#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::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 }
const NodeHandle & PastryRoutingTable::lookupNextHop | ( | const OverlayKey & | destination | ) |
gets the next hop according to the Pastry routing scheme.
destination | the destination key |
00067 { 00068 if (destination == owner.key) opp_error("trying to lookup own key!"); 00069 00070 uint shl = owner.key.sharedPrefixLength(destination) / bitsPerDigit; 00071 uint digit = digitAt(shl, destination); 00072 00073 if (shl >= rows.size()) 00074 { 00075 EV << "Pastry: Unable to find next hop for " << destination 00076 << ", row is empty." << endl; 00077 return NodeHandle::UNSPECIFIED_NODE; 00078 } 00079 00080 const PastryExtendedNode& next = nodeAt(shl, digit); 00081 00082 if (next.node.isUnspecified()) 00083 { 00084 EV << "Pastry: Unable to find next hop for " << destination << 00085 ", routing table entry is empty." << endl; 00086 } 00087 return next.node; 00088 }
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.
00092 { 00093 if (destination == owner.key) 00094 opp_error("trying to find closer node to own key!"); 00095 00096 const PastryExtendedNode* entry; 00097 00098 if (optimize) 00099 { 00100 // pointer to later return value, initialize to unspecified, so 00101 // the specialCloserCondition() check will be done against our own 00102 // node as long as no node closer to the destination than our own was 00103 // found. 00104 const NodeHandle* ret = &NodeHandle::UNSPECIFIED_NODE; 00105 00106 // a numerically closer node can only be found in the row containing 00107 // nodes with the same prefix length and in the row above. 00108 int shl = owner.key.sharedPrefixLength(destination) / bitsPerDigit; 00109 int digit = digitAt(shl, destination); 00110 int x = digitAt(shl, owner.key); // position index of own node 00111 00112 // first try the row with same prefix length: 00113 int n = nodesPerRow; 00114 int a = digit - 1; // position index of search to the left 00115 int b = digit + 1; // position index of search to the right 00116 00117 while ((a >= 0) || (b < n)) 00118 { 00119 // no need to continue search in one direction when own entry is 00120 // reached: 00121 if (a == x) a = -1; 00122 if (b == x) b = n; 00123 00124 if (a >= 0) 00125 { 00126 entry = &(nodeAt(shl, a)); 00127 if ((!entry->node.isUnspecified()) && 00128 specialCloserCondition(entry->node, destination, *ret)) 00129 ret = &(entry->node); 00130 a--; 00131 } 00132 if (b < n) 00133 { 00134 entry = &(nodeAt(shl, b)); 00135 if ((!entry->node.isUnspecified()) && 00136 specialCloserCondition(entry->node, destination, *ret)) 00137 ret = &(entry->node); 00138 b++; 00139 } 00140 } 00141 00142 // it this was not the first row, two more nodes to check: 00143 if (shl != 0) 00144 { 00145 // go up one row: 00146 x = digitAt(--shl, owner.key); 00147 00148 if (destination < owner.key) 00149 { 00150 entry = &(nodeAt(shl, digit - 1)); 00151 if ((!entry->node.isUnspecified()) && 00152 specialCloserCondition(entry->node, destination, *ret)) 00153 ret = &(entry->node); 00154 } 00155 else 00156 { 00157 entry = &(nodeAt(shl, digit + 1)); 00158 if ((!entry->node.isUnspecified()) && 00159 specialCloserCondition(entry->node, destination, *ret)) 00160 ret = &(entry->node); 00161 } 00162 } 00163 00164 return *ret; // still unspecified if no closer node was found 00165 } 00166 else 00167 { 00168 // no optimization, return the first closer node found 00169 for (uint y = 0; y < rows.size(); ++y) 00170 { 00171 for (uint x = 0; x < nodesPerRow; ++x) 00172 { 00173 entry = &(nodeAt(y, x)); 00174 if ((!entry->node.isUnspecified()) && 00175 specialCloserCondition(entry->node, destination)) 00176 return entry->node; 00177 } 00178 } 00179 00180 return NodeHandle::UNSPECIFIED_NODE; 00181 } 00182 }
const TransportAddress & PastryRoutingTable::failedNode | ( | const TransportAddress & | failed | ) | [virtual] |
tells the routing table that a node has failed
failed | the failed node |
Implements PastryStateObject.
