Files
rippled/SHAMapDiff.cpp
JoelKatz 04cc08748e Half the new map diff implementation. This is the part that handles
a branch that's either empty in the other tree or matched by only
a leaf.
2012-02-05 21:22:20 -08:00

233 lines
8.4 KiB
C++

#include "SHAMap.h"
#include <stack>
// This code is used to compare another node's transaction tree
// to our own. It returns a map containing all items that are different
// between two SHA maps. It is optimized not to descend down tree
// branches with the same branch hash. A limit can be passed so
// that we will abort early if a node sends a map to us that
// makes no sense at all. (And our sync algorithm will avoid
// synchronizing matching brances too.)
class SHAMapDiffNode
{
public:
SHAMapNode mNodeID;
uint256 mOurHash, mOtherHash;
SHAMapDiffNode(SHAMapNode id, const uint256& ourHash, const uint256& otherHash) :
mNodeID(id), mOurHash(ourHash), mOtherHash(otherHash) { ; }
};
bool SHAMap::walkBranch(SHAMapTreeNode::pointer node, SHAMapItem::pointer otherMapItem, bool isFirstMap,
SHAMapDiff& differences, int& maxCount)
{
// Walk a branch of a SHAMap that's matched by an empty branch or single item in the other map
std::stack<SHAMapTreeNode::pointer> nodeStack;
nodeStack.push(node);
while(!nodeStack.empty())
{
SHAMapTreeNode::pointer node=nodeStack.top();
nodeStack.pop();
if(node->isInner())
{ // This is an inner node, add all non-empty branches
for(int i=0; i<16; i++)
if(!node->isEmptyBranch(i))
{
SHAMapTreeNode::pointer newNode=getNode(node->getChildNodeID(i), node->getChildHash(i), false);
if(!newNode) throw SHAMapException(MissingNode);
nodeStack.push(newNode);
}
}
else
{ // This is a leaf node, process its item
SHAMapItem::pointer item=node->peekItem();
if(otherMapItem && otherMapItem->getTag()<item->getTag())
{ // this item comes after the item from the other map, so add the other item
if(isFirstMap) // this is first map, so other item is from second
differences.insert(std::make_pair(otherMapItem->getTag(),
std::make_pair(SHAMapItem::pointer(), otherMapItem)));
else
differences.insert(std::make_pair(otherMapItem->getTag(),
std::make_pair(otherMapItem, SHAMapItem::pointer())));
if((--maxCount)<=0) return false;
otherMapItem=SHAMapItem::pointer();
}
if( (!otherMapItem) || (item->getTag()<otherMapItem->getTag()) )
{ // unmatched
if(isFirstMap)
differences.insert(std::make_pair(item->getTag(), std::make_pair(item, SHAMapItem::pointer())));
else
differences.insert(std::make_pair(item->getTag(), std::make_pair(SHAMapItem::pointer(), item)));
if((--maxCount)<=0) return false;
}
else if(item->getTag()==otherMapItem->getTag())
{
if(item->getData()!=otherMapItem->getData())
{ // non-matching items
if(isFirstMap)
differences.insert(std::make_pair(otherMapItem->getTag(),
std::make_pair(item, otherMapItem)));
else
differences.insert(std::make_pair(otherMapItem->getTag(),
std::make_pair(otherMapItem, item)));
if((--maxCount)<=0) return false;
item=SHAMapItem::pointer();
}
}
else assert(false);
}
}
if(otherMapItem)
{ // otherMapItem was unmatched, must add
if(isFirstMap) // this is first map, so other item is from second
differences.insert(std::make_pair(otherMapItem->getTag(),
std::make_pair(SHAMapItem::pointer(), otherMapItem)));
else
differences.insert(std::make_pair(otherMapItem->getTag(),
std::make_pair(otherMapItem, SHAMapItem::pointer())));
if((--maxCount)<=0) return false;
}
return true;
}
bool SHAMap::compare(SHAMap::pointer otherMap, SHAMapDiff& differences, int maxCount)
{ // compare two hash trees, add up to maxCount differences to the difference table
// return value: true=complete table of differences given, false=too many differences
// throws on corrupt tables or missing nodes
#if 0
// FIXME: Temporarily disabled
std::stack<SHAMapDiffNode> nodeStack; // track nodes we've pushed
nodeStack.push(SHAMapDiffNode(SHAMapNode(), getHash(), otherMap->getHash()));
ScopedLock sl(Lock());
while(!nodeStack.empty())
