// Copyright 2024 The gRPC 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 "src/core/lib/channel/metrics.h"

#include <memory>

#include "absl/container/flat_hash_map.h"
#include "absl/strings/match.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/str_join.h"
#include "gmock/gmock.h"
#include "gtest/gtest.h"

#include "test/core/util/fake_stats_plugin.h"
#include "test/core/util/test_config.h"

namespace grpc_core {
namespace {

using experimental::StatsPluginChannelScope;

class MetricsTest : public ::testing::Test {
 public:
  void TearDown() override {
    GlobalInstrumentsRegistryTestPeer::ResetGlobalInstrumentsRegistry();
    GlobalStatsPluginRegistryTestPeer::ResetGlobalStatsPluginRegistry();
  }
};

TEST_F(MetricsTest, UInt64Counter) {
  const absl::string_view kLabelKeys[] = {"label_key_1", "label_key_2"};
  const absl::string_view kOptionalLabelKeys[] = {"optional_label_key_1",
                                                  "optional_label_key_2"};
  auto uint64_counter_handle = GlobalInstrumentsRegistry::RegisterUInt64Counter(
      "uint64_counter", "A simple uint64 counter.", "unit", kLabelKeys,
      kOptionalLabelKeys, true);
  constexpr absl::string_view kLabelValues[] = {"label_value_1",
                                                "label_value_2"};
  constexpr absl::string_view kOptionalLabelValues[] = {
      "optional_label_value_1", "optional_label_value_2"};
  constexpr absl::string_view kDomain1To4 = "domain1.domain2.domain3.domain4";
  constexpr absl::string_view kDomain2To4 = "domain2.domain3.domain4";
  constexpr absl::string_view kDomain3To4 = "domain3.domain4";
  auto plugin1 = MakeStatsPluginForTarget(kDomain1To4);
  auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
  auto plugin3 = MakeStatsPluginForTarget(kDomain3To4);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain1To4, ""))
      .AddCounter(uint64_counter_handle, 1, kLabelValues, kOptionalLabelValues);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain2To4, ""))
      .AddCounter(uint64_counter_handle, 2, kLabelValues, kOptionalLabelValues);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain3To4, ""))
      .AddCounter(uint64_counter_handle, 3, kLabelValues, kOptionalLabelValues);
  EXPECT_THAT(plugin1->GetCounterValue(uint64_counter_handle, kLabelValues,
                                       kOptionalLabelValues),
              ::testing::Optional(1));
  EXPECT_THAT(plugin2->GetCounterValue(uint64_counter_handle, kLabelValues,
                                       kOptionalLabelValues),
              ::testing::Optional(3));
  EXPECT_THAT(plugin3->GetCounterValue(uint64_counter_handle, kLabelValues,
                                       kOptionalLabelValues),
              ::testing::Optional(6));
}

TEST_F(MetricsTest, DoubleCounter) {
  const absl::string_view kLabelKeys[] = {"label_key_1", "label_key_2"};
  const absl::string_view kOptionalLabelKeys[] = {"optional_label_key_1",
                                                  "optional_label_key_2"};
  auto double_counter_handle = GlobalInstrumentsRegistry::RegisterDoubleCounter(
      "double_counter", "A simple double counter.", "unit", kLabelKeys,
      kOptionalLabelKeys, true);
  constexpr absl::string_view kLabelValues[] = {"label_value_1",
                                                "label_value_2"};
  constexpr absl::string_view kOptionalLabelValues[] = {
      "optional_label_value_1", "optional_label_value_2"};
  constexpr absl::string_view kDomain1To4 = "domain1.domain2.domain3.domain4";
  constexpr absl::string_view kDomain2To4 = "domain2.domain3.domain4";
  constexpr absl::string_view kDomain3To4 = "domain3.domain4";
  auto plugin1 = MakeStatsPluginForTarget(kDomain1To4);
  auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
  auto plugin3 = MakeStatsPluginForTarget(kDomain3To4);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain1To4, ""))
      .AddCounter(double_counter_handle, 1.23, kLabelValues,
                  kOptionalLabelValues);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain2To4, ""))
      .AddCounter(double_counter_handle, 2.34, kLabelValues,
                  kOptionalLabelValues);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain3To4, ""))
      .AddCounter(double_counter_handle, 3.45, kLabelValues,
                  kOptionalLabelValues);
  EXPECT_THAT(plugin1->GetCounterValue(double_counter_handle, kLabelValues,
                                       kOptionalLabelValues),
              ::testing::Optional(1.23));
  EXPECT_THAT(plugin2->GetCounterValue(double_counter_handle, kLabelValues,
                                       kOptionalLabelValues),
              ::testing::Optional(3.57));
  EXPECT_THAT(plugin3->GetCounterValue(double_counter_handle, kLabelValues,
                                       kOptionalLabelValues),
              ::testing::Optional(7.02));
}

