Merge pull request #15 from thomvet/grow-cache-on-demand

Enlarging dualcache on demand first time it's called.

Author: ChrisRackauckas

Project.toml

@@ -1,7 +1,7 @@
 name = "PreallocationTools"
 uuid = "d236fae5-4411-538c-8e31-a6e3d9e00b46"
 authors = ["Chris Rackauckas <accounts@chrisrackauckas.com>"]
-version = "0.2.0"
+version = "0.2.1"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"

src/PreallocationTools.jl

@@ -35,23 +35,41 @@ Returns the `Dual` or normal cache array stored in `dc` based on the type of `u`
 """
 function get_tmp(dc::DiffCache, u::T) where T<:ForwardDiff.Dual
     nelem = div(sizeof(T), sizeof(eltype(dc.dual_du)))*length(dc.du)
+    if nelem > length(dc.dual_du)
+        enlargedualcache!(dc, nelem)
+    end
     ArrayInterface.restructure(dc.du, reinterpret(T, view(dc.dual_du, 1:nelem)))
 end
 
 function get_tmp(dc::DiffCache, u::AbstractArray{T}) where T<:ForwardDiff.Dual
     nelem = div(sizeof(T), sizeof(eltype(dc.dual_du)))*length(dc.du)
+    if nelem > length(dc.dual_du)
+        enlargedualcache!(dc, nelem)
+    end
     ArrayInterface.restructure(dc.du, reinterpret(T, view(dc.dual_du, 1:nelem)))
 end
 
 function get_tmp(dc::DiffCache, u::LabelledArrays.LArray{T,N,D,Syms}) where {T,N,D,Syms}
     nelem = div(sizeof(T), sizeof(eltype(dc.dual_du)))*length(dc.du)
+    if nelem > length(dc.dual_du)
+        enlargedualcache!(dc, nelem)
+    end
     _x = ArrayInterface.restructure(dc.du, reinterpret(T, view(dc.dual_du, 1:nelem)))
     LabelledArrays.LArray{T,N,D,Syms}(_x)
 end
 
 get_tmp(dc::DiffCache, u::Number) = dc.du
 get_tmp(dc::DiffCache, u::AbstractArray) = dc.du
 
+function enlargedualcache!(dc, nelem) #warning comes only once per dualcache.
+    chunksize = div(nelem, length(dc.du)) - 1
+    @warn "The supplied dualcache was too small and was enlarged. This incurrs allocations 
+    on the first call to get_tmp. If few calls to get_tmp occur and optimal performance is essential,
+    consider changing 'N'/chunk size of this dualcache to $chunksize."
+    resize!(dc.dual_du, nelem)
+end
+
+
 """
     b = LazyBufferCache(f=identity)