From bcbb0a9c29c264946f5f1bbeab64b917192483b4 Mon Sep 17 00:00:00 2001
From: Matt Dancho <mdancho@gmail.com>
Date: Tue, 22 Oct 2024 11:12:10 -0400
Subject: [PATCH] #253 Add .export_vars to parallel_start()

---
 NEWS.md               |  8 ++++++++
 R/utils-control-par.R | 31 +++++++++++++++++++++++++++----
 man/parallel_start.Rd | 11 ++++++++++-
 3 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/NEWS.md b/NEWS.md
index 7a70dd2f..d4a7c98b 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,3 +1,11 @@
+# modeltime 1.3.0.9000
+
+Parallel Computation:
+- `parallel_start()`: New parameters `.export_vars` and `.packages` allows passing environment variables and packages to the parallel workers. 
+
+Fixes:
+- Adam (`adam_reg()`): Fixes #254 
+
 # modeltime 1.3.0
 
 #### Overview
diff --git a/R/utils-control-par.R b/R/utils-control-par.R
index 26d84bd4..47ac7562 100644
--- a/R/utils-control-par.R
+++ b/R/utils-control-par.R
@@ -8,6 +8,8 @@
 #'
 #'  - "parallel" - Uses the `parallel` and `doParallel` packages
 #'  - "spark" - Uses the `sparklyr` package
+#' @param .export_vars Environment variables that can be sent to the workers
+#' @param .packages Packages that can be sent to the workers
 #'
 #'
 #' @details
@@ -44,7 +46,8 @@
 
 #' @export
 #' @rdname parallel_start
-parallel_start <- function(..., .method = c("parallel", "spark")) {
+parallel_start <- function(..., .method = c("parallel", "spark"),
+                           .export_vars = NULL, .packages = NULL) {
 
     meth <- tolower(.method[1])
 
@@ -53,11 +56,31 @@ parallel_start <- function(..., .method = c("parallel", "spark")) {
     }
 
     if (meth == "parallel") {
+        # Step 1: Create the cluster
         cl <- parallel::makeCluster(...)
+
+        # Step 2: Register the cluster
         doParallel::registerDoParallel(cl)
-        invisible(
-            parallel::clusterCall(cl, function(x) .libPaths(x), .libPaths())
-        )
+
+        # Step 3: Export variables (if provided)
+        if (!is.null(.export_vars)) {
+            parallel::clusterExport(cl, varlist = .export_vars)
+        }
+
+        # Step 4: Load .packages (if provided)
+        if (!is.null(.packages)) {
+            parallel::clusterCall(cl, function(pkgs) {
+                lapply(pkgs, function(pkg) {
+                    if (!requireNamespace(pkg, quietly = TRUE)) {
+                        stop(paste("Package", pkg, "is not installed."))
+                    }
+                    library(pkg, character.only = TRUE)
+                })
+            }, .packages)
+        }
+
+        # Step 5: Set the library paths for each worker
+        invisible(parallel::clusterCall(cl, function(x) .libPaths(x), .libPaths()))
     }
 
     if (meth == "spark") {
diff --git a/man/parallel_start.Rd b/man/parallel_start.Rd
index 68032016..45880284 100644
--- a/man/parallel_start.Rd
+++ b/man/parallel_start.Rd
@@ -5,7 +5,12 @@
 \alias{parallel_stop}
 \title{Start parallel clusters using \code{parallel} package}
 \usage{
-parallel_start(..., .method = c("parallel", "spark"))
+parallel_start(
+  ...,
+  .method = c("parallel", "spark"),
+  .export_vars = NULL,
+  .packages = NULL
+)
 
 parallel_stop()
 }
@@ -17,6 +22,10 @@ parallel_stop()
 \item "parallel" - Uses the \code{parallel} and \code{doParallel} packages
 \item "spark" - Uses the \code{sparklyr} package
 }}
+
+\item{.export_vars}{Environment variables that can be sent to the workers}
+
+\item{.packages}{Packages that can be sent to the workers}
 }
 \description{
 Start parallel clusters using \code{parallel} package