Add compression and histogram metric type for Prometheus (#987)

Fixes #932 Also fixes #966 Decided not to add Summary type because it has the same functionality as Histogram but makes more calculations on client side (Clio side). See https://prometheus.io/docs/practices/histograms for detailed comparison.
2025-12-06 17:27:58 +00:00 · 2023-11-22 12:55:06 +00:00
parent 8ebe2d6a80
commit b998473673
41 changed files with 2230 additions and 619 deletions
--- a/unittests/util/prometheus/HistogramTests.cpp
+++ b/unittests/util/prometheus/HistogramTests.cpp
@@ -0,0 +1,115 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2023, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <util/prometheus/Histogram.h>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+using namespace util::prometheus;
+
+struct AnyHistogramTests : ::testing::Test {
+    struct MockHistogramImpl {
+        MockHistogramImpl()
+        {
+            EXPECT_CALL(*this, setBuckets);
+        }
+        using ValueType = std::int64_t;
+        MOCK_METHOD(void, observe, (ValueType));
+        MOCK_METHOD(void, setBuckets, (std::vector<ValueType> const&));
+        MOCK_METHOD(void, serializeValue, (std::string const&, std::string, OStream&), (const));
+    };
+
+    ::testing::StrictMock<MockHistogramImpl> mockHistogramImpl;
+    std::string const name = "test_histogram";
+    std::string labelsString = R"({label1="value1",label2="value2"})";
+    HistogramInt histogram{name, labelsString, {1, 2, 3}, static_cast<MockHistogramImpl&>(mockHistogramImpl)};
+};
+
+TEST_F(AnyHistogramTests, name)
+{
+    EXPECT_EQ(histogram.name(), name);
+}
+
+TEST_F(AnyHistogramTests, labelsString)
+{
+    EXPECT_EQ(histogram.labelsString(), labelsString);
+}
+
+TEST_F(AnyHistogramTests, observe)
+{
+    EXPECT_CALL(mockHistogramImpl, observe(42));
+    histogram.observe(42);
+}
+
+TEST_F(AnyHistogramTests, serializeValue)
+{
+    OStream stream{false};
+    EXPECT_CALL(mockHistogramImpl, serializeValue(name, labelsString, ::testing::_));
+    histogram.serializeValue(stream);
+}
+
+struct HistogramTests : ::testing::Test {
+    std::string labelsString = R"({label1="value1",label2="value2"})";
+    HistogramInt histogram{"t", labelsString, {1, 2, 3}};
+
+    std::string
+    serialize() const
+    {
+        OStream stream{false};
+        histogram.serializeValue(stream);
+        return std::move(stream).data();
+    }
+};
+
+TEST_F(HistogramTests, observe)
+{
+    histogram.observe(0);
+    EXPECT_EQ(
+        serialize(),
+        "t_bucket{label1=\"value1\",label2=\"value2\",le=\"1\"} 1\n"
+        "t_bucket{label1=\"value1\",label2=\"value2\",le=\"2\"} 1\n"
+        "t_bucket{label1=\"value1\",label2=\"value2\",le=\"3\"} 1\n"
+        "t_bucket{label1=\"value1\",label2=\"value2\",le=\"+Inf\"} 1\n"
+        "t_sum{label1=\"value1\",label2=\"value2\"} 0\n"
+        "t_count{label1=\"value1\",label2=\"value2\"} 1\n"
+    ) << serialize();
+
+    histogram.observe(2);
+    EXPECT_EQ(
+        serialize(),
+        "t_bucket{label1=\"value1\",label2=\"value2\",le=\"1\"} 1\n"
+        "t_bucket{label1=\"value1\",label2=\"value2\",le=\"2\"} 2\n"
+        "t_bucket{label1=\"value1\",label2=\"value2\",le=\"3\"} 2\n"
+        "t_bucket{label1=\"value1\",label2=\"value2\",le=\"+Inf\"} 2\n"
+        "t_sum{label1=\"value1\",label2=\"value2\"} 2\n"
+        "t_count{label1=\"value1\",label2=\"value2\"} 2\n"
+    );
+
+    histogram.observe(123);
+    EXPECT_EQ(
+        serialize(),
+        "t_bucket{label1=\"value1\",label2=\"value2\",le=\"1\"} 1\n"
+        "t_bucket{label1=\"value1\",label2=\"value2\",le=\"2\"} 2\n"
+        "t_bucket{label1=\"value1\",label2=\"value2\",le=\"3\"} 2\n"
+        "t_bucket{label1=\"value1\",label2=\"value2\",le=\"+Inf\"} 3\n"
+        "t_sum{label1=\"value1\",label2=\"value2\"} 125\n"
+        "t_count{label1=\"value1\",label2=\"value2\"} 3\n"
+    );
+}