gradle-master/subprojects/process-services/src/main/java/org/gradle/process/internal/health/memory/MBeanOsMemoryInfo.java
/*
 * Copyright 2016 the original author or 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.
 */

package org.gradle.process.internal.health.memory;

import org.gradle.internal.jvm.Jvm;

/**
 * Uses the JVM's own interpretation of total and free memory. Gives accurate values on Windows and Solaris.
 * On Linux or MacOs, the free memory metric doesn't include reclaimable file system caches and will thus always report that the system is almost out of memory.
 * Use {@link MemInfoOsMemoryInfo} and {@link NativeOsMemoryInfo} instead.
 */
public class MBeanOsMemoryInfo implements OsMemoryInfo {

    @Override
    public OsMemoryStatus getOsSnapshot() {
        String totalMemoryAttribute = Jvm.current().isIbmJvm() ? "TotalPhysicalMemory" : "TotalPhysicalMemorySize";
        long total = MBeanAttributeProvider.getMbeanAttribute("java.lang:type=OperatingSystem", totalMemoryAttribute, Long.class);
        long free = MBeanAttributeProvider.getMbeanAttribute("java.lang:type=OperatingSystem", "FreePhysicalMemorySize", Long.class);
        return new OsMemoryStatusSnapshot(total, free);
    }
}
