0  |  2  |  0  |
+  EXPECT_EQ(histogram.CountsByBucket()[1], 1);
+  EXPECT_EQ(histogram.CountsByBucket()[2], 0);
+  EXPECT_EQ(histogram.CountsByBucket()[3], 2);
+  EXPECT_EQ(histogram.CumulativeCount(), values.size());
+  EXPECT_EQ(histogram.Sum(), std::accumulate(values.begin(), values.end(), 0.));
+
+  // Values above the last bucket boundary should go to the "infinite" bucket.
+  histogram.Observe(3.5);
+  //     1     2     3    inf
+  //  1  |  0  |  2  |  1  |
+  EXPECT_EQ(histogram.CountsByBucket()[kInfiniteBoundary], 1);
+}
+
+TEST(Metrics, HistogramScaledPowersOfTest) {
+  auto boundaries =
+      ::cartographer::metrics::Histogram::ScaledPowersOf(2, 1, 2048);
+  Histogram histogram(boundaries);
+
+  // Observe some values that fit in finite buckets.
+  std::array<double, 3> values = {{256, 512, 666}};
+  for (const auto& value : values) {
+    histogram.Observe(value);
+  }
+  // ... 256   512   1024  inf
+  // ...  |  1  |  2  |  0  |
+  EXPECT_EQ(histogram.CountsByBucket()[256], 0);
+  EXPECT_EQ(histogram.CountsByBucket()[512], 1);
+  EXPECT_EQ(histogram.CountsByBucket()[1024], 2);
+  EXPECT_EQ(histogram.CumulativeCount(), values.size());
+  EXPECT_EQ(histogram.Sum(), std::accumulate(values.begin(), values.end(), 0.));
+
+  // Values above the last bucket boundary should go to the "infinite" bucket.
+  histogram.Observe(2048);
+  // ... 256   512   1024  inf
+  // ...  |  1  |  2  |  1  |
+  EXPECT_EQ(histogram.CountsByBucket()[kInfiniteBoundary], 1);
+}
+
+}  // namespace metrics
+}  // namespace cartographer_ros

cartographer_ros_msgs/CMakeLists.txt

@@ -24,26 +24,18 @@ set(PACKAGE_DEPENDENCIES
 find_package(catkin REQUIRED COMPONENTS message_generation ${PACKAGE_DEPENDENCIES})
 
 add_message_files(
-  FILES
-    LandmarkEntry.msg
-    LandmarkList.msg
-    StatusCode.msg
-    StatusResponse.msg
-    SubmapList.msg
-    SubmapEntry.msg
-    SubmapTexture.msg
-    SensorTopics.msg
-    TrajectoryOptions.msg
-    TrajectoryStates.msg
+  DIRECTORY
+    msg
+)
+
+add_message_files(
+  DIRECTORY
+    msg/metrics
 )
 
 add_service_files(
-  FILES
-    FinishTrajectory.srv
-    GetTrajectoryStates.srv
-    StartTrajectory.srv
-    SubmapQuery.srv
-    WriteState.srv  
+  DIRECTORY
+    srv
 )
 
 generate_messages(

cartographer_ros_msgs/msg/metrics/HistogramBucket.msg

@@ -0,0 +1,19 @@
+# 2018 The Cartographer Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# A histogram bucket counts values x for which:
+#   previous_boundary < x <= bucket_boundary
+# holds.
+float64 bucket_boundary
+float64 count

cartographer_ros_msgs/msg/metrics/Metric.msg

@@ -0,0 +1,26 @@
+# 2018 The Cartographer Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+uint8 TYPE_COUNTER=0
+uint8 TYPE_GAUGE=1
+uint8 TYPE_HISTOGRAM=2
+
+uint8 type
+cartographer_ros_msgs/MetricLabel[] labels
+
+# TYPE_COUNTER or TYPE_GAUGE
+float64 value
+
+# TYPE_HISTOGRAM
+cartographer_ros_msgs/HistogramBucket[] counts_by_bucket

cartographer_ros_msgs/msg/metrics/MetricFamily.msg

@@ -0,0 +1,17 @@
+# 2018 The Cartographer Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+string name
+string description
+cartographer_ros_msgs/Metric[] metrics

cartographer_ros_msgs/msg/metrics/MetricLabel.msg

@@ -0,0 +1,16 @@
+# 2018 The Cartographer Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+string key
+string value