# RDMA (SMB Direct) Feature - Detailed Design Document

## 1. Overview

SMB Direct enables high-performance data transfer using Remote Direct Memory Access (RDMA) technology. This provides ultra-low latency and high bandwidth data transfer by bypassing the traditional TCP/IP stack and allowing direct memory-to-memory transfers between client and server.

## 2. Protocol Specification Reference

- **MS-SMBD**: SMB2 Remote Direct Memory Access (RDMA) Transport Protocol

The response answers the request with a code (like 200 for success or 404 for not found), headers, and its own optional body.

## Rewriting Requests

When you provide OkHttp with an HTTP request, you’re describing the request at a high-level: _“fetch me this URL with these headers.”_ For correctness and efficiency, OkHttp rewrites your request before transmitting it.

        // Adaptive strategy based on message type and size

        if (isLargeTransfer(message)) {
            // For large transfers, prefer high-bandwidth channels
            ChannelInfo maxBandwidthChannel = null;
            int maxBandwidth = 0;
            for (ChannelInfo channel : channels) {

  @Override
  Hasher putChar(char c);

  /**
   * Equivalent to processing each {@code char} value in the {@code CharSequence}, in order. In
   * other words, no character encoding is performed; the low byte and high byte of each {@code
   * char} are hashed directly (in that order). The input must not be updated while this method is
   * in progress.
   *

            }
        }

        // If we've had many errors, consider fallback
        double errorRate = statistics.getErrorRate();
        if (errorRate > 0.1) { // More than 10% error rate
            log.warn("High RDMA error rate ({:.1f}%), TCP fallback recommended", errorRate * 100);
            return true;
        }

        return false;
    }

    /**

                    handleChannelFailure(channel, e);
                }
            }
            
            // Check error rate
            if (channel.getErrorRate() > 0.1) {
                log.warn("High error rate on channel {}: {}", 
                    channel.getChannelId(), channel.getErrorRate());
                // Consider removing channel
            }
        }
    }
    

        if ((this.server.scapabilities & SmbConstants.CAP_EXTENDED_SECURITY) == SmbConstants.CAP_EXTENDED_SECURITY) {
            this.capabilities |= SmbConstants.CAP_EXTENDED_SECURITY; // & doesn't copy high bit
        }

        if (ctx.getConfig().isUseUnicode() || ctx.getConfig().isForceUnicode()) {
            this.capabilities |= SmbConstants.CAP_UNICODE;
        }

    CompactLinkedHashSet<E> set = createWithExpectedSize(elements.length);
    Collections.addAll(set, elements);
    return set;
  }

  /**
   * Creates a {@code CompactLinkedHashSet} instance, with a high enough "initial capacity" that it
   * <i>should</i> hold {@code expectedSize} elements without rebuilding internal data structures.
   *
   * @param expectedSize the number of elements you expect to add to the returned set

        a full-time Guava team member. [Feedback](https://stackoverflow.com/a/4543114) from our
        users indicates that they really appreciate Guava's high power-to-weight ratio. It's
        important to us to keep Guava as easy to use and understand as we can. That means boiling
        features down to compact but powerful abstractions, and controlling feature bloat carefully.

/**
 * {@code Escaper} instances suitable for strings to be included in XML attribute values and
 * elements' text contents. When possible, avoid manual escaping by using templating systems and
 * high-level APIs that provide autoescaping. For example, consider <a
 * href="http://www.xom.nu/">XOM</a>.
 *
 * <p><b>Note:</b> Currently the escapers provided by this class do not escape any characters