int walks_per_source() {

return 100;

}

bool is_source(vid_t v) {

return (v % 50 == 0);

}

/**

void update(graphchi_vertex<VertexDataType, EdgeDataType > &vertex, graphchi_context &gcontext) {

if (gcontext.iteration == 0) {

if (is_source(vertex.id())) {

for(int i=0; i < walks_per_source(); i++) {

/* Get random out edge's vector */

graphchi_edge<EdgeDataType> * outedge = vertex.random_outedge();

if (outedge != NULL) {

chivector<vid_t> * evector = outedge->get_vector();

/* Add a random walk particle, represented by the vertex-id of the source (this vertex) */

evector->add(vertex.id());

gcontext.scheduler->add_task(outedge->vertex_id()); // Schedule destination

}

}

}

vertex.set_data(0);

} else {

/* Check inbound edges for walks and advance them. */

int num_walks = 0;

for(int i=0; i < vertex.num_inedges(); i++) {

graphchi_edge<EdgeDataType> * edge = vertex.inedge(i);

chivector<vid_t> * invector = edge->get_vector();

for(int j=0; j < invector->size(); j++) {

/* Get one walk */

vid_t walk = invector->get(j);

/* Move to a random out-edge */

graphchi_edge<EdgeDataType> * outedge = vertex.random_outedge();

if (outedge != NULL) {

chivector<vid_t> * outvector = outedge->get_vector();

/* Add a random walk particle, represented by the vertex-id of the source (this vertex) */

outvector->add(walk);

gcontext.scheduler->add_task(outedge->vertex_id()); // Schedule destination

}

num_walks ++;

}

/* Remove all walks from the inbound vector */

invector->clear();

}

/* Keep track of the walks passed by via this vertex */

vertex.set_data(vertex.get_data() + num_walks);

}

}

/**

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 initialization will read the command line

graphchi_init(argc, argv);

/* Metrics object for keeping track of performance counters

metrics m("randomwalk");

/* Basic arguments for application */

std::string filename = get_option_string("file"); // Base filename

int niters = get_option_int("niters", 4); // Number of iterations

bool scheduler = true; // Whether to use selective scheduling

/* Detect the number of shards or preprocess an input to create them */

bool preexisting_shards;

int nshards = convert_if_notexists<vid_t>(filename, get_option_string("nshards", "auto"), preexisting_shards);

/* Run */

RandomWalkProgram program;

graphchi_engine<VertexDataType, EdgeDataType> engine(filename, nshards, scheduler, m);

if (preexisting_shards) {

engine.reinitialize_edge_data(0);

}

engine.run(program, niters);

/* List top 20 */

int ntop = 20;

std::vector< vertex_value<VertexDataType> > top = get_top_vertices<VertexDataType>(filename, ntop);

std::cout << "Print top 20 vertices: " << std::endl;

for(int i=0; i < (int) top.size(); i++) {

std::cout << (i+1) << ". " << top[i].vertex << "\t" << top[i].value << std::endl;

}

/* Report execution metrics */

metrics_report(m);

return 0;