From 129cf50a046d0800f8c5ba2d92d1b90dc7c888ed Mon Sep 17 00:00:00 2001
From: Jozef <jozef.hajnala@gmail.com>
Date: Fri, 14 Jun 2019 20:12:14 +0000
Subject: [PATCH] support custom build functions for build_site()

---
 R/render.R        | 21 +++++++++++++++++++--
 man/build_site.Rd |  5 ++++-
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/R/render.R b/R/render.R
index ec9c486d..36316943 100644
--- a/R/render.R
+++ b/R/render.R
@@ -28,13 +28,15 @@
 #'   option \code{getOption('blogdown.method')} when it is set.
 #' @param run_hugo Whether to run \code{hugo_build()} after R Markdown files are
 #'   compiled.
+#' @param build_fun Function used to build the Rmd files.
 #' @note This function recompiles all R Markdown files by default, even if the
 #'   output files are newer than the source files. If you want to build the site
 #'   without rebuilding all R Markdown files, you should use
 #'   \code{\link{hugo_build}()} instead.
 #' @export
 build_site = function(
-  local = FALSE, method = c('html', 'custom'), run_hugo = TRUE
+  local = FALSE, method = c('html', 'custom'), run_hugo = TRUE,
+  build_fun = getOption('blogdown.build_rmds', build_rmds)
 ) {
   if (missing(method)) method = getOption('blogdown.method', method)
   method = match.arg(method)
@@ -44,7 +46,7 @@ build_site = function(
   if (local && length(files)) {
     files = getOption('blogdown.files_filter', timestamp_filter)(files)
   }
-  build_rmds(files)
+  build_fun(files)
   if (run_hugo) on.exit(hugo_build(local), add = TRUE)
   invisible()
 }
@@ -163,3 +165,18 @@ encode_paths = function(x, deps, parent, base = '/', to_md = FALSE) {
   dirs_rename(libs, to, clean = TRUE)
   x
 }
+
+build_rmds_parallel = function(files) {
+  on.exit(if (exists("cl")) parallel::stopCluster(cl), add = TRUE)
+  no_cores = getOption('blogdown.parallelcores', parallel::detectCores())
+  # revert to legacy where parallelization irrelevant
+  valid_parallel = isTRUE(as.integer(no_cores) > 1L) && length(files) > 1L
+  if (!valid_parallel) build_rmds(files)
+  cl = parallel::makeCluster(no_cores)
+  # propagate blogdown-relevant options to the nodes
+  opts = options()
+  blogdown_opts = opts[grepl('^blogdown\\.', names(opts))]
+  if (length(blogdown_opts) > 0L) parallel::clusterCall(cl, options, blogdown_opts)
+  files = parallel::clusterSplit(cl = cl, seq = files)
+  parallel::parLapply(cl = cl, X = files, fun = build_rmds)
+}
diff --git a/man/build_site.Rd b/man/build_site.Rd
index 80bb5f27..d884f682 100644
--- a/man/build_site.Rd
+++ b/man/build_site.Rd
@@ -4,7 +4,8 @@
 \alias{build_site}
 \title{Build a website}
 \usage{
-build_site(local = FALSE, method = c("html", "custom"), run_hugo = TRUE)
+build_site(local = FALSE, method = c("html", "custom"), run_hugo = TRUE, 
+    build_fun = getOption("blogdown.build_rmds", build_rmds))
 }
 \arguments{
 \item{local}{Whether to build the website locally to be served via
@@ -16,6 +17,8 @@ option \code{getOption('blogdown.method')} when it is set.}
 
 \item{run_hugo}{Whether to run \code{hugo_build()} after R Markdown files are
 compiled.}
+
+\item{build_fun}{Function used to build the Rmd files.}
 }
 \description{
 Compile all Rmd files and build the site through Hugo.