mojo/public/java/bindings/src/org/chromium/mojo/bindings/MessageHeader.java - chromium/src - Git at Google

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 package org.chromium.mojo.bindings;

 import java.nio.ByteBuffer;

 /**
  * Header information for a message.
  */
 public class MessageHeader {

     private static final int SIMPLE_MESSAGE_SIZE = 24;
     private static final int SIMPLE_MESSAGE_VERSION = 0;
     private static final DataHeader SIMPLE_MESSAGE_STRUCT_INFO =
             new DataHeader(SIMPLE_MESSAGE_SIZE, SIMPLE_MESSAGE_VERSION);

     private static final int MESSAGE_WITH_REQUEST_ID_SIZE = 32;
     private static final int MESSAGE_WITH_REQUEST_ID_VERSION = 1;
     private static final DataHeader MESSAGE_WITH_REQUEST_ID_STRUCT_INFO =
             new DataHeader(MESSAGE_WITH_REQUEST_ID_SIZE, MESSAGE_WITH_REQUEST_ID_VERSION);

     private static final int INTERFACE_ID_OFFSET = 8;
     private static final int TYPE_OFFSET = 12;
     private static final int FLAGS_OFFSET = 16;
     private static final int REQUEST_ID_OFFSET = 24;

     /**
      * Flag for a header of a simple message.
      */
     public static final int NO_FLAG = 0;

     /**
      * Flag for a header of a message that expected a response.
      */
     public static final int MESSAGE_EXPECTS_RESPONSE_FLAG = 1 << 0;

     /**
      * Flag for a header of a message that is a response.
      */
     public static final int MESSAGE_IS_RESPONSE_FLAG = 1 << 1;

     private final DataHeader mDataHeader;
     private final int mType;
     private final int mFlags;
     private long mRequestId;

     /**
      * Constructor for the header of a message which does not have a response.
      */
     public MessageHeader(int type) {
         mDataHeader = SIMPLE_MESSAGE_STRUCT_INFO;
         mType = type;
         mFlags = 0;
         mRequestId = 0;
     }

     /**
      * Constructor for the header of a message which have a response or being itself a response.
      */
     public MessageHeader(int type, int flags, long requestId) {
         assert mustHaveRequestId(flags);
         mDataHeader = MESSAGE_WITH_REQUEST_ID_STRUCT_INFO;
         mType = type;
         mFlags = flags;
         mRequestId = requestId;
     }

     /**
      * Constructor, parsing the header from a message. Should only be used by {@link Message}
      * itself.
      */
     MessageHeader(Message message) {
         Decoder decoder = new Decoder(message);
         mDataHeader = decoder.readDataHeader();
         validateDataHeader(mDataHeader);

         // Currently associated interfaces are not supported.
         int interfaceId = decoder.readInt(INTERFACE_ID_OFFSET);
         if (interfaceId != 0) {
           throw new DeserializationException("Non-zero interface ID, expecting zero since "
                   + "associated interfaces are not yet supported.");
         }

         mType = decoder.readInt(TYPE_OFFSET);
         mFlags = decoder.readInt(FLAGS_OFFSET);
         if (mustHaveRequestId(mFlags)) {
             if (mDataHeader.size < MESSAGE_WITH_REQUEST_ID_SIZE) {
                 throw new DeserializationException("Incorrect message size, expecting at least "
                         + MESSAGE_WITH_REQUEST_ID_SIZE
                         + " for a message with a request identifier, but got: " + mDataHeader.size);

             }
             mRequestId = decoder.readLong(REQUEST_ID_OFFSET);
         } else {
             mRequestId = 0;
         }
     }

     /**
      * Returns the size in bytes of the serialization of the header.
      */
     public int getSize() {
         return mDataHeader.size;
     }

     /**
      * Returns the type of the message.
      */
     public int getType() {
         return mType;
     }

     /**
      * Returns the flags associated to the message.
      */
     public int getFlags() {
         return mFlags;
     }

     /**
      * Returns if the message has the given flag.
      */
     public boolean hasFlag(int flag) {
         return (mFlags & flag) == flag;
     }

     /**
      * Returns if the message has a request id.
      */
     public boolean hasRequestId() {
         return mustHaveRequestId(mFlags);
     }

