discourse/app/models/topic_link.rb
Guo Xiang Tan 44eba0bb60 FIX: Don't rescue PG::UniqueViolation within a transaction.
Also acquire a transaction per link instead of failing when
any of the links can't be processed.

This prevents ActiveRecord from rolling back the transaction
and the next SQL statement sent to PG will fail. This is
however hard to test as it only happens when there are
two competing process trying to process this method at the
same time.
2018-10-18 10:54:30 +08:00

312 lines
10 KiB
Ruby

require 'uri'
require_dependency 'slug'
require_dependency 'discourse'
class TopicLink < ActiveRecord::Base
def self.max_domain_length
100
end
def self.max_url_length
500
end
belongs_to :topic
belongs_to :user
belongs_to :post
belongs_to :link_topic, class_name: 'Topic'
belongs_to :link_post, class_name: 'Post'
validates_presence_of :url
validates_length_of :url, maximum: 500
validates_uniqueness_of :url, scope: [:topic_id, :post_id]
has_many :topic_link_clicks, dependent: :destroy
validate :link_to_self
after_commit :crawl_link_title
# Make sure a topic can't link to itself
def link_to_self
errors.add(:base, "can't link to the same topic") if (topic_id == link_topic_id)
end
def self.topic_map(guardian, topic_id)
# Sam: complicated reports are really hard in AR
builder = DB.build <<-SQL
SELECT ftl.url,
COALESCE(ft.title, ftl.title) AS title,
ftl.link_topic_id,
ftl.reflection,
ftl.internal,
ftl.domain,
MIN(ftl.user_id) AS user_id,
SUM(clicks) AS clicks
FROM topic_links AS ftl
LEFT JOIN topics AS ft ON ftl.link_topic_id = ft.id
LEFT JOIN categories AS c ON c.id = ft.category_id
/*where*/
GROUP BY ftl.url, ft.title, ftl.title, ftl.link_topic_id, ftl.reflection, ftl.internal, ftl.domain
ORDER BY clicks DESC, count(*) DESC
LIMIT 50
SQL
builder.where('ftl.topic_id = :topic_id', topic_id: topic_id)
builder.where('ft.deleted_at IS NULL')
# note that ILIKE means "case insensitive LIKE"
builder.where("NOT(ftl.url ILIKE '%.png' OR ftl.url ILIKE '%.jpg' OR ftl.url ILIKE '%.gif')")
builder.where("COALESCE(ft.archetype, 'regular') <> :archetype", archetype: Archetype.private_message)
# do not show links with 0 click
builder.where("clicks > 0")
builder.secure_category(guardian.secure_category_ids)
builder.query
end
def self.counts_for(guardian, topic, posts)
return {} if posts.blank?
# Sam: this is not tidy in AR and also happens to be a critical path
# for topic view
builder = DB.build("SELECT
l.post_id,
l.url,
l.clicks,
COALESCE(t.title, l.title) AS title,
l.internal,
l.reflection,
l.domain
FROM topic_links l
LEFT JOIN topics t ON t.id = l.link_topic_id
LEFT JOIN categories AS c ON c.id = t.category_id
/*where*/
ORDER BY reflection ASC, clicks DESC")
builder.where('t.deleted_at IS NULL')
builder.where("COALESCE(t.archetype, 'regular') <> :archetype", archetype: Archetype.private_message)
# not certain if pluck is right, cause it may interfere with caching
builder.where('l.post_id in (:post_ids)', post_ids: posts.map(&:id))
builder.secure_category(guardian.secure_category_ids)
result = {}
builder.query.each do |l|
result[l.post_id] ||= []
result[l.post_id] << { url: l.url,
clicks: l.clicks,
title: l.title,
internal: l.internal,
reflection: l.reflection }
end
result
end
def self.extract_from(post)
return if post.blank? || post.whisper?
added_urls = []
reflected_ids = []
PrettyText
.extract_links(post.cooked)
.map do |u|
uri = begin
URI.parse(u.url)
rescue URI::Error
end
[u, uri]
end
.reject { |_, p| p.nil? || "mailto".freeze == p.scheme }
.uniq { |_, p| p }
.each do |link, parsed|
TopicLink.transaction do
begin
url = link.url
internal = false
topic_id = nil
post_number = nil
if upload = Upload.get_from_url(url)
internal = Discourse.store.internal?
# Store the same URL that will be used in the cooked version of the post
url = UrlHelper.cook_url(upload.url)
elsif route = Discourse.route_for(parsed)
internal = true
# We aren't interested in tracking internal links to users
next if route[:controller] == 'users'
topic_id = route[:topic_id].to_i
post_number = route[:post_number] || 1
