7 files changed, 343 insertions, 0 deletions
diff --git a/core/java/com/android/internal/expresslog/Histogram.java b/core/java/com/android/internal/expresslog/Histogram.java
new file mode 100644
index 000000000000..fe950c4c2932
--- /dev/null
+++ b/core/java/com/android/internal/expresslog/Histogram.java
@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * 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 com.android.internal.expresslog;
+
+import android.annotation.NonNull;
+
+import com.android.internal.util.FrameworkStatsLog;
+
+/** CounterHistogram encapsulates StatsD write API calls */
+public final class Histogram {
+
+    private final long mMetricIdHash;
+    private final BinOptions mBinOptions;
+
+    public Histogram(@NonNull String metricId, @NonNull BinOptions binOptions) {
+        mMetricIdHash = Utils.hashString(metricId);
+        mBinOptions = binOptions;
+    }
+
+    /**
+     * Logs increment sample count for automatically calculated bin
+     *
+     * @hide
+     */
+    public void logSample(float sample) {
+        final int binIndex = mBinOptions.getBinForSample(sample);
+        FrameworkStatsLog.write(FrameworkStatsLog.EXPRESS_HISTOGRAM_SAMPLE_REPORTED, mMetricIdHash,
+                /*count*/ 1, binIndex);
+    }
+
+    /** Used by CounterHistogram to map data sample to corresponding bin */
+    public interface BinOptions {
+        /**
+         * Returns bins count to be used by counter histogram
+         *
+         * @return bins count used to initialize Options, including overflow & underflow bins
+         * @hide
+         */
+        int getBinsCount();
+
+        /**
+         * @return zero based index
+         * Calculates bin index for the input sample value
+         * index == 0 stands for underflow
+         * index == getBinsCount() - 1 stands for overflow
+         * @hide
+         */
+        int getBinForSample(float sample);
+    }
+
+    /** Used by CounterHistogram to map data sample to corresponding bin for on uniform bins */
+    public static final class UniformOptions implements BinOptions {
+
+        private final int mBinCount;
+        private final float mMinValue;
+        private final float mExclusiveMaxValue;
+        private final float mBinSize;
+
+        public UniformOptions(int binCount, float minValue, float exclusiveMaxValue) {
+            if (binCount < 1) {
+                throw new IllegalArgumentException("Bin count should be positive number");
+            }
+
+            if (exclusiveMaxValue <= minValue) {
+                throw new IllegalArgumentException("Bins range invalid (maxValue < minValue)");
+            }
+
+            mMinValue = minValue;
+            mExclusiveMaxValue = exclusiveMaxValue;
+            mBinSize = (mExclusiveMaxValue - minValue) / binCount;
+
+            // Implicitly add 2 for the extra undeflow & overflow bins
+            mBinCount = binCount + 2;
+        }
+
+        @Override
+        public int getBinsCount() {
+            return mBinCount;
+        }
+
+        @Override
+        public int getBinForSample(float sample) {
+            if (sample < mMinValue) {
+                // goes to underflow
+                return 0;
+            } else if (sample >= mExclusiveMaxValue) {
+                // goes to overflow
+                return mBinCount - 1;
+            }
+            return (int) ((sample - mMinValue) / mBinSize + 1);
+        }
+    }
+}
diff --git a/core/java/com/android/internal/expresslog/TEST_MAPPING b/core/java/com/android/internal/expresslog/TEST_MAPPING
new file mode 100644
index 000000000000..c9b0cf80a1e6
--- /dev/null
+++ b/core/java/com/android/internal/expresslog/TEST_MAPPING
@@ -0,0 +1,12 @@
+{
+  "presubmit": [
+    {
+      "name": "ExpressLogTests",
+      "options": [
+        {
+          "exclude-annotation": "org.junit.Ignore"
+        }
+      ]
+    }
+  ]
+}
+\ No newline at end of file
diff --git a/core/tests/expresslog/Android.bp b/core/tests/expresslog/Android.bp
new file mode 100644
index 000000000000..cab49a76a734
--- /dev/null
+++ b/core/tests/expresslog/Android.bp
@@ -0,0 +1,47 @@
+// Copyright (C) 2023 The Android Open Source Project
+//
+// 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 {
+    // See: http://go/android-license-faq
+    // A large-scale-change added 'default_applicable_licenses' to import
+    // all of the 'license_kinds' from "frameworks_base_license"
+    // to get the below license kinds:
+    //   SPDX-license-identifier-Apache-2.0
+    default_applicable_licenses: ["frameworks_base_license"],
+}
+
+android_test {
+    name: "ExpressLogTests",
+
+    srcs: [
+        "src/**/*.java",
+    ],
+
+    static_libs: [
+        "androidx.test.rules",
+        "modules-utils-build",
+    ],
+
+    libs: [
+        "android.test.base",
+        "android.test.runner",
+    ],
+
+    platform_apis: true,
+    test_suites: [
+        "general-tests",
+    ],
+
+    certificate: "platform",
+}
diff --git a/core/tests/expresslog/AndroidManifest.xml b/core/tests/expresslog/AndroidManifest.xml
new file mode 100644
index 000000000000..94a39e06c974
--- /dev/null
+++ b/core/tests/expresslog/AndroidManifest.xml
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2023 The Android Open Source Project
+
+     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.
