gradle-master/subprojects/process-services/src/main/java/org/gradle/process/internal/health/memory/DefaultJvmMemoryInfo.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;

public class DefaultJvmMemoryInfo implements JvmMemoryInfo {
    private final long totalMemory; //this does not change

    public DefaultJvmMemoryInfo() {
        this.totalMemory = Runtime.getRuntime().maxMemory();
    }

    /**
     * Max memory that this process can commit in bytes. Always returns the same value because maximum memory is determined at jvm start.
     */
    long getMaxMemory() {
        return totalMemory;
    }

    /**
     * Currently committed memory of this process in bytes. May return different value depending on how the heap has expanded. The returned value is <= {@link #getMaxMemory()}
     */
    long getCommittedMemory() {
        //querying runtime for each invocation
        return Runtime.getRuntime().totalMemory();
    }

    @Override
    public JvmMemoryStatus getJvmSnapshot() {
        return new JvmMemoryStatusSnapshot(getMaxMemory(), getCommittedMemory());
    }
}
