momento_functions_collections_common/
lib.rs

1//! Common types shared across Momento Cache collection interfaces.
2
3use std::time::Duration;
4
5/// Represents the desired behavior for managing the TTL on collections.
6///
7/// The first time the collection is created, it needs to set a TTL. For subsequent operations
8/// that modify the collection, you may choose to update the TTL in order to prolong the life
9/// of the cached collection, or to leave the TTL unmodified to ensure the collection expires
10/// at the original TTL.
11#[derive(Copy, Clone, Debug, PartialEq, Eq)]
12pub struct CollectionTtl {
13    ttl: Duration,
14    refresh: bool,
15}
16
17impl CollectionTtl {
18    /// Create a collection TTL with the provided `ttl` and `refresh` settings.
19    pub const fn new(ttl: Duration, refresh: bool) -> Self {
20        Self { ttl, refresh }
21    }
22
23    /// Create a collection TTL that updates the TTL for the collection any time it is
24    /// modified.
25    pub fn refresh_on_update(ttl: impl Into<Duration>) -> Self {
26        Self::new(ttl.into(), true)
27    }
28
29    /// Create a collection TTL that will not refresh the TTL for the collection when
30    /// it is updated.
31    ///
32    /// Use this if you want to be sure that the collection expires at the originally
33    /// specified time, even if you make modifications to the value of the collection.
34    ///
35    /// The TTL will still be used when a new collection is created.
36    pub fn initialize_only(ttl: impl Into<Duration>) -> Self {
37        Self::new(ttl.into(), false)
38    }
39
40    /// Return a new collection TTL which uses the same TTL but refreshes on updates.
41    pub fn with_refresh_on_update(self) -> Self {
42        Self::new(self.ttl(), true)
43    }
44
45    /// Return a new collection TTL which uses the same TTL but does not refresh on
46    /// updates.
47    pub fn with_no_refresh_on_update(self) -> Self {
48        Self::new(self.ttl(), false)
49    }
50
51    /// Return a new collection TTL which has the same refresh behavior but uses the
52    /// provided TTL.
53    pub fn with_ttl(self, ttl: impl Into<Duration>) -> Self {
54        Self::new(ttl.into(), self.refresh())
55    }
56
57    /// Constructs a CollectionTtl with the specified TTL. The TTL for the collection will be
58    /// refreshed any time the collection is modified.
59    pub fn of(ttl: Duration) -> Self {
60        Self::new(ttl, true)
61    }
62
63    /// The [`Duration`] after which the cached collection should be expired from the
64    /// cache.
65    pub fn ttl(&self) -> Duration {
66        self.ttl
67    }
68
69    /// Whether the collection's TTL will be refreshed on every update.
70    ///
71    /// If true, this will extend the time at which the collection would expire when
72    /// an update operation happens. Otherwise, the collection's TTL will only be set
73    /// when it is initially created.
74    pub fn refresh(&self) -> bool {
75        self.refresh
76    }
77}
78
79/// Saturate a Duration to u64 milliseconds, clamping at u64::MAX.
80pub fn saturate_ttl(ttl: Duration) -> u64 {
81    ttl.as_millis().min(u64::MAX as u128) as u64
82}
momento_functions_collections_common/lib.rs

momento_functions_collections_common/
lib.rs
