From 38f811aa78db5eaf6421cff2e8d4aae234f6fb3f Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Thu, 6 Aug 2020 18:31:41 -0700
Subject: [PATCH 01/15] Add PrometheusExporter header, source, and test files

---
 .../prometheus/prometheus_exporter.h          |  92 +++++++++
 .../prometheus/src/prometheus_exporter.cc     |  91 +++++++++
 .../test/prometheus_exporter_test.cc          | 193 ++++++++++++++++++
 3 files changed, 376 insertions(+)
 create mode 100644 exporters/prometheus/include/opentelemetry/exporters/prometheus/prometheus_exporter.h
 create mode 100644 exporters/prometheus/src/prometheus_exporter.cc
 create mode 100644 exporters/prometheus/test/prometheus_exporter_test.cc

diff --git a/exporters/prometheus/include/opentelemetry/exporters/prometheus/prometheus_exporter.h b/exporters/prometheus/include/opentelemetry/exporters/prometheus/prometheus_exporter.h
new file mode 100644
index 0000000000..48ef6e7a5c
--- /dev/null
+++ b/exporters/prometheus/include/opentelemetry/exporters/prometheus/prometheus_exporter.h
@@ -0,0 +1,92 @@
+#pragma once
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "opentelemetry/sdk/metrics/exporter.h"
+#include "opentelemetry/sdk/metrics/record.h"
+#include "opentelemetry/version.h"
+#include "prometheus/exposer.h"
+#include "prometheus_collector.h"
+
+/**
+ * This class is an implementation of the MetricsExporter interface and
+ * exports Prometheus metrics data. Functions in this class should be
+ * called by the Controller in our data pipeline.
+ */
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace exporter
+{
+namespace prometheus
+{
+class PrometheusExporter : public sdk::metrics::MetricsExporter
+{
+public:
+  /**
+   * Constructor - binds an exposer and collector to the exporter
+   * @param address: an address for an exposer that exposes
+   *  an HTTP endpoint for the exporter to connect to
+   */
+  PrometheusExporter(std::string &address);
+
+  /**
+   * Exports a batch of Metric Records.
+   * @param records: a collection of records to export
+   * @return: returns a ReturnCode detailing a success, or type of failure
+   */
+  sdk::metrics::ExportResult Export(const std::vector<sdk::metrics::Record> &records) noexcept override;
+
+/**
+ * Shuts down the exporter and does cleanup.
+ * Since Prometheus is a pull based interface, 
+ * we cannot serve data remaining in the intermediate
+ * collection to to client an HTTP request being sent, 
+ * so we flush the data.
+ */
+  void Shutdown() noexcept;
+
+  /**
+   * @return: returns a shared_ptr to
+   * the PrometheusCollector instance
+   */
+  std::shared_ptr<PrometheusCollector> &GetCollector();
+
+  /**
+   * @return: Gets the shutdown status of the exporter
+   */
+  bool IsShutdown() const;
+
+private:
+  /**
+   * exporter shutdown status
+   */
+  bool is_shutdown_;
+
+  /**
+   * Pointer to a
+   * PrometheusCollector instance
+   */
+  std::shared_ptr<PrometheusCollector> collector_;
+
+  /**
+   * Pointer to an
+   * Exposer instance
+   */
+  std::unique_ptr<::prometheus::Exposer> exposer_;
+
+  /**
+   * friend class for testing
+   */
+  friend class PrometheusExporterTest;
+
+  /**
+   * PrometheusExporter constructor with no parameters
+   * Used for testing only
+   */
+  PrometheusExporter();
+};
+}  // namespace prometheus
+}  // namespace exporter
+OPENTELEMETRY_END_NAMESPACE
diff --git a/exporters/prometheus/src/prometheus_exporter.cc b/exporters/prometheus/src/prometheus_exporter.cc
new file mode 100644
index 0000000000..ee38925294
--- /dev/null
+++ b/exporters/prometheus/src/prometheus_exporter.cc
@@ -0,0 +1,91 @@
+#include "opentelemetry/exporters/prometheus/prometheus_exporter.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace exporter
+{
+namespace prometheus
+{
+/**
+ * Constructor - binds an exposer and collector to the exporter
+ * @param address: an address for an exposer that exposes
+ *  an HTTP endpoint for the exporter to connect to
+ */
+PrometheusExporter::PrometheusExporter(std::string &address) : is_shutdown_(false)
+{