{
SHAMapDiffNode node(nodeStack.top());
nodeStack.pop();
if(node.mOurHash!=node.mOtherHash)
{
if(node.mNodeID.isLeaf())
{
if(!node.mOurHash)
{ // leaf only in our tree
SHAMapLeafNode::pointer thisNode=getLeaf(node.mNodeID, node.mOurHash, false);
for(SHAMapItem::pointer item=thisNode->firstItem(); item; item=thisNode->nextItem(item->getTag()))
{ // items in leaf only in our tree
differences.insert(std::make_pair(item->getTag(),
std::make_pair(item, SHAMapItem::pointer())));
if((--maxCount)<=0) return false;
}
}
else if(!node.mOtherHash)
{ // leaf only in other tree
SHAMapLeafNode::pointer otherNode=otherMap->getLeaf(node.mNodeID, node.mOtherHash, false);
for(SHAMapItem::pointer item=otherNode->firstItem(); item; item=otherNode->nextItem(item->getTag()))
{ // items in leaf only in our tree
differences.insert(std::make_pair(item->getTag(),
std::make_pair(SHAMapItem::pointer(), item)));
if((--maxCount)<=0) return false;
}
}
else
{ // leaf in both trees, but differs
SHAMapLeafNode::pointer thisNode=getLeaf(node.mNodeID, node.mOurHash, false);
SHAMapLeafNode::pointer otherNode=otherMap->getLeaf(node.mNodeID, node.mOtherHash, false);
SHAMapItem::pointer ourItem=thisNode->firstItem();
SHAMapItem::pointer otherMapItem=otherNode->firstItem();
while(ourItem || otherMapItem)
{
if(!otherMapItem)
{ // we have items, other tree does not
differences.insert(std::make_pair(ourItem->getTag(),
std::make_pair(ourItem, otherMapItem)));
if((--maxCount)<=0) return false;
otherMapItem=otherNode->nextItem(otherMapItem->getTag());
}
else if(!ourItem)
{ // we have no items, other tree does
differences.insert(std::make_pair(otherMapItem->getTag(),
std::make_pair(ourItem, otherMapItem)));
if((--maxCount)<=0) return false;
otherMapItem=thisNode->nextItem(otherMapItem->getTag());
}
else if(ourItem->getTag()==otherMapItem->getTag())
{ // we have items with the same tag
if(ourItem->getData()!=otherMapItem->getData())
{ // different data
differences.insert(std::make_pair(ourItem->getTag(),
std::make_pair(ourItem, otherMapItem)));
if((--maxCount)<=0) return false;
}
ourItem=thisNode->nextItem(ourItem->getTag());
otherMapItem=otherNode->nextItem(otherMapItem->getTag());
}
else if(ourItem->getTag()<otherMapItem->getTag())
{ // our item comes first
differences.insert(std::make_pair(ourItem->getTag(),
std::make_pair(ourItem, SHAMapItem::pointer())));
if((--maxCount)<=0) return false;
ourItem=thisNode->nextItem(ourItem->getTag());
}
else
{ // other item comes first
differences.insert(std::make_pair(otherMapItem->getTag(),
std::make_pair(SHAMapItem::pointer(), otherMapItem)));
if((--maxCount)<=0) return false;
otherMapItem=otherNode->nextItem(otherMapItem->getTag());
}
}
}
}
else
{ // inner node different in two trees
if(!node.mOurHash)
{ // node only exist in our tree
SHAMapInnerNode::pointer thisNode=getInner(node.mNodeID, node.mOurHash, false);
for(int i=0; i<32; i++)
{ // push all existing branches onto the stack
if(!!thisNode->getChildHash(i))
nodeStack.push(SHAMapDiffNode(thisNode->getChildNodeID(i),
thisNode->getChildHash(i), uint256()));
}
}
else if(!node.mOtherHash)
{ // node only exists in other tree
SHAMapInnerNode::pointer otherNode=otherMap->getInner(node.mNodeID, node.mOtherHash, false);
for(int i=0; i<32; i++)
{ // push all existing branches onto the stack
if(!!otherNode->getChildHash(i))
nodeStack.push(SHAMapDiffNode(otherNode->getChildNodeID(i),
uint256(), otherNode->getChildHash(i)));
}
}
else
{ // node in both trees, but differs
SHAMapInnerNode::pointer thisNode=getInner(node.mNodeID, node.mOurHash, false);
SHAMapInnerNode::pointer otherNode=otherMap->getInner(node.mNodeID, node.mOtherHash, false);
for(int i=0; i<32; i++)
{ // push all differing branches onto the stack
if(thisNode->getChildHash(i)!=otherNode->getChildHash(i))
nodeStack.push(SHAMapDiffNode(thisNode->getChildNodeID(i),
thisNode->getChildHash(i), otherNode->getChildHash(i)));
}
}
}
}
}
#endif
return true;
}