# SMB3 Lease Feature - Detailed Design Document

## 1. Overview

SMB3 leases provide a client caching mechanism that replaces the traditional oplock mechanism. Leases enable better performance through client-side caching while maintaining cache coherency across multiple clients.

## 2. Protocol Specification Reference

- **MS-SMB2 Section 2.2.13**: SMB2 CREATE Request with Lease Context
- **MS-SMB2 Section 2.2.14**: SMB2 CREATE Response with Lease State

with HDFS. These workloads rely on HDFS atomic rename functionality to complete writing data to the datastore. Object storage operations are atomic by nature and they do not require/implement rename API. The default S3A committer emulates renames through copy and delete APIs. This interaction pattern causes significant loss of performance because of the write amplification. _Netflix_, for example, developed two new staging committers - the Directory staging committer and the Partitioned staging committer...

 *       ImmutableList#subList} may retain a reference to the entire data set, preventing it from
 *       being garbage collected. If some of the data is no longer reachable through other means,
 *       this constitutes a memory leak. Pass the view collection to the appropriate {@code copyOf}
 *       method to obtain a correctly-sized copy.

     */
    private void removeIdleConnections() {
        long now = System.currentTimeMillis();
        List<SmbTransportImpl> idle = new ArrayList<>();

        // Iterate through connections without synchronization - ConcurrentLinkedQueue is thread-safe
        for (SmbTransportImpl transport : connections) {
            try {
                // Check if connection has been idle too long

        }
        return t.getTreeNum();
    }

    /**
     *
     * Only call this method while holding a tree handle
     *
     * @return session that this file has been loaded through
     */
    @SuppressWarnings("resource")
    public SmbSessionImpl getSession() {
        final SmbTreeImpl t = getTreeInternal();
        if (t != null) {
            return t.getSession();
        }

                    return 0L;
                }
            });

    /**
     * Private constructor to prevent instantiation of this utility class.
     * This class is intended to be used only through its static methods.
     */
    protected FessFunctions() {
        // nothing
    }

    /**
     * Generates an HTML opening or closing tag with appropriate language attribute.
     *

   * initializer.
   */
  private static class LocalClassWithSeeminglyHiddenThisInStaticInitializer {
    static {
      class Local {
        @SuppressWarnings("unused") // through reflection
        Local(LocalClassWithSeeminglyHiddenThisInStaticInitializer outer) {}
      }
      Constructor<?> constructor = Local.class.getDeclaredConstructors()[0];
      int miscalculated = 0;

 * {@link TypeToken#resolveType} since it's simpler and more type safe. This class should only be
 * used when the type mapping isn't implied by the static type hierarchy, but provided through other
 * means such as an annotation or external configuration file.
 *
 * @author Ben Yu
 * @since 15.0
 */
public final class TypeResolver {

  private final TypeTable typeTable;

    E[] items = this.items;
    // if removing front item, just advance
    if (i == takeIndex) {
      items[takeIndex] = null;
      takeIndex = inc(takeIndex);
    } else {
      // slide over all others up through putIndex.
      for (; ; ) {
        int nexti = inc(i);
        if (nexti != putIndex) {
          items[i] = items[nexti];
          i = nexti;
        } else {
          items[i] = null;

   * Cache.asMap().get(Object)} and {@code Cache.asMap().put(K, V)}), but not by {@code
   * containsKey(Object)}, nor by operations on the collection-views of {@link Cache#asMap}}. So,
   * for example, iterating through {@code Cache.asMap().entrySet()} does not reset access time for
   * the entries you retrieve.
   *
   * <p>When {@code duration} is zero, this method hands off to {@link #maximumSize(long)