+  exposer_   = std::unique_ptr<::prometheus::Exposer>(new ::prometheus::Exposer{address});
+  collector_ = std::shared_ptr<PrometheusCollector>(new PrometheusCollector);
+
+  exposer_->RegisterCollectable(collector_);
+}
+
+/**
+ * PrometheusExporter constructor with no parameters
+ * Used for testing only
+ */
+PrometheusExporter::PrometheusExporter() : is_shutdown_(false)
+{
+  exposer_   = nullptr;
+  collector_ = std::unique_ptr<PrometheusCollector>(new PrometheusCollector);
+}
+
+/**
+ * Exports a batch of Metric Records.
+ * @param records: a collection of records to export
+ * @return: returns a ReturnCode detailing a success, or type of failure
+ */
+sdk::metrics::ExportResult PrometheusExporter::Export(
+    const std::vector<sdk::metrics::Record> &records) noexcept
+{
+  if (is_shutdown_)
+  {
+    return sdk::metrics::ExportResult::kFailure;
+  }
+  else if (records.empty())
+  {
+    return sdk::metrics::ExportResult::kFailureInvalidArgument;
+  }
+  else if (collector_->GetCollection().size() + records.size() > collector_->GetMaxCollectionSize())
+  {
+    return sdk::metrics::ExportResult::kFailureFull;
+  }
+  else
+  {
+    collector_->AddMetricData(records);
+    return sdk::metrics::ExportResult::kSuccess;
+  }
+}
+
+/**
+ * Shuts down the exporter and does cleanup.
+ * Since Prometheus is a pull based interface, 
+ * we cannot serve data remaining in the intermediate
+ * collection to to client an HTTP request being sent, 
+ * so we flush the data.
+ */
+void PrometheusExporter::Shutdown() noexcept
+{
+  is_shutdown_ = true;
+
+  collector_->GetCollection().clear();
+}
+
+/**
+ * @return: returns a shared_ptr to
+ * the PrometheusCollector instance
+ */
+std::shared_ptr<PrometheusCollector> &PrometheusExporter::GetCollector()
+{
+  return collector_;
+}
+
+/**
+ * @return: Gets the shutdown status of the exporter
+ */
+bool PrometheusExporter::IsShutdown() const
+{
+  return is_shutdown_;
+}
+
+}  // namespace prometheus
+}  // namespace exporter
+OPENTELEMETRY_END_NAMESPACE
diff --git a/exporters/prometheus/test/prometheus_exporter_test.cc b/exporters/prometheus/test/prometheus_exporter_test.cc
new file mode 100644
index 0000000000..0b541308a1
--- /dev/null
+++ b/exporters/prometheus/test/prometheus_exporter_test.cc
@@ -0,0 +1,193 @@
+#include <gtest/gtest.h>
+#include <typeinfo>
+
+#include "opentelemetry/exporters/prometheus/prometheus_collector.h"
+#include "opentelemetry/exporters/prometheus/prometheus_exporter.h"
+#include "opentelemetry/sdk/metrics/aggregator/counter_aggregator.h"
+#include "opentelemetry/version.h"
+
+/**
+ * PrometheusExporterTest is a friend class of PrometheusExporter.
+ * It has access to a private constructor that does not take in
+ * an exposer as an argument, and instead takes no arguments; this
+ * private constructor is only to be used here for testing
+ */
+class opentelemetry::exporter::prometheus::PrometheusExporterTest
+{
+public:
+  opentelemetry::exporter::prometheus::PrometheusExporter GetExporter()
+  {
+    return opentelemetry::exporter::prometheus::PrometheusExporter();
+  }
+};
+
+using opentelemetry::exporter::prometheus::PrometheusCollector;
+using opentelemetry::exporter::prometheus::PrometheusExporter;
+using opentelemetry::exporter::prometheus::PrometheusExporterTest;
+using opentelemetry::sdk::metrics::CounterAggregator;
+using opentelemetry::sdk::metrics::Record;
+using opentelemetry::sdk::metrics::ExportResult;
+
+/**
+ * Helper function to create a collection of records taken from
+ * a counter aggregator
+ */
+std::vector<Record> CreateRecords(int num)
+{
+
+  std::vector<Record> records;
+
+  for (int i = 0; i < num; i++)
+  {
+    std::string name        = "record-" + std::to_string(i);
+    std::string description = "record-" + std::to_string(i);
+    std::string labels      = "record-" + std::to_string(i) + "-label-1.0";
+    auto aggregator         = std::shared_ptr<opentelemetry::sdk::metrics::Aggregator<int>>(
+        new opentelemetry::sdk::metrics::CounterAggregator<int>(
+            opentelemetry::metrics::InstrumentKind::Counter));