00279 { 00280 std::vector<PRTRow>::iterator itRows; 00281 PRTRow::iterator itCols; 00282 PRTTrackRepair tmpTrack; 00283 00284 bool found = false; 00285 00286 // find node in table: 00287 for (itRows = rows.begin(); itRows != rows.end(); itRows++) 00288 { 00289 for (itCols = itRows->begin(); itCols != itRows->end(); itCols++) 00290 { 00291 if ((! itCols->node.isUnspecified()) && 00292 (itCols->node.ip == failed.ip)) 00293 { 00294 itCols->node = NodeHandle::UNSPECIFIED_NODE; 00295 itCols->rtt = PASTRY_PROX_UNDEF; 00296 found = true; 00297 break; 00298 } 00299 } 00300 if (found) break; 00301 } 00302 00303 // not found, nothing to do: 00304 if (!found) return TransportAddress::UNSPECIFIED_NODE; 00305 00306 // else fill temporary record: 00307 tmpTrack.failedRow = itRows - rows.begin(); 00308 tmpTrack.failedCol = itCols - itRows->begin(); 00309 tmpTrack.node = TransportAddress::UNSPECIFIED_NODE; 00310 findNextNodeToAsk(tmpTrack); 00311 tmpTrack.timestamp = simTime(); 00312 00313 if (tmpTrack.node.isUnspecified()) 00314 return TransportAddress::UNSPECIFIED_NODE; 00315 awaitingRepair.push_back(tmpTrack); 00316 return awaitingRepair.back().node; 00317 }
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.
00321 { 00322 std::vector<PRTTrackRepair>::iterator it; 00323 simtime_t now = simTime(); 00324 00325 // first eliminate outdated entries in awaitingRepair: 00326 for (it = awaitingRepair.begin(); it != awaitingRepair.end();) 00327 { 00328 if (it->timestamp < (now - repairTimeout)) 00329 it = awaitingRepair.erase(it); 00330 else it++; 00331 } 00332 00333 // don't expect any more repair messages: 00334 if (awaitingRepair.empty()) return TransportAddress::UNSPECIFIED_NODE; 00335 00336 // look for source node in our list: 00337 for (it = awaitingRepair.begin(); it != awaitingRepair.end(); it++) 00338 if (it->node == msg->getSender()) break; 00339 00340 // if not found, return from function: 00341 if (it == awaitingRepair.end()) return TransportAddress::UNSPECIFIED_NODE; 00342 00343 // merge state: 00344 mergeState(msg, prox); 00345 00346 // repair not yet done? 00347 if (nodeAt(it->failedRow, it->failedCol).node.isUnspecified()) 00348 { 00349 // ask next node 00350 findNextNodeToAsk(*it); 00351 if (it->node.isUnspecified()) 00352 { 00353 // no more nodes to ask, give up: 00354 EV << "Pastry: RoutingTable giving up repair attempt." << endl; 00355 awaitingRepair.erase(it); 00356 return TransportAddress::UNSPECIFIED_NODE; 00357 } 00358 else return it->node; 00359 } 00360 00361 // repair done: clean up 00362 EV << "Pastry: RoutingTable repair was successful." << endl; 00363 awaitingRepair.erase(it); 00364 return TransportAddress::UNSPECIFIED_NODE; 00365 }
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.
00185 { 00186 uint i = 0; 00187 std::vector<PRTRow>::const_iterator itRows; 00188 PRTRow::const_iterator itCols; 00189 00190 msg->setRoutingTableArraySize(rows.size() * nodesPerRow); 00191 00192 for (itRows = rows.begin(); itRows != rows.end(); itRows++) 00193 for (itCols = itRows->begin(); itCols != itRows->end(); itCols++) 00194 msg->setRoutingTable(i++, itCols->node); 00195 }
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.
