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407 lines (322 loc) · 13.7 KB
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/**
* @file
* @author Aapo Kyrola <akyrola@cs.cmu.edu>
* @version 1.0
*
* @section LICENSE
*
* Copyright [2012] [Aapo Kyrola, Guy Blelloch, Carlos Guestrin / Carnegie Mellon University]
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* @section DESCRIPTION
*
* Strongly Connected Components. Based on technical report (2012):
@article{salihoglucomputing,
title={Computing Strongly Connected Components in Pregel-like Systems},
author={Salihoglu, Semih and Widom, Jennifer},
publisher={Stanford InfoLab}
}
*/
#define SUPPORT_DELETIONS 1
#include <string>
#include <ostream>
#include "graphchi_basic_includes.hpp"
#include "util/labelanalysis.hpp"
using namespace graphchi;
/**
* Unlike in weakly connected components, we need
* to ensure that neighbors do not overwrite each
* others values. This is achieved by keeping two values
* in an edge. In this struct, smaller_one is the id of the
* vertex that has smaller id, and larger_one the others.
* This complexity is due to us ignoring the direction of an edge.
*/
struct bidirectional_label {
vid_t smaller_one;
vid_t larger_one;
vid_t & neighbor_label(vid_t myid, vid_t nbid) {
assert(larger_one != 0xffffffffu);
assert(smaller_one != 0xffffffffu);
if (myid < nbid) {
return larger_one;
} else {
return smaller_one;
}
}
vid_t & my_label(vid_t myid, vid_t nbid) {
assert(larger_one != 0xffffffffu);
assert(smaller_one != 0xffffffffu);
if (myid < nbid) {
return smaller_one;
} else {
return larger_one;
}
}
// Annoying hack
bool deleted() {
return smaller_one == 0xffffffffu;
}
};
int super_step = 0;
// Id for the output stream for contracted graph
int CONTRACTED_GRAPH_OUTPUT;
struct SCCinfo {
vid_t color;
bool confirmed;
SCCinfo() : color(0), confirmed(false) {}
SCCinfo(vid_t color) : color(color), confirmed(false) {}
SCCinfo(vid_t color, bool confirmed) : color(color), confirmed(confirmed) {}
friend std::ostream& operator<< (std::ostream &out, SCCinfo &scc) {
out << scc.color;
return out;
}
};
/* Overloaded operators to help with labelanalysis.hpp */
bool operator<(const SCCinfo &a, const SCCinfo &b);
bool operator<(const SCCinfo &a, const SCCinfo &b) {
return a.color < b.color;
}
bool operator==(const SCCinfo &a, const SCCinfo &b);
bool operator==(const SCCinfo &a, const SCCinfo &b) {
return a.color == b.color;
}
bool operator!=(const SCCinfo &a, const SCCinfo &b);
bool operator!=(const SCCinfo &a, const SCCinfo &b) {
return a.color != b.color;
}
typedef SCCinfo VertexDataType;
typedef bidirectional_label EdgeDataType;
static inline bool VARIABLE_IS_NOT_USED is_deleted_edge_value(bidirectional_label val);
static inline bool VARIABLE_IS_NOT_USED is_deleted_edge_value(bidirectional_label val) {
return 0xffffffffu == val.smaller_one;
}
static void VARIABLE_IS_NOT_USED remove_edgev(graphchi_edge<bidirectional_label> * e);
static void VARIABLE_IS_NOT_USED remove_edgev(graphchi_edge<bidirectional_label> * e) {
bidirectional_label deletedlabel;
deletedlabel.smaller_one = 0xffffffffu;
deletedlabel.larger_one = 0xffffffffu;
e->set_data(deletedlabel);
}
bool first_iteration = true;
bool remainingvertices = true;
/**
* FORWARD-PHASE
*/
struct SCCForward : public GraphChiProgram<VertexDataType, EdgeDataType> {
/**
* Vertex update function.