+    aggregator->update(10);
+    aggregator->checkpoint();
+
+    Record r{name, description, labels, aggregator};
+    records.push_back(r);
+  }
+  return records;
+}
+
+/**
+ * When a PrometheusExporter is initialized,
+ * isShutdown should be false.
+ */
+TEST(PrometheusExporter, InitializeConstructorIsNotShutdown)
+{
+  PrometheusExporterTest p;
+  PrometheusExporter exporter = p.GetExporter();
+
+  // Asserts that the exporter is not shutdown.
+  ASSERT_TRUE(!exporter.IsShutdown());
+}
+
+/**
+ * The shutdown() function should set the isShutdown field to true.
+ */
+TEST(PrometheusExporter, ShutdownSetsIsShutdownToTrue)
+{
+  PrometheusExporterTest p;
+  PrometheusExporter exporter = p.GetExporter();
+
+  // exporter shuold not be shutdown by default
+  ASSERT_TRUE(!exporter.IsShutdown());
+
+  exporter.Shutdown();
+
+  // the exporter shuold be shutdown
+  ASSERT_TRUE(exporter.IsShutdown());
+
+  // shutdown function should be idempotent
+  exporter.Shutdown();
+  ASSERT_TRUE(exporter.IsShutdown());
+}
+
+/**
+ * The Export() function should return SUCCESS = 0
+ *  when data is exported successfully.
+ */
+TEST(PrometheusExporter, ExportSuccessfully)
+{
+  PrometheusExporterTest p;
+  PrometheusExporter exporter = p.GetExporter();
+
+  int num_records = 2;
+
+  std::vector<Record> records = CreateRecords(num_records);
+
+  auto res = exporter.Export(records);
+
+  // result should be SUCCESS = 0
+  ExportResult code = ExportResult::kSuccess;
+  ASSERT_EQ(res, code);
+}
+
+/**
+ * If the exporter is shutdown, it cannot process
+ * any more export requests and returns FAILURE_ALREADY_SHUTDOWN = 4.
+ */
+TEST(PrometheusExporter, ExporterIsShutdown)
+{
+  PrometheusExporterTest p;
+  PrometheusExporter exporter = p.GetExporter();
+
+  int num_records = 1;
+
+  std::vector<Record> records = CreateRecords(num_records);
+
+  exporter.Shutdown();
+
+  // send export request after shutdown
+  auto res = exporter.Export(records);
+
+  // result code should be FAILURE_ALREADY_SHUTDOWN = 4
+  ExportResult code = ExportResult::kFailure;
+  ASSERT_EQ(res, code);
+}
+
+/**
+ * The Export() function should return
+ * FAILURE_FULL_COLLECTION = 1 when the collection is full,
+ * or when the collection is not full but does not have enough
+ * space to hold the batch data.
+ */
+TEST(PrometheusExporter, CollectionNotEnoughSpace)
+{
+  PrometheusExporterTest p;
+  PrometheusExporter exporter = p.GetExporter();
+
+  int num_records = 2;
+
+  // prepare two collections of records to export,
+  // one close to max size and another one that, when added
+  // to the first, will exceed the size of the collection
+
+  int max_collection_size = exporter.GetCollector()->GetMaxCollectionSize();
+
+  std::vector<Record> full_records = CreateRecords(max_collection_size - 1);
+  std::vector<Record> records      = CreateRecords(num_records);
+
+  // send export request to fill the
+  // collection in the collector
+  auto res = exporter.Export(full_records);
+
+  // the result code should be SUCCESS = 0
+  ExportResult code = ExportResult::kSuccess;
+  ASSERT_EQ(res, code);
+
+  // send export request that does not complete
+  // due to not enough space in the collection
+  res = exporter.Export(records);
+
+  // the result code should be FAILURE_FULL_COLLECTION = 1
+  code = ExportResult::kFailureFull;
+  ASSERT_EQ(res, code);
+}
+
+/**
+ *  The Export() function should return
+ *  FAILURE_INVALID_ARGUMENT = 3 when an empty collection
+ *  of records is passed to the Export() function.
+ */
+TEST(PrometheusExporter, InvalidArgumentWhenPassedEmptyRecordCollection)
+{
+  PrometheusExporterTest p;
+  PrometheusExporter exporter = p.GetExporter();
+
+  // Initializes an empty colelction of records
+  std::vector<Record> records;
+
+  // send export request to fill the
+  // collection in the collector
+  auto res = exporter.Export(records);
+
+  // the result code should be FAILURE_INVALID_ARGUMENT = 3
+  ExportResult code = ExportResult::kFailureInvalidArgument;
+  ASSERT_EQ(res, code);
+}