TEST_F(MetricsTest, UInt64Histogram) {
  const absl::string_view kLabelKeys[] = {"label_key_1", "label_key_2"};
  const absl::string_view kOptionalLabelKeys[] = {"optional_label_key_1",
                                                  "optional_label_key_2"};
  auto uint64_histogram_handle =
      GlobalInstrumentsRegistry::RegisterUInt64Histogram(
          "uint64_histogram", "A simple uint64 histogram.", "unit", kLabelKeys,
          kOptionalLabelKeys, true);
  constexpr absl::string_view kLabelValues[] = {"label_value_1",
                                                "label_value_2"};
  constexpr absl::string_view kOptionalLabelValues[] = {
      "optional_label_value_1", "optional_label_value_2"};
  constexpr absl::string_view kDomain1To4 = "domain1.domain2.domain3.domain4";
  constexpr absl::string_view kDomain2To4 = "domain2.domain3.domain4";
  constexpr absl::string_view kDomain3To4 = "domain3.domain4";
  auto plugin1 = MakeStatsPluginForTarget(kDomain1To4);
  auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
  auto plugin3 = MakeStatsPluginForTarget(kDomain3To4);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain1To4, ""))
      .RecordHistogram(uint64_histogram_handle, 1, kLabelValues,
                       kOptionalLabelValues);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain2To4, ""))
      .RecordHistogram(uint64_histogram_handle, 2, kLabelValues,
                       kOptionalLabelValues);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain3To4, ""))
      .RecordHistogram(uint64_histogram_handle, 3, kLabelValues,
                       kOptionalLabelValues);
  EXPECT_THAT(plugin1->GetHistogramValue(uint64_histogram_handle, kLabelValues,
                                         kOptionalLabelValues),
              ::testing::Optional(::testing::UnorderedElementsAre(1)));
  EXPECT_THAT(plugin2->GetHistogramValue(uint64_histogram_handle, kLabelValues,
                                         kOptionalLabelValues),
              ::testing::Optional(::testing::UnorderedElementsAre(1, 2)));
  EXPECT_THAT(plugin3->GetHistogramValue(uint64_histogram_handle, kLabelValues,
                                         kOptionalLabelValues),
              ::testing::Optional(::testing::UnorderedElementsAre(1, 2, 3)));
}

