#include <PastryRoutingTable.h>
Inheritance diagram for PastryRoutingTable:
This module contains the routing table of the Chord implementation.
Public Member Functions | |
void | initializeTable (uint bitsPerDigit, double repairTimeout, const NodeHandle &owner) |
Initializes the routing table. | |
const NodeHandle & | lookupNextHop (const OverlayKey &destination) |
gets the next hop according to the Pastry routing scheme. | |
virtual const NodeHandle & | findCloserNode (const OverlayKey &destination, bool optimize=false) |
try to find a node numerically closer to a given key with the same shared prefix as the current node in the routing table. | |
virtual const TransportAddress & | failedNode (const TransportAddress &failed) |
tells the routing table that a node has failed | |
virtual const TransportAddress & | repair (const PastryStateMessage *msg, const PastryStateMsgProximity &prox) |
attempt to repair the routing using a received REPAIR message | |
virtual void | dumpToStateMessage (PastryStateMessage *msg) const |
dump content of the table to a PastryStateMessage | |
bool | mergeNode (const NodeHandle &node, simtime_t prox) |
merge a node in the RoutingTable | |
bool | initStateFromMsgVector (const std::vector< PastryStateMessage * > &messages, const std::vector< PastryStateMsgProximity > &proximities) |
initialize table from vector of PastryStateMessages received during JOIN phase. | |
virtual void | dumpToVector (std::vector< TransportAddress > &affected) const |
appends all routing table entries to a given vector of TransportAddresses, needed to find all Nodes to be notified after joining. | |
Private Member Functions | |
virtual void | earlyInit (void) |
initialize watches etc. | |
void | addRow (void) |
adds a new line to the routing table | |
uint32_t | digitAt (uint n, const OverlayKey &key) const |
returns n'th pastry digit from a key | |
const PastryExtendedNode & | nodeAt (uint row, uint col) const |
returns routing table entry at specified position | |
void | findNextNodeToAsk (PRTTrackRepair &track) const |
helper function, updates a PRTTrackRepair structure to point to the next node that can be asked for repair | |
Private Attributes | |
uint | bitsPerDigit |
double | repairTimeout |
uint | nodesPerRow |
std::vector< PRTRow > | rows |
std::vector< PRTTrackRepair > | awaitingRepair |
void PastryRoutingTable::addRow | ( | void | ) | [private] |
adds a new line to the routing table
00252 { 00253 PRTRow row(nodesPerRow, unspecNode); 00254 00255 // place own node at correct position: 00256 (row.begin() + digitAt(rows.size(), owner.key))->node = owner; 00257 rows.push_back(row); 00258 }
uint32_t PastryRoutingTable::digitAt | ( | uint | n, | |
const OverlayKey & | key | |||
) | const [inline, private] |
returns n'th pastry digit from a key
n | which digit to return | |
key | extract digit from this key |
00030 { 00031 return key.get(OverlayKey::getLength() - ++n*bitsPerDigit, bitsPerDigit); 00032 }
void PastryRoutingTable::dumpToStateMessage | ( | PastryStateMessage * | msg | ) | const [virtual] |
dump content of the table to a PastryStateMessage
msg | the PastryStateMessage to be filled with entries |
Implements PastryStateObject.
00180 { 00181 uint i = 0; 00182 std::vector<PRTRow>::const_iterator itRows; 00183 PRTRow::const_iterator itCols; 00184 00185 msg->setRoutingTableArraySize(rows.size() * nodesPerRow); 00186 00187 for (itRows = rows.begin(); itRows != rows.end(); itRows++) 00188 for (itCols = itRows->begin(); itCols != itRows->end(); itCols++) 00189 msg->setRoutingTable(i++, itCols->node); 00190 }
void PastryRoutingTable::dumpToVector | ( | std::vector< TransportAddress > & | affected | ) | const [virtual] |
appends all routing table entries to a given vector of TransportAddresses, needed to find all Nodes to be notified after joining.
affected | the vector to fill with routing table entries |
Implements PastryStateObject.
00241 { 00242 std::vector<PRTRow>::const_iterator itRows; 00243 PRTRow::const_iterator itCols; 00244 00245 for (itRows = rows.begin(); itRows != rows.end(); itRows++) 00246 for (itCols = itRows->begin(); itCols != itRows->end(); itCols++) 00247 if (!itCols->node.isUnspecified()) 00248 affected.push_back(itCols->node); 00249 }
void PastryRoutingTable::earlyInit | ( | void | ) | [private, virtual] |
const TransportAddress & PastryRoutingTable::failedNode | ( | const TransportAddress & | failed | ) | [virtual] |
tells the routing table that a node has failed
failed | the failed node |
Implements PastryStateObject.