# Store the canonical URL
topic = Topic.find_by(id: topic_id)
topic_id = nil unless topic
if topic.present?
url = "#{Discourse.base_url_no_prefix}#{topic.relative_url}"
url << "/#{post_number}" if post_number.to_i > 1
end
end
# Skip linking to ourselves
next if topic_id == post.topic_id
reflected_post = nil
if post_number && topic_id
reflected_post = Post.find_by(topic_id: topic_id, post_number: post_number.to_i)
end
url = url[0...TopicLink.max_url_length]
next if parsed && parsed.host && parsed.host.length > TopicLink.max_domain_length
added_urls << url
unless TopicLink.exists?(topic_id: post.topic_id, post_id: post.id, url: url)
file_extension = File.extname(parsed.path)[1..10].downcase unless parsed.path.nil? || File.extname(parsed.path).empty?
begin
TopicLink.create!(post_id: post.id,
user_id: post.user_id,
topic_id: post.topic_id,
url: url,
domain: parsed.host || Discourse.current_hostname,
internal: internal,
link_topic_id: topic_id,
link_post_id: reflected_post.try(:id),
quote: link.is_quote,
extension: file_extension)
rescue ActiveRecord::RecordNotUnique
# it's fine
end
end
# Create the reflection if we can
if topic_id.present?
topic = Topic.find_by(id: topic_id)
if topic && post.topic && topic.archetype != 'private_message' && post.topic.archetype != 'private_message' && post.topic.visible?
prefix = Discourse.base_url_no_prefix
reflected_url = "#{prefix}#{post.topic.relative_url(post.post_number)}"
tl = TopicLink.find_by(topic_id: topic_id,
post_id: reflected_post.try(:id),
url: reflected_url)
unless tl
tl = TopicLink.create(user_id: post.user_id,
topic_id: topic_id,
post_id: reflected_post.try(:id),
url: reflected_url,
domain: Discourse.current_hostname,
reflection: true,
internal: true,
link_topic_id: post.topic_id,
link_post_id: post.id)
end
reflected_ids << tl.id if tl.persisted?
end
end
rescue URI::Error
# if the URI is invalid, don't store it.
rescue ActionController::RoutingError
# If we can't find the route, no big deal
end
end
# Remove links that aren't there anymore
if added_urls.present?
TopicLink.where(
"(url not in (:urls)) AND (post_id = :post_id AND NOT reflection)",
urls: added_urls, post_id: post.id
).delete_all
reflected_ids.compact!
if reflected_ids.present?
TopicLink.where(
"(id not in (:reflected_ids)) AND (link_post_id = :post_id AND reflection)",
reflected_ids: reflected_ids, post_id: post.id
).delete_all
else
TopicLink
.where("link_post_id = :post_id AND reflection", post_id: post.id)
.delete_all
end
else
TopicLink
.where(
"(post_id = :post_id AND NOT reflection) OR (link_post_id = :post_id AND reflection)",
post_id: post.id
)
.delete_all
end
end
end
# Crawl a link's title after it's saved
def crawl_link_title
Jobs.enqueue(:crawl_topic_link, topic_link_id: id)
end
def self.duplicate_lookup(topic)
results = TopicLink
.includes(:post, :user)
.joins(:post, :user)
.where("posts.id IS NOT NULL AND users.id IS NOT NULL")
.where(topic_id: topic.id, reflection: false)
.last(200)
lookup = {}
results.each do |tl|
normalized = tl.url.downcase.sub(/^https?:\/\//, '').sub(/\/$/, '')
lookup[normalized] = { domain: tl.domain,
username: tl.user.username_lower,
posted_at: tl.post.created_at,
post_number: tl.post.post_number }
end
lookup
end
end
# == Schema Information
#
# Table name: topic_links
#
# id :integer not null, primary key
# topic_id :integer not null
# post_id :integer
# user_id :integer not null
# url :string(500) not null
# domain :string(100) not null
# internal :boolean default(FALSE), not null
# link_topic_id :integer
# created_at :datetime not null
# updated_at :datetime not null
# reflection :boolean default(FALSE)
# clicks :integer default(0), not null
# link_post_id :integer
# title :string
# crawled_at :datetime
# quote :boolean default(FALSE), not null
# extension :string(10)
#
# Indexes
#
# index_topic_links_on_extension (extension)
# index_topic_links_on_link_post_id_and_reflection (link_post_id,reflection)
# index_topic_links_on_post_id (post_id)
# index_topic_links_on_topic_id (topic_id)
# unique_post_links (topic_id,post_id,url) UNIQUE
#