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Commit8b256c1

Browse files
knizhnikkelvich
authored andcommitted
Implement Bron-Kerbosch algiruithm for clique detection
1 parent3a62970 commit8b256c1

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3 files changed

+117
-0
lines changed

3 files changed

+117
-0
lines changed

‎bkb.c

Lines changed: 111 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,111 @@
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/*
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* Bron–Kerbosch algorithm to find maximum clque in graph
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*/
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typedefstruct {
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intsize;
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intnodes[MAX_NODES];
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}List;
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staticvoidlist_append(List*list,intn)
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{
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nodes[list->size++]=n;
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}
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staticvoidlist_copy(List*dst,List*src)
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{
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inti;
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intn=src->size;
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dst->size=n;
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for (i=0;i<n;i++) {
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dst->nodes[i]=src->nodes[i];
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}
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}
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staticvoidfindMaximumIndependentSet(List*cur,List*result,nodemask_t*graph,int*oldSet,intne,intce)
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{
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intnod=0;
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intminnod=ce;
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intfixp=-1;
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ints=-1;
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inti,j;
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intnewSet[MAX_NODES];
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for (i=0;i<ce&&minnod!=0;i++) {
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intp=oldSet[i];
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intcnt=0;
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intpos=-1;
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for (j=ne;j<ce;j++) {
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if (!BIT_CHECK(graph[p],oldSet[j])) {
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if (++cnt==minnod)
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break;
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pos=j;
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}
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}
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if (minnod>cnt) {
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minnod=cnt;
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fixp=p;
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if (i<ne) {
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s=pos;
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}else {
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s=i;
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nod=1;
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}
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}
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}
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for (intk=minnod+nod;k >=1;k--) {
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intsel=oldSet[s];
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oldSet[s]=oldSet[ne];
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oldSet[ne]=sel;
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intnewne=0;
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for (inti=0;i<ne;i++) {
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if (BIT_CHECK(graph[sel],oldSet[i])) {
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newSet[newne++]=oldSet[i];
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}
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}
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intnewce=newne;
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for (inti=ne+1;i<ce;i++) {
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if (BIT_CHECK(graph[sel],oldSet[i])) {
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newSet[newce++]=oldSet[i];
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}
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}
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list_append(cur,sel);
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if (newce==0) {
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if (result->size<cur->size) {
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list_copy(result,cur);
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}
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}elseif (newne<newce) {
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if (cur->size+newce-newne>result->size) {
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findMaximumIndependentSet(cur,result,graph,newSet,newne,newce);
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}
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}
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cur.size-=1;
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if (k>1) {
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for (s=++ne;BIT_CHECK(graph[fixp],oldSet[s]);s++);
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}
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}
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}
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nodemask_tMtmFindMaxClique(nodemask_t*graphs,inn_nodes);
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{
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Listtmp;
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Listresult;
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nodemask_tmask=0;
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intall[MAX_NODES];
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inti;
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tmp.size=0;
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result.size=0;
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for (i=0;i<n_nodes;i++) {
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all[i]=i;
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}
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findMaximumIndependentSet(&tmp,&result,graph,all,0,n_nodes);
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for (i=0;i<result.size;i++) {
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mask |= (nodemask_t)1 <<result.nodes[i];
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}
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return ~mask;
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}

‎multimaster.c

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1023,6 +1023,10 @@ _PG_init(void)
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if (MtmNodes<2) {
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elog(ERROR,"Multimaster should have at least two nodes");
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}
1026+
if (MtmNodes>MAX_NODES) {
1027+
elog(ERROR,"Multimaster with mor than %d nodes is not currently supported",MAX_NODES);
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}
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BgwPoolStart(MtmWorkers,MtmPoolConstructor);
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MtmArbiterInitialize();

‎multimaster.h

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -25,6 +25,7 @@
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#defineAnum_mtm_ddl_log_issued1
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#defineAnum_mtm_ddl_log_query2
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#defineMAX_NODES 64
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typedefuint64csn_t;/* commit serial number */
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#defineINVALID_CSN ((csn_t)-1)
@@ -146,5 +147,6 @@ extern MtmState* MtmGetState(void);
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externtimestamp_tMtmGetCurrentTime(void);
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externvoidMtmSleep(timestamp_tinterval);
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externboolMtmIsRecoveredNode(intnodeId);
150+
externnodemask_tMtmFindMaxClique(nodemask_t*matrix,inn_modes);
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#endif

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