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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
* Copyright (C) 2014 Named Data Networking Project
* See COPYING for copyright and distribution information.
*/
// Name Tree (Name Prefix Hash Table)
#include "name-tree.hpp"
#include "core/logger.hpp"
namespace nfd {
NFD_LOG_INIT("NameTree");
namespace name_tree {
// Interface of different hash functions
uint32_t
hashName(const Name& prefix)
{
// fixed value. Used for debugging only.
uint32_t ret = 0;
// Boost hash
// requires the /boost/functional/hash.hpp header file
// TODO: improve hash efficiency with Name type
boost::hash<std::string> stringHash;
ret = stringHash(prefix.toUri());
return ret;
}
} // namespace name_tree
NameTree::NameTree(size_t nBuckets)
: m_nItems(0)
, m_nBuckets(nBuckets)
, m_loadFactor(0.5)
, m_resizeFactor(2)
, m_endIterator(FULL_ENUMERATE_TYPE, *this, m_end)
{
m_resizeThreshold = static_cast<size_t>(m_loadFactor *
static_cast<double>(m_nBuckets));
// array of node pointers
m_buckets = new name_tree::Node*[m_nBuckets];
// Initialize the pointer array
for (size_t i = 0; i < m_nBuckets; i++)
m_buckets[i] = 0;
}
NameTree::~NameTree()
{
for (size_t i = 0; i < m_nBuckets; i++)
{
if (m_buckets[i] != 0)
delete m_buckets[i];
}
delete [] m_buckets;
}
// insert() is a private function, and called by only lookup()
std::pair<shared_ptr<name_tree::Entry>, bool>
NameTree::insert(const Name& prefix)
{
NFD_LOG_DEBUG("insert " << prefix);
uint32_t hashValue = name_tree::hashName(prefix);
uint32_t loc = hashValue % m_nBuckets;
NFD_LOG_DEBUG("Name " << prefix << " hash value = " << hashValue << " location = " << loc);
// Check if this Name has been stored
name_tree::Node* node = m_buckets[loc];
name_tree::Node* nodePrev = node; // initialize nodePrev to node
for (node = m_buckets[loc]; node != 0; node = node->m_next)
{
if (static_cast<bool>(node->m_entry))
{
if (prefix == node->m_entry->m_prefix)
{
return std::make_pair(node->m_entry, false); // false: old entry
}
}
nodePrev = node;
}
NFD_LOG_DEBUG("Did not find " << prefix << ", need to insert it to the table");
// If no bucket is empty occupied, we need to create a new node, and it is
// linked from nodePrev
node = new name_tree::Node();
node->m_prev = nodePrev;
if (nodePrev == 0)
{
m_buckets[loc] = node;
}
else
{
nodePrev->m_next = node;
}
// Create a new Entry
shared_ptr<name_tree::Entry> entry(make_shared<name_tree::Entry>(prefix));
entry->setHash(hashValue);
node->m_entry = entry; // link the Entry to its Node
entry->m_node = node; // link the node to Entry. Used in eraseEntryIfEmpty.
return std::make_pair(entry, true); // true: new entry
}
// Name Prefix Lookup. Create Name Tree Entry if not found
shared_ptr<name_tree::Entry>
NameTree::lookup(const Name& prefix)
{
NFD_LOG_DEBUG("lookup " << prefix);
shared_ptr<name_tree::Entry> entry;
shared_ptr<name_tree::Entry> parent;
for (size_t i = 0; i <= prefix.size(); i++)
{
Name temp = prefix.getPrefix(i);
// insert() will create the entry if it does not exist.
