/// <summary>
/// Retrieve the resource at the specified page and segment offset
/// </summary>
/// <param name="pageId">The ID of the page that holds the resource to be retrieved</param>
/// <param name="segment">The index of the segment within the page that holds the start of the resource</param>
/// <param name="profiler"></param>
/// <returns>The resource</returns>
public string GetResource(ulong pageId, byte segment, BrightstarProfiler profiler)
{
using (profiler.Step("ResourceTable.GetResource"))
{
var currentPage = _pageStore.Retrieve(pageId, profiler);
int resourceLength = BitConverter.ToInt32(currentPage, segment * _segmentSize);
int totalLength = resourceLength + 4;
int segmentsToLoad = totalLength / _segmentSize;
if (totalLength % _segmentSize > 0)
{
segmentsToLoad++;
}
var buffer = new byte[segmentsToLoad * _segmentSize];
byte segmentIndex = segment;
for (int i = 0; i < segmentsToLoad; i++)
{
if (segmentIndex == _pointerSegment)
{
ulong nextPageId = BitConverter.ToUInt64(currentPage, _pageStore.PageSize - 8);
currentPage = _pageStore.Retrieve(nextPageId, profiler);
segmentIndex = 0;
}
Array.Copy(currentPage, segmentIndex * _segmentSize, buffer, i * _segmentSize, _segmentSize);
segmentIndex++;
}
return(Encoding.UTF8.GetString(buffer, 4, resourceLength));
}
}
public INode GetNode(ulong nodeId, BrightstarProfiler profiler)
{
using (profiler.Step("BPlusTree.GetNode"))
{
INode ret;
if (_modifiedNodes.TryGetValue(nodeId, out ret))
{
profiler.Incr("NodeCache Hit");
return(ret);
}
if (_nodeCache.TryGetValue(nodeId, out ret))
{
profiler.Incr("NodeCache Hit");
return(ret);
}
profiler.Incr("NodeCache Miss");
using (profiler.Step("Load Node"))
{
var nodePage = _pageStore.Retrieve(nodeId, profiler);
var header = BitConverter.ToInt32(nodePage, 0);
if (header < 0)
{
ret = new InternalNode(nodeId, nodePage, ~header, _config);
}
else
{
ret = new LeafNode(nodeId, nodePage, header, _config);
}
_nodeCache.Add(ret);
return(ret);
}
}
}
public INode GetNode(ulong nodeId, BrightstarProfiler profiler)
{
using (profiler.Step("BPlusTree.GetNode"))
{
INode ret;
if (_nodeCache.TryGetValue(nodeId, out ret))
{
profiler.Incr("NodeCache Hit");
return(ret);
}
profiler.Incr("NodeCache Miss");
using (profiler.Step("Load Node"))
{
var nodePage = _pageStore.Retrieve(nodeId, profiler);
var header = BitConverter.ToInt32(nodePage.Data, 0);
if (header < 0)
{
ret = MakeInternalNode(nodePage, ~header);
#if DEBUG_BTREE
_config.BTreeDebug("{0}: Loaded INTERNAL node from page {1}. {2}", _config.DebugId, nodePage.Id, ret.ToString());
#endif
}
else
{
ret = MakeLeafNode(nodePage, header);
#if DEBUG_BTREE
_config.BTreeDebug("{0}: Loaded LEAF node from page {1}. {2}", _config.DebugId, nodePage.Id, ret.ToString());
#endif
}
_nodeCache.Add(ret);
return(ret);
}
}
}
public PrefixManager(IPageStore pageStore, ulong startPageId, BrightstarProfiler profiler)
{
_pageStore = pageStore;
var startPage = _pageStore.Retrieve(startPageId, profiler);
Load(startPage, profiler);
}
/// <summary>
/// Performs the actual load of prefixes from a page.
/// </summary>
/// <param name="page"></param>
/// <param name="profiler"></param>
/// <remarks>Calls to this method should be made inside a critical section of code protected with a mutex or reader/writer lock</remarks>
private void InterlockedLoad(IPage page, BrightstarProfiler profiler)
{
using (profiler.Step("PrefixManager.InterlockedLoad"))
{
int offset = 0;
while (offset < _pageStore.PageSize)
{
ushort prefixLength = BitConverter.ToUInt16(page.Data, offset);
offset += 2;
if (prefixLength == ushort.MaxValue)
{
ulong nextPageId = BitConverter.ToUInt64(page.Data, offset);
if (nextPageId == 0)
{
// End of data
return;
}
page = _pageStore.Retrieve(nextPageId, profiler);
offset = 0;
}
else
{
var prefix = Encoding.UTF8.GetString(page.Data, offset, prefixLength);
offset += prefixLength;
var uriLen = BitConverter.ToUInt16(page.Data, offset);
offset += 2;
var uri = Encoding.UTF8.GetString(page.Data, offset, uriLen);
offset += uriLen;
_prefixMappings[uri] = prefix;
_shortValueMappings[prefix] = uri;
}
}
}
}
public Store(string storeLocation, IPageStore dataPageStore, IResourceTable resourceTable, ulong storePageId, BrightstarProfiler profiler)
{
using (profiler.Step("Load Store"))
{
DirectoryPath = storeLocation;
_pageStore = dataPageStore;
_resourceTable = resourceTable;
var storePage = _pageStore.Retrieve(storePageId, profiler);
Load(storePage, profiler);
}
}
public Store(string storeLocation, IPageStore dataPageStore, IResourceTable resourceTable, ulong storePageId, BrightstarProfiler profiler)
{
using (profiler.Step("Load Store"))
{
DirectoryPath = storeLocation;
_pageStore = dataPageStore;
_resourceTable = resourceTable;
var storePage = _pageStore.Retrieve(storePageId, profiler);
Load(storePage, profiler);
}
}
void Read(ulong rootPageId, BrightstarProfiler profiler)
{
IPage currentPage = _pageStore.Retrieve(rootPageId, profiler);
int offset = 0;
int entryIndex = 0;
while (true)
{
var marker = currentPage.Data[offset++];
if (marker == 0xff)
{
ulong nextPageId = BitConverter.ToUInt64(currentPage.Data, _pageStore.PageSize - 8);
if (nextPageId == 0)
{
return;
}
currentPage = _pageStore.Retrieve(nextPageId, profiler);
offset = 0;
}
else if (marker == 2)
{
_allEntries.Add(new GraphIndexEntry(entryIndex++, null, true));
}
else
{
int uriByteLength = BitConverter.ToInt32(currentPage.Data, offset);
offset += 4;
var uri = Encoding.UTF8.GetString(currentPage.Data, offset, uriByteLength);
offset += uriByteLength;
var newEntry = new GraphIndexEntry(entryIndex++, uri, marker == 1);
_allEntries.Add(newEntry);
if (!newEntry.IsDeleted)
{
_graphUriIndex[newEntry.Uri] = newEntry.Id;
}
}
}
}
public PrefixManager(IPageStore pageStore, ulong startPageId, BrightstarProfiler profiler)
{
_pageStore = pageStore;
var startPage = _pageStore.Retrieve(startPageId, profiler);
Load(startPage, profiler);
}