private void DoDisposeNode(NodeId id)
{
// If the node is a special node, then we don't dispose it
if (id.IsSpecial)
{
return;
}
// Is 'id' a leaf node?
IMutableArea nodeArea = nodeStore.GetMutableArea(ToInt64StoreAddress(id));
// Are we a leaf?
nodeArea.Position = 0;
int nodeType = nodeArea.ReadInt2();
if (nodeType == StoreLeafType)
{
// Yes, get its reference_count,
lock (referenceCountLock) {
nodeArea.Position = 4;
int refCount = nodeArea.ReadInt4();
// If the reference_count is >1 then decrement it and return
if (refCount > 1)
{
nodeArea.Position = 4;
nodeArea.WriteInt4(refCount - 1);
return;
}
}
}
else if (nodeType != StoreBranchType)
{
// Has to be a branch type, otherwise failure
throw new IOException("Unknown node type.");
}
// 'id' is a none leaf branch or its reference count is 1, so delete the
// area.
// NOTE, we delete from the cache first before we delete the area
// because the deleted area may be reclaimed immediately and deleting
// from the cache after may be too late.
// Delete from the cache because the given ref may be recycled for a new
// node at some point.
lock (branchCache) {
branchCache.Remove(id);
}
// Delete the area
nodeStore.DeleteArea(ToInt64StoreAddress(id));
}
public bool LinkLeaf(Key key, NodeId id)
{
// If the node is a special node, then we don't need to reference count it.
if (id.IsSpecial)
{
return(true);
}
try {
nodeStore.LockForWrite();
// Get the area as a MutableArea object
IMutableArea leafArea = nodeStore.GetMutableArea(ToInt64StoreAddress(id));
// We synchronize over a reference count lock
// (Pending: should we lock by area instead? I'm not sure it will be
// worth the complexity of a more fine grained locking mechanism for the
// performance improvements - maybe we should implement a locking
// mechanism inside MutableArea).
lock (referenceCountLock) {
// Assert this is a leaf
leafArea.Position = 0;
short nodeType = leafArea.ReadInt2();
if (nodeType != StoreLeafType)
{
throw new IOException("Can only link to a leaf node.");
}
leafArea.Position = 4;
int refCount = leafArea.ReadInt4();
// If reference counter is near overflowing, return false.
if (refCount > Int32.MaxValue - 8)
{
return(false);
}
leafArea.Position = 4;
leafArea.WriteInt4(refCount + 1);
}
return(true);
} finally {
nodeStore.UnlockForWrite();
}
}
public bool Start()
{
lock (lockObject) {
treeSystem = new StoreTreeSystem(store, branchNodeSize, leafNodeSize, heapNodeCacheSize, branchNodeCacheSize);
treeSystem.Create();
treeSystem.CheckPoint();
// The actual database
StoreTreeSystem treeStore;
// Get the header area
IArea headerArea = store.GetArea(-1);
int magicValue = headerArea.ReadInt4();
// If header area magic value is zero, then we assume this is a brand
// new database and initialize it with the configuration information
// given.
if (magicValue == 0)
{
// Create a tree store inside the file store,
treeStore = new StoreTreeSystem(store, branchNodeSize, leafNodeSize, heapNodeCacheSize,
branchNodeCacheSize);
// Create the tree and returns a pointer to the tree,
long treePointer = treeStore.Create();
// Create an area object with state information about the tree
IAreaWriter awriter = store.CreateArea(128);
awriter.WriteInt4(0x0101); // The version value
awriter.WriteInt8(treePointer);
awriter.WriteInt4(branchNodeSize);
awriter.WriteInt4(leafNodeSize);
awriter.Finish();
long dummy = awriter.Id;
IMutableArea harea = store.GetMutableArea(-1);
harea.WriteInt4(0x092BA001); // The magic value
harea.WriteInt8(awriter.Id);
harea.CheckOut();
}
else if (magicValue == 0x092BA001)
{
long apointer = headerArea.ReadInt8();
// The area that contains configuration details,
IArea initArea = store.GetArea(apointer);
int version = initArea.ReadInt4();
if (version != 0x0101)
{
throw new IOException("Unknown version in tree initialization area");
}
// Read the pointer to the tree store
long treePointer = initArea.ReadInt8();
// Read the branch and leaf node sizes as set when the database was
// created.
int ibranchNodeSize = initArea.ReadInt4();
int ileafNodeSize = initArea.ReadInt4();
// Create the tree store
treeStore = new StoreTreeSystem(store, ibranchNodeSize, ileafNodeSize, heapNodeCacheSize,
branchNodeCacheSize);
// Initialize the tree
treeStore.Init(treePointer);
}
else
{
throw new IOException("Data is corrupt, invalid magic value in store");
}
// Set the point of the tree store
treeStore.CheckPoint();
// Set up final internal state and return true
treeSystem = treeStore;
databaseStarted = true;
return(true);
}
}
public bool Start()
{
lock (lockObject) {
// We can't start a database that is already started,
if (databaseStarted || treeSystem != null)
{
return(false);
}
// Make a data.koi file with a single TreeSystem structure mapped into it
const string fileExt = "cdb";
const string dbFileName = "data";
bufferManager = new LoggingBufferManager(path, path, false, maxPageCount, pageSize, fileExt, fileRolloverSize,
logger, true);
bufferManager.Start();
// The backing store
fileStore = new JournalledFileStore(dbFileName, bufferManager, false);
fileStore.Open();
// The actual database
StoreTreeSystem treeStore;
// Get the header area
IArea headerArea = fileStore.GetArea(-1);
int magicValue = headerArea.ReadInt4();
// If header area magic value is zero, then we assume this is a brand
// new database and initialize it with the configuration information
// given.
if (magicValue == 0)
{
// Create a tree store inside the file store,
treeStore = new StoreTreeSystem(fileStore, branchNodeSize, leafNodeSize, heapNodeCacheSize,
branchNodeCacheSize);
// Create the tree and returns a pointer to the tree,
long treePointer = treeStore.Create();
// Create an area object with state information about the tree
IAreaWriter awriter = fileStore.CreateArea(128);
awriter.WriteInt4(0x0101); // The version value
awriter.WriteInt8(treePointer);
awriter.WriteInt4(branchNodeSize);
awriter.WriteInt4(leafNodeSize);
awriter.Finish();
long dummy = awriter.Id;
IMutableArea harea = fileStore.GetMutableArea(-1);
harea.WriteInt4(0x092BA001); // The magic value
harea.WriteInt8(awriter.Id);
harea.CheckOut();
}
else if (magicValue == 0x092BA001)
{
long apointer = headerArea.ReadInt8();
// The area that contains configuration details,
IArea initArea = fileStore.GetArea(apointer);
int version = initArea.ReadInt4();
if (version != 0x0101)
{
throw new IOException("Unknown version in tree initialization area");
}
// Read the pointer to the tree store
long treePointer = initArea.ReadInt8();
// Read the branch and leaf node sizes as set when the database was
// created.
int ibranchNodeSize = initArea.ReadInt4();
int ileafNodeSize = initArea.ReadInt4();
// Create the tree store
treeStore = new StoreTreeSystem(fileStore, ibranchNodeSize, ileafNodeSize, heapNodeCacheSize,
branchNodeCacheSize);
// Initialize the tree
treeStore.Init(treePointer);
}
else
{
throw new IOException("Data is corrupt, invalid magic value in store");
}
// Set the point of the tree store
treeStore.CheckPoint();
// Set up final internal state and return true
treeSystem = treeStore;
databaseStarted = true;
return(true);
}
}