std::pair<shared_ptr<name_tree::Entry>, bool> ret = insert(temp);
entry = ret.first;
if (ret.second == true)
{
m_nItems++; /* Increase the counter */
entry->m_parent = parent;
if (static_cast<bool>(parent))
{
parent->m_children.push_back(entry);
}
}
if (m_nItems > m_resizeThreshold)
{
resize(m_resizeFactor * m_nBuckets);
}
parent = entry;
}
return entry;
}
// Exact Match
shared_ptr<name_tree::Entry>
NameTree::findExactMatch(const Name& prefix) const
{
NFD_LOG_DEBUG("findExactMatch " << prefix);
uint32_t hashValue = name_tree::hashName(prefix);
uint32_t loc = hashValue % m_nBuckets;
NFD_LOG_DEBUG("Name " << prefix << " hash value = " << hashValue <<
" location = " << loc);
shared_ptr<name_tree::Entry> entry;
name_tree::Node* node = 0;
for (node = m_buckets[loc]; node != 0; node = node->m_next)
{
entry = node->m_entry;
if (static_cast<bool>(entry))
{
if (hashValue == entry->getHash() && prefix == entry->getPrefix())
{
return entry;
}
} // if entry
} // for node
// if not found, the default value of entry (null pointer) will be returned
entry.reset();
return entry;
}
// Longest Prefix Match
// Return the longest matching Entry address
// start from the full name, and then remove 1 name comp each time
shared_ptr<name_tree::Entry>
NameTree::findLongestPrefixMatch(const Name& prefix, const name_tree::EntrySelector& entrySelector) const
{
NFD_LOG_DEBUG("findLongestPrefixMatch " << prefix);
shared_ptr<name_tree::Entry> entry;
for (int i = prefix.size(); i >= 0; i--)
{
entry = findExactMatch(prefix.getPrefix(i));
if (static_cast<bool>(entry) && entrySelector(*entry))
return entry;
}
return shared_ptr<name_tree::Entry>();
}
// return {false: this entry is not empty, true: this entry is empty and erased}
bool
NameTree::eraseEntryIfEmpty(shared_ptr<name_tree::Entry> entry)
{
BOOST_ASSERT(static_cast<bool>(entry));
NFD_LOG_DEBUG("eraseEntryIfEmpty " << entry->getPrefix());
// first check if this Entry can be erased
if (entry->isEmpty())
{
// update child-related info in the parent
shared_ptr<name_tree::Entry> parent = entry->getParent();
if (static_cast<bool>(parent))
{
std::vector<shared_ptr<name_tree::Entry> >& parentChildrenList =
parent->getChildren();
bool isFound = false;
size_t size = parentChildrenList.size();
for (size_t i = 0; i < size; i++)
{
if (parentChildrenList[i] == entry)
{
parentChildrenList[i] = parentChildrenList[size - 1];
parentChildrenList.pop_back();
isFound = true;
break;
}
}
BOOST_ASSERT(isFound == true);
}
// remove this Entry and its Name Tree Node
name_tree::Node* node = entry->m_node;
name_tree::Node* nodePrev = node->m_prev;
// configure the previous node
if (nodePrev != 0)
{
// link the previous node to the next node
nodePrev->m_next = node->m_next;
}
else
{
m_buckets[entry->getHash() % m_nBuckets] = node->m_next;
}
// link the previous node with the next node (skip the erased one)
if (node->m_next != 0)
{
node->m_next->m_prev = nodePrev;
node->m_next = 0;
}
BOOST_ASSERT(node->m_next == 0);
m_nItems--;
delete node;
if (static_cast<bool>(parent))
eraseEntryIfEmpty(parent);
return true;
} // if this entry is empty
return false; // if this entry is not empty
}
NameTree::const_iterator
NameTree::fullEnumerate(const name_tree::EntrySelector& entrySelector) const
{
NFD_LOG_DEBUG("fullEnumerate");
// find the first eligible entry
for (size_t i = 0; i < m_nBuckets; i++)
{
for (name_tree::Node* node = m_buckets[i]; node != 0; node = node->m_next)
{
if (static_cast<bool>(node->m_entry) && entrySelector(*node->m_entry))
{
const_iterator it(FULL_ENUMERATE_TYPE, *this, node->m_entry, entrySelector);
return it;
}
}
}
// If none of the entry satisfies the requirements, then return the end() iterator.
return end();
}
NameTree::const_iterator
NameTree::partialEnumerate(const Name& prefix,
const name_tree::EntrySubTreeSelector& entrySubTreeSelector) const
{
// the first step is to process the root node
shared_ptr<name_tree::Entry> entry = findExactMatch(prefix);
if (!static_cast<bool>(entry))
{
return end();
}
std::pair<bool, bool>result = entrySubTreeSelector(*entry);
const_iterator it(PARTIAL_ENUMERATE_TYPE,
*this,
entry,
name_tree::AnyEntry(),
entrySubTreeSelector);
it.m_shouldVisitChildren = (result.second && entry->hasChildren());
if (result.first)
{
// root node is acceptable
return it;
}
else
{
// let the ++ operator handle it
++it;
return it;
}
}
NameTree::const_iterator
NameTree::findAllMatches(const Name& prefix,
const name_tree::EntrySelector& entrySelector) const
{
NFD_LOG_DEBUG("NameTree::findAllMatches" << prefix);
// As we are using Name Prefix Hash Table, and the current LPM() is
// implemented as starting from full name, and reduce the number of
// components by 1 each time, we could use it here.