From 140efcde01008490e2e28961e708e3e5495a093f Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Fri, 7 Aug 2020 10:51:36 -0700
Subject: [PATCH 02/15] CI formatting, added copyright headers

---
 .../prometheus/prometheus_exporter.h          | 33 ++++++++++++++-----
 .../prometheus/src/prometheus_exporter.cc     | 20 +++++++++--
 .../test/prometheus_exporter_test.cc          | 18 +++++++++-
 3 files changed, 60 insertions(+), 11 deletions(-)

diff --git a/exporters/prometheus/include/opentelemetry/exporters/prometheus/prometheus_exporter.h b/exporters/prometheus/include/opentelemetry/exporters/prometheus/prometheus_exporter.h
index 48ef6e7a5c..82e6be0d6a 100644
--- a/exporters/prometheus/include/opentelemetry/exporters/prometheus/prometheus_exporter.h
+++ b/exporters/prometheus/include/opentelemetry/exporters/prometheus/prometheus_exporter.h
@@ -1,3 +1,19 @@
+/*
+ * Copyright The OpenTelemetry 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.
+ */
+
 #pragma once
 
 #include <memory>
@@ -36,15 +52,16 @@ class PrometheusExporter : public sdk::metrics::MetricsExporter
    * @param records: a collection of records to export
    * @return: returns a ReturnCode detailing a success, or type of failure
    */
-  sdk::metrics::ExportResult Export(const std::vector<sdk::metrics::Record> &records) noexcept override;
+  sdk::metrics::ExportResult Export(
+      const std::vector<sdk::metrics::Record> &records) noexcept override;
 
-/**
- * Shuts down the exporter and does cleanup.
- * Since Prometheus is a pull based interface, 
- * we cannot serve data remaining in the intermediate
- * collection to to client an HTTP request being sent, 
- * so we flush the data.
- */
+  /**
+   * Shuts down the exporter and does cleanup.
+   * Since Prometheus is a pull based interface,
+   * we cannot serve data remaining in the intermediate
+   * collection to to client an HTTP request being sent,
+   * so we flush the data.
+   */
   void Shutdown() noexcept;
 
   /**
diff --git a/exporters/prometheus/src/prometheus_exporter.cc b/exporters/prometheus/src/prometheus_exporter.cc
index ee38925294..116b736029 100644
--- a/exporters/prometheus/src/prometheus_exporter.cc
+++ b/exporters/prometheus/src/prometheus_exporter.cc
@@ -1,3 +1,19 @@
+/*
+ * Copyright The OpenTelemetry 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 "opentelemetry/exporters/prometheus/prometheus_exporter.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
@@ -57,9 +73,9 @@ sdk::metrics::ExportResult PrometheusExporter::Export(
 
 /**
  * Shuts down the exporter and does cleanup.
- * Since Prometheus is a pull based interface, 
+ * Since Prometheus is a pull based interface,
  * we cannot serve data remaining in the intermediate
- * collection to to client an HTTP request being sent, 
+ * collection to to client an HTTP request being sent,
  * so we flush the data.
  */
 void PrometheusExporter::Shutdown() noexcept
diff --git a/exporters/prometheus/test/prometheus_exporter_test.cc b/exporters/prometheus/test/prometheus_exporter_test.cc
index 0b541308a1..6358d25cf7 100644
--- a/exporters/prometheus/test/prometheus_exporter_test.cc
+++ b/exporters/prometheus/test/prometheus_exporter_test.cc
@@ -1,3 +1,19 @@
+/*
+ * Copyright The OpenTelemetry 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 <gtest/gtest.h>
 #include <typeinfo>
 
@@ -25,8 +41,8 @@ using opentelemetry::exporter::prometheus::PrometheusCollector;
 using opentelemetry::exporter::prometheus::PrometheusExporter;
 using opentelemetry::exporter::prometheus::PrometheusExporterTest;
 using opentelemetry::sdk::metrics::CounterAggregator;
-using opentelemetry::sdk::metrics::Record;
 using opentelemetry::sdk::metrics::ExportResult;
+using opentelemetry::sdk::metrics::Record;
 
 /**
  * Helper function to create a collection of records taken from

From feb7126b514ef97bd155114412aac8e8fe64f29c Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Tue, 18 Aug 2020 10:53:50 -0700
Subject: [PATCH 03/15] Added build files

---
 exporters/prometheus/BUILD               | 48 ++++++++++++++++++++++++
 exporters/prometheus/CMakeLists.txt      | 23 ++++++++++++
 exporters/prometheus/test/CMakeLists.txt |  8 ++++
 3 files changed, 79 insertions(+)
 create mode 100644 exporters/prometheus/BUILD
 create mode 100644 exporters/prometheus/CMakeLists.txt
 create mode 100644 exporters/prometheus/test/CMakeLists.txt

