ruby-ng.eclass: optimize: avoid subshell for ruby_get_all_impls

We go from ~4s -> ~3.5s for sourcing dev-ruby/*.

For sinatra:

```
$ pk pkg source $(pkg) --repo ~/g/ --bench 5s # before
dev-ruby/sinatra-2.2.3::/home/sam/g/: mean: 66.68ms, min: 56.938ms, max: 74.248ms, σ = 4.832ms, N = 75
dev-ruby/sinatra-3.0.6::/home/sam/g/: mean: 73.618ms, min: 60.153ms, max: 77.978ms, σ = 3.195ms, N = 68
dev-ruby/sinatra-3.0.5::/home/sam/g/: mean: 72.069ms, min: 58.736ms, max: 78.223ms, σ = 3.277ms, N = 70
dev-ruby/sinatra-3.0.5-r1::/home/sam/g/: mean: 73.265ms, min: 60.738ms, max: 81.06ms, σ = 3.227ms, N = 69

$ pk pkg source $(pkg) --repo ~/g/ --bench 5s # after
dev-ruby/sinatra-3.0.5-r1::/home/sam/g/: mean: 59.677ms, min: 49.141ms, max: 63.282ms, σ = 2.511ms, N = 84
dev-ruby/sinatra-3.0.6::/home/sam/g/: mean: 59.693ms, min: 48.637ms, max: 62.862ms, σ = 2.628ms, N = 84
dev-ruby/sinatra-3.0.5::/home/sam/g/: mean: 56.697ms, min: 46.782ms, max: 60.367ms, σ = 2.822ms, N = 89
dev-ruby/sinatra-2.2.3::/home/sam/g/: mean: 54.915ms, min: 45.832ms, max: 59.513ms, σ = 3.52ms, N = 92
```

Bug: https://bugs.gentoo.org/908465
Signed-off-by: Sam James <sam@gentoo.org>

1 files changed, 13 insertions, 10 deletions

diff --git a/eclass/ruby-ng.eclass b/eclass/ruby-ng.eclass
index 2bf1885d3803..ee2e6b89edb4 100644
--- a/eclass/ruby-ng.eclass
+++ b/eclass/ruby-ng.eclass
@@ -102,6 +102,7 @@ ruby_implementation_depend() {
 # @DESCRIPTION:
 # Return a list of valid implementations in USE_RUBY, skipping the old
 # implementations that are no longer supported.
+_RUBY_GET_ALL_IMPLS=()
 _ruby_get_all_impls() {
 	local i found_valid_impl
 	for i in ${USE_RUBY}; do
@@ -111,7 +112,8 @@ _ruby_get_all_impls() {
 				;;
 			*)
 				found_valid_impl=1
-				echo ${i};;
+				_RUBY_GET_ALL_IMPLS+=( ${i} )
+				;;
 		esac
 	done
 
@@ -131,7 +133,7 @@ ruby_samelib() {
 	debug-print-function ${FUNCNAME} "${@}"
 
 	local res=
-	for _ruby_implementation in $(_ruby_get_all_impls); do
+	for _ruby_implementation in "${_RUBY_GET_ALL_IMPLS[@]}"; do
 		has -${_ruby_implementation} $@ || \
 			res="${res}ruby_targets_${_ruby_implementation}(-)?,"
 	done
@@ -174,7 +176,7 @@ ruby_implementation_command() {
 _ruby_atoms_samelib() {
 	local atoms=$(_ruby_atoms_samelib_generic "$*")
 
-	for _ruby_implementation in $(_ruby_get_all_impls); do
+	for _ruby_implementation in "${_RUBY_GET_ALL_IMPLS[@]}"; do
 		echo "${atoms//RUBYTARGET/ruby_targets_${_ruby_implementation}}"
 	done
 }
@@ -310,7 +312,7 @@ ruby_get_use_implementations() {
 	debug-print-function ${FUNCNAME} "${@}"
 
 	local i implementation
-	for implementation in $(_ruby_get_all_impls); do
+	for implementation in "${_RUBY_GET_ALL_IMPLS[@]}"; do
 		use ruby_targets_${implementation} && i+=" ${implementation}"
 	done
 	echo $i
@@ -322,8 +324,8 @@ ruby_get_use_implementations() {
 ruby_get_use_targets() {
 	debug-print-function ${FUNCNAME} "${@}"
 
-
-	local impls="$(_ruby_get_all_impls)"
+	_ruby_get_all_impls
+	local impls="${_RUBY_GET_ALL_IMPLS[@]}"
 	echo "${impls//ruby/ruby_targets_ruby}"
 }
 
@@ -346,13 +348,14 @@ ruby_get_use_targets() {
 ruby_implementations_depend() {
 	debug-print-function ${FUNCNAME} "${@}"
 
-	local depend
-	for _ruby_implementation in $(_ruby_get_all_impls); do
+	for _ruby_implementation in "${_RUBY_GET_ALL_IMPLS[@]}"; do
 		depend="${depend}${depend+ }ruby_targets_${_ruby_implementation}? ( $(ruby_implementation_depend $_ruby_implementation) )"
 	done
 	echo "${depend}"
 }
 
+_ruby_get_all_impls
+
 IUSE+=" $(ruby_get_use_targets)"
 # If you specify RUBY_OPTIONAL you also need to take care of
 # ruby useflag and dependency.
@@ -412,7 +415,7 @@ _ruby_invoke_environment() {
 
 _ruby_each_implementation() {
 	local invoked=no
-	for _ruby_implementation in $(_ruby_get_all_impls); do
+	for _ruby_implementation in "${_RUBY_GET_ALL_IMPLS[@]}"; do
 		# only proceed if it's requested
 		use ruby_targets_${_ruby_implementation} || continue
 
@@ -435,7 +438,7 @@ _ruby_each_implementation() {
 
 	if [[ ${invoked} == "no" ]]; then
 		eerror "You need to select at least one compatible Ruby installation target via RUBY_TARGETS in make.conf."
-		eerror "Compatible targets for this package are: $(_ruby_get_all_impls)"
+		eerror "Compatible targets for this package are: ${_RUBY_GET_ALL_IMPLS[@]}"
 		eerror
 		eerror "See https://www.gentoo.org/proj/en/prog_lang/ruby/index.xml#doc_chap3 for more information."
 		eerror