66   SnapshotImpl* New(SnapshotImpl* s, SequenceNumber seq, uint64_t unix_time,  in New()  argument
68     s->number_ = seq;  in New()
69     s->unix_time_ = unix_time;  in New()
70     s->is_write_conflict_boundary_ = is_write_conflict_boundary;  in New()
71     s->list_ = this;  in New()
72     s->next_ = &list_;  in New()
73     s->prev_ = list_.prev_;  in New()
74     s->prev_->next_ = s;  in New()
75     s->next_->prev_ = s;  in New()
77     return s;  in New()
81   void Delete(const SnapshotImpl* s) {  in Delete()  argument
82     assert(s->list_ == this);  in Delete()
83     s->prev_->next_ = s->next_;  in Delete()
84     s->next_->prev_ = s->prev_;  in Delete()
112     const SnapshotImpl* s = &list_;  variable
113     while (s->next_ != &list_) {
114       if (s->next_->number_ > max_seq) {
118       if (ret.empty() || ret.back() != s->next_->number_) {
119         ret.push_back(s->next_->number_);
124           s->next_->is_write_conflict_boundary_) {
127         *oldest_write_conflict_snapshot = s->next_->number_;
130       s = s->next_;