diff --git a/exporters/prometheus/BUILD b/exporters/prometheus/BUILD
new file mode 100644
index 0000000000..f3cf46100a
--- /dev/null
+++ b/exporters/prometheus/BUILD
@@ -0,0 +1,48 @@
+# Copyright 2020, OpenTelemetry 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.
+
+package(default_visibility = ["//visibility:public"])
+
+cc_library(
+    name = "prometheus_exporter",
+    srcs = [
+        "src/prometheus_exporter.cc",
+    ],
+    hdrs = [
+        "include/opentelemetry/exporters/prometheus/prometheus_collector.h",
+        "include/opentelemetry/exporters/prometheus/prometheus_exporter.h",
+        "include/opentelemetry/exporters/prometheus/prometheus_exporter_utils.h",
+    ],
+    strip_include_prefix = "include",
+    deps = [
+        "//api",
+        "//sdk:headers",
+        "@com_github_jupp0r_prometheus_cpp//core",
+        "@com_github_jupp0r_prometheus_cpp//pull",
+    ],
+)
+
+cc_test(
+    name = "prometheus_exporter_test",
+    srcs = [
+        "test/prometheus_exporter_test.cc",
+    ],
+    deps = [
+        ":prometheus_collector",
+        ":prometheus_exporter",
+        "@com_github_jupp0r_prometheus_cpp//core",
+        "@com_github_jupp0r_prometheus_cpp//pull",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
\ No newline at end of file
diff --git a/exporters/prometheus/CMakeLists.txt b/exporters/prometheus/CMakeLists.txt
new file mode 100644
index 0000000000..3004fd0951
--- /dev/null
+++ b/exporters/prometheus/CMakeLists.txt
@@ -0,0 +1,23 @@
+# Copyright 2020, OpenTelemetry 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_directories(include)
+
+find_package(prometheus-cpp CONFIG REQUIRED)
+add_library(
+        prometheus_exporter src/prometheus_exporter.cc)
+
+if (BUILD_TESTING)
+    add_subdirectory(test)
+endif ()
\ No newline at end of file
diff --git a/exporters/prometheus/test/CMakeLists.txt b/exporters/prometheus/test/CMakeLists.txt
new file mode 100644
index 0000000000..bfd5e2e2f6
--- /dev/null
+++ b/exporters/prometheus/test/CMakeLists.txt
@@ -0,0 +1,8 @@
+foreach (testname prometheus_exporter_test)
+    add_executable(${testname} "${testname}.cc")
+    target_link_libraries(
+            ${testname} ${GTEST_BOTH_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT}
+            prometheus_exporter prometheus-cpp::pull)
+    gtest_add_tests(TARGET ${testname} TEST_PREFIX exporter. TEST_LIST ${testname})
+endforeach ()
+

From 5d6fc7e731553c9f9ee6c61f82b19e837f512a63 Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Wed, 19 Aug 2020 11:30:50 -0700
Subject: [PATCH 04/15] modified comments to reflect removal of ReturnCodes
 class, removal of kFailureTimeout

---
 .../test/prometheus_exporter_test.cc           | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/exporters/prometheus/test/prometheus_exporter_test.cc b/exporters/prometheus/test/prometheus_exporter_test.cc
index 6358d25cf7..0656a16a9b 100644
--- a/exporters/prometheus/test/prometheus_exporter_test.cc
+++ b/exporters/prometheus/test/prometheus_exporter_test.cc
@@ -105,7 +105,7 @@ TEST(PrometheusExporter, ShutdownSetsIsShutdownToTrue)
 }
 
 /**
- * The Export() function should return SUCCESS = 0
+ * The Export() function should return kSuccess = 0
  *  when data is exported successfully.
  */
 TEST(PrometheusExporter, ExportSuccessfully)
@@ -119,14 +119,14 @@ TEST(PrometheusExporter, ExportSuccessfully)
 
   auto res = exporter.Export(records);
 
-  // result should be SUCCESS = 0
+  // result should be kSuccess = 0
   ExportResult code = ExportResult::kSuccess;
   ASSERT_EQ(res, code);
 }
 
 /**
  * If the exporter is shutdown, it cannot process
- * any more export requests and returns FAILURE_ALREADY_SHUTDOWN = 4.
+ * any more export requests and returns kFailure = 1.
  */
 TEST(PrometheusExporter, ExporterIsShutdown)
 {
@@ -142,14 +142,14 @@ TEST(PrometheusExporter, ExporterIsShutdown)
   // send export request after shutdown
   auto res = exporter.Export(records);
 
-  // result code should be FAILURE_ALREADY_SHUTDOWN = 4
+  // result code should be kFailure = 1
   ExportResult code = ExportResult::kFailure;
   ASSERT_EQ(res, code);
 }
 
 /**
  * The Export() function should return
- * FAILURE_FULL_COLLECTION = 1 when the collection is full,
+ * kFailureFull = 2 when the collection is full,
  * or when the collection is not full but does not have enough
  * space to hold the batch data.
  */
@@ -173,7 +173,7 @@ TEST(PrometheusExporter, CollectionNotEnoughSpace)
   // collection in the collector
   auto res = exporter.Export(full_records);
 
-  // the result code should be SUCCESS = 0
+  // the result code should be kSuccess = 0
   ExportResult code = ExportResult::kSuccess;
   ASSERT_EQ(res, code);
 
@@ -181,14 +181,14 @@ TEST(PrometheusExporter, CollectionNotEnoughSpace)
   // due to not enough space in the collection
   res = exporter.Export(records);
 