TEST_F(MetricsTest, DoubleHistogram) {
  const absl::string_view kLabelKeys[] = {"label_key_1", "label_key_2"};
  const absl::string_view kOptionalLabelKeys[] = {"optional_label_key_1",
                                                  "optional_label_key_2"};
  auto double_histogram_handle =
      GlobalInstrumentsRegistry::RegisterDoubleHistogram(
          "double_histogram", "A simple double histogram.", "unit", kLabelKeys,
          kOptionalLabelKeys, true);
  constexpr absl::string_view kLabelValues[] = {"label_value_1",
                                                "label_value_2"};
  constexpr absl::string_view kOptionalLabelValues[] = {
      "optional_label_value_1", "optional_label_value_2"};
  constexpr absl::string_view kDomain1To4 = "domain1.domain2.domain3.domain4";
  constexpr absl::string_view kDomain2To4 = "domain2.domain3.domain4";
  constexpr absl::string_view kDomain3To4 = "domain3.domain4";
  auto plugin1 = MakeStatsPluginForTarget(kDomain1To4);
  auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
  auto plugin3 = MakeStatsPluginForTarget(kDomain3To4);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain1To4, ""))
      .RecordHistogram(double_histogram_handle, 1.23, kLabelValues,
                       kOptionalLabelValues);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain2To4, ""))
      .RecordHistogram(double_histogram_handle, 2.34, kLabelValues,
                       kOptionalLabelValues);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain3To4, ""))
      .RecordHistogram(double_histogram_handle, 3.45, kLabelValues,
                       kOptionalLabelValues);
  EXPECT_THAT(plugin1->GetHistogramValue(double_histogram_handle, kLabelValues,
                                         kOptionalLabelValues),
              ::testing::Optional(::testing::UnorderedElementsAre(1.23)));
  EXPECT_THAT(plugin2->GetHistogramValue(double_histogram_handle, kLabelValues,
                                         kOptionalLabelValues),
              ::testing::Optional(::testing::UnorderedElementsAre(1.23, 2.34)));
  EXPECT_THAT(
      plugin3->GetHistogramValue(double_histogram_handle, kLabelValues,
                                 kOptionalLabelValues),
      ::testing::Optional(::testing::UnorderedElementsAre(1.23, 2.34, 3.45)));
}

TEST_F(MetricsTest, Int64Gauge) {
  const absl::string_view kLabelKeys[] = {"label_key_1", "label_key_2"};
  const absl::string_view kOptionalLabelKeys[] = {"optional_label_key_1",
                                                  "optional_label_key_2"};
  auto int64_gauge_handle = GlobalInstrumentsRegistry::RegisterInt64Gauge(
      "int64_gauge", "A simple int64 gauge.", "unit", kLabelKeys,
      kOptionalLabelKeys, true);
  constexpr absl::string_view kLabelValues[] = {"label_value_1",
                                                "label_value_2"};
  constexpr absl::string_view kOptionalLabelValues[] = {
      "optional_label_value_1", "optional_label_value_2"};
  constexpr absl::string_view kDomain1To4 = "domain1.domain2.domain3.domain4";
  constexpr absl::string_view kDomain2To4 = "domain2.domain3.domain4";
  constexpr absl::string_view kDomain3To4 = "domain3.domain4";
  auto plugin1 = MakeStatsPluginForTarget(kDomain1To4);
  auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
  auto plugin3 = MakeStatsPluginForTarget(kDomain3To4);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain1To4, ""))
      .SetGauge(int64_gauge_handle, 1, kLabelValues, kOptionalLabelValues);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain2To4, ""))
      .SetGauge(int64_gauge_handle, 2, kLabelValues, kOptionalLabelValues);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain3To4, ""))
      .SetGauge(int64_gauge_handle, 3, kLabelValues, kOptionalLabelValues);
  EXPECT_THAT(plugin1->GetGaugeValue(int64_gauge_handle, kLabelValues,
                                     kOptionalLabelValues),
              ::testing::Optional(1));
  EXPECT_THAT(plugin2->GetGaugeValue(int64_gauge_handle, kLabelValues,
                                     kOptionalLabelValues),
              ::testing::Optional(2));
  EXPECT_THAT(plugin3->GetGaugeValue(int64_gauge_handle, kLabelValues,
                                     kOptionalLabelValues),
              ::testing::Optional(3));
}

