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handle crawl timestamps in db

This commit is contained in:
Tao Bojlén 2019-08-07 16:53:34 +00:00
parent 1e4cebb26b
commit f0f3f76f6c
5 changed files with 72 additions and 122 deletions
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31
backend/lib/backend/crawler/crawler.ex
View File

@ -119,14 +119,24 @@ defmodule Backend.Crawler do
user_count: result.user_count,
status_count: result.status_count,
type: instance_type,
base_domain: get_base_domain(domain)
base_domain: get_base_domain(domain),
next_crawl: NaiveDateTime.add(now, get_config(:crawl_interval_mins) * 60, :second)
}
Repo.insert!(
instance,
on_conflict:
{:replace,
[:description, :version, :user_count, :status_count, :type, :base_domain, :updated_at]},
[
:description,
:version,
:user_count,
:status_count,
:type,
:base_domain,
:updated_at,
:next_crawl
]},
conflict_target: :domain
)
@ -153,7 +163,7 @@ defmodule Backend.Crawler do
peers =
peers_domains
|> Enum.map(&%{domain: &1, inserted_at: now, updated_at: now})
|> Enum.map(&%{domain: &1, inserted_at: now, updated_at: now, next_crawl: now})
Instance
|> Repo.insert_all(peers, on_conflict: :nothing, conflict_target: :domain)
@ -220,6 +230,8 @@ defmodule Backend.Crawler do
end
defp save(%{domain: domain, error: error, allows_crawling?: allows_crawling}) do
now = get_now()
error =
cond do
not allows_crawling -> "robots.txt"
@ -227,13 +239,22 @@ defmodule Backend.Crawler do
true -> "unknown error"
end
# The "+1" is this error!
error_count = get_recent_crawl_error_count(domain) + 1
# The crawl interval grows exponentially at first but never goes above 24 hours
crawl_interval_mins =
min(get_config(:crawl_interval_mins) * round(:math.pow(2, error_count)), 1440)
next_crawl = NaiveDateTime.add(now, crawl_interval_mins * 60, :second)
Repo.transaction(fn ->
Repo.insert!(
%Instance{
domain: domain,
base_domain: get_base_domain(domain)
base_domain: get_base_domain(domain),
next_crawl: next_crawl
},
on_conflict: {:replace, [:base_domain]},
on_conflict: {:replace, [:next_crawl]},
conflict_target: :domain
)