// For trie-like design, it could be more efficient by walking down the
// trie from the root node.
shared_ptr<name_tree::Entry> entry = findLongestPrefixMatch(prefix, entrySelector);
if (static_cast<bool>(entry))
{
const_iterator it(FIND_ALL_MATCHES_TYPE, *this, entry, entrySelector);
return it;
}
// If none of the entry satisfies the requirements, then return the end() iterator.
return end();
}
// Hash Table Resize
void
NameTree::resize(size_t newNBuckets)
{
NFD_LOG_DEBUG("resize");
name_tree::Node** newBuckets = new name_tree::Node*[newNBuckets];
size_t count = 0;
// referenced ccnx hashtb.c hashtb_rehash()
name_tree::Node** pp = 0;
name_tree::Node* p = 0;
name_tree::Node* pre = 0;
name_tree::Node* q = 0; // record p->m_next
size_t i;
uint32_t h;
uint32_t b;
for (i = 0; i < newNBuckets; i++)
{
newBuckets[i] = 0;
}
for (i = 0; i < m_nBuckets; i++)
{
for (p = m_buckets[i]; p != 0; p = q)
{
count++;
q = p->m_next;
BOOST_ASSERT(static_cast<bool>(p->m_entry));
h = p->m_entry->m_hash;
b = h % newNBuckets;
for (pp = &newBuckets[b]; *pp != 0; pp = &((*pp)->m_next))
{
pre = *pp;
continue;
}
p->m_prev = pre;
p->m_next = *pp; // Actually *pp always == 0 in this case
*pp = p;
}
}
BOOST_ASSERT(count == m_nItems);
name_tree::Node** oldBuckets = m_buckets;
m_buckets = newBuckets;
delete oldBuckets;
m_nBuckets = newNBuckets;
m_resizeThreshold = (int)(m_loadFactor * (double)m_nBuckets);
}
// For debugging
void
NameTree::dump(std::ostream& output) const
{
NFD_LOG_DEBUG("dump()");
name_tree::Node* node = 0;
shared_ptr<name_tree::Entry> entry;
using std::endl;
for (size_t i = 0; i < m_nBuckets; i++)
{
for (node = m_buckets[i]; node != 0; node = node->m_next)
{
entry = node->m_entry;
// if the Entry exist, dump its information
if (static_cast<bool>(entry))
{
output << "Bucket" << i << "\t" << entry->m_prefix.toUri() << endl;
output << "\t\tHash " << entry->m_hash << endl;
if (static_cast<bool>(entry->m_parent))
{
output << "\t\tparent->" << entry->m_parent->m_prefix.toUri();
}
else
{
output << "\t\tROOT";
}
output << endl;
if (entry->m_children.size() != 0)
{
output << "\t\tchildren = " << entry->m_children.size() << endl;
for (size_t j = 0; j < entry->m_children.size(); j++)
{
output << "\t\t\tChild " << j << " " <<
entry->m_children[j]->getPrefix() << endl;
}
}
} // if (static_cast<bool>(entry))
} // for node
} // for int i
output << "Bucket count = " << m_nBuckets << endl;
output << "Stored item = " << m_nItems << endl;
output << "--------------------------\n";
}
NameTree::const_iterator::const_iterator(NameTree::IteratorType type,
const NameTree& nameTree,
shared_ptr<name_tree::Entry> entry,
const name_tree::EntrySelector& entrySelector,
const name_tree::EntrySubTreeSelector& entrySubTreeSelector)
: m_nameTree(nameTree)
, m_entry(entry)
, m_subTreeRoot(entry)
, m_entrySelector(make_shared<name_tree::EntrySelector>(entrySelector))
, m_entrySubTreeSelector(make_shared<name_tree::EntrySubTreeSelector>(entrySubTreeSelector))
, m_type(type)
, m_shouldVisitChildren(true)
{
}
// operator++()
NameTree::const_iterator
NameTree::const_iterator::operator++()
{
NFD_LOG_DEBUG("const_iterator::operator++()");
BOOST_ASSERT(m_entry != m_nameTree.m_end);
if (m_type == FULL_ENUMERATE_TYPE) // fullEnumerate
{
bool isFound = false;
// process the entries in the same bucket first
while (m_entry->m_node->m_next != 0)
{
m_entry = m_entry->m_node->m_next->m_entry;
