feat: add close(::CDFDataset)

src/dataset.jl

@@ -39,13 +39,17 @@ end
 function _load_dataset(fname, buffer, ::Type{FieldSizeType}) where {FieldSizeType}
     compression = NoCompression
     if is_compressed(read_be(buffer, 5, UInt32))
+        mmapped = buffer
         buffer, compression = decompress_bytes(buffer, FieldSizeType)
+        finalize(mmapped)
     end
     cdr = CDR(buffer, 8, FieldSizeType)
     gdr = GDR(buffer, Int(cdr.gdr_offset), FieldSizeType)
     return CDFDataset{FieldSizeType}(fname, cdr, gdr, buffer, compression)
 end
 
+Base.close(cdf::CDFDataset) = (finalize(parent(cdf)); nothing)
+
 is_big_endian_encoding(cdf::CDFDataset) = is_big_endian_encoding(cdf.cdr.encoding)
 
 is_compressed(magic_numbers::UInt32) = magic_numbers != 0x0000FFFF

src/decompress.jl

@@ -49,7 +49,7 @@ function decompress_bytes!(decompressor, dest, doffs, src::AbstractVector{UInt8}
         n_out = N * sizeof(eltype(dest))
         GC.@preserve dest src begin
             out = _unsafe_gzip_decompress!(decompressor, pointer(dest, doffs), n_out, pointer(src, soffs), n_in)
-            out isa LibDeflateError && throw(ArgumentError("gzip decompression failed: $out"))
+            out isa LibDeflateError && throw(ArgumentError("gzip decompression failed"))
         end
     elseif compression == RLECompression
         n_out = N * sizeof(eltype(dest))

test/runtests.jl

@@ -38,6 +38,16 @@ end
     @test string(Epoch(-1.0e31)) == "FILLVAL"
 end
 
+@testset "close" begin
+    ds = CDFDataset(data_path("a_cdf.cdf"))
+    v = ds["var"][:]
+    @test isnothing(close(ds))
+    cds = CDFDataset(data_path("a_compressed_cdf.cdf"))
+    @test cds["var"][:] == v # compressed data lives in memory; close is a no-op
+    @test isnothing(close(cds))
+    @test cds["var"][:] == v
+end
+
 @testset "Uncompressed cdf file" begin
     file = data_path("a_cdf.cdf")
     ds = CDFDataset(file)