+-->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+          android:installLocation="internalOnly"
+          package="com.android.internal.expresslog" >
+
+    <application >
+        <uses-library android:name="android.test.runner" />
+    </application>
+
+    <instrumentation android:name="androidx.test.runner.AndroidJUnitRunner"
+            android:targetPackage="com.android.internal.expresslog"
+            android:label="Telemetry Express Logging Helper Tests" />
+
+</manifest>
diff --git a/core/tests/expresslog/OWNERS b/core/tests/expresslog/OWNERS
new file mode 100644
index 000000000000..3dc958b07f9c
--- /dev/null
+++ b/core/tests/expresslog/OWNERS
@@ -0,0 +1,3 @@
+# Bug component: 719316
+# Stats/expresslog
+file:/services/core/java/com/android/server/stats/OWNERS
diff --git a/core/tests/expresslog/TEST_MAPPING b/core/tests/expresslog/TEST_MAPPING
new file mode 100644
index 000000000000..c9b0cf80a1e6
--- /dev/null
+++ b/core/tests/expresslog/TEST_MAPPING
@@ -0,0 +1,12 @@
+{
+  "presubmit": [
+    {
+      "name": "ExpressLogTests",
+      "options": [
+        {
+          "exclude-annotation": "org.junit.Ignore"
+        }
+      ]
+    }
+  ]
+}
+\ No newline at end of file
diff --git a/core/tests/expresslog/src/com/android/internal/expresslog/UniformOptionsTest.java b/core/tests/expresslog/src/com/android/internal/expresslog/UniformOptionsTest.java
new file mode 100644
index 000000000000..9fa6d0634fbe
--- /dev/null
+++ b/core/tests/expresslog/src/com/android/internal/expresslog/UniformOptionsTest.java
@@ -0,0 +1,133 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * 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 com.android.internal.expresslog;
+
+import androidx.test.filters.SmallTest;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public class UniformOptionsTest {
+    private static final String TAG = UniformOptionsTest.class.getSimpleName();
+
+    @Test
+    @SmallTest
+    public void testGetBinsCount() {
+        Histogram.UniformOptions options1 = new Histogram.UniformOptions(1, 100, 1000);
+        assertEquals(3, options1.getBinsCount());
+
+        Histogram.UniformOptions options10 = new Histogram.UniformOptions(10, 100, 1000);
+        assertEquals(12, options10.getBinsCount());
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    @SmallTest
+    public void testConstructZeroBinsCount() {
+        new Histogram.UniformOptions(0, 100, 1000);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    @SmallTest
+    public void testConstructNegativeBinsCount() {
+        new Histogram.UniformOptions(-1, 100, 1000);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    @SmallTest
+    public void testConstructMaxValueLessThanMinValue() {
+        new Histogram.UniformOptions(10, 1000, 100);
+    }
+
+    @Test
+    @SmallTest
+    public void testBinIndexForRangeEqual1() {
+        Histogram.UniformOptions options = new Histogram.UniformOptions(10, 1, 11);
+        for (int i = 0, bins = options.getBinsCount(); i < bins; i++) {
+            assertEquals(i, options.getBinForSample(i));
+        }
+    }
+
+    @Test
+    @SmallTest
+    public void testBinIndexForRangeEqual2() {
+        Histogram.UniformOptions options = new Histogram.UniformOptions(10, 1, 21);
+        for (int i = 0, bins = options.getBinsCount(); i < bins; i++) {
+            assertEquals(i, options.getBinForSample(i * 2));
+            assertEquals(i, options.getBinForSample(i * 2 - 1));
+        }
+    }
+
+    @Test
+    @SmallTest
+    public void testBinIndexForRangeEqual5() {
+        Histogram.UniformOptions options = new Histogram.UniformOptions(2, 0, 10);
+        assertEquals(4, options.getBinsCount());
+        for (int i = 0; i < 2; i++) {
+            for (int sample = 0; sample < 5; sample++) {
+                assertEquals(i + 1, options.getBinForSample(i * 5 + sample));
+            }
+        }
+    }
+
+    @Test
+    @SmallTest
+    public void testBinIndexForRangeEqual10() {
+        Histogram.UniformOptions options = new Histogram.UniformOptions(10, 1, 101);
+        assertEquals(0, options.getBinForSample(0));
+        assertEquals(options.getBinsCount() - 2, options.getBinForSample(100));
+        assertEquals(options.getBinsCount() - 1, options.getBinForSample(101));
+
+        final float binSize = (101 - 1) / 10f;
+        for (int i = 1, bins = options.getBinsCount() - 1; i < bins; i++) {
+            assertEquals(i, options.getBinForSample(i * binSize));
+        }
+    }
+
+    @Test
+    @SmallTest
+    public void testBinIndexForRangeEqual90() {
+        final int binCount = 10;
+        final int minValue = 100;
+        final int maxValue = 100000;
+
+        Histogram.UniformOptions options = new Histogram.UniformOptions(binCount, minValue,
+                maxValue);
+
+        // logging underflow sample
+        assertEquals(0, options.getBinForSample(minValue - 1));
+
+        // logging overflow sample
+        assertEquals(binCount + 1, options.getBinForSample(maxValue));
+        assertEquals(binCount + 1, options.getBinForSample(maxValue + 1));
+
+        // logging min edge sample
+        assertEquals(1, options.getBinForSample(minValue));
+
+        // logging max edge sample
+        assertEquals(binCount, options.getBinForSample(maxValue - 1));
+
+        // logging single valid sample per bin
+        final int binSize = (maxValue - minValue) / binCount;
+
+        for (int i = 0; i < binCount; i++) {
+            assertEquals(i + 1, options.getBinForSample(minValue + binSize * i));
+        }
+    }
+}