*/
void update(graphchi_vertex<VertexDataType, EdgeDataType> &vertex, graphchi_context &gcontext) {
if (first_iteration) {
vertex.set_data(SCCinfo(vertex.id()));
}
if (vertex.get_data().confirmed) {
if (vertex.num_edges() > 0) {
vertex.remove_alledges();
}
return;
}
/* Vertices with only in or out edges cannot be part of a SCC (Trimming) */
if (vertex.num_inedges() == 0 || vertex.num_outedges() == 0) {
if (vertex.num_edges() > 0) {
// TODO: check this logic!
vertex.set_data(SCCinfo(vertex.id(), true));
}
vertex.remove_alledges();
return;
}
remainingvertices = true;
VertexDataType vertexdata = vertex.get_data();
bool propagate = false;
if (gcontext.iteration == 0) {
vertexdata = vertex.id();
propagate = true;
/* Clean up in-edges. This would be nicer in the messaging abstraction... */
for(int i=0; i < vertex.num_inedges(); i++) {
bidirectional_label edgedata = vertex.inedge(i)->get_data();
if (!edgedata.deleted()) {
edgedata.my_label(vertex.id(), vertex.inedge(i)->vertexid) = vertex.id();
vertex.inedge(i)->set_data(edgedata);
}
}
} else {
/* Loop over in-edges and choose minimum color */
vid_t minid = vertexdata.color;
for(int i=0; i < vertex.num_inedges(); i++) {
if (!vertex.inedge(i)->get_data().deleted()) {
minid = std::min(minid, vertex.inedge(i)->get_data().neighbor_label(vertex.id(), vertex.inedge(i)->vertexid));
}
}
if (minid != vertexdata.color) {
vertexdata.color = minid;
propagate = true;
}
}
vertex.set_data(vertexdata);
if (propagate) {
for(int i=0; i < vertex.num_outedges(); i++) {
bidirectional_label edgedata = vertex.outedge(i)->get_data();
if (!edgedata.deleted()) {
edgedata.my_label(vertex.id(), vertex.outedge(i)->vertexid) = vertexdata.color;
vertex.outedge(i)->set_data(edgedata);
gcontext.scheduler->add_task(vertex.outedge(i)->vertexid, true);
}
}
}
}
void after_iteration(int iteration, graphchi_context &gcontext) {
first_iteration = false;
}
};
/**
* BACKWARD phase
*/
struct SCCBackward : public GraphChiProgram<VertexDataType, EdgeDataType> {
/**
* Vertex update function.
*/
void update(graphchi_vertex<VertexDataType, EdgeDataType> &vertex, graphchi_context &gcontext) {
if (vertex.get_data().confirmed) {
return;
}
VertexDataType vertexdata = vertex.get_data();
bool propagate = false;
if (gcontext.iteration == 0) {
/* "Leader" of the SCC */
if (vertexdata.color == vertex.id()) {
propagate = true;
vertex.remove_alloutedges();
}
} else {
/* Loop over in-edges and see if there is a match */
bool match = false;
for(int i=0; i < vertex.num_outedges(); i++) {
if (!vertex.outedge(i)->get_data().deleted()) {
if (vertex.outedge(i)->get_data().neighbor_label(vertex.id(), vertex.outedge(i)->vertexid) == vertexdata.color) {
match = true;
break;
}
}
}
if (match) {
propagate = true;
vertex.remove_alloutedges();
vertex.set_data(SCCinfo(vertexdata.color, true));
} else {
vertex.set_data(SCCinfo(vertex.id(), false));
}
}
if (propagate) {
for(int i=0; i < vertex.num_inedges(); i++) {
bidirectional_label edgedata = vertex.inedge(i)->get_data();
if (!edgedata.deleted()) {
edgedata.my_label(vertex.id(), vertex.inedge(i)->vertexid) = vertexdata.color;
vertex.inedge(i)->set_data(edgedata);
gcontext.scheduler->add_task(vertex.inedge(i)->vertexid, true);
}
}
}
}
void before_iteration(int iteration, graphchi_context &gcontext) {}
void after_iteration(int iteration, graphchi_context &gcontext) {}
void before_exec_interval(vid_t window_st, vid_t window_en, graphchi_context &gcontext) { }
void after_exec_interval(vid_t window_st, vid_t window_en, graphchi_context &gcontext) {}
};
graphchi_engine<VertexDataType, EdgeDataType> * gengine = NULL;
/* Simple contraction step that just outputs the non-deleted edges. Would be better
done automatically, but the dynamic engine is a bit flaky. */
struct ContractionStep : public GraphChiProgram<VertexDataType, EdgeDataType> {
ContractionStep() {
}
void update(graphchi_vertex<VertexDataType, EdgeDataType> &vertex, graphchi_context &gcontext) {
// Loop over only in-edges and output them. This way deleted edges won't be included.
