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# Pleroma: A lightweight social networking server
# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Activity.HTML do
alias Pleroma.HTML
alias Pleroma.Object
@cachex Pleroma.Config.get([:cachex, :provider], Cachex)
# We store a list of cache keys related to an activity in a
# separate cache, scrubber_management_cache. It has the same
# size as scrubber_cache (see application.ex). Every time we add
# a cache to scrubber_cache, we update scrubber_management_cache.
#
# The most recent write of a certain key in the management cache
# is the same as the most recent write of any record related to that
# key in the main cache.
# Assuming LRW ( https://hexdocs.pm/cachex/Cachex.Policy.LRW.html ),
# this means when the management cache is evicted by cachex, all
# related records in the main cache will also have been evicted.
defp get_cache_keys_for(activity_id) do
with {:ok, list} when is_list(list) <- @cachex.get(:scrubber_management_cache, activity_id) do
list
else
_ -> []
end
end
defp add_cache_key_for(activity_id, additional_key) do
current = get_cache_keys_for(activity_id)
unless additional_key in current do
@cachex.put(:scrubber_management_cache, activity_id, [additional_key | current])
end
end
def invalidate_cache_for(activity_id) do
keys = get_cache_keys_for(activity_id)
Enum.map(keys, &@cachex.del(:scrubber_cache, &1))
@cachex.del(:scrubber_management_cache, activity_id)
end
def get_cached_scrubbed_html_for_activity(
content,
scrubbers,
activity,
key \\ "",
callback \\ fn x -> x end
) do
key = "#{key}#{generate_scrubber_signature(scrubbers)}|#{activity.id}"
@cachex.fetch!(:scrubber_cache, key, fn _key ->
object = Object.normalize(activity, fetch: false)
add_cache_key_for(activity.id, key)
HTML.ensure_scrubbed_html(content, scrubbers, object.data["fake"] || false, callback)
end)
end
def get_cached_stripped_html_for_activity(content, activity, key) do
get_cached_scrubbed_html_for_activity(
content,
FastSanitize.Sanitizer.StripTags,
activity,
key,
&HtmlEntities.decode/1
)
end
defp generate_scrubber_signature(scrubber) when is_atom(scrubber) do
generate_scrubber_signature([scrubber])
end
defp generate_scrubber_signature(scrubbers) do
Enum.reduce(scrubbers, "", fn scrubber, signature ->
"#{signature}#{to_string(scrubber)}"
end)
end
end
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