示例#1
0
        /// <summary>
        /// insert this segment into cache, kick out other if needed
        /// </summary>
        /// <param name="seg"></param>
        /// <precondition>seg is a new page brought in memory</precondition>
        /// <postcondition>seg is insert into the cache, and the front of the LRU list, kick out one page if needed.</postcondition>
        internal void _put_in_cache(Segment seg)
        {
            //if the cache is full, kick least recently used one out
            if (m_cache.Count > m_cacheLimit)
            {
                //pick least recently used one
                Segment victim = m_LRU.Prev;
                Debug.Assert(victim != m_LRU);
                if (victim.Dirty)
                {
                    _write_back(victim);
                }
                victim.BreakLinks();
                bool t = m_cache.Delete(victim.SegmentID);                //removed this one out of the cache
                Debug.Assert(t);
            }

            if (m_cache.Insert(seg) == false)
            {
                throw new OOD.Exception.ProgramLogicError(
                          this,
                          "Trying to insert an existing key into CacheHashtable");
            }
            seg.BuildLinks(m_LRU, m_LRU.Next);             //move it the front of the LRU list
        }
示例#2
0
        /// <summary>
        /// insert this segment into cache, kick out other if needed
        /// </summary>
        /// <param name="seg"></param>
        /// <precondition>seg is a new page brought in memory</precondition>
        /// <postcondition>seg is insert into the cache, and the front of the LRU list, kick out one page if needed.</postcondition>
        internal void _put_in_cache(Segment seg)
        {
            //if the cache is full, kick least recently used one out
            if (m_cache.Count > m_cacheLimit)
            {
                //pick least recently used one
                Segment victim = m_LRU.Prev;
                Debug.Assert(victim != m_LRU);
                if (victim.Dirty)
                {
                    //write it out to the disk
                    byte[] content = victim.Serialize();
                    Debug.Assert(content.Length <= m_pageSize);
                    m_diskFile.SynWrite(content, 0, victim.SegmentID * m_pageSize, content.Length);
                }
                victim.BreakLinks();
                bool t = m_cache.Delete(victim.SegmentID);                //removed this one out of the cache
                Debug.Assert(t);
            }

            if (m_cache.Insert(seg) == false)
            {
                throw new OOD.Exception.ProgramLogicError(
                          this,
                          "Trying to insert a existing key into CacheHashtable.");
            }
            seg.BuildLinks(m_LRU, m_LRU.Next);             //move it the front of the LRU list
        }
示例#3
0
        public override Segment GetSegment(uint segId, Segment segFactory, object helper)
        {
            Debug.Assert(segId >= (m_bitmap.Data.Length >> m_pageBits));
            Debug.Assert(m_bitmap.PageFree(segId) == false);

            if (m_cache.Exists(segId))
            {
                //requested page is in the cache
                Segment seg = m_cache.Retrive(segId);
                //update recently used page list, move this one to the front of the list, most recently used.
                seg.BreakLinks();
                seg.BuildLinks(m_LRU, m_LRU.Next);

                return(seg);
            }
            else
            {
                //the requested page is not in the cache, read it from disk
                byte[]  content = m_diskFile.SynRead(segId * m_pageSize, m_pageSize);
                Segment seg     = segFactory.Deserialize(segId, helper, content);

                _put_in_cache(seg);

                return(seg);
            }
        }
示例#4
0
        public override Segment GetSegment(uint segId, Segment segFactory, object helper)
        {
            Segment result = null;

            //check if this segment is already in cache
            if (m_cache.Exists(segId))
            {
                result = m_cache.Retrive(segId);

                //update the least recently used list
                result.BreakLinks();
                result.BuildLinks(m_LRU, m_LRU.Next);

                return(result);
            }
            else
            {
                //if not, read that from disk
                uint offset = 0;
                int  length = 0;
                if (m_segTree.GetAddr(segId, ref offset, ref length))
                {
                    // put this segment into cache
                    byte[] content = m_diskFile.SynRead(offset, length);
                    result = segFactory.Deserialize(segId, helper, content);

                    _put_in_cache(result);
                }
                else
                {
                    throw new OOD.Exception.ProgramLogicError(
                              this,
                              "Trying to access a non-existing segment.");
                }
                return(result);
            }
        }
示例#5
0
		/// <summary>
		/// insert this segment into cache, kick out other if needed
		/// </summary>
		/// <param name="seg"></param>
		/// <precondition>seg is a new page brought in memory</precondition>
		/// <postcondition>seg is insert into the cache, and the front of the LRU list, kick out one page if needed.</postcondition>
		internal void _put_in_cache(Segment seg)
		{
			//if the cache is full, kick least recently used one out
			if (m_cache.Count > m_cacheLimit)
			{
				//pick least recently used one
				Segment victim = m_LRU.Prev;
				Debug.Assert(victim != m_LRU);
				if (victim.Dirty)
				{

					_write_back(victim);
				}
				victim.BreakLinks();
				bool t = m_cache.Delete(victim.SegmentID);//removed this one out of the cache
				Debug.Assert(t);
			}

			if (m_cache.Insert(seg) == false)
				throw new OOD.Exception.ProgramLogicError(
					this,
					"Trying to insert an existing key into CacheHashtable");
			seg.BuildLinks(m_LRU, m_LRU.Next); //move it the front of the LRU list
		}
示例#6
0
		/// <summary>
		/// insert this segment into cache, kick out other if needed
		/// </summary>
		/// <param name="seg"></param>
		/// <precondition>seg is a new page brought in memory</precondition>
		/// <postcondition>seg is insert into the cache, and the front of the LRU list, kick out one page if needed.</postcondition>
		internal void _put_in_cache(Segment seg)
		{
			//if the cache is full, kick least recently used one out
			if (m_cache.Count > m_cacheLimit)
			{
				//pick least recently used one
				Segment victim = m_LRU.Prev;
				Debug.Assert(victim != m_LRU);
				if (victim.Dirty)
				{
					//write it out to the disk
					byte[] content = victim.Serialize();
					Debug.Assert(content.Length <= m_pageSize);
					m_diskFile.SynWrite(content, 0, victim.SegmentID*m_pageSize, content.Length);
				}
				victim.BreakLinks();
				bool t = m_cache.Delete(victim.SegmentID);//removed this one out of the cache
				Debug.Assert(t);
			}

			if (m_cache.Insert(seg) == false)
				throw new OOD.Exception.ProgramLogicError(
					this,
					"Trying to insert a existing key into CacheHashtable.");
			seg.BuildLinks(m_LRU, m_LRU.Next); //move it the front of the LRU list
		}