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Commit f0f7303

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author
Ian Sturdy
authored
Add a TagSet class providing equality and hashing for key/value maps. (#95)
1 parent f83b273 commit f0f7303

5 files changed

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‎opencensus/stats/BUILD‎

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@@ -65,6 +65,7 @@ cc_library(
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"internal/set_aggregation_window.cc",
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"internal/stats_exporter.cc",
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"internal/stats_manager.cc",
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"internal/tag_set.cc",
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"internal/view.cc",
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"internal/view_data.cc",
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"internal/view_data_impl.cc",
@@ -84,6 +85,7 @@ cc_library(
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"measure_descriptor.h",
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"measure_registry.h",
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"stats_exporter.h",
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"tag_set.h",
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"view.h",
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"view_data.h",
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"view_descriptor.h",
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],
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)
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cc_test(
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name = "tag_set_test",
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size = "small",
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srcs = ["internal/tag_set_test.cc"],
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copts = TEST_COPTS,
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deps = [
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":core",
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"@com_google_googletest//:gtest_main",
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],
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)
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cc_test(
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name = "view_data_impl_test",
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srcs = ["internal/view_data_impl_test.cc"],

‎opencensus/stats/internal/tag_set.cc‎

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// Copyright 2018, OpenCensus Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "opencensus/stats/tag_set.h"
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#include <functional>
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#include <initializer_list>
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#include <string>
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#include <utility>
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#include <vector>
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#include "absl/strings/string_view.h"
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namespace opencensus {
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namespace stats {
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TagSet::TagSet(
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std::initializer_list<std::pair<absl::string_view, absl::string_view>>
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tags) {
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tags_.reserve(tags.size());
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for (const auto& tag : tags) {
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tags_.emplace_back(std::string(tag.first), std::string(tag.second));
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}
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Initialize();
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}
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TagSet::TagSet(std::vector<std::pair<std::string, std::string>> tags)
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: tags_(std::move(tags)) {
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Initialize();
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}
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void TagSet::Initialize() {
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std::sort(tags_.begin(), tags_.end());
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std::hash<std::string> hasher;
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hash_ = 1;
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for (const auto& tag : tags_) {
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static const size_t kMul = static_cast<size_t>(0xdc3eb94af8ab4c93ULL);
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hash_ *= kMul;
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hash_ = ((hash_ << 19) |
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(hash_ >> (std::numeric_limits<size_t>::digits - 19))) +
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hasher(tag.first);
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hash_ *= kMul;
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hash_ = ((hash_ << 19) |
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(hash_ >> (std::numeric_limits<size_t>::digits - 19))) +
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hasher(tag.second);
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}
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}
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std::size_t TagSet::Hash::operator()(const TagSet& tag_set) const {
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return tag_set.hash_;
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}
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bool TagSet::operator==(const TagSet& other) const {
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return tags_ == other.tags_;
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}
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} // namespace stats
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} // namespace opencensus