TEST_F(MetricsTest, DoubleGauge) {
  const absl::string_view kLabelKeys[] = {"label_key_1", "label_key_2"};
  const absl::string_view kOptionalLabelKeys[] = {"optional_label_key_1",
                                                  "optional_label_key_2"};
  auto double_gauge_handle = GlobalInstrumentsRegistry::RegisterDoubleGauge(
      "double_gauge", "A simple double gauge.", "unit", kLabelKeys,
      kOptionalLabelKeys, true);
  constexpr absl::string_view kLabelValues[] = {"label_value_1",
                                                "label_value_2"};
  constexpr absl::string_view kOptionalLabelValues[] = {
      "optional_label_value_1", "optional_label_value_2"};
  constexpr absl::string_view kDomain1To4 = "domain1.domain2.domain3.domain4";
  constexpr absl::string_view kDomain2To4 = "domain2.domain3.domain4";
  constexpr absl::string_view kDomain3To4 = "domain3.domain4";
  auto plugin1 = MakeStatsPluginForTarget(kDomain1To4);
  auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
  auto plugin3 = MakeStatsPluginForTarget(kDomain3To4);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain1To4, ""))
      .SetGauge(double_gauge_handle, 1.23, kLabelValues, kOptionalLabelValues);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain2To4, ""))
      .SetGauge(double_gauge_handle, 2.34, kLabelValues, kOptionalLabelValues);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain3To4, ""))
      .SetGauge(double_gauge_handle, 3.45, kLabelValues, kOptionalLabelValues);
  EXPECT_THAT(plugin1->GetGaugeValue(double_gauge_handle, kLabelValues,
                                     kOptionalLabelValues),
              ::testing::Optional(1.23));
  EXPECT_THAT(plugin2->GetGaugeValue(double_gauge_handle, kLabelValues,
                                     kOptionalLabelValues),
              ::testing::Optional(2.34));
  EXPECT_THAT(plugin3->GetGaugeValue(double_gauge_handle, kLabelValues,
                                     kOptionalLabelValues),
              ::testing::Optional(3.45));
}

