66 lines
1.8 KiB
Nim
66 lines
1.8 KiB
Nim
## Nim-LibP2P
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## Copyright (c) 2019 Status Research & Development GmbH
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## Licensed under either of
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## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
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## * MIT license ([LICENSE-MIT](LICENSE-MIT))
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## at your option.
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## This file may not be copied, modified, or distributed except according to
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## those terms.
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import std/[heapqueue, sets]
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import chronos/timer
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const Timeout* = 10.seconds # default timeout in ms
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type
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TimedEntry*[K] = ref object of RootObj
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key: K
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expiresAt: Moment
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TimedCache*[K] = object of RootObj
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expiries: HeapQueue[TimedEntry[K]]
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entries: HashSet[K]
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timeout: Duration
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func `<`*(a, b: TimedEntry): bool =
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a.expiresAt < b.expiresAt
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func expire*(t: var TimedCache, now: Moment = Moment.now()) =
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while t.expiries.len() > 0 and t.expiries[0].expiresAt < now:
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t.entries.excl(t.expiries.pop().key)
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func del*[K](t: var TimedCache[K], key: K): bool =
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# Removes existing key from cache, returning false if it was not present
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if not t.entries.missingOrExcl(key):
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for i in 0..<t.expiries.len:
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if t.expiries[i].key == key:
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t.expiries.del(i)
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break
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true
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else:
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false
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func put*[K](t: var TimedCache[K], k: K, now = Moment.now()): bool =
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# Puts k in cache, returning true if the item was already present and false
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# otherwise. If the item was already present, its expiry timer will be
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# refreshed.
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t.expire(now)
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var res = t.del(k) # Refresh existing item
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t.entries.incl(k)
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t.expiries.push(TimedEntry[K](key: k, expiresAt: now + t.timeout))
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res
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func contains*[K](t: TimedCache[K], k: K): bool =
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k in t.entries
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func init*[K](T: type TimedCache[K], timeout: Duration = Timeout): T =
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T(
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expiries: initHeapQueue[TimedEntry[K]](),
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entries: initHashSet[K](),
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timeout: timeout
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)
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