// Protocol Buffers - Google's data interchange format
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// https://developers.google.com/protocol-buffers/
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package com.google.protobuf;

import java.io.IOException;
import java.nio.ByteBuffer;

Provides a number of unsafe byte operations to be used by advanced applications with high performance requirements. These methods are referred to as "unsafe" due to the fact that they potentially expose the backing buffer of a ByteString to the application. 
DISCLAIMER: The methods in this class should only be called if it is guaranteed that the buffer backing the ByteString will never change! Mutation of a ByteString can lead to unexpected and undesirable consequences in your application, and will likely be difficult to debug. Proceed with caution! 
This can have a number of significant side affects that have spooky-action-at-a-distance-like
behavior. In particular, if the bytes value changes out from under a Protocol Buffer:

  
serialization may throw
  
serialization may succeed but the wrong bytes may be written out
  
messages are no longer threadsafe
  
hashCode may be incorrect
      

        
can result in a permanent memory leak when used as a key in a long-lived HashMap
        
the semantics of many programs may be violated if this is the case
      

Each of these issues will occur in parts of the code base that are entirely distinct from the
parts of the code base modifying the buffer. In fact, both parts of the code base may be correct
- it is the bridging with the unsafe operations that was in error!
/**
 * Provides a number of unsafe byte operations to be used by advanced applications with high
 * performance requirements. These methods are referred to as "unsafe" due to the fact that they
 * potentially expose the backing buffer of a {@link ByteString} to the application.
 *
 * <p><strong>DISCLAIMER:</strong> The methods in this class should only be called if it is
 * guaranteed that the buffer backing the {@link ByteString} will never change! Mutation of a {@link
 * ByteString} can lead to unexpected and undesirable consequences in your application, and will
 * likely be difficult to debug. Proceed with caution!
 *
 * <p>This can have a number of significant side affects that have spooky-action-at-a-distance-like
 * behavior. In particular, if the bytes value changes out from under a Protocol Buffer:
 *
 * <ul>
 *   <li>serialization may throw
 *   <li>serialization may succeed but the wrong bytes may be written out
 *   <li>messages are no longer threadsafe
 *   <li>hashCode may be incorrect
 *       <ul>
 *         <li>can result in a permanent memory leak when used as a key in a long-lived HashMap
 *         <li>the semantics of many programs may be violated if this is the case
 *       </ul>
 * </ul>
 *
 * Each of these issues will occur in parts of the code base that are entirely distinct from the
 * parts of the code base modifying the buffer. In fact, both parts of the code base may be correct
 * - it is the bridging with the unsafe operations that was in error!
 */
@ExperimentalApi
public final class UnsafeByteOperations {
  private UnsafeByteOperations() {}

  
An unsafe operation that returns a ByteString that is backed by the provided buffer. 
Params:
buffer – the buffer to be wrapped
Returns:
a ByteString backed by the provided buffer/**
   * An unsafe operation that returns a {@link ByteString} that is backed by the provided buffer.
   *
   * @param buffer the buffer to be wrapped
   * @return a {@link ByteString} backed by the provided buffer
   */
  public static ByteString unsafeWrap(byte[] buffer) {
    return ByteString.wrap(buffer);
  }

  
An unsafe operation that returns a ByteString that is backed by a subregion of the provided buffer. 
Params:
buffer – the buffer to be wrapped
offset – the offset of the wrapped region
length – the number of bytes of the wrapped region
Returns:
a ByteString backed by the provided buffer/**
   * An unsafe operation that returns a {@link ByteString} that is backed by a subregion of the
   * provided buffer.
   *
   * @param buffer the buffer to be wrapped
   * @param offset the offset of the wrapped region
   * @param length the number of bytes of the wrapped region
   * @return a {@link ByteString} backed by the provided buffer
   */
  public static ByteString unsafeWrap(byte[] buffer, int offset, int length) {
    return ByteString.wrap(buffer, offset, length);
  }

  
An unsafe operation that returns a ByteString that is backed by the provided buffer. 
Params:
buffer – the Java NIO buffer to be wrapped
Returns:
a ByteString backed by the provided buffer/**
   * An unsafe operation that returns a {@link ByteString} that is backed by the provided buffer.
   *
   * @param buffer the Java NIO buffer to be wrapped
   * @return a {@link ByteString} backed by the provided buffer
   */
  public static ByteString unsafeWrap(ByteBuffer buffer) {
    return ByteString.wrap(buffer);
  }

  
Writes the given ByteString to the provided ByteOutput. Calling this method may result in multiple operations on the target ByteOutput (i.e. for roped ByteStrings). 
This method exposes the internal backing buffer(s) of the ByteString to the ByteOutput in order to avoid additional copying overhead. It would be possible for a malicious ByteOutput to corrupt the ByteString. Use with caution! 
NOTE: The ByteOutput MUST NOT modify the provided buffers. Doing so
may result in corrupted data, which would be difficult to debug.
Params:
bytes – the ByteString to be written
output – the output to receive the bytes
Throws:
IOException – if an I/O error occurs/**
   * Writes the given {@link ByteString} to the provided {@link ByteOutput}. Calling this method may
   * result in multiple operations on the target {@link ByteOutput} (i.e. for roped {@link
   * ByteString}s).
   *
   * <p>This method exposes the internal backing buffer(s) of the {@link ByteString} to the {@link
   * ByteOutput} in order to avoid additional copying overhead. It would be possible for a malicious
   * {@link ByteOutput} to corrupt the {@link ByteString}. Use with caution!
   *
   * <p>NOTE: The {@link ByteOutput} <strong>MUST NOT</strong> modify the provided buffers. Doing so
   * may result in corrupted data, which would be difficult to debug.
   *
   * @param bytes the {@link ByteString} to be written
   * @param output the output to receive the bytes
   * @throws IOException if an I/O error occurs
   */
  public static void unsafeWriteTo(ByteString bytes, ByteOutput output) throws IOException {
    bytes.writeTo(output);
  }

}