TEST_F(MetricsTest, Int64CallbackGauge) {
  const absl::string_view kLabelKeys[] = {"label_key_1", "label_key_2"};
  const absl::string_view kOptionalLabelKeys[] = {"optional_label_key_1",
                                                  "optional_label_key_2"};
  auto int64_gauge_handle =
      GlobalInstrumentsRegistry::RegisterCallbackInt64Gauge(
          "int64_gauge", "A simple int64 gauge.", "unit", kLabelKeys,
          kOptionalLabelKeys, true);
  constexpr absl::string_view kLabelValues[] = {"label_value_1",
                                                "label_value_2"};
  constexpr absl::string_view kLabelValues2[] = {"label_value_3",
                                                 "label_value_2"};
  constexpr absl::string_view kOptionalLabelValues[] = {
      "optional_label_value_1", "optional_label_value_2"};
  constexpr absl::string_view kDomain1To4 = "domain1.domain2.domain3.domain4";
  constexpr absl::string_view kDomain2To4 = "domain2.domain3.domain4";
  constexpr absl::string_view kDomain3To4 = "domain3.domain4";
  auto plugin1 = MakeStatsPluginForTarget(kDomain3To4);
  auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
  auto plugin3 = MakeStatsPluginForTarget(kDomain1To4);
  // Register two callbacks that set the same metric but with different
  // label values.  The callbacks get used only by plugin1.
  gpr_log(GPR_INFO, "testing callbacks for: plugin1");
  auto group1 = GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain3To4, ""));
  auto callback1 = group1.RegisterCallback(
      [&](CallbackMetricReporter& reporter) {
        reporter.Report(int64_gauge_handle, 1, kLabelValues,
                        kOptionalLabelValues);
      },
      {int64_gauge_handle});
  auto callback2 = group1.RegisterCallback(
      [&](CallbackMetricReporter& reporter) {
        reporter.Report(int64_gauge_handle, 2, kLabelValues2,
                        kOptionalLabelValues);
      },
      {int64_gauge_handle});
  // No plugins have data yet.
  EXPECT_EQ(plugin1->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin1->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin2->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin2->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  // Now invoke the callbacks.
  plugin1->TriggerCallbacks();
  plugin2->TriggerCallbacks();
  plugin3->TriggerCallbacks();
  // Now plugin1 should have data, but the others should not.
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(1));
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(2));
  EXPECT_EQ(plugin2->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin2->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  // De-register the callbacks.
  callback1.reset();
  callback2.reset();
  // Now register callbacks that hit both plugin1 and plugin2.
  gpr_log(GPR_INFO, "testing callbacks for: plugin1, plugin2");
  auto group2 = GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain2To4, ""));
  callback1 = group2.RegisterCallback(
      [&](CallbackMetricReporter& reporter) {
        reporter.Report(int64_gauge_handle, 3, kLabelValues,
                        kOptionalLabelValues);
      },
      {int64_gauge_handle});
  callback2 = group2.RegisterCallback(
      [&](CallbackMetricReporter& reporter) {
        reporter.Report(int64_gauge_handle, 4, kLabelValues2,
                        kOptionalLabelValues);
      },
      {int64_gauge_handle});
  // Plugin1 still has data from before, but the others have none.
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(1));
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(2));
  EXPECT_EQ(plugin2->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin2->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  // Now invoke the callbacks.
  plugin1->TriggerCallbacks();
  plugin2->TriggerCallbacks();
  plugin3->TriggerCallbacks();
  // Now plugin1 and plugin2 should have data, but plugin3 should not.
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(3));
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(4));
  EXPECT_THAT(plugin2->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(3));
  EXPECT_THAT(plugin2->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(4));
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  // De-register the callbacks.
  callback1.reset();
  callback2.reset();
  // Now register callbacks that hit all three plugins.
  gpr_log(GPR_INFO, "testing callbacks for: plugin1, plugin2, plugin3");
  auto group3 = GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain1To4, ""));
  callback1 = group3.RegisterCallback(
      [&](CallbackMetricReporter& reporter) {
        reporter.Report(int64_gauge_handle, 5, kLabelValues,
                        kOptionalLabelValues);
      },
      {int64_gauge_handle});
  callback2 = group3.RegisterCallback(
      [&](CallbackMetricReporter& reporter) {
        reporter.Report(int64_gauge_handle, 6, kLabelValues2,
                        kOptionalLabelValues);
      },
      {int64_gauge_handle});
  // Plugin1 and plugin2 still has data from before, but plugin3 has none.
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(3));
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(4));
  EXPECT_THAT(plugin2->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(3));
  EXPECT_THAT(plugin2->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(4));
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  // Now invoke the callbacks.
  plugin1->TriggerCallbacks();
  plugin2->TriggerCallbacks();
  plugin3->TriggerCallbacks();
  // Now plugin1 and plugin2 should have data, but plugin3 should not.
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(5));
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(6));
  EXPECT_THAT(plugin2->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(5));
  EXPECT_THAT(plugin2->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(6));
  EXPECT_THAT(plugin3->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(5));
  EXPECT_THAT(plugin3->GetCallbackGaugeValue(int64_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(6));
  // Need to destroy callbacks before the plugin group that created them.
  callback1.reset();
  callback2.reset();
}

