Add marshalling for 'bigmemory'

DESCRIPTION

@@ -1,12 +1,13 @@
 Package: marshal
-Version: 0.0.1-9004
+Version: 0.0.1-9005
 Title: Framework to Marshal Objects to be Used in Another R Process
 Depends:
     R (>= 3.2.0)
 Suggests:
     knitr,
       DT,
       jsonlite,
+    bigmemory,
     bundle,
     caret,
     data.table,

NAMESPACE

@@ -14,6 +14,7 @@ S3method(marshal,SOCKnode)
 S3method(marshal,SpatVector)
 S3method(marshal,XMLAbstractDocument)
 S3method(marshal,XMLAbstractNode)
+S3method(marshal,big.matrix)
 S3method(marshal,connection)
 S3method(marshal,data.table)
 S3method(marshal,default)
@@ -46,6 +47,7 @@ S3method(marshallable,SOCKnode)
 S3method(marshallable,SpatVector)
 S3method(marshallable,XMLAbstractDocument)
 S3method(marshallable,XMLAbstractNode)
+S3method(marshallable,big.memory)
 S3method(marshallable,connection)
 S3method(marshallable,data.table)
 S3method(marshallable,default)

R/marshal.bigmemory.R

@@ -0,0 +1,70 @@
+#' Marshalling of 'bigmemory' objects
+#'
+#' @param x A [bigmemory::big.matrix] object.
+#'
+#' @param \dots Not used.
+#'
+#' @return
+#' A `marshalled` object as described in [marshal()].
+#'
+#' @details
+#' [bigmemory::write.big.matrix()] is used to produce a marshalled version
+#' of the original object.
+#' [bigmemory::read.big.matrix()] is used to reconstruct a version of the
+#' original object from the marshalled object.
+#'
+#' @example incl/marshal.bigmemory.R
+#'
+#' @rdname marshal.bigmemory
+#' @aliases marshal.bigmemory
+#' @export
+marshal.big.matrix <- function(x, ...) {
+  marshal_bigmemory(x, ...)
+}
+
+marshal_bigmemory <- function(x, ...) {
+  tf <- tempfile(fileext = ".bigmemory")
+  on.exit(if (!is.null(tf)) file.remove(tf))
+  bigmemory::write.big.matrix(x, filename = tf)
+  raw <- readBin(tf, what = "raw", n = file.size(tf))
+  file.remove(tf)
+  tf <- NULL
+
+  res <- list(
+    marshalled = list(
+      typeof = bigmemory::typeof(x),
+      raw = raw
+    )
+  )
+  class(res) <- marshal_class(x)
+  rm(list = "raw")
+
+  res[["unmarshal"]] <- unmarshal_bigmemory
+
+  assert_no_references(res)
+  res
+}
+
+unmarshal_bigmemory <- function(x, ...) {
+  object <- x[["marshalled"]]
+  raw <- object[["raw"]]
+  typeof <- object[["typeof"]]
+
+  tf <- tempfile(fileext = ".bigmemory")
+  on.exit(if (!is.null(tf)) file.remove(tf))
+  writeBin(raw, con = tf)
+
+  res <- bigmemory::read.big.matrix(tf, type = typeof)
+  file.remove(tf)
+  tf <- NULL
+
+  res
+}
+
+
+#' @rdname marshal.bigmemory
+#' @aliases marshallable.big.memory
+#' @export
+marshallable.big.memory <- function(...) {
+  TRUE
+}

incl/marshal.bigmemory.R

@@ -0,0 +1,15 @@
+if (requireNamespace("bigmemory", quietly = TRUE)) {
+  library(bigmemory)
+
+  x <- big.matrix(nrow = 3, ncol = 2, type = "double")
+  x[] <- seq_along(x)
+
+  ## Marshal
+  x_ <- marshal(x)
+
+  ## Unmarshal
+  x2 <- unmarshal(x_)
+
+  stopifnot(identical(x2[], x[]))
+}
+

inst/known_cases.json

@@ -27,6 +27,13 @@
     "can_be_marshalled": true,
     "must_be_marshalled": true
   },
+  {
+    "package": "bigmemory",
+    "type": "big.matrix",
+    "if_not_marshalled": "segmentation fault",
+    "can_be_marshalled": true,
+    "must_be_marshalled": true
+  },
   {
     "package": "caret",
     "type": "train",

tests/marshal.bigmemory.R

@@ -0,0 +1,16 @@
+library(marshal)
+
+if (requireNamespace("bigmemory", quietly = TRUE)) {
+  library(bigmemory)
+
+  x <- big.matrix(nrow = 3, ncol = 2, type = "double")
+  x[] <- seq_along(x)
+
+  ## Marshal
+  x_ <- marshal(x)
+
+  ## Unmarshal
+  x2 <- unmarshal(x_)
+
+  stopifnot(identical(x2[], x[]))
+}