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streaming/stream_transfer_task: avoid pointless iterations in has_relevant_range_on_this_shard()

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When has_relevant_range_on_this_shard() found a relevant range, it will unnecessarily
iterate through the end. Verified manually that this could be thousands of pointless
iterations when streaming data to a node just added. The relevant code could be
simplified by de-futurizing it but I think it remains so to allow task scheduler
to preempt it if necessary.

Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <20200220224048.28804-2-raphaelsc@scylladb.com>
This commit is contained in:
Raphael S. Carvalho
2020-02-20 19:40:48 -03:00
committed by Pekka Enberg
parent 8a986bc23b
commit 40e75fb109
1 changed files with 5 additions and 2 deletions
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7
streaming/stream_transfer_task.cc
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@@ -99,8 +99,10 @@ struct send_info {
, reader(cf.make_streaming_reader(cf.schema(), prs)) {
}
future<bool> has_relevant_range_on_this_shard() {
return do_with(false, [this] (bool& found_relevant_range) {
return do_for_each(ranges, [this, &found_relevant_range] (dht::token_range range) {
return do_with(false, ranges.begin(), [this] (bool& found_relevant_range, dht::token_range_vector::iterator& ranges_it) {
auto stop_cond = [this, &found_relevant_range, &ranges_it] { return ranges_it == ranges.end() || found_relevant_range; };
return do_until(std::move(stop_cond), [this, &found_relevant_range, &ranges_it] {
dht::token_range range = *ranges_it++;
if (!found_relevant_range) {
auto sharder = dht::selective_token_range_sharder(cf.schema()->get_partitioner(), std::move(range), engine().cpu_id());
auto range_shard = sharder.next();
@@ -108,6 +110,7 @@ struct send_info {
found_relevant_range = true;
}
}
return make_ready_future<>();
}).then([&found_relevant_range] {
return found_relevant_range;
});