TEST_F(MetricsTest, DoubleCallbackGauge) {
  const absl::string_view kLabelKeys[] = {"label_key_1", "label_key_2"};
  const absl::string_view kOptionalLabelKeys[] = {"optional_label_key_1",
                                                  "optional_label_key_2"};
  auto double_gauge_handle =
      GlobalInstrumentsRegistry::RegisterCallbackDoubleGauge(
          "double_gauge", "A simple double gauge.", "unit", kLabelKeys,
          kOptionalLabelKeys, true);
  constexpr absl::string_view kLabelValues[] = {"label_value_1",
                                                "label_value_2"};
  constexpr absl::string_view kLabelValues2[] = {"label_value_3",
                                                 "label_value_2"};
  constexpr absl::string_view kOptionalLabelValues[] = {
      "optional_label_value_1", "optional_label_value_2"};
  constexpr absl::string_view kDomain1To4 = "domain1.domain2.domain3.domain4";
  constexpr absl::string_view kDomain2To4 = "domain2.domain3.domain4";
  constexpr absl::string_view kDomain3To4 = "domain3.domain4";
  auto plugin1 = MakeStatsPluginForTarget(kDomain3To4);
  auto plugin2 = MakeStatsPluginForTarget(kDomain2To4);
  auto plugin3 = MakeStatsPluginForTarget(kDomain1To4);
  // Register two callbacks that set the same metric but with different
  // label values.  The callbacks get used only by plugin1.
  gpr_log(GPR_INFO, "testing callbacks for: plugin1");
  auto group1 = GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain3To4, ""));
  auto callback1 = group1.RegisterCallback(
      [&](CallbackMetricReporter& reporter) {
        reporter.Report(double_gauge_handle, 1.23, kLabelValues,
                        kOptionalLabelValues);
      },
      {double_gauge_handle});
  auto callback2 = group1.RegisterCallback(
      [&](CallbackMetricReporter& reporter) {
        reporter.Report(double_gauge_handle, 2.34, kLabelValues2,
                        kOptionalLabelValues);
      },
      {double_gauge_handle});
  // No plugins have data yet.
  EXPECT_EQ(plugin1->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin1->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin2->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin2->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  // Now invoke the callbacks.
  plugin1->TriggerCallbacks();
  plugin2->TriggerCallbacks();
  plugin3->TriggerCallbacks();
  // Now plugin1 should have data, but the others should not.
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(1.23));
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(2.34));
  EXPECT_EQ(plugin2->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin2->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  // De-register the callbacks.
  callback1.reset();
  callback2.reset();
  // Now register callbacks that hit both plugin1 and plugin2.
  gpr_log(GPR_INFO, "testing callbacks for: plugin1, plugin2");
  auto group2 = GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain2To4, ""));
  callback1 = group2.RegisterCallback(
      [&](CallbackMetricReporter& reporter) {
        reporter.Report(double_gauge_handle, 3.45, kLabelValues,
                        kOptionalLabelValues);
      },
      {double_gauge_handle});
  callback2 = group2.RegisterCallback(
      [&](CallbackMetricReporter& reporter) {
        reporter.Report(double_gauge_handle, 4.56, kLabelValues2,
                        kOptionalLabelValues);
      },
      {double_gauge_handle});
  // Plugin1 still has data from before, but the others have none.
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(1.23));
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(2.34));
  EXPECT_EQ(plugin2->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin2->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  // Now invoke the callbacks.
  plugin1->TriggerCallbacks();
  plugin2->TriggerCallbacks();
  plugin3->TriggerCallbacks();
  // Now plugin1 and plugin2 should have data, but plugin3 should not.
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(3.45));
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(4.56));
  EXPECT_THAT(plugin2->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(3.45));
  EXPECT_THAT(plugin2->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(4.56));
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  // De-register the callbacks.
  callback1.reset();
  callback2.reset();
  // Now register callbacks that hit all three plugins.
  gpr_log(GPR_INFO, "testing callbacks for: plugin1, plugin2, plugin3");
  auto group3 = GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain1To4, ""));
  callback1 = group3.RegisterCallback(
      [&](CallbackMetricReporter& reporter) {
        reporter.Report(double_gauge_handle, 5.67, kLabelValues,
                        kOptionalLabelValues);
      },
      {double_gauge_handle});
  callback2 = group3.RegisterCallback(
      [&](CallbackMetricReporter& reporter) {
        reporter.Report(double_gauge_handle, 6.78, kLabelValues2,
                        kOptionalLabelValues);
      },
      {double_gauge_handle});
  // Plugin1 and plugin2 still has data from before, but plugin3 has none.
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(3.45));
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(4.56));
  EXPECT_THAT(plugin2->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(3.45));
  EXPECT_THAT(plugin2->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(4.56));
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                           kOptionalLabelValues),
            absl::nullopt);
  EXPECT_EQ(plugin3->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                           kOptionalLabelValues),
            absl::nullopt);
  // Now invoke the callbacks.
  plugin1->TriggerCallbacks();
  plugin2->TriggerCallbacks();
  plugin3->TriggerCallbacks();
  // Now plugin1 and plugin2 should have data, but plugin3 should not.
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(5.67));
  EXPECT_THAT(plugin1->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(6.78));
  EXPECT_THAT(plugin2->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(5.67));
  EXPECT_THAT(plugin2->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(6.78));
  EXPECT_THAT(plugin3->GetCallbackGaugeValue(double_gauge_handle, kLabelValues,
                                             kOptionalLabelValues),
              ::testing::Optional(5.67));
  EXPECT_THAT(plugin3->GetCallbackGaugeValue(double_gauge_handle, kLabelValues2,
                                             kOptionalLabelValues),
              ::testing::Optional(6.78));
  // Need to destroy callbacks before the plugin group that created them.
  callback1.reset();
  callback2.reset();
}

