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/**
* Copyright (c) 2005-2006 Arch Rock Corporation
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
* - Neither the name of the Arch Rock Corporation nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* ARCHED ROCK OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE
*
* Copyright (c) 2002-2006 Intel Corporation
* All rights reserved.
*
* This file is distributed under the terms in the attached INTEL-LICENSE
* file. If you do not find these files, copies can be found by writing to
* Intel Research Berkeley, 2150 Shattuck Avenue, Suite 1300, Berkeley, CA,
* 94704. Attention: Intel License Inquiry.
*/
/**
* Read interface for the log storage abstraction described in
* TEP103.
*
* @author Jonathan Hui <jhui@archrock.com>
* @author David Gay
* @version $Revision: 1.5 $ $Date: 2008-06-04 03:00:29 $
*/
#include "Storage.h"
interface LogRead {
/**
* Initiate a read operation from the current position within a given log
* volume. On SUCCESS, the <code>readDone</code> event will signal
* completion of the operation.
*
* @param 'void* COUNT(len) buf' buffer to place read data.
* @param len number of bytes to read.
* @return
* <li>SUCCESS if the request was accepted,
* <li>EBUSY if a request is already being processed.
*/
command error_t read(void* buf, storage_len_t len);
/**
* Signals the completion of a read operation. The current read position is
* advanced by <code>len</code> bytes.
*
* @param addr starting address of read.
* @param 'void* COUNT(len) buf' buffer where read data was placed.
* @param len number of bytes read - this may be less than requested
* (even equal to 0) if the end of the log was reached
* @param error SUCCESS if read was possible, FAIL otherwise
*/
event void readDone(void* buf, storage_len_t len, error_t error);
/**
* Return a "cookie" representing the current read offset within the
* log. This cookie can be used in a subsequent seek operation to
* return to the same place in the log (if it hasn't been overwritten).
*
* @return Cookie representing current offset.
* <code>SEEK_BEGINNING</code> will be returned if:<ul>
* <li> a write in a circular log overwrote the previous read position
* <li> seek was passed a cookie representing a position before the
* current beginning of a circular log
* </ul>
* Note that <code>SEEK_BEGINNING</code> can also be returned at
* other times (just after erasing a log, etc).
*/
command storage_cookie_t currentOffset();
/**
* Set the read position in the log, using a cookie returned by the
* <code>currentOffset</code> commands of <code>LogRead</code> or
* <code>LogWrite</code>, or the special value <code>SEEK_BEGINNING</code>.
*
* If the specified position has been overwritten, the read position
* will be set to the beginning of the log.
*
* @return
* <li>SUCCESS if the request was accepted,
* <li>EBUSY if a request is already being processed.
*/
command error_t seek(storage_cookie_t offset);
/**
* Report success of seek operation. If <code>SUCCESS</code> is returned,
* the read position has been changed as requested. If other values are
* returned, the read position is undefined.
*
* @param error SUCCESS if the seek was succesful, EINVAL if the cookie
* was invalid and FAIL for other errors.
*/
event void seekDone(error_t error);
/**
* Report approximate log capacity in bytes. Note that use of
* <code>sync</code>, failures and general overhead may reduce the number
* of bytes available to the log.
*
* @return Volume size.
*/
command storage_len_t getSize();
}
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