blob: 862ec35e2f6c5762152a1bad28eb4dc28ec06242 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
|
#pragma once
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include <chrono>
namespace DB
{
/// Simple class for checking expired sessions. Main idea -- to round sessions
/// timeouts and place all sessions into buckets rounded by their expired time.
/// So we will have not too many different buckets and can check expired
/// sessions quite fast.
/// So buckets looks like this:
/// [1630580418000] -> {1, 5, 6}
/// [1630580418500] -> {2, 3}
/// ...
/// When new session appear it's added to the existing bucket or create new bucket.
class SessionExpiryQueue
{
private:
/// Session -> timeout ms
std::unordered_map<int64_t, int64_t> session_to_expiration_time;
/// Expire time -> session expire near this time
std::map<int64_t, std::unordered_set<int64_t>> expiry_to_sessions;
int64_t expiration_interval;
static int64_t getNowMilliseconds()
{
using namespace std::chrono;
return duration_cast<milliseconds>(system_clock::now().time_since_epoch()).count();
}
/// Round time to the next expiration interval. The result used as a key for
/// expiry_to_sessions map.
int64_t roundToNextInterval(int64_t time) const
{
return (time / expiration_interval + 1) * expiration_interval;
}
public:
/// expiration_interval -- how often we will check new sessions and how small
/// buckets we will have. In ZooKeeper normal session timeout is around 30 seconds
/// and expiration_interval is about 500ms.
explicit SessionExpiryQueue(int64_t expiration_interval_)
: expiration_interval(expiration_interval_)
{
}
/// Session was actually removed
bool remove(int64_t session_id);
/// Update session expiry time (must be called on heartbeats)
void addNewSessionOrUpdate(int64_t session_id, int64_t timeout_ms);
/// Get all expired sessions
std::vector<int64_t> getExpiredSessions() const;
void clear();
};
}
|
