From 84664b0fc0b9128b4316afb85274271389aab00f Mon Sep 17 00:00:00 2001
From: Jacek Sieka <jacek@status.im>
Date: Thu, 3 Oct 2024 12:34:38 +0200
Subject: [PATCH] discv5: migrate to minilru (#741)

As it happens, the two share the exact same interface (even the test
suite removed in this PR passes) - `minilru` has an edge on efficiency
however, avoiding the doubly linked list node allocations etc
---
 eth.nimble                       |   3 +-
 eth/p2p/discoveryv5/lru.nim      |  45 +----------
 eth/p2p/discoveryv5/sessions.nim |   6 +-
 tests/p2p/all_discv5_tests.nim   |   1 -
 tests/p2p/test_lru.nim           | 134 -------------------------------
 5 files changed, 9 insertions(+), 180 deletions(-)
 delete mode 100644 tests/p2p/test_lru.nim

diff --git a/eth.nimble b/eth.nimble
index c2d1acf..1cd29d0 100644
--- a/eth.nimble
+++ b/eth.nimble
@@ -19,7 +19,8 @@ requires "nim >= 1.6.0",
          "confutils",
          "testutils",
          "unittest2",
-         "results"
+         "results",
+         "minilru"
 
 let nimc = getEnv("NIMC", "nim") # Which nim compiler to use
 let lang = getEnv("NIMLANG", "c") # Which backend (c/cpp/js)
diff --git a/eth/p2p/discoveryv5/lru.nim b/eth/p2p/discoveryv5/lru.nim
index 77ad5f5..4ec557c 100644
--- a/eth/p2p/discoveryv5/lru.nim
+++ b/eth/p2p/discoveryv5/lru.nim
@@ -6,46 +6,9 @@
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 #
 
+{.deprecated: "Use minilru directly".}
+
 {.push raises: [].}
 
-import std/[tables, lists], results
-
-export results
-
-type
-  LRUCache*[K, V] = object of RootObj
-    list: DoublyLinkedList[(K, V)] # Head is MRU k:v and tail is LRU k:v
-    table: Table[K, DoublyLinkedNode[(K, V)]] # DoublyLinkedNode is already ref
-    capacity: int
-
-func init*[K, V](T: type LRUCache[K, V], capacity: int): LRUCache[K, V] =
-  LRUCache[K, V](capacity: capacity) # Table and list init is done default
-
-func get*[K, V](lru: var LRUCache[K, V], key: K): Opt[V] =
-  let node = lru.table.getOrDefault(key, nil)
-  if node.isNil:
-    return Opt.none(V)
-
-  lru.list.remove(node)
-  lru.list.prepend(node)
-  return Opt.some(node.value[1])
-
-func put*[K, V](lru: var LRUCache[K, V], key: K, value: V) =
-  let node = lru.table.getOrDefault(key, nil)
-  if not node.isNil:
-    lru.list.remove(node)
-  else:
-    if lru.table.len >= lru.capacity:
-      lru.table.del(lru.list.tail.value[0])
-      lru.list.remove(lru.list.tail)
-
-  lru.list.prepend((key, value))
-  lru.table[key] = lru.list.head
-
-func del*[K, V](lru: var LRUCache[K, V], key: K) =
-  var node: DoublyLinkedNode[(K, V)]
-  if lru.table.pop(key, node):
-    lru.list.remove(node)
-
-func len*[K, V](lru: LRUCache[K, V]): int =
-  lru.table.len
+import minilru
+export minilru
diff --git a/eth/p2p/discoveryv5/sessions.nim b/eth/p2p/discoveryv5/sessions.nim
index 3df12d0..ae4385c 100644
--- a/eth/p2p/discoveryv5/sessions.nim
+++ b/eth/p2p/discoveryv5/sessions.nim
@@ -14,9 +14,9 @@
 import
   std/net,
   stint, stew/endians2,
-  node, lru
+  ./node, minilru
 