     /**
      * Return the request id for the message. Must only be called if the message has a request id.
      */
     public long getRequestId() {
         assert hasRequestId();
         return mRequestId;
     }

     /**
      * Encode the header.
      */
     public void encode(Encoder encoder) {
         encoder.encode(mDataHeader);
         // Set the interface ID field to 0.
         encoder.encode(0, INTERFACE_ID_OFFSET);
         encoder.encode(getType(), TYPE_OFFSET);
         encoder.encode(getFlags(), FLAGS_OFFSET);
         if (hasRequestId()) {
             encoder.encode(getRequestId(), REQUEST_ID_OFFSET);
         }
     }

     /**
      * Returns true if the header has the expected flags. Only considers flags this class knows
      * about in order to allow this class to work with future version of the header format.
      */
     public boolean validateHeader(int expectedFlags) {
         int knownFlags = getFlags() & (MESSAGE_EXPECTS_RESPONSE_FLAG | MESSAGE_IS_RESPONSE_FLAG);
         return knownFlags == expectedFlags;
     }

     /**
      * Returns true if the header has the expected type and flags. Only consider flags this class
      * knows about in order to allow this class to work with future version of the header format.
      */
     public boolean validateHeader(int expectedType, int expectedFlags) {
         return getType() == expectedType && validateHeader(expectedFlags);
     }

     /**
      * @see Object#hashCode()
      */
     @Override
     public int hashCode() {
         final int prime = 31;
         int result = 1;
         result = prime * result + ((mDataHeader == null) ? 0 : mDataHeader.hashCode());
         result = prime * result + mFlags;
         result = prime * result + (int) (mRequestId ^ (mRequestId >>> 32));
         result = prime * result + mType;
         return result;
     }

     /**
      * @see Object#equals(Object)
      */
     @Override
     public boolean equals(Object object) {
         if (object == this) return true;
         if (object == null) return false;
         if (getClass() != object.getClass()) return false;

         MessageHeader other = (MessageHeader) object;
         return (BindingsHelper.equals(mDataHeader, other.mDataHeader)
                 && mFlags == other.mFlags
                 && mRequestId == other.mRequestId
                 && mType == other.mType);
     }

     /**
      * Set the request id on the message contained in the given buffer.
      */
     void setRequestId(ByteBuffer buffer, long requestId) {
         assert mustHaveRequestId(buffer.getInt(FLAGS_OFFSET));
         buffer.putLong(REQUEST_ID_OFFSET, requestId);
         mRequestId = requestId;
     }

     /**
      * Returns whether a message with the given flags must have a request Id.
      */
     private static boolean mustHaveRequestId(int flags) {
         return (flags & (MESSAGE_EXPECTS_RESPONSE_FLAG | MESSAGE_IS_RESPONSE_FLAG)) != 0;
     }

     /**
      * Validate that the given {@link DataHeader} can be the data header of a message header.
      */
     private static void validateDataHeader(DataHeader dataHeader) {
         if (dataHeader.elementsOrVersion < SIMPLE_MESSAGE_VERSION) {
             throw new DeserializationException("Incorrect number of fields, expecting at least "
                     + SIMPLE_MESSAGE_VERSION + ", but got: " + dataHeader.elementsOrVersion);
         }
         if (dataHeader.size < SIMPLE_MESSAGE_SIZE) {
             throw new DeserializationException(
                     "Incorrect message size, expecting at least " + SIMPLE_MESSAGE_SIZE
                     + ", but got: " + dataHeader.size);
         }
         if (dataHeader.elementsOrVersion == SIMPLE_MESSAGE_VERSION
                 && dataHeader.size != SIMPLE_MESSAGE_SIZE) {
             throw new DeserializationException("Incorrect message size for a message with "
                     + SIMPLE_MESSAGE_VERSION + " fields, expecting " + SIMPLE_MESSAGE_SIZE
                     + ", but got: " + dataHeader.size);
         }
         if (dataHeader.elementsOrVersion == MESSAGE_WITH_REQUEST_ID_VERSION
                 && dataHeader.size != MESSAGE_WITH_REQUEST_ID_SIZE) {
             throw new DeserializationException("Incorrect message size for a message with "
                     + MESSAGE_WITH_REQUEST_ID_VERSION + " fields, expecting "
                     + MESSAGE_WITH_REQUEST_ID_SIZE + ", but got: " + dataHeader.size);
         }
     }