00271 { 00272 std::vector<PRTRow>::iterator itRows; 00273 PRTRow::iterator itCols; 00274 PRTTrackRepair tmpTrack; 00275 00276 bool found = false; 00277 00278 // find node in table: 00279 for (itRows = rows.begin(); itRows != rows.end(); itRows++) 00280 { 00281 for (itCols = itRows->begin(); itCols != itRows->end(); itCols++) 00282 { 00283 if ((! itCols->node.isUnspecified()) && 00284 (itCols->node.ip == failed.ip)) 00285 { 00286 itCols->node = NodeHandle::UNSPECIFIED_NODE; 00287 itCols->rtt = PASTRY_PROX_UNDEF; 00288 found = true; 00289 break; 00290 } 00291 } 00292 if (found) break; 00293 } 00294 00295 // not found, nothing to do: 00296 if (!found) return TransportAddress::UNSPECIFIED_NODE; 00297 00298 // else fill temporary record: 00299 tmpTrack.failedRow = itRows - rows.begin(); 00300 tmpTrack.failedCol = itCols - itRows->begin(); 00301 tmpTrack.node = TransportAddress::UNSPECIFIED_NODE; 00302 findNextNodeToAsk(tmpTrack); 00303 tmpTrack.timestamp = simTime(); 00304 00305 if (tmpTrack.node.isUnspecified()) 00306 return TransportAddress::UNSPECIFIED_NODE; 00307 awaitingRepair.push_back(tmpTrack); 00308 return awaitingRepair.back().node; 00309 }
const NodeHandle & PastryRoutingTable::findCloserNode | ( | const OverlayKey & | destination, | |
bool | optimize = false | |||
) | [virtual] |
try to find a node numerically closer to a given key with the same shared prefix as the current node in the routing table.
this method is to be called, when a regular next hop couldn't be found or wasn't reachable.
destination | the destination key | |
optimize | if set, check all nodes and return the best/closest one |
Implements PastryStateObject.
00090 { 00091 const PastryExtendedNode* entry; 00092 00093 if (optimize) 00094 { 00095 // pointer to later return value, initialize to unspecified, so 00096 // the specialCloserCondition() check will be done against our own 00097 // node as long as no node closer to the destination than our own was 00098 // found. 00099 const NodeHandle* ret = &NodeHandle::UNSPECIFIED_NODE; 00100 00101 // a numerically closer node can only be found in the row containing 00102 // nodes with the same prefix length and in the row above. 00103 int shl = owner.key.sharedPrefixLength(destination) / bitsPerDigit; 00104 int digit = digitAt(shl, destination); 00105 int x = digitAt(shl, owner.key); // position index of own node 00106 00107 // first try the row with same prefix length: 00108 int n = nodesPerRow; 00109 int a = digit - 1; // position index of search to the left 00110 int b = digit + 1; // position index of search to the right 00111 00112 while ((a >= 0) || (b < n)) 00113 { 00114 // no need to continue search in one direction when own entry is 00115 // reached: 00116 if (a == x) a = -1; 00117 if (b == x) b = n; 00118 00119 if (a >= 0) 00120 { 00121 entry = &(nodeAt(shl, a)); 00122 if ((!entry->node.isUnspecified()) && 00123 specialCloserCondition(entry->node, destination, *ret)) 00124 ret = &(entry->node); 00125 a--; 00126 } 00127 if (b < n) 00128 { 00129 entry = &(nodeAt(shl, b)); 00130 if ((!entry->node.isUnspecified()) && 00131 specialCloserCondition(entry->node, destination, *ret)) 00132 ret = &(entry->node); 00133 b++; 00134 } 00135 } 00136 00137 // it this was not the first row, two more nodes to check: 00138 if (shl != 0) 00139 { 00140 // go up one row: 00141 x = digitAt(--shl, owner.key); 00142 00143 if (destination < owner.key) 00144 { 00145 entry = &(nodeAt(shl, digit - 1)); 00146 if ((!entry->node.isUnspecified()) && 00147 specialCloserCondition(entry->node, destination, *ret)) 00148 ret = &(entry->node); 00149 } 00150 else 00151 { 00152 entry = &(nodeAt(shl, digit + 1)); 00153 if ((!entry->node.isUnspecified()) && 00154 specialCloserCondition(entry->node, destination, *ret)) 00155 ret = &(entry->node); 00156 } 00157 } 00158 00159 return *ret; // still unspecified if no closer node was found 00160 } 00161 else 00162 { 00163 // no optimization, return the first closer node found 00164 for (uint y = 0; y < rows.size(); ++y) 00165 { 00166 for (uint x = 0; x < nodesPerRow; ++x) 00167 { 00168 entry = &(nodeAt(y, x)); 00169 if ((!entry->node.isUnspecified()) && 00170 specialCloserCondition(entry->node, destination)) 00171 return entry->node; 00172 } 00173 } 00174 00175 return NodeHandle::UNSPECIFIED_NODE; 00176 } 00177 }
