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There is a newer version: 3.0.1

/*
 * Copyright (c) 2023 Snowflake Computing Inc. All rights reserved.
 */

package net.snowflake.ingest.streaming.internal;

import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/** Reads memory information from JVM runtime */
public class MemoryInfoProviderFromRuntime implements MemoryInfoProvider {
  private final long maxMemory;
  private volatile long totalFreeMemory;
  private final ScheduledExecutorService executorService;
  private static final long FREE_MEMORY_UPDATE_INTERVAL_MS = 100;
  private static final MemoryInfoProviderFromRuntime INSTANCE =
      new MemoryInfoProviderFromRuntime(FREE_MEMORY_UPDATE_INTERVAL_MS);

  private MemoryInfoProviderFromRuntime(long freeMemoryUpdateIntervalMs) {
    maxMemory = Runtime.getRuntime().maxMemory();
    totalFreeMemory =
        Runtime.getRuntime().freeMemory() + (maxMemory - Runtime.getRuntime().totalMemory());
    executorService =
        new ScheduledThreadPoolExecutor(
            1,
            r -> {
              Thread th = new Thread(r, "MemoryInfoProviderFromRuntime");
              th.setDaemon(true);
              return th;
            });
    executorService.scheduleAtFixedRate(
        this::updateFreeMemory, 0, freeMemoryUpdateIntervalMs, TimeUnit.MILLISECONDS);
  }

  private void updateFreeMemory() {
    totalFreeMemory =
        Runtime.getRuntime().freeMemory() + (maxMemory - Runtime.getRuntime().totalMemory());
  }

  public static MemoryInfoProviderFromRuntime getInstance() {
    return INSTANCE;
  }

  @Override
  public long getMaxMemory() {
    return maxMemory;
  }

  @Override
  public long getFreeMemory() {
    return totalFreeMemory;
  }
}