if ((*m_entrySelector)(*m_entry))
{
isFound = true;
return *this;
}
}
// process other buckets
for (int newLocation = m_entry->m_hash % m_nameTree.m_nBuckets + 1;
newLocation < static_cast<int>(m_nameTree.m_nBuckets);
++newLocation)
{
// process each bucket
name_tree::Node* node = m_nameTree.m_buckets[newLocation];
while (node != 0)
{
m_entry = node->m_entry;
if ((*m_entrySelector)(*m_entry))
{
isFound = true;
return *this;
}
node = node->m_next;
}
}
BOOST_ASSERT(isFound == false);
// Reach to the end()
m_entry = m_nameTree.m_end;
return *this;
}
if (m_type == PARTIAL_ENUMERATE_TYPE) // partialEnumerate
{
// We use pre-order traversal.
// if at the root, it could have already been accepted, or this
// iterator was just declared, and root doesn't satisfy the
// requirement
// The if() section handles this special case
// Essentially, we need to check root's fist child, and the rest will
// be the same as normal process
if (m_entry == m_subTreeRoot)
{
if (m_shouldVisitChildren)
{
m_entry = m_entry->getChildren()[0];
std::pair<bool, bool> result = ((*m_entrySubTreeSelector)(*m_entry));
m_shouldVisitChildren = (result.second && m_entry->hasChildren());
if(result.first)
{
return *this;
}
else
{
// the first child did not meet the requirement
// the rest of the process can just fall through the while loop
// as normal
}
}
else
{
// no children, should return end();
// just fall through
}
}
// The first thing to do is to visit its child, or go to find its possible
// siblings
while (m_entry != m_subTreeRoot)
{
if (m_shouldVisitChildren)
{
// If this subtree should be visited
m_entry = m_entry->getChildren()[0];
std::pair<bool, bool> result = ((*m_entrySubTreeSelector)(*m_entry));
m_shouldVisitChildren = (result.second && m_entry->hasChildren());
if (result.first) // if this node is acceptable
{
return *this;
}
else
{
// do nothing, as this node is essentially ignored
// send this node to the while loop.
}
}
else
{
// Should try to find its sibling
shared_ptr<name_tree::Entry> parent = m_entry->getParent();
std::vector<shared_ptr<name_tree::Entry> >& parentChildrenList = parent->getChildren();
bool isFound = false;
size_t i = 0;
for (i = 0; i < parentChildrenList.size(); i++)
{
if (parentChildrenList[i] == m_entry)
{
isFound = true;
break;
}
}
BOOST_ASSERT(isFound == true);
if (i < parentChildrenList.size() - 1) // m_entry not the last child
{
m_entry = parentChildrenList[i + 1];
std::pair<bool, bool> result = ((*m_entrySubTreeSelector)(*m_entry));
m_shouldVisitChildren = (result.second && m_entry->hasChildren());
if (result.first) // if this node is acceptable
{
return *this;
}
else
{
// do nothing, as this node is essentially ignored
// send this node to the while loop.
}
}
else
{
// m_entry is the last child, no more sibling, should try to find parent's sibling
m_shouldVisitChildren = false;
m_entry = parent;
}
}
}
m_entry = m_nameTree.m_end;
return *this;
}
if (m_type == FIND_ALL_MATCHES_TYPE) // findAllMatches
{
// Assumption: at the beginning, m_entry was initialized with the first
// eligible Name Tree entry (i.e., has a PIT entry that can be satisfied
// by the Data packet)
while (static_cast<bool>(m_entry->getParent()))
{
m_entry = m_entry->getParent();
if ((*m_entrySelector)(*m_entry))
return *this;
}
// Reach to the end (Root)
m_entry = m_nameTree.m_end;
return *this;
}
BOOST_ASSERT(false); // unknown type
return *this;
}
} // namespace nfd