00198 { 00199 if (node.key == owner.key) 00200 opp_error("trying to merge node with same key!"); 00201 00202 uint shl; 00203 uint digit; 00204 PRTRow::iterator position; 00205 00206 shl = owner.key.sharedPrefixLength(node.key) / bitsPerDigit; 00207 digit = digitAt(shl, node.key); 00208 00209 while (rows.size() <= shl) addRow(); 00210 position = (rows.begin() + shl)->begin() + digit; 00211 if (position->node.isUnspecified() || (prox < position->rtt)) 00212 { 00213 EV << "Pastry: Node " << owner.key << endl; 00214 EV << " placing node " << node.key << "in row " 00215 << shl << ", col" << digit << endl; 00216 if (! position->node.isUnspecified()) 00217 { 00218 EV << " (replaced because of better proximity: " 00219 << prox << " < " << position->rtt << ")" << endl; 00220 } 00221 position->node = node; 00222 position->rtt = prox; 00223 return true; 00224 } 00225 return false; 00226 }
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 |
00231 { 00232 std::vector<PastryStateMessage*>::const_iterator itMsg; 00233 std::vector<PastryStateMsgProximity>::const_iterator itProx; 00234 PastryStateMessage* msg; 00235 int hopCheck = 0; 00236 00237 itProx = proximities.begin(); 00238 for (itMsg = messages.begin(); itMsg != messages.end(); itMsg++) 00239 { 00240 msg = *itMsg; 00241 if (msg->getJoinHopCount() != ++hopCheck) return false; 00242 mergeState(msg, *(itProx++)); 00243 } 00244 return true; 00245 }
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.
00249 { 00250 std::vector<PRTRow>::const_iterator itRows; 00251 PRTRow::const_iterator itCols; 00252 00253 for (itRows = rows.begin(); itRows != rows.end(); itRows++) 00254 for (itCols = itRows->begin(); itCols != itRows->end(); itCols++) 00255 if (!itCols->node.isUnspecified()) 00256 affected.push_back(itCols->node); 00257 }
void PastryRoutingTable::earlyInit | ( | void | ) | [private, virtual] |
void PastryRoutingTable::addRow | ( | void | ) | [private] |
adds a new line to the routing table
00260 { 00261 PRTRow row(nodesPerRow, unspecNode); 00262 00263 // place own node at correct position: 00264 (row.begin() + digitAt(rows.size(), owner.key))->node = owner; 00265 rows.push_back(row); 00266 }
uint32_t PastryRoutingTable::digitAt | ( | uint | n, | |
const OverlayKey & | key | |||
) | const [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 }
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 }
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 |
00368 { 00369 const TransportAddress* ask; 00370 00371 if (track.node.isUnspecified()) 00372 { 00373 track.askedRow = track.failedRow; 00374 if (track.failedCol == 0) 00375 track.askedCol = 1; 00376 else 00377 track.askedCol = 0; 00378 ask = static_cast<const TransportAddress*>( 00379 &(nodeAt(track.askedRow, track.askedCol).node)); 00380 track.node = *ask; 00381 if ( (! track.node.isUnspecified()) && 00382 (track.node != owner) ) 00383 return; 00384 } 00385 00386 do 00387 { 00388 // point to next possible position in routing table: 00389 track.askedCol++; 00390 if ((track.askedRow == track.failedRow) && 00391 (track.askedCol == track.failedCol)) track.askedCol++; 00392 if (track.askedCol == nodesPerRow) 00393 { 00394 if ((track.askedRow > track.askedCol) || 00395 (track.askedRow == (rows.size() - 1))) 00396 { 00397 // no more nodes that could be asked, give up: 00398 track.node = TransportAddress::UNSPECIFIED_NODE; 00399 return; 00400 } 00401 track.askedRow++; 00402 track.askedCol = 0; 00403 } 00404 00405 ask = static_cast<const TransportAddress*>( 00406 &(nodeAt(track.askedRow, track.askedCol).node)); 00407 track.node = *ask; 00408 } 00409 while (track.node.isUnspecified() || (track.node == owner) ); 00410 }
uint PastryRoutingTable::bitsPerDigit [private] |
double PastryRoutingTable::repairTimeout [private] |
uint PastryRoutingTable::nodesPerRow [private] |
std::vector<PRTRow> PastryRoutingTable::rows [private] |
std::vector<PRTTrackRepair> PastryRoutingTable::awaitingRepair [private] |