‎opencensus/stats/internal/tag_set_test.cc‎

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// Copyright 2018, OpenCensus Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "opencensus/stats/tag_set.h"
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#include <string>
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#include <unordered_map>
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#include <utility>
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#include <vector>
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#include "gmock/gmock.h"
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#include "gtest/gtest.h"
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namespace opencensus {
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namespace stats {
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namespace {
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TEST(TagSetTest, ConstructorsEquivalent) {
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const std::vector<std::pair<std::string, std::string>> tags({{"k", "v"}});
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EXPECT_EQ(TagSet(tags), TagSet({{"k", "v"}}));
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}
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TEST(TagSetTest, TagsSorted) {
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const std::vector<std::pair<std::string, std::string>> expected = {
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{"B", "v"}, {"a", "v"}, {"b", "v"}};
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const std::vector<std::pair<std::string, std::string>> tags(
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{{"b", "v"}, {"a", "v"}, {"B", "v"}});
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EXPECT_THAT(TagSet(tags).tags(), ::testing::ElementsAreArray(expected));
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EXPECT_THAT(TagSet({{"B", "v"}, {"b", "v"}, {"a", "v"}}).tags(),
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::testing::ElementsAreArray(expected));
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}
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TEST(TagSetTest, EqualityDisregardsOrder) {
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EXPECT_EQ(TagSet({{"k1", "v1"}, {"k2", "v2"}}),
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TagSet({{"k2", "v2"}, {"k1", "v1"}}));
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}
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TEST(TagSetTest, EqualityRespectsMissingKeys) {
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EXPECT_NE(TagSet({{"k1", "v1"}, {"k2", "v2"}}), TagSet({{"k1", "v1"}}));
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}
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TEST(TagSetTest, EqualityRespectsKeyValuePairings) {
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EXPECT_NE(TagSet({{"k1", "v1"}, {"k2", "v2"}}),
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TagSet({{"k1", "v2"}, {"k2", "v1"}}));
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}
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TEST(TagSetTest, HashDisregardsOrder) {
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TagSet ts1({{"k1", "v1"}, {"k2", "v2"}});
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TagSet ts2({{"k2", "v2"}, {"k1", "v1"}});
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EXPECT_EQ(TagSet::Hash()(ts1), TagSet::Hash()(ts2));
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}
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TEST(TagSetTest, HashRespectsKeyValuePairings) {
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TagSet ts1({{"k1", "v1"}, {"k2", "v2"}});
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TagSet ts2({{"k1", "v2"}, {"k2", "v1"}});
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EXPECT_NE(TagSet::Hash()(ts1), TagSet::Hash()(ts2));
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}
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TEST(TagSetTest, UnorderedMap) {
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// Test that the operators and hash are compatible with std::unordered_map.
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std::unordered_map<TagSet, int, TagSet::Hash> map;
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TagSet ts = {{"key", "value"}};
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map.emplace(ts, 1);
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EXPECT_NE(map.end(), map.find(ts));
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EXPECT_EQ(1, map.erase(ts));
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}
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} // namespace
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} // namespace stats
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} // namespace opencensus

‎opencensus/stats/stats.h‎

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#include "opencensus/stats/measure_registry.h" // IWYU pragma: export
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#include "opencensus/stats/recording.h" // IWYU pragma: export
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#include "opencensus/stats/stats_exporter.h" // IWYU pragma: export
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#include "opencensus/stats/tag_set.h" // IWYU pragma: export
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#include "opencensus/stats/view.h" // IWYU pragma: export
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#include "opencensus/stats/view_data.h" // IWYU pragma: export
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#include "opencensus/stats/view_descriptor.h" // IWYU pragma: export

‎opencensus/stats/tag_set.h‎

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// Copyright 2018, OpenCensus Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef OPENCENSUS_STATS_TAG_SET_H_
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#define OPENCENSUS_STATS_TAG_SET_H_
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#include <initializer_list>
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#include <string>
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#include <utility>
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#include <vector>
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#include "absl/strings/string_view.h"
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namespace opencensus {
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namespace stats {
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// TagSet represents a set of key-value tags, and provides efficient equality
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// and hash operations. A TagSet is expensive to construct, and should be shared
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// between uses where possible.
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// TagSet is immutable.
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class TagSet final {
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public:
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// Both constructors are not explicit so that Record({}, {{"k", "v"}}) works.
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// This constructor is needed because even though we copy to a vector
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// internally because c++ cannot deduce the conversion needed.
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TagSet(std::initializer_list<std::pair<absl::string_view, absl::string_view>>
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tags);
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// This constructor is needed so that callers can dynamically construct
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// tagsets. It takes the argument by value to allow it to be moved.
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TagSet(std::vector<std::pair<std::string, std::string>> tags);
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// Accesses the tags sorted by key.
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const std::vector<std::pair<std::string, std::string>>& tags() const {
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return tags_;
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}
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struct Hash {
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std::size_t operator()(const TagSet& tag_set) const;
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};
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bool operator==(const TagSet& other) const;
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bool operator!=(const TagSet& other) const { return !(*this == other); }
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private:
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void Initialize();
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std::size_t hash_;
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// TODO: add an option to store string_views to avoid copies.
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std::vector<std::pair<std::string, std::string>> tags_;
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};
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} // namespace stats
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} // namespace opencensus
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#endif // OPENCENSUS_STATS_TAG_SET_H_

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