Add ThreadsCount type

pom.xml

@@ -49,6 +49,18 @@
             <optional>true</optional>
         </dependency>
 
+        <dependency>
+            <groupId>com.github.oshi</groupId>
+            <artifactId>oshi-core</artifactId>
+            <version>6.4.1</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>*</groupId>
+                    <artifactId>*</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+
         <!-- for testing -->
         <dependency>
             <groupId>org.testng</groupId>

src/main/java/io/airlift/units/PowerOfTwo.java

@@ -0,0 +1,38 @@
+/*
+ * 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 io.airlift.units;
+
+import javax.validation.Constraint;
+import javax.validation.Payload;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+@Target({METHOD, ANNOTATION_TYPE})
+@Retention(RUNTIME)
+@Documented
+@Constraint(validatedBy = PowerOfTwoValidator.class)
+public @interface PowerOfTwo
+{
+    String message() default "is not a power of two";
+
+    Class<?>[] groups() default {};
+
+    Class<? extends Payload>[] payload() default {};
+}

src/main/java/io/airlift/units/PowerOfTwoValidator.java

@@ -0,0 +1,32 @@
+/*
+ * 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 io.airlift.units;
+
+import javax.validation.ConstraintValidator;
+import javax.validation.ConstraintValidatorContext;
+
+public class PowerOfTwoValidator
+        implements ConstraintValidator<PowerOfTwo, Integer>
+{
+    @Override
+    public void initialize(PowerOfTwo powerOfTwo)
+    {
+    }
+
+    @Override
+    public boolean isValid(Integer value, ConstraintValidatorContext context)
+    {
+        return value == null || Integer.bitCount(value) == 1;
+    }
+}

src/main/java/io/airlift/units/ThreadsCount.java

@@ -0,0 +1,183 @@
+/*
+ * 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 io.airlift.units;
+
+import oshi.SystemInfo;
+
+import java.util.function.Supplier;
+
+import static io.airlift.units.Preconditions.checkArgument;
+import static java.lang.Math.min;
+import static java.lang.Math.round;
+import static java.lang.String.format;
+
+public class ThreadsCount
+        implements Comparable<ThreadsCount>
+{
+    private static final String PER_CORE_SUFFIX = "C";
+    private static final Supplier<Integer> AVAILABLE_PROCESSORS = MachineInfo::getAvailablePhysicalProcessorCount;
+    private final int threadsCount;
+
+    ThreadsCount(int threadsCount)
+    {
+        checkArgument(threadsCount >= 0, "Threads count cannot be smaller than 0");
+        this.threadsCount = threadsCount;
+    }
+
+    public int getThreadsCount()
+    {
+        return threadsCount;
+    }
+
+    public ThreadsCount nextPowerOf2()
+    {
+        return new ThreadsCount(nextPowerOfTwo(getThreadsCount()));
+    }
+
+    public static ThreadsCount exactValueOf(int value)
+    {
+        return new ThreadsCount(value);
+    }
+
+    public static ThreadsCount valueOf(String value)
+    {
+        if (value.endsWith(PER_CORE_SUFFIX)) {
+            float parsedMultiplier = parseFloat(value.substring(0, value.lastIndexOf(PER_CORE_SUFFIX)));
+            return new ThreadsCount(round(parsedMultiplier * AVAILABLE_PROCESSORS.get()));
+        }
+
+        return new ThreadsCount(parseInteger(value));
+    }
+
+    public static ThreadsCount boundedValueOf(String value, String minValue, String maxValue)
+    {
+        ThreadsCount parsed = ThreadsCount.valueOf(value);
+        ThreadsCount min = ThreadsCount.valueOf(minValue);
+        ThreadsCount max = ThreadsCount.valueOf(maxValue);
+
+        if (parsed.compareTo(min) < 0) {
+            return min;
+        }
+
+        if (parsed.compareTo(max) > 0) {
+            return max;
+        }
+        return parsed;
+    }
+
+    private static float parseFloat(String value)
+    {
+        try {
+            return Float.parseFloat(value);
+        }
+        catch (NumberFormatException e) {
+            throw new IllegalArgumentException(format("Cannot parse value '%s' as float", value), e);
+        }
+    }
+
+    private static int parseInteger(String value)
+    {
+        try {
+            return Integer.parseInt(value);
+        }
+        catch (NumberFormatException e) {
+            throw new IllegalArgumentException(format("Cannot parse value '%s' as integer", value), e);
+        }
+    }
+
+    static int nextPowerOfTwo(int x)
+    {
+        if (x == 0) {
+            return 1;
+        }
+
+        --x;
+        x |= x >> 1;
+        x |= x >> 2;
+        x |= x >> 4;
+        x |= x >> 8;
+        return (x | x >> 16) + 1;
+    }
+
+    @Override
+    public int compareTo(ThreadsCount o)
+    {
+        return Integer.compare(threadsCount, o.threadsCount);
+    }
+
+    @Override
+    public boolean equals(Object o)
+    {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+
+        ThreadsCount that = (ThreadsCount) o;
+        return threadsCount == that.threadsCount;
+    }
+
+    @Override
+    public int hashCode()
+    {
+        return threadsCount;
+    }
+
+    @Override
+    public String toString()
+    {
+        if (threadsCount == 1) {
+            return "1 thread";
+        }
+        return format("%d threads", threadsCount);
+    }
+
+    public static final class MachineInfo
+    {
+        // cache physical processor count, so that it's not queried multiple times during tests
+        private static volatile int physicalProcessorCount = -1;
+
+        private MachineInfo() {}
+
+        public static int getAvailablePhysicalProcessorCount()
+        {
+            if (physicalProcessorCount != -1) {
+                return physicalProcessorCount;
+            }
+
+            String osArch = System.getProperty("os.arch");
+            // logical core count (including container cpu quota if there is any)
+            int availableProcessorCount = Runtime.getRuntime().availableProcessors();
+            int totalPhysicalProcessorCount;
+            if ("amd64".equals(osArch) || "x86_64".equals(osArch)) {
+                // Oshi can recognize physical processor count (without hyper threading) for x86 platforms.
+                // However, it doesn't correctly recognize physical processor count for ARM platforms.
+                totalPhysicalProcessorCount = new SystemInfo()
+                        .getHardware()
+                        .getProcessor()
+                        .getPhysicalProcessorCount();
+            }
+            else {
+                // ARM platforms do not support hyper threading, therefore each logical processor is separate core
+                totalPhysicalProcessorCount = availableProcessorCount;
+            }
+
+            // cap available processor count to container cpu quota (if there is any).
+            physicalProcessorCount = min(totalPhysicalProcessorCount, availableProcessorCount);
+            return physicalProcessorCount;
+        }
+    }
+}