void PastryRoutingTable::findNextNodeToAsk | ( | PRTTrackRepair & | track | ) | const [private] |
helper function, updates a PRTTrackRepair structure to point to the next node that can be asked for repair
track | the PRTTrackRepair structure |
00360 { 00361 const TransportAddress* ask; 00362 00363 if (track.node.isUnspecified()) 00364 { 00365 track.askedRow = track.failedRow; 00366 if (track.failedCol == 0) 00367 track.askedCol = 1; 00368 else 00369 track.askedCol = 0; 00370 ask = static_cast<const TransportAddress*>( 00371 &(nodeAt(track.askedRow, track.askedCol).node)); 00372 track.node = *ask; 00373 if (! track.node.isUnspecified()) return; 00374 } 00375 00376 do 00377 { 00378 // point to next possible position in routing table: 00379 track.askedCol++; 00380 if ((track.askedRow == track.failedRow) && 00381 (track.askedCol == track.failedCol)) track.askedCol++; 00382 if (track.askedCol == nodesPerRow) 00383 { 00384 if ((track.askedRow > track.askedCol) || 00385 (track.askedRow == (rows.size() - 1))) 00386 { 00387 // no more nodes that could be asked, give up: 00388 track.node = TransportAddress::UNSPECIFIED_NODE; 00389 return; 00390 } 00391 track.askedRow++; 00392 track.askedCol = 0; 00393 } 00394 00395 ask = static_cast<const TransportAddress*>( 00396 &(nodeAt(track.askedRow, track.askedCol).node)); 00397 track.node = *ask; 00398 } 00399 while (track.node.isUnspecified()); 00400 }
void PastryRoutingTable::initializeTable | ( | uint | bitsPerDigit, | |
double | repairTimeout, | |||
const NodeHandle & | owner | |||
) |
Initializes the routing table.
This should be called on startup
bitsPerDigit | Pastry configuration parameter | |
repairTimeout | Pastry configuration parameter | |
owner | the node this table belongs to |
00041 { 00042 this->owner = owner; 00043 this->repairTimeout = repairTimeout; 00044 this->bitsPerDigit = bitsPerDigit; 00045 nodesPerRow = 1 << bitsPerDigit; // 2 ^ bitsPerDigit 00046 00047 // forget old routing table contents in case of restart: 00048 if (!rows.empty()) rows.clear(); 00049 00050 // clear pending repair requests: 00051 if (!awaitingRepair.empty()) awaitingRepair.clear(); 00052 00053 // Create first row in table: 00054 addRow(); 00055 }
bool PastryRoutingTable::initStateFromMsgVector | ( | const std::vector< PastryStateMessage * > & | messages, | |
const std::vector< PastryStateMsgProximity > & | proximities | |||
) |
initialize table from vector of PastryStateMessages received during JOIN phase.
The vector has to be sorted by JoinHopCount of the messages
messages | the vector of PastryStateMessages | |
proximities | a vector of corresponding proximity tables |
00223 { 00224 std::vector<PastryStateMessage*>::const_iterator itMsg; 00225 std::vector<PastryStateMsgProximity>::const_iterator itProx; 00226 PastryStateMessage* msg; 00227 int hopCheck = 0; 00228 00229 itProx = proximities.begin(); 00230 for (itMsg = messages.begin(); itMsg != messages.end(); itMsg++) 00231 { 00232 msg = *itMsg; 00233 if (msg->getJoinHopCount() != ++hopCheck) return false; 00234 mergeState(msg, *(itProx++)); 00235 } 00236 return true; 00237 }
const NodeHandle & PastryRoutingTable::lookupNextHop | ( | const OverlayKey & | destination | ) |
gets the next hop according to the Pastry routing scheme.