for(int i=0; i < vertex.num_inedges(); i++) {
graphchi_edge<EdgeDataType> * e = vertex.inedge(i);
((sharded_graph_output<VertexDataType, EdgeDataType> *)gengine->output(CONTRACTED_GRAPH_OUTPUT))->output_edgeval(e->vertex_id(), vertex.id(),
e->get_data());
}
}
};
int main(int argc, const char ** argv) {
/* GraphChi initialization will read the command line
arguments and the configuration file. */
graphchi_init(argc, argv);
global_logger().set_log_level(LOG_DEBUG);
/* Metrics object for keeping track of performance counters
and other information. Currently required. */
metrics m("strongly-connected-components");
/* Basic arguments for application */
std::string filename = get_option_string("file"); // Base filename
bool scheduler = true;
/* Detect the number of shards or preprocess an input to create them */
int nshards = find_shards<EdgeDataType>(filename);
if (nshards > 0) {
delete_shards<EdgeDataType>(filename, nshards);
}
nshards = convert_if_notexists<EdgeDataType>(filename,
get_option_string("nshards", "auto"));
/* Run */
while(remainingvertices) {
std::cout << "STARTING SUPER STEP: " << super_step << std::endl;
super_step++;
remainingvertices = false;
SCCForward forwardSCC;
graphchi_engine<VertexDataType, EdgeDataType> engine(filename, nshards, scheduler, m);
if (first_iteration) {
engine.set_reset_vertexdata(true);
}
engine.set_save_edgesfiles_after_inmemmode(true);
engine.run(forwardSCC, 1000);
if (remainingvertices) {
std::cout << "STARTING BACKWARD " << std::endl;
SCCBackward backwardSCC;
graphchi_engine<VertexDataType, EdgeDataType> engine2(filename, nshards, scheduler, m);
engine2.set_save_edgesfiles_after_inmemmode(true);
engine2.run(backwardSCC, 1000);
int orig_numshards = (int) engine2.get_intervals().size();
if (orig_numshards > 1) {
metrics_entry me = m.start_time();
// Contract deleted edges --- this is a bit hacky solution, as the dynamic engine would
// do it automatically. But currently one cannot call the dynamic engine repetitively.
graphchi_engine<VertexDataType, EdgeDataType> engine3(filename, nshards, false, m);
std::string contractedname = filename + "C";
ContractionStep contraction;
sharded_graph_output<VertexDataType, EdgeDataType> shardedout(contractedname, NULL);
gengine = &engine3;
CONTRACTED_GRAPH_OUTPUT = (int)engine3.add_output(&shardedout);
engine3.set_disable_vertexdata_storage();
engine3.set_modifies_inedges(false);
engine3.set_modifies_outedges(false);
engine3.set_disable_outedges(true);
engine3.run(contraction, 1);
// Copy vertex file
std::string old_vertex_filename = filename_vertex_data<VertexDataType>(filename);
std::string new_vertex_filename = filename_vertex_data<VertexDataType>(contractedname);
rename(old_vertex_filename.c_str(), new_vertex_filename.c_str());
// Clean up
delete_shards<EdgeDataType>(filename, orig_numshards);
nshards = (int)shardedout.finish_sharding();
filename = contractedname;
gengine = NULL;
logstream(LOG_INFO) << "New filename: " << filename << ", edges:" << shardedout.num_edges() << std::endl;
m.stop_time(me, "runtime"); // include sharding in runtime
}
}
}
analyze_labels<VertexDataType>(filename);
delete_shards<EdgeDataType>(filename, nshards);
/* Report execution metrics */
metrics_report(m);
return 0;
}
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