-export lru
+export minilru
 
 const
   aesKeySize* = 128 div 8
@@ -28,7 +28,7 @@ type
   AesKey* = array[aesKeySize, byte]
   SessionKey* = array[keySize, byte]
   SessionValue* = array[sizeof(AesKey) + sizeof(AesKey), byte]
-  Sessions* = LRUCache[SessionKey, SessionValue]
+  Sessions* = LruCache[SessionKey, SessionValue]
 
 func makeKey(id: NodeId, address: Address): SessionKey =
   var pos = 0
diff --git a/tests/p2p/all_discv5_tests.nim b/tests/p2p/all_discv5_tests.nim
index b20317b..95a81dc 100644
--- a/tests/p2p/all_discv5_tests.nim
+++ b/tests/p2p/all_discv5_tests.nim
@@ -3,7 +3,6 @@
 import
   ./test_enr,
   ./test_hkdf,
-  ./test_lru,
   ./test_ip_vote,
   ./test_routing_table,
   ./test_discoveryv5_encoding,
diff --git a/tests/p2p/test_lru.nim b/tests/p2p/test_lru.nim
deleted file mode 100644
index 26ec5f4..0000000
--- a/tests/p2p/test_lru.nim
+++ /dev/null
@@ -1,134 +0,0 @@
-{.used.}
-
-import
-  std/options,
-  unittest2,
-  ../../eth/p2p/discoveryv5/lru
-
-suite "LRUCache":
-  const
-    capacity = 10
-    target = 4
-  test "LRU value gets removed":
-    var lru = LRUCache[int, int].init(capacity = capacity)
-
-    # Fully fill the LRU
-    for i in 0..<capacity:
-      lru.put(i, i) # new key, so new put
-
-    # Get value for each key
-    for i in 0..<capacity:
-      let val = lru.get(i)
-      check:
-        val.isSome()
-        val.get() == i
-
-    check lru.len() == capacity
-
-    # Add one new key
-    lru.put(capacity, 0)
-    # Oldest one should be gone
-    check:
-      lru.len() == capacity
-      lru.get(0).isNone()
-      lru.get(capacity).isSome()
-
-  test "LRU renew oldest by get":
-    var lru = LRUCache[int, int].init(capacity = capacity)
-
-    for i in 0..<capacity:
-      lru.put(i, i)
-
-    var val = lru.get(0)
-    check:
-      val.isSome
-      val.get() == 0
-
-    lru.put(capacity, 0)
-
-    val = lru.get(0)
-    check:
-      lru.len() == capacity
-      val.isSome()
-      val.get() == 0
-
-  test "LRU renew oldest by put":
-    var lru = LRUCache[int, int].init(capacity = capacity)
-
-    for i in 0..<capacity:
-      lru.put(i, i)
-
-    lru.put(0, 1)
-    check lru.len() == capacity
-
-    lru.put(capacity, 0)
-
-    let val = lru.get(0)
-    check:
-      lru.len() == capacity
-      val.isSome()
-      val.get() == 1
-
-  test "LRU renew by put":
-    var lru = LRUCache[int, int].init(capacity = capacity)
-
-    for i in 0..<capacity:
-      lru.put(i, i)
-
-    lru.put(target, 1)
-    check lru.len() == capacity
-
-    lru.put(capacity, 0)
-
-    let val = lru.get(target)
-    check:
-      lru.len() == capacity
-      val.isSome()
-      val.get() == 1
-
-  test "LRU renew by get":
-    var lru = LRUCache[int, int].init(capacity = capacity)
-
-    for i in 0..<capacity:
-      lru.put(i, i)
-
-    var val = lru.get(target)
-    check:
-      val.isSome
-      val.get() == target
-
-    lru.put(capacity, 0)
-
-    val = lru.get(target)
-    check:
-      lru.len() == capacity
-      val.isSome()
-      val.get() == target
-
-  test "LRU delete oldest and add":
-    var lru = LRUCache[int, int].init(capacity = capacity)
-
-    for i in 0..<capacity:
-      lru.put(i, i)
-
-    lru.del(0)
-    check lru.len == capacity - 1
-
-    lru.put(0, 1)
-    check lru.len == capacity
-
-    lru.put(capacity, 0)
-
-    let val = lru.get(0)
-    check:
-      lru.len() == capacity
-      val.isSome()
-      val.get() == 1
-  test "LRU delete not existing":
-    var lru = LRUCache[int, int].init(capacity = capacity)
-
-    for i in 0..<capacity:
-      lru.put(i, i)
-
-    lru.del(capacity)
-    check lru.len == capacity