124
backend/lib/backend/crawler/stale_instance_manager.ex
View File

@ -1,6 +1,6 @@
defmodule Backend.Crawler.StaleInstanceManager do
use GenServer
alias Backend.{Crawl, Instance, Repo}
alias Backend.{Instance, Repo}
import Ecto.Query
import Backend.Util
require Logger
@ -49,10 +49,14 @@ defmodule Backend.Crawler.StaleInstanceManager do
end
defp queue_stale_domains() do
now = get_now()
stale_domains =
get_live_domains_to_crawl()
|> MapSet.union(get_dead_domains_to_crawl())
|> MapSet.union(get_new_domains_to_crawl())
Instance
|> select([i], i.domain)
|> where([i], i.next_crawl < ^now)
|> Repo.all()
|> MapSet.new()
# Don't add a domain that's already in the queue
domains_in_queue = get_domains_in_queue(stale_domains)
@ -68,118 +72,6 @@ defmodule Backend.Crawler.StaleInstanceManager do
{:run, [domain]} |> Honeydew.async(:crawl_queue)
end
# Handles instances where the most recent crawl was successful
@spec get_live_domains_to_crawl() :: MapSet.t()
defp get_live_domains_to_crawl() do
interval_mins = -1 * get_config(:crawl_interval_mins)
most_recent_crawl_subquery =
Crawl
|> select([c], %{
instance_domain: c.instance_domain,
inserted_at: max(c.inserted_at)
})
|> group_by([c], c.instance_domain)
Instance
|> join(:left, [i], most_recent_crawl in subquery(most_recent_crawl_subquery),
on: i.domain == most_recent_crawl.instance_domain
)
# Joining on a timestamp is really gross, but since we're joining on a timestamp in the same table, we should be OK.
|> join(:left, [i, most_recent_crawl], crawls in Crawl,
on:
i.domain == crawls.instance_domain and most_recent_crawl.inserted_at == crawls.inserted_at
)
|> where(
[i, most_recent_crawl, crawls],
is_nil(crawls.error) and
most_recent_crawl.inserted_at <
datetime_add(^NaiveDateTime.utc_now(), ^interval_mins, "minute") and not i.opt_out
)
|> select([i], i.domain)
|> Repo.all()
|> MapSet.new()
end
# Handles instances that have never been crawled at all.
@spec get_new_domains_to_crawl() :: MapSet.t()
defp get_new_domains_to_crawl() do
all_crawls_subquery =
Crawl
|> select([c], %{
instance_domain: c.instance_domain,
crawl_count: count(c.id)
})
|> group_by([c], c.instance_domain)
Instance
|> join(:left, [i], c in subquery(all_crawls_subquery), on: i.domain == c.instance_domain)
|> where([i, c], (is_nil(c.crawl_count) or c.crawl_count == 0) and not i.opt_out)
|> select([i], i.domain)
|> Repo.all()
|> MapSet.new()
end
# Handles instances where the previous crawl(s) were unsuccessful.
# These are crawled with an increasing delay
@spec get_dead_domains_to_crawl() :: MapSet.t()
defp get_dead_domains_to_crawl() do
now = get_now()
interval_mins = get_config(:crawl_interval_mins)
most_recent_successful_crawl_subquery =
Crawl
|> select([c], %{
instance_domain: c.instance_domain,
timestamp: max(c.inserted_at)
})
|> where([c], is_nil(c.error))
|> group_by([c], c.instance_domain)
Instance
|> join(
:left,
[i],
most_recent_successful_crawl in subquery(most_recent_successful_crawl_subquery),
on: i.domain == most_recent_successful_crawl.instance_domain
)
|> join(:left, [i, most_recent_successful_crawl_subquery], crawls in Crawl,
on: i.domain == crawls.instance_domain
)
|> select([i, most_recent_successful_crawl, crawls], %{
domain: i.domain,
most_recent_crawl: max(crawls.inserted_at),
failed_crawls: count(crawls.id)
})
|> group_by([i, most_recent_successful_crawl, crawls], i.domain)
|> where(
[i, most_recent_successful_crawl, crawls],
crawls.inserted_at > most_recent_successful_crawl.timestamp and not i.opt_out
)
|> Repo.all()
# We now have a list of domains, the # of failed crawls, and the most recent crawl timestamp.
# Now we filter down to those that should be crawled now.
|> Enum.map(fn %{
domain: domain,
most_recent_crawl: most_recent_crawl,
failed_crawls: failed_crawls
} ->
# The interval is never more than 24 hours
curr_interval = min(1440, interval_mins * round(:math.pow(2, failed_crawls)))
next_crawl = NaiveDateTime.add(most_recent_crawl, curr_interval * 60, :second)
%{
domain: domain,
next_crawl: next_crawl
}
end)
|> Enum.filter(fn %{next_crawl: next_crawl} ->
NaiveDateTime.compare(now, next_crawl) == :gt
end)
|> Enum.map(fn %{domain: domain} -> domain end)
|> MapSet.new()
end
@spec get_domains_in_queue(MapSet.t()) :: MapSet.t()
defp get_domains_in_queue(domains) do
Honeydew.filter(:crawl_queue, fn job ->

4
backend/lib/backend/instance.ex
View File

@ -14,6 +14,7 @@ defmodule Backend.Instance do
field :base_domain, :string
field :opt_in, :boolean
field :opt_out, :boolean
field :next_crawl, :naive_datetime
many_to_many :peers, Backend.Instance,
join_through: Backend.InstancePeer,
@ -43,7 +44,8 @@ defmodule Backend.Instance do
:statuses_per_day,
:base_domain,
:opt_in,
:opt_out
:opt_out,
:next_crawl
])
|> validate_required([:domain])
|> put_assoc(:peers, attrs.peers)

24
backend/lib/backend/util.ex
View File

@ -167,4 +167,28 @@ defmodule Backend.Util do
def convert_keys_to_atoms(map) do
map |> Map.new(fn {k, v} -> {String.to_atom(k), v} end)
end
# Given a domain, returns the number of n most recent crawls that errored
@spec get_recent_crawl_error_count(String.t()) :: integer
def get_recent_crawl_error_count(domain) do
most_recent_success_crawl_subquery =
Crawl
|> select([c], %{
instance_domain: c.instance_domain,
timestamp: max(c.inserted_at)
})
|> where([c], c.instance_domain == ^domain and is_nil(c.error))
|> group_by([c], c.instance_domain)
Crawl
|> join(:left, [c1], c2 in subquery(most_recent_success_crawl_subquery),
on: c1.instance_domain == c2.instance_domain
)
|> where(
[c1, c2],
c1.instance_domain == ^domain and (c1.inserted_at > c2.timestamp or is_nil(c2.timestamp))
)
|> select([c1, c2], count(c1.id))
|> Repo.one()
end
end

11
backend/priv/repo/migrations/20190807155906_add_next_crawl_to_instances.exs Normal file
View File

@ -0,0 +1,11 @@
defmodule Backend.Repo.Migrations.AddNextCrawlToInstances do
use Ecto.Migration
def change do
alter table(:instances) do
add :next_crawl, :naive_datetime
end
create index(:instances, [:next_crawl])
end
end