 }
	// Copyright 2014 The Chromium Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	package org.chromium.mojo.bindings;

	import java.nio.ByteBuffer;

	/**
	* Header information for a message.
	*/
	public class MessageHeader {

	private static final int SIMPLE_MESSAGE_SIZE = 24;
	private static final int SIMPLE_MESSAGE_VERSION = 0;
	private static final DataHeader SIMPLE_MESSAGE_STRUCT_INFO =
	new DataHeader(SIMPLE_MESSAGE_SIZE, SIMPLE_MESSAGE_VERSION);

	private static final int MESSAGE_WITH_REQUEST_ID_SIZE = 32;
	private static final int MESSAGE_WITH_REQUEST_ID_VERSION = 1;
	private static final DataHeader MESSAGE_WITH_REQUEST_ID_STRUCT_INFO =
	new DataHeader(MESSAGE_WITH_REQUEST_ID_SIZE, MESSAGE_WITH_REQUEST_ID_VERSION);

	private static final int INTERFACE_ID_OFFSET = 8;
	private static final int TYPE_OFFSET = 12;
	private static final int FLAGS_OFFSET = 16;
	private static final int REQUEST_ID_OFFSET = 24;

	/**
	* Flag for a header of a simple message.
	*/
	public static final int NO_FLAG = 0;

	/**
	* Flag for a header of a message that expected a response.
	*/
	public static final int MESSAGE_EXPECTS_RESPONSE_FLAG = 1 << 0;

	/**
	* Flag for a header of a message that is a response.
	*/
	public static final int MESSAGE_IS_RESPONSE_FLAG = 1 << 1;

	private final DataHeader mDataHeader;
	private final int mType;
	private final int mFlags;
	private long mRequestId;

	/**
	* Constructor for the header of a message which does not have a response.
	*/
	public MessageHeader(int type) {
	mDataHeader = SIMPLE_MESSAGE_STRUCT_INFO;
	mType = type;
	mFlags = 0;
	mRequestId = 0;
	}

	/**
	* Constructor for the header of a message which have a response or being itself a response.
	*/
	public MessageHeader(int type, int flags, long requestId) {
	assert mustHaveRequestId(flags);
	mDataHeader = MESSAGE_WITH_REQUEST_ID_STRUCT_INFO;
	mType = type;
	mFlags = flags;
	mRequestId = requestId;
	}

	/**
	* Constructor, parsing the header from a message. Should only be used by {@link Message}
	* itself.
	*/
	MessageHeader(Message message) {
	Decoder decoder = new Decoder(message);
	mDataHeader = decoder.readDataHeader();
	validateDataHeader(mDataHeader);

	// Currently associated interfaces are not supported.
	int interfaceId = decoder.readInt(INTERFACE_ID_OFFSET);
	if (interfaceId != 0) {
	throw new DeserializationException("Non-zero interface ID, expecting zero since "
	+ "associated interfaces are not yet supported.");
	}

	mType = decoder.readInt(TYPE_OFFSET);
	mFlags = decoder.readInt(FLAGS_OFFSET);
	if (mustHaveRequestId(mFlags)) {
	if (mDataHeader.size < MESSAGE_WITH_REQUEST_ID_SIZE) {
	throw new DeserializationException("Incorrect message size, expecting at least "
	+ MESSAGE_WITH_REQUEST_ID_SIZE
	+ " for a message with a request identifier, but got: " + mDataHeader.size);

	}
	mRequestId = decoder.readLong(REQUEST_ID_OFFSET);
	} else {
	mRequestId = 0;
	}
	}

	/**
	* Returns the size in bytes of the serialization of the header.
	*/
	public int getSize() {
	return mDataHeader.size;
	}

	/**
	* Returns the type of the message.
	*/
	public int getType() {
	return mType;
	}

	/**
	* Returns the flags associated to the message.
	*/
	public int getFlags() {
	return mFlags;
	}

	/**
	* Returns if the message has the given flag.
	*/
	public boolean hasFlag(int flag) {
	return (mFlags & flag) == flag;
	}

	/**
	* Returns if the message has a request id.
	*/
	public boolean hasRequestId() {
	return mustHaveRequestId(mFlags);
	}

	/**
	* Return the request id for the message. Must only be called if the message has a request id.
	*/
	public long getRequestId() {
	assert hasRequestId();
	return mRequestId;
	}

