protected function init_cookie() {

		$cookie = $this->get_cookie();

		$set_cookie = false;

		if ( $cookie ) {

			$this->id       = $cookie[0];
			$this->expires  = $cookie[1];
			$this->expiring = $cookie[2];
			$this->data     = $this->read( $this->id );

			// If the user has logged in, update the session data.
			$update_id = $this->maybe_update_id();

			// If the session is nearing expiration, update the session.
			$extend_expiration = $this->maybe_extend_expiration();

			// If either of these two items are true, the cookie needs to be updated.
			$set_cookie = $update_id || $extend_expiration;

		} else {

			$this->id   = $this->generate_id();
			$this->data = array();
			$this->set_expiration();

			/**
			 * Defer emitting the session cookie until session data is actually written.
			 *
			 * The session stays in memory only (no `Set-Cookie` header, no database row)
			 * until `set()` stores something, which keeps anonymous, cache-eligible
			 * responses free of a `Set-Cookie` header. The cookie is emitted from `set()`
			 * the moment the first piece of data is written.
			 */
			$this->is_new = true;
			$set_cookie   = false;

		}

		if ( $set_cookie ) {
			$this->set_cookie();
		}
	}