destination | the destination key |
00067 { 00068 uint shl = owner.key.sharedPrefixLength(destination) / bitsPerDigit; 00069 uint digit = digitAt(shl, destination); 00070 00071 if (shl >= rows.size()) 00072 { 00073 EV << "Pastry: Unable to find next hop for " << destination 00074 << ", row is empty." << endl; 00075 return NodeHandle::UNSPECIFIED_NODE; 00076 } 00077 00078 const PastryExtendedNode& next = nodeAt(shl, digit); 00079 00080 if (next.node.isUnspecified()) 00081 { 00082 EV << "Pastry: Unable to find next hop for " << destination << 00083 ", routing table entry is empty." << endl; 00084 } 00085 return next.node; 00086 }
bool PastryRoutingTable::mergeNode | ( | const NodeHandle & | node, | |
simtime_t | prox | |||
) | [virtual] |
merge a node in the RoutingTable
node | the node to merge | |
prox | proximity value of the node |
Implements PastryStateObject.
00193 { 00194 uint shl; 00195 uint digit; 00196 PRTRow::iterator position; 00197 00198 shl = owner.key.sharedPrefixLength(node.key) / bitsPerDigit; 00199 digit = digitAt(shl, node.key); 00200 00201 while (rows.size() <= shl) addRow(); 00202 position = (rows.begin() + shl)->begin() + digit; 00203 if (position->node.isUnspecified() || (prox < position->rtt)) 00204 { 00205 EV << "Pastry: Node " << owner.key << endl; 00206 EV << " placing node " << node.key << "in row " 00207 << shl << ", col" << digit << endl; 00208 if (! position->node.isUnspecified()) 00209 { 00210 EV << " (replaced because of better proximity: " 00211 << prox << " < " << position->rtt << ")" << endl; 00212 } 00213 position->node = node; 00214 position->rtt = prox; 00215 return true; 00216 } 00217 return false; 00218 }
const PastryExtendedNode & PastryRoutingTable::nodeAt | ( | uint | row, | |
uint | col | |||
) | const [private] |
returns routing table entry at specified position
row | the number of the row | |
col | the number of the column |
00058 { 00059 if (rows.size() <= row) return unspecNode; 00060 if (col >= nodesPerRow) return unspecNode; 00061 00062 return *((rows.begin()+row)->begin()+col); 00063 }
const TransportAddress & PastryRoutingTable::repair | ( | const PastryStateMessage * | msg, | |
const PastryStateMsgProximity & | prox | |||
) | [virtual] |
attempt to repair the routing using a received REPAIR message
msg | the state message of type REPAIR | |
prox | record of proximity values matching the state message |
Reimplemented from PastryStateObject.
00313 { 00314 std::vector<PRTTrackRepair>::iterator it; 00315 simtime_t now = simTime(); 00316 00317 // first eliminate outdated entries in awaitingRepair: 00318 for (it = awaitingRepair.begin(); it != awaitingRepair.end();) 00319 { 00320 if (it->timestamp < (now - repairTimeout)) 00321 it = awaitingRepair.erase(it); 00322 else it++; 00323 } 00324 00325 // don't expect any more repair messages: 00326 if (awaitingRepair.empty()) return TransportAddress::UNSPECIFIED_NODE; 00327 00328 // look for source node in our list: 00329 for (it = awaitingRepair.begin(); it != awaitingRepair.end(); it++) 00330 if (it->node == msg->getSender()) break; 00331 00332 // if not found, return from function: 00333 if (it == awaitingRepair.end()) return TransportAddress::UNSPECIFIED_NODE; 00334 00335 // merge state: 00336 mergeState(msg, prox); 00337 00338 // repair not yet done? 00339 if (nodeAt(it->failedRow, it->failedCol).node.isUnspecified()) 00340 { 00341 // ask next node 00342 findNextNodeToAsk(*it); 00343 if (it->node.isUnspecified()) 00344 { 00345 // no more nodes to ask, give up: 00346 EV << "Pastry: RoutingTable giving up repair attempt." << endl; 00347 awaitingRepair.erase(it); 00348 return TransportAddress::UNSPECIFIED_NODE; 00349 } 00350 else return it->node; 00351 } 00352 00353 // repair done: clean up 00354 EV << "Pastry: RoutingTable repair was successful." << endl; 00355 awaitingRepair.erase(it); 00356 return TransportAddress::UNSPECIFIED_NODE; 00357 }
std::vector<PRTTrackRepair> PastryRoutingTable::awaitingRepair [private] |
uint PastryRoutingTable::bitsPerDigit [private] |
uint PastryRoutingTable::nodesPerRow [private] |
double PastryRoutingTable::repairTimeout [private] |
std::vector<PRTRow> PastryRoutingTable::rows [private] |