-  // the result code should be FAILURE_FULL_COLLECTION = 1
+  // the result code should be kFailureFull = 2
   code = ExportResult::kFailureFull;
   ASSERT_EQ(res, code);
 }
 
 /**
  *  The Export() function should return
- *  FAILURE_INVALID_ARGUMENT = 3 when an empty collection
+ *  kFailureInvalidArgument = 3 when an empty collection
  *  of records is passed to the Export() function.
  */
 TEST(PrometheusExporter, InvalidArgumentWhenPassedEmptyRecordCollection)
@@ -203,7 +203,7 @@ TEST(PrometheusExporter, InvalidArgumentWhenPassedEmptyRecordCollection)
   // collection in the collector
   auto res = exporter.Export(records);
 
-  // the result code should be FAILURE_INVALID_ARGUMENT = 3
+  // the result code should be kFailureInvalidArgument = 3
   ExportResult code = ExportResult::kFailureInvalidArgument;
   ASSERT_EQ(res, code);
 }

From 32880b0075c236f9b4b6e79f909bb5fdd8483b17 Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Fri, 28 Aug 2020 17:30:36 -0700
Subject: [PATCH 05/15] minor change to structure of friend class

---
 .../test/prometheus_exporter_test.cc           | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/exporters/prometheus/test/prometheus_exporter_test.cc b/exporters/prometheus/test/prometheus_exporter_test.cc
index 0656a16a9b..9e6c638a94 100644
--- a/exporters/prometheus/test/prometheus_exporter_test.cc
+++ b/exporters/prometheus/test/prometheus_exporter_test.cc
@@ -28,14 +28,22 @@
  * an exposer as an argument, and instead takes no arguments; this
  * private constructor is only to be used here for testing
  */
-class opentelemetry::exporter::prometheus::PrometheusExporterTest
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace exporter
+{
+namespace prometheus
+{
+class PrometheusExporterTest // : public ::testing::Test
 {
 public:
-  opentelemetry::exporter::prometheus::PrometheusExporter GetExporter()
-  {
-    return opentelemetry::exporter::prometheus::PrometheusExporter();
-  }
+    PrometheusExporter GetExporter()
+    {
+        return PrometheusExporter();
+    }
 };
+}
+}
+OPENTELEMETRY_END_NAMESPACE
 
 using opentelemetry::exporter::prometheus::PrometheusCollector;
 using opentelemetry::exporter::prometheus::PrometheusExporter;

From 94af70dda0e430b654180e65afccdde2397d98a9 Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Mon, 31 Aug 2020 09:55:40 -0700
Subject: [PATCH 06/15] removed assignment of exposer_ to nullptr in testing
 constructor

---
 exporters/prometheus/src/prometheus_exporter.cc | 1 -
 1 file changed, 1 deletion(-)

diff --git a/exporters/prometheus/src/prometheus_exporter.cc b/exporters/prometheus/src/prometheus_exporter.cc
index 116b736029..32014fb98d 100644
--- a/exporters/prometheus/src/prometheus_exporter.cc
+++ b/exporters/prometheus/src/prometheus_exporter.cc
@@ -40,7 +40,6 @@ PrometheusExporter::PrometheusExporter(std::string &address) : is_shutdown_(fals
  */
 PrometheusExporter::PrometheusExporter() : is_shutdown_(false)
 {
-  exposer_   = nullptr;
   collector_ = std::unique_ptr<PrometheusCollector>(new PrometheusCollector);
 }
 

From 367d6a31c35171bf785f649b854abd7520550395 Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Wed, 2 Sep 2020 11:35:44 -0700
Subject: [PATCH 07/15] removed usage of release9.0 of Prometheus

---
 ci/do_ci.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ci/do_ci.sh b/ci/do_ci.sh
index e97686b0b7..5da359a719 100755
--- a/ci/do_ci.sh
+++ b/ci/do_ci.sh
@@ -49,7 +49,7 @@ elif [[ "$1" == "cmake.exporter.prometheus.test" ]]; then
   cd third_party
   git clone https://github.com/jupp0r/prometheus-cpp
   cd prometheus-cpp
-  git checkout v0.9.0
+  # git checkout v0.9.0
   git submodule init
   git submodule update
   mkdir _build && cd _build

From a5e2cfb8cee212e10e285155237360f5c7ff1edf Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Wed, 2 Sep 2020 12:11:06 -0700
Subject: [PATCH 08/15] BUILD file changes

---
 exporters/prometheus/BUILD | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/exporters/prometheus/BUILD b/exporters/prometheus/BUILD
index 850ca2ed48..238c62a6de 100644
--- a/exporters/prometheus/BUILD
+++ b/exporters/prometheus/BUILD
@@ -26,6 +26,7 @@ cc_library(
     ],
     strip_include_prefix = "include",
     deps = [
+        ":prometheus_collector",
         "//api",
         "//sdk:headers",
         "@com_github_jupp0r_prometheus_cpp//core",
@@ -73,10 +74,7 @@ cc_test(
         "test/prometheus_exporter_test.cc",
     ],
     deps = [
-        ":prometheus_collector",
         ":prometheus_exporter",
-        "@com_github_jupp0r_prometheus_cpp//core",
-        "@com_github_jupp0r_prometheus_cpp//pull",
         "@com_google_googletest//:gtest_main",
     ],
 )