TEST_F(MetricsTest, DisableByDefaultMetricIsNotRecordedByFakeStatsPlugin) {
  const absl::string_view kLabelKeys[] = {"label_key_1", "label_key_2"};
  const absl::string_view kOptionalLabelKeys[] = {"optional_label_key_1",
                                                  "optional_label_key_2"};
  auto double_histogram_handle =
      GlobalInstrumentsRegistry::RegisterDoubleHistogram(
          "double_histogram", "A simple double histogram.", "unit", kLabelKeys,
          kOptionalLabelKeys, /*enable_by_default=*/false);
  constexpr absl::string_view kLabelValues[] = {"label_value_1",
                                                "label_value_2"};
  constexpr absl::string_view kOptionalLabelValues[] = {
      "optional_label_value_1", "optional_label_value_2"};
  constexpr absl::string_view kDomain1To4 = "domain1.domain2.domain3.domain4";
  auto plugin = MakeStatsPluginForTarget(kDomain1To4);
  GlobalStatsPluginRegistry::GetStatsPluginsForChannel(
      StatsPluginChannelScope(kDomain1To4, ""))
      .RecordHistogram(double_histogram_handle, 1.23, kLabelValues,
                       kOptionalLabelValues);
  EXPECT_EQ(plugin->GetHistogramValue(double_histogram_handle, kLabelValues,
                                      kOptionalLabelValues),
            absl::nullopt);
}

using MetricsDeathTest = MetricsTest;

TEST_F(MetricsDeathTest, RegisterTheSameMetricNameWouldCrash) {
  const absl::string_view kLabelKeys[] = {"label_key_1", "label_key_2"};
  const absl::string_view kOptionalLabelKeys[] = {"optional_label_key_1",
                                                  "optional_label_key_2"};
  (void)GlobalInstrumentsRegistry::RegisterDoubleHistogram(
      "double_histogram", "A simple double histogram.", "unit", kLabelKeys,
      kOptionalLabelKeys, true);
  EXPECT_DEATH(GlobalInstrumentsRegistry::RegisterDoubleHistogram(
                   "double_histogram", "A simple double histogram.", "unit",
                   kLabelKeys, kOptionalLabelKeys, true),
               "Metric name double_histogram has already been registered.");
}

}  // namespace
}  // namespace grpc_core

int main(int argc, char** argv) {
  grpc::testing::TestEnvironment env(&argc, argv);
  ::testing::InitGoogleTest(&argc, argv);
  int ret = RUN_ALL_TESTS();
  return ret;
}