Don't evict whole cache for large entries (#40)

Project.toml

@@ -1,6 +1,6 @@
 name = "LRUCache"
 uuid = "8ac3fa9e-de4c-5943-b1dc-09c6b5f20637"
-version = "1.4.1"
+version = "1.5.0"
 
 [compat]
 julia = "1"

src/LRUCache.jl

@@ -146,11 +146,14 @@ function Base.getindex(lru::LRU, key)
     end
 end
 function _unsafe_addindex!(lru::LRU{K}, v, key) where K
+    s = lru.by(v)::Int
+    # If entry is larger than entire cache, don't add it
+    s > lru.maxsize && return
     n = LinkedNode{K}(key)
     rotate!(_push!(lru.keyset, n))
-    s = lru.by(v)::Int
     lru.currentsize += s
     lru.dict[key] = (v, n, s)
+    return
 end
 function Base.setindex!(lru::LRU{K, V}, v, key) where {K, V}
     evictions = Tuple{K, V}[]
@@ -162,9 +165,18 @@ function Base.setindex!(lru::LRU{K, V}, v, key) where {K, V}
             end
             lru.currentsize -= s
             s = lru.by(v)::Int
-            lru.currentsize += s
-            lru.dict[key] = (v, n, s)
-            _move_to_front!(lru.keyset, n)
+            # If new entry is larger than entire cache, don't add it
+            # (but still evict the old entry!)
+            if s > lru.maxsize
+                # We are inside the lock still, so we will remove it manually rather than
+                # `delete!(lru, key)` which would need the lock again.
+                delete!(lru.dict, key)
+                _delete!(lru.keyset, n)
+            else # add the new entry
+                lru.currentsize += s
+                lru.dict[key] = (v, n, s)
+                _move_to_front!(lru.keyset, n)
+            end
         else
             _unsafe_addindex!(lru, v, key)
         end

test/runtests.jl

@@ -218,4 +218,38 @@ end
     @test [k => v for (k,v) in rlru] == ["second" => 2, "third" => 3, "fourth" => 4, "fifth" => 5]
 end
 
+# https://github.com/JuliaCollections/LRUCache.jl/issues/37
+@testset "Large entries" begin
+    lru = LRU{Int, Vector{Int}}(; maxsize=10, by=length)
+    get!(lru, 1, 1:9)
+    @test !isempty(lru)
+    @test lru[1] == 1:9
+
+    # Add too-big entry
+    get!(lru, 2, 1:11)
+    # did not add entry 2, it is too big
+    @test !haskey(lru, 2)
+
+    # Still have old entries
+    @test !isempty(lru)
+    @test lru[1] == 1:9
+
+    # Same with `setindex!`
+    lru[2] = 1:11
+    @test !haskey(lru, 2)
+    @test !isempty(lru)
+    @test lru[1] == 1:9
+
+    # Add a second small entry
+    lru[2] = 1:1
+    @test haskey(lru, 2)
+    @test lru[1] == 1:9
+    @test lru[2] == 1:1
+
+    # Re-assign it to a too-big entry
+    lru[2] = 1:11
+    @test !haskey(lru, 2) # don't keep the old entry!
+    @test lru[1] == 1:9
+end
+
 include("originaltests.jl")