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VoteRepository.ts
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VoteRepository.ts
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import DB from '../DB';
export type VoteWithUsername = {
vote: number;
username: string;
userId: number;
voterId: number;
};
export type UserRatingOnSubsite = {
site_id: number;
site_name: string;
subdomain: string;
comment_rating: number;
post_rating: number;
};
export default class VoteRepository {
private db: DB;
constructor(db: DB) {
this.db = db;
}
async getUserVote(userId: number, byUserId: number): Promise<number> {
const voteResult = await this.db.fetchOne<{ vote: number }>(
'select vote from user_karma where user_id=:user_id and voter_id=:voter_id', {
user_id: userId,
voter_id: byUserId
});
return voteResult?.vote || 0;
}
private async setVotes(entityId: number, vote: number, userId: number,
comments: boolean): Promise<number> {
const entityField = comments ? 'comment_id' : 'post_id';
const entityVotesTable = comments ? 'comment_votes' : 'post_votes';
const entityTable = comments ? 'comments' : 'posts';
const userSiteRatingField = comments ? 'comment_rating' : 'post_rating';
const [entitySite, authorId] = await this.db.fetchOne<{
site_id: string, author_id: string
}>(`select site_id, author_id
from ${entityTable}
where ${entityField} = :entity_id`, {
entity_id: entityId
}).then(res => [parseInt(res.site_id), parseInt(res.author_id)]);
await this.db.query(`insert ignore into ${entityVotesTable} ( ${entityField}, voter_id, vote ) values ( :entity_id, :voter_id, 0 )`, {
entity_id: entityId,
voter_id: userId,
});
await this.db.query(`insert ignore into user_site_rating (user_id, site_id, ${userSiteRatingField} ) values ( :user_id, :site_id, 0 )`, {
user_id: authorId,
site_id: entitySite,
});
return await this.db.inTransaction(async conn => {
// Important! transaction must start with locking the most "coarse" table first (entity table)
// to prevent deadlocks
// tricky: related tables (entity_votes), are implicitly locking records in the entity table
const prevRating = await conn.fetchOne<{ rating: string; }>(
`select rating
from ${entityTable}
where ${entityField} = :entity_id
FOR UPDATE /* locks the row */`, {
entity_id: entityId
}).then(res => Number(res.rating || 0));
const prevVote = await conn.fetchOne<{ vote: string; }>(
`select vote
from ${entityVotesTable}
where ${entityField} = :entity_id
and voter_id = :voter_id
FOR UPDATE` /* Locks the row, or waits for the lock */, {
entity_id: entityId,
voter_id: userId
}).then(res => Number(res.vote || 0));
if (prevVote === vote) {
return prevRating;
}
await conn.query(
`update ${entityVotesTable}
set vote=:vote
where ${entityField} = :entity_id
and voter_id = :voter_id
and vote = :prev_vote`, {
entity_id: entityId,
voter_id: userId,
vote: vote,
prev_vote: prevVote
});
await conn.query(
`update ${entityTable}
set rating=rating + :delta
where ${entityField} = :entity_id`, {
entity_id: entityId,
delta: vote - prevVote
});
// lock the row to prevent concurrent updates
await conn.query(
`select ${userSiteRatingField}
from user_site_rating
where user_id = :user_id
and site_id = :site_id
FOR UPDATE` /*locks the row*/, {
user_id: authorId,
site_id: entitySite
});
await conn.query(`update user_site_rating
set ${userSiteRatingField}=${userSiteRatingField} + :delta
where user_id = :user_id
and site_id = :site_id`, {
user_id: authorId,
site_id: entitySite,
delta: vote - prevVote
});
return prevRating + vote - prevVote;
});
}
async postSetVote(postId: number, vote: number, userId: number): Promise<number> {
return this.setVotes(postId, vote, userId, false);
}
async commentSetVote(commentId: number, vote: number, userId: number): Promise<number> {
return this.setVotes(commentId, vote, userId, true);
}
async userSetVote(toUserId: number, vote: number, voterId: number): Promise<number> {
return await this.db.inTransaction(async conn => {
await conn.query('insert into user_karma (user_id, voter_id, vote) values (:user_id, :voter_id, :vote) on duplicate key update vote=:vote', {
user_id: toUserId,
voter_id: voterId,
vote: vote
});
const ratingResult = await conn.fetchOne<{ rating: number }>('select sum(vote) rating from user_karma where user_id=:user_id', {
user_id: toUserId
});
const rating = Number(ratingResult.rating || 0);
await conn.query('update users set karma=:karma where user_id=:user_id', {
karma: rating,
user_id: toUserId
});
return rating;
});
}
async getPostVotes(postId: number): Promise<VoteWithUsername[]> {
return await this.db.fetchAll(`select u.username, v.vote, u.user_id as userId, v.voter_id as voterId
from post_votes v
join users u on (v.voter_id = u.user_id)
where v.post_id = :post_id
order by voted_at desc`, {
post_id: postId
});
}
async getCommentVotes(commentId: number): Promise<VoteWithUsername[]> {
return await this.db.fetchAll(`select u.username, v.vote, u.user_id as userId, v.voter_id as voterId
from comment_votes v
join users u on (v.voter_id = u.user_id)
where v.comment_id = :comment_id
order by voted_at desc`, {
comment_id: commentId
});
}
/**
* Returns votes FOR a user (votes made by other users)
* @param userId for whom to get votes
*/
async getUserVotes(userId: number): Promise<VoteWithUsername[]> {
return await this.db.fetchAll(`select u.username, v.vote, v.user_id as userId, v.voter_id as voterId
from user_karma v
join users u on (v.voter_id = u.user_id)
where v.user_id = :user_id and v.vote != 0
order by voted_at desc`, {
user_id: userId
});
}
async getSecondaryVotes(primaryVoters: number[]): Promise<VoteWithUsername[]> {
if (primaryVoters.length === 0) {
return [];
}
return await this.db.fetchAll(
`select u.username, v.vote as vote, v.user_id as userId, v.voter_id as voterId
from user_karma v join users u on (v.voter_id = u.user_id)
where v.user_id in (:primary_voters) and (v.vote != 0)
`, {
primary_voters: primaryVoters
});
}
/**
* Returns votes BY a user (votes FOR other users).
* @param userId whose votes to get
*/
async getVotesByUser(userId: number): Promise<VoteWithUsername[]> {
return await this.db.fetchAll(`select u.username, v.vote, v.user_id as userId, v.voter_id as voterId
from user_karma v
join users u on (v.user_id = u.user_id)
where v.voter_id = :user_id
order by voted_at desc`, {
user_id: userId
});
}
async getUserRatingOnSubsites(userId: number): Promise<UserRatingOnSubsite[]> {
return await this.db.fetchAll(
`select usr.site_id as site_id, comment_rating, post_rating, s.name as site_name, subdomain
from user_site_rating usr
left join sites s on (usr.site_id = s.site_id)
where user_id = :user_id`, {
user_id: userId
});
}
getTrialsApprovers(userId: number): Promise<VoteWithUsername[]> {
return this.db.fetchAll(`select u.username, v.vote, v.user_id as userId, v.voter_id as voterId
from user_trial_approvers v
join users u on (v.voter_id = u.user_id)
where v.user_id = :user_id`, {
user_id: userId
});
}
}