From 6bbb0510f3baefda2c9f0cf68ca6e84e8eb0fe86 Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Wed, 2 Sep 2020 12:43:57 -0700
Subject: [PATCH 09/15] changed Prometheus client back to 9.0

---
 ci/do_ci.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ci/do_ci.sh b/ci/do_ci.sh
index 5da359a719..e97686b0b7 100755
--- a/ci/do_ci.sh
+++ b/ci/do_ci.sh
@@ -49,7 +49,7 @@ elif [[ "$1" == "cmake.exporter.prometheus.test" ]]; then
   cd third_party
   git clone https://github.com/jupp0r/prometheus-cpp
   cd prometheus-cpp
-  # git checkout v0.9.0
+  git checkout v0.9.0
   git submodule init
   git submodule update
   mkdir _build && cd _build

From d3d44f3c362a05ec22df32e8c7ab52f8853036a7 Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Wed, 2 Sep 2020 14:47:34 -0700
Subject: [PATCH 10/15] removed a test for debugging

---
 exporters/prometheus/test/prometheus_exporter_test.cc | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/exporters/prometheus/test/prometheus_exporter_test.cc b/exporters/prometheus/test/prometheus_exporter_test.cc
index 9e6c638a94..5476dba1e9 100644
--- a/exporters/prometheus/test/prometheus_exporter_test.cc
+++ b/exporters/prometheus/test/prometheus_exporter_test.cc
@@ -84,11 +84,11 @@ std::vector<Record> CreateRecords(int num)
  */
 TEST(PrometheusExporter, InitializeConstructorIsNotShutdown)
 {
-  PrometheusExporterTest p;
-  PrometheusExporter exporter = p.GetExporter();
+  // PrometheusExporterTest p;
+  // PrometheusExporter exporter = p.GetExporter();
 
-  // Asserts that the exporter is not shutdown.
-  ASSERT_TRUE(!exporter.IsShutdown());
+  // // Asserts that the exporter is not shutdown.
+  // ASSERT_TRUE(!exporter.IsShutdown());
 }
 
 /**

From 8dc5cb11ca7cf5bdb3d08b28dbeb28e7f5fea130 Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Wed, 2 Sep 2020 15:00:35 -0700
Subject: [PATCH 11/15] Revert "removed a test for debugging"

This reverts commit d3d44f3c362a05ec22df32e8c7ab52f8853036a7.
---
 exporters/prometheus/test/prometheus_exporter_test.cc | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/exporters/prometheus/test/prometheus_exporter_test.cc b/exporters/prometheus/test/prometheus_exporter_test.cc
index 5476dba1e9..9e6c638a94 100644
--- a/exporters/prometheus/test/prometheus_exporter_test.cc
+++ b/exporters/prometheus/test/prometheus_exporter_test.cc
@@ -84,11 +84,11 @@ std::vector<Record> CreateRecords(int num)
  */
 TEST(PrometheusExporter, InitializeConstructorIsNotShutdown)
 {
-  // PrometheusExporterTest p;
-  // PrometheusExporter exporter = p.GetExporter();
+  PrometheusExporterTest p;
+  PrometheusExporter exporter = p.GetExporter();
 
-  // // Asserts that the exporter is not shutdown.
-  // ASSERT_TRUE(!exporter.IsShutdown());
+  // Asserts that the exporter is not shutdown.
+  ASSERT_TRUE(!exporter.IsShutdown());
 }
 
 /**

From 94f78c8f604befc1bb907d5a6447d65675a9d108 Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Wed, 2 Sep 2020 16:16:31 -0700
Subject: [PATCH 12/15] format

---
 exporters/prometheus/CMakeLists.txt                   |  6 +++---
 exporters/prometheus/test/CMakeLists.txt              |  3 ++-
 exporters/prometheus/test/prometheus_exporter_test.cc | 11 ++++-------
 3 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/exporters/prometheus/CMakeLists.txt b/exporters/prometheus/CMakeLists.txt
index fa0a3e9a8f..337527de12 100644
--- a/exporters/prometheus/CMakeLists.txt
+++ b/exporters/prometheus/CMakeLists.txt
@@ -16,9 +16,9 @@ include_directories(include)
 
 find_package(prometheus-cpp CONFIG REQUIRED)
 