	/**
	* Encode the header.
	*/
	public void encode(Encoder encoder) {
	encoder.encode(mDataHeader);
	// Set the interface ID field to 0.
	encoder.encode(0, INTERFACE_ID_OFFSET);
	encoder.encode(getType(), TYPE_OFFSET);
	encoder.encode(getFlags(), FLAGS_OFFSET);
	if (hasRequestId()) {
	encoder.encode(getRequestId(), REQUEST_ID_OFFSET);
	}
	}

	/**
	* Returns true if the header has the expected flags. Only considers flags this class knows
	* about in order to allow this class to work with future version of the header format.
	*/
	public boolean validateHeader(int expectedFlags) {
	int knownFlags = getFlags() & (MESSAGE_EXPECTS_RESPONSE_FLAG \| MESSAGE_IS_RESPONSE_FLAG);
	return knownFlags == expectedFlags;
	}

	/**
	* Returns true if the header has the expected type and flags. Only consider flags this class
	* knows about in order to allow this class to work with future version of the header format.
	*/
	public boolean validateHeader(int expectedType, int expectedFlags) {
	return getType() == expectedType && validateHeader(expectedFlags);
	}

	/**
	* @see Object#hashCode()
	*/
	@Override
	public int hashCode() {
	final int prime = 31;
	int result = 1;
	result = prime * result + ((mDataHeader == null) ? 0 : mDataHeader.hashCode());
	result = prime * result + mFlags;
	result = prime * result + (int) (mRequestId ^ (mRequestId >>> 32));
	result = prime * result + mType;
	return result;
	}

	/**
	* @see Object#equals(Object)
	*/
	@Override
	public boolean equals(Object object) {
	if (object == this) return true;
	if (object == null) return false;
	if (getClass() != object.getClass()) return false;

	MessageHeader other = (MessageHeader) object;
	return (BindingsHelper.equals(mDataHeader, other.mDataHeader)
	&& mFlags == other.mFlags
	&& mRequestId == other.mRequestId
	&& mType == other.mType);
	}

	/**
	* Set the request id on the message contained in the given buffer.
	*/
	void setRequestId(ByteBuffer buffer, long requestId) {
	assert mustHaveRequestId(buffer.getInt(FLAGS_OFFSET));
	buffer.putLong(REQUEST_ID_OFFSET, requestId);
	mRequestId = requestId;
	}

	/**
	* Returns whether a message with the given flags must have a request Id.
	*/
	private static boolean mustHaveRequestId(int flags) {
	return (flags & (MESSAGE_EXPECTS_RESPONSE_FLAG \| MESSAGE_IS_RESPONSE_FLAG)) != 0;
	}

	/**
	* Validate that the given {@link DataHeader} can be the data header of a message header.
	*/
	private static void validateDataHeader(DataHeader dataHeader) {
	if (dataHeader.elementsOrVersion < SIMPLE_MESSAGE_VERSION) {
	throw new DeserializationException("Incorrect number of fields, expecting at least "
	+ SIMPLE_MESSAGE_VERSION + ", but got: " + dataHeader.elementsOrVersion);
	}
	if (dataHeader.size < SIMPLE_MESSAGE_SIZE) {
	throw new DeserializationException(
	"Incorrect message size, expecting at least " + SIMPLE_MESSAGE_SIZE
	+ ", but got: " + dataHeader.size);
	}
	if (dataHeader.elementsOrVersion == SIMPLE_MESSAGE_VERSION
	&& dataHeader.size != SIMPLE_MESSAGE_SIZE) {
	throw new DeserializationException("Incorrect message size for a message with "
	+ SIMPLE_MESSAGE_VERSION + " fields, expecting " + SIMPLE_MESSAGE_SIZE
	+ ", but got: " + dataHeader.size);
	}
	if (dataHeader.elementsOrVersion == MESSAGE_WITH_REQUEST_ID_VERSION
	&& dataHeader.size != MESSAGE_WITH_REQUEST_ID_SIZE) {
	throw new DeserializationException("Incorrect message size for a message with "
	+ MESSAGE_WITH_REQUEST_ID_VERSION + " fields, expecting "
	+ MESSAGE_WITH_REQUEST_ID_SIZE + ", but got: " + dataHeader.size);
	}
	}

	}