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YuruToot/app/models/concerns/account_counters.rb
Claire 526332c545
Fix account deletion sometimes failing because of optimistic locks (#16317)
* Fix account deletion sometimes failing because of optimistic locks

In some rare occasions[1], deleting accounts would fail with a
`StaleObjectError` exception.

Indeed, account deletion manually sets the `AccountStat` values without
handling cases where the optimistic locking on `AccountStat` would fail.

To my knowledge, with the rewrite of account counters in #15913, the
`DeleteAccountService` is now the only place that changes the counters in
a way that is not atomic.

Since in this specific case, we do not care about the previous values of the
account counters, it appears we don't need locking at all for this table
anymore.

[1]: https://discourse.joinmastodon.org/t/account-cant-be-deleted/3602

* Bump MAX_SUPPORTED_VERSION in maintenance script
2021-06-02 17:41:25 +02:00

88 lines
2.8 KiB
Ruby

# frozen_string_literal: true
module AccountCounters
extend ActiveSupport::Concern
ALLOWED_COUNTER_KEYS = %i(statuses_count following_count followers_count).freeze
included do
has_one :account_stat, inverse_of: :account
after_save :save_account_stat
end
delegate :statuses_count,
:statuses_count=,
:following_count,
:following_count=,
:followers_count,
:followers_count=,
:last_status_at,
to: :account_stat
# @param [Symbol] key
def increment_count!(key)
update_count!(key, 1)
end
# @param [Symbol] key
def decrement_count!(key)
update_count!(key, -1)
end
# @param [Symbol] key
# @param [Integer] value
def update_count!(key, value)
raise ArgumentError, "Invalid key #{key}" unless ALLOWED_COUNTER_KEYS.include?(key)
raise ArgumentError, 'Do not call update_count! on dirty objects' if association(:account_stat).loaded? && account_stat&.changed? && account_stat.changed_attribute_names_to_save == %w(id)
value = value.to_i
default_value = value.positive? ? value : 0
# We do an upsert using manually written SQL, as Rails' upsert method does
# not seem to support writing expressions in the UPDATE clause, but only
# re-insert the provided values instead.
# Even ARel seem to be missing proper handling of upserts.
sql = if value.positive? && key == :statuses_count
<<-SQL.squish
INSERT INTO account_stats(account_id, #{key}, created_at, updated_at, last_status_at)
VALUES (:account_id, :default_value, now(), now(), now())
ON CONFLICT (account_id) DO UPDATE
SET #{key} = account_stats.#{key} + :value,
last_status_at = now(),
updated_at = now()
RETURNING id;
SQL
else
<<-SQL.squish
INSERT INTO account_stats(account_id, #{key}, created_at, updated_at)
VALUES (:account_id, :default_value, now(), now())
ON CONFLICT (account_id) DO UPDATE
SET #{key} = account_stats.#{key} + :value,
updated_at = now()
RETURNING id;
SQL
end
sql = AccountStat.sanitize_sql([sql, account_id: id, default_value: default_value, value: value])
account_stat_id = AccountStat.connection.exec_query(sql)[0]['id']
# Reload account_stat if it was loaded, taking into account newly-created unsaved records
if association(:account_stat).loaded?
account_stat.id = account_stat_id if account_stat.new_record?
account_stat.reload
end
end
def account_stat
super || build_account_stat
end
private
def save_account_stat
return unless association(:account_stat).loaded? && account_stat&.changed?
account_stat.save
end
end