-add_library(prometheus_exporter src/prometheus_exporter.cc
-                                src/prometheus_collector.cc
-                                src/prometheus_exporter_utils.cc)
+add_library(
+  prometheus_exporter src/prometheus_exporter.cc src/prometheus_collector.cc
+                      src/prometheus_exporter_utils.cc)
 
 if(BUILD_TESTING)
   add_subdirectory(test)
diff --git a/exporters/prometheus/test/CMakeLists.txt b/exporters/prometheus/test/CMakeLists.txt
index 2b324608f9..a0280b4e15 100644
--- a/exporters/prometheus/test/CMakeLists.txt
+++ b/exporters/prometheus/test/CMakeLists.txt
@@ -1,4 +1,5 @@
-foreach(testname prometheus_exporter_test prometheus_collector_test prometheus_exporter_utils_test)
+foreach(testname prometheus_exporter_test prometheus_collector_test
+                 prometheus_exporter_utils_test)
   add_executable(${testname} "${testname}.cc")
   target_link_libraries(
     ${testname} ${GTEST_BOTH_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT}
diff --git a/exporters/prometheus/test/prometheus_exporter_test.cc b/exporters/prometheus/test/prometheus_exporter_test.cc
index 9e6c638a94..f2e1626603 100644
--- a/exporters/prometheus/test/prometheus_exporter_test.cc
+++ b/exporters/prometheus/test/prometheus_exporter_test.cc
@@ -33,16 +33,13 @@ namespace exporter
 {
 namespace prometheus
 {
-class PrometheusExporterTest // : public ::testing::Test
+class PrometheusExporterTest  // : public ::testing::Test
 {
 public:
-    PrometheusExporter GetExporter()
-    {
-        return PrometheusExporter();
-    }
+  PrometheusExporter GetExporter() { return PrometheusExporter(); }
 };
-}
-}
+}  // namespace prometheus
+}  // namespace exporter
 OPENTELEMETRY_END_NAMESPACE
 
 using opentelemetry::exporter::prometheus::PrometheusCollector;

From 5938aa8fe68f24e830a3d511456cff18382cca78 Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Thu, 3 Sep 2020 09:49:57 -0700
Subject: [PATCH 13/15] added MAKE_EXE_LINKER_FLAGS cmake link option

---
 ci/do_ci.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/ci/do_ci.sh b/ci/do_ci.sh
index e97686b0b7..77611ba8ad 100755
--- a/ci/do_ci.sh
+++ b/ci/do_ci.sh
@@ -63,6 +63,7 @@ elif [[ "$1" == "cmake.exporter.prometheus.test" ]]; then
   cmake -DCMAKE_BUILD_TYPE=Debug  \
         -DWITH_PROMETHEUS=ON \
         -DCMAKE_CXX_FLAGS="-Werror" \
+        MAKE_EXE_LINKER_FLAGS="-lpthread" \
         "${SRC_DIR}"
   make
   make test

From dc28f848e2052d3433ff159312fa7f8e2ffa4e62 Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Thu, 3 Sep 2020 10:04:07 -0700
Subject: [PATCH 14/15] added -D to flag

---
 ci/do_ci.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ci/do_ci.sh b/ci/do_ci.sh
index 77611ba8ad..87eea78c40 100755
--- a/ci/do_ci.sh
+++ b/ci/do_ci.sh
@@ -63,7 +63,7 @@ elif [[ "$1" == "cmake.exporter.prometheus.test" ]]; then
   cmake -DCMAKE_BUILD_TYPE=Debug  \
         -DWITH_PROMETHEUS=ON \
         -DCMAKE_CXX_FLAGS="-Werror" \
-        MAKE_EXE_LINKER_FLAGS="-lpthread" \
+        -DMAKE_EXE_LINKER_FLAGS="-lpthread" \
         "${SRC_DIR}"
   make
   make test

From 75e23e56af9b7d6050bbe74d71db8655d30f1c14 Mon Sep 17 00:00:00 2001
From: erichsueh3 <hsuehe@amazon.com>
Date: Thu, 3 Sep 2020 10:14:44 -0700
Subject: [PATCH 15/15] changed -DMAKE_EXE_LINKER_FLAGS to
 -DCMAKE_EXE_LINKER_FLAGS

---
 ci/do_ci.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ci/do_ci.sh b/ci/do_ci.sh
index 87eea78c40..4d68b22125 100755
--- a/ci/do_ci.sh
+++ b/ci/do_ci.sh
@@ -63,7 +63,7 @@ elif [[ "$1" == "cmake.exporter.prometheus.test" ]]; then
   cmake -DCMAKE_BUILD_TYPE=Debug  \
         -DWITH_PROMETHEUS=ON \
         -DCMAKE_CXX_FLAGS="-Werror" \
-        -DMAKE_EXE_LINKER_FLAGS="-lpthread" \
+        -DCMAKE_EXE_LINKER_FLAGS="-lpthread" \
         "${SRC_DIR}"
   make
   make test