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use std::collections::HashMap;
use timely::dataflow::{InputHandle, ProbeHandle};
use timely::dataflow::operators::{Feedback, ConnectLoop, Probe};
use timely::dataflow::operators::generic::Operator;
use timely::dataflow::channels::pact::Exchange;
fn main() {
timely::execute_from_args(std::env::args().skip(3), move |worker| {
let mut input = InputHandle::new();
let probe = ProbeHandle::new();
worker.dataflow::<usize,_,_>(|scope| {
// create a new input, into which we can push edge changes.
let edge_stream = input.to_stream(scope);
// create a new feedback stream, which will be changes to ranks.
let (handle, rank_stream) = scope.feedback(1);
// bring edges and ranks together!
let changes = edge_stream.binary_frontier(
rank_stream,
Exchange::new(|x: &((usize, usize), i64)| (x.0).0 as u64),
Exchange::new(|x: &(usize, i64)| x.0 as u64),
"PageRank",
|_capability, _info| {
// where we stash out-of-order data.
let mut edge_stash: HashMap<_, Vec<_>> = HashMap::new();
let mut rank_stash: HashMap<_, Vec<_>> = HashMap::new();
// lists of edges, ranks, and changes.
let mut edges = Vec::new();
let mut ranks = Vec::new();
let mut diffs = Vec::new(); // for received but un-acted upon deltas.
let mut delta = Vec::new();
let timer = ::std::time::Instant::now();
move |(input1, frontier1), (input2, frontier2), output| {
// hold on to edge changes until it is time.
input1.for_each_time(|time, data| {
let entry = edge_stash.entry(time.retain(output.output_index())).or_default();
data.for_each(|data| entry.append(data));
});
// hold on to rank changes until it is time.
input2.for_each_time(|time, data| {
let entry = rank_stash.entry(time.retain(output.output_index())).or_default();
data.for_each(|data| entry.append(data));
});
let frontiers = &[frontier1, frontier2];
for (time, edge_changes) in edge_stash.iter_mut() {
if frontiers.iter().all(|f| !f.less_equal(time)) {
let mut session = output.session(time);
compact(edge_changes);
for ((src, dst), diff) in edge_changes.drain(..) {
// 0. ensure enough state allocated
while edges.len() <= src { edges.push(Vec::new()); }
while ranks.len() <= src { ranks.push(1_000); }
while diffs.len() <= src { diffs.push(0); }
// 1. subtract previous distribution.
allocate(ranks[src], &edges[src][..], &mut delta);
for x in delta.iter_mut() { x.1 *= -1; }
// 2. update edges.
edges[src].push((dst, diff));
compact(&mut edges[src]);
// 3. re-distribute allocations.
allocate(ranks[src], &edges[src][..], &mut delta);
// 4. compact down and send cumulative changes.
compact(&mut delta);
for (dst, diff) in delta.drain(..) {
session.give((dst, diff));
}
}
}
}
edge_stash.retain(|_key, val| !val.is_empty());
for (time, rank_changes) in rank_stash.iter_mut() {
if frontiers.iter().all(|f| !f.less_equal(time)) {
let mut session = output.session(time);
compact(rank_changes);
let mut cnt = 0;
let mut sum = 0;
let mut max = 0;
for (src, diff) in rank_changes.drain(..) {
cnt += 1;
sum += diff.abs();
max = if max < diff.abs() { diff.abs() } else { max };
// 0. ensure enough state allocated
while edges.len() <= src { edges.push(Vec::new()); }
while ranks.len() <= src { ranks.push(1_000); }
while diffs.len() <= src { diffs.push(0); }
// 1. subtract previous distribution.
allocate(ranks[src], &edges[src][..], &mut delta);
for x in delta.iter_mut() { x.1 *= -1; }
// 2. update ranks.
diffs[src] += diff;
if diffs[src].abs() >= 6 {
ranks[src] += diffs[src];
diffs[src] = 0;
}
// 3. re-distribute allocations.
allocate(ranks[src], &edges[src][..], &mut delta);
// 4. compact down and send cumulative changes.
compact(&mut delta);
for (dst, diff) in delta.drain(..) {
session.give((dst, diff));
}
}
println!("{:?}:\t{:?}\t{}\t{}\t{}", timer.elapsed(), time.time(), cnt, sum, max);
}
}
rank_stash.retain(|_key, val| !val.is_empty());
}
}
);
changes
.probe_with(&probe)
.connect_loop(handle);
});
let nodes: usize = std::env::args().nth(1).unwrap().parse().unwrap();
let edges: usize = std::env::args().nth(2).unwrap().parse().unwrap();
let index = worker.index();
// Generate roughly random data.
use std::hash::{BuildHasher, BuildHasherDefault, DefaultHasher};
let hasher = BuildHasherDefault::<DefaultHasher>::new();
let mut insert = (0..).map(move |i| (hasher.hash_one(&(i,index,0)) as usize % nodes,
hasher.hash_one(&(i,index,1)) as usize % nodes));
let remove = insert.clone();
for ins in (&mut insert).take(edges / worker.peers()) {
input.send((ins, 1));
}
input.advance_to(1);
while probe.less_than(input.time()) {
worker.step();
}
for (ins, del) in insert.zip(remove).take(1000) {
input.send((ins, 1));
input.send((del,-1));
input.advance_to(input.time() + 1);
while probe.less_than(input.time()) {
worker.step();
}
}
}).unwrap(); // asserts error-free execution;
}
fn compact<T: Ord>(list: &mut Vec<(T, i64)>) {
if !list.is_empty() {
list.sort_by(|x,y| x.0.cmp(&y.0));
for i in 0 .. list.len() - 1 {
if list[i].0 == list[i+1].0 {
list[i+1].1 += list[i].1;
list[i].1 = 0;
}
}
list.retain(|x| x.1 != 0);
}
}
// this method allocates some rank between elements of `edges`.
fn allocate(rank: i64, edges: &[(usize, i64)], send: &mut Vec<(usize, i64)>) {
if !edges.is_empty() {
assert!(rank >= 0);
assert!(edges.iter().all(|x| x.1 > 0));
let distribute = (rank * 5) / 6;
let degree = edges.len() as i64;
let share = distribute / degree;
for i in 0 .. edges.len() {
if (i as i64) < (distribute % (edges.len() as i64)) {
send.push((edges[i].0, edges[i].1 * (share + 1)));
}
else {
send.push((edges[i].0, edges[i].1 * share));
}
}
}
}