src/test/java/io/airlift/units/TestPowerOfTwoValidator.java

@@ -0,0 +1,87 @@
+/*
+ * 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 io.airlift.units;
+
+import org.testng.annotations.Test;
+
+import static io.airlift.testing.ValidationAssertions.assertFailsValidation;
+import static io.airlift.testing.ValidationAssertions.assertValidates;
+
+public class TestPowerOfTwoValidator
+{
+    @Test
+    public void testValidator()
+    {
+        assertValid(1);
+        assertValid(2);
+        assertValid(64);
+        assertInvalid(0);
+        assertInvalid(3);
+        assertInvalid(99);
+        assertInvalid(-1);
+        assertInvalid(-2);
+        assertInvalid(-4);
+    }
+
+    @Test
+    public void testAllowsNullPowerOfTwoAnnotation()
+    {
+        assertValidates(new NullPowerOfTwoAnnotation());
+    }
+
+    private static void assertValid(int value)
+    {
+        assertValidates(new ConstrainedPowerOfTwo(value));
+    }
+
+    private static void assertInvalid(int value)
+    {
+        Object object = new ConstrainedPowerOfTwo(value);
+        assertFailsValidation(object, "unboxed", "is not a power of two", PowerOfTwo.class);
+        assertFailsValidation(object, "boxed", "is not a power of two", PowerOfTwo.class);
+    }
+
+    @SuppressWarnings("UnusedDeclaration")
+    public static class ConstrainedPowerOfTwo
+    {
+        private final int value;
+
+        public ConstrainedPowerOfTwo(int value)
+        {
+            this.value = value;
+        }
+
+        @PowerOfTwo
+        public int getUnboxed()
+        {
+            return value;
+        }
+
+        @PowerOfTwo
+        public Integer getBoxed()
+        {
+            return value;
+        }
+    }
+
+    @SuppressWarnings("UnusedDeclaration")
+    public static class NullPowerOfTwoAnnotation
+    {
+        @PowerOfTwo
+        public Integer getNull()
+        {
+            return null;
+        }
+    }
+}