feat(sqlite): add sqlite support

[no-on3]

this #287
Tests fixed.

[muco-rolle]

Thank you @animir for bringing the support of SQLite. When is this planned to be released?

[animir]

@no-on3 Hello, can you make it atomic upsert?

All limiters from this package do atomic upserts. If there is no way to implement the same with SQLite, please, rename the class to RateLimiterSQLiteNonAtomic.

[muco-rolle]

I believe SQLite supports atomic upserts. Here's how the code would look. I haven't tested it in depth, but if @no-on3 isn't available, I'd be happy to look into it and add it.

_upsert(rlKey, points, msDuration, forceExpire = false) {
    if (!this.tableCreated) {
      return Promise.reject(Error("Table is not created yet"));
    }

    return new Promise((resolve, reject) => {
      const dateNow = Date.now();
      const newExpire = msDuration > 0 ? dateNow + msDuration : null;

      this.client.serialize(() => {
        this.client.run("BEGIN TRANSACTION", (err) => {
          if (err) return reject(err);

          let query, params;

          if (forceExpire) {
            query = `
            INSERT INTO ${this.tableName} (key, points, expire)
            VALUES (?, ?, ?)
            ON CONFLICT(key) DO UPDATE SET
              points = excluded.points,
              expire = excluded.expire
          `;
            params = [rlKey, points, newExpire];
          } else {
            query = `
            INSERT INTO ${this.tableName} (key, points, expire)
            VALUES (?, ?, ?)
            ON CONFLICT(key) DO UPDATE SET
              points = CASE
                WHEN (expire > ? OR expire IS NULL) THEN points + excluded.points
                ELSE excluded.points
              END,
              expire = CASE
                WHEN (expire > ? OR expire IS NULL) THEN expire
                ELSE excluded.expire
              END
          `;
            params = [rlKey, points, newExpire, dateNow, dateNow];
          }

          this.client.run(query, params, (errUpsert) => {
            if (errUpsert) {
              this.client.run("ROLLBACK");
              return reject(errUpsert);
            }

            this.client.get(
              `SELECT points, expire FROM ${this.tableName} WHERE key = ?`,
              [key],
              (errSelect, result) => {
                if (errSelect) {
                  this.client.run("ROLLBACK");
                  return reject(errSelect);
                }

                this.client.run("COMMIT", (errCommit) => {
                  if (errCommit) {
                    this.client.run("ROLLBACK");
                    return reject(errCommit);
                  }
                  resolve(result || { points, expire: newExpire });
                });
              }
            );
          });
        });
      });
    });
  }