Replace threat handler file with named pipe

This was causing problems in MacOS for some reason. The named pipe is
probably a better solution in general, but it's strange that it happened
at all.

Author: alpiccioni

src/threads/thread_controller.sh

@@ -19,20 +19,22 @@ PURR_THREAD_START="purr_thread_start"
 PURR_THREAD_STOP="purr_thread_stop"
 
 # The background handler is responsible for starting and killing
-# the stream threads. It uses the purr_background_handler_cache
+# the stream threads. It uses the thread_io_pipe
 # as a one-way communication between the core process and itself,
 # and then handles asynchronous processes related to the stream threads.
 __purr_background_handler() {
 	__purr_start_streams
 
-	while read line; do
-		if [ $line = "$PURR_THREAD_STOP" ]; then
-			__purr_cleanup_streams
-		elif [ $line = "$PURR_THREAD_START" ]; then
-			__purr_start_streams
-		elif [ $line = "$PURR_THREAD_CLEANUP" ]; then
-			__purr_cleanup_streams
-			exit 0
+	while true; do
+		if read line <$thread_io_pipe; then
+			if [ $line = "$PURR_THREAD_STOP" ]; then
+				__purr_cleanup_streams
+			elif [ $line = "$PURR_THREAD_START" ]; then
+				__purr_start_streams
+			elif [ $line = "$PURR_THREAD_CLEANUP" ]; then
+				__purr_cleanup_streams
+				exit 0
+			fi
 		fi
-	done < <(/usr/bin/tail -f $purr_background_handler_cache 2>/dev/null)
+	done
 }

src/threads/thread_interface.sh

@@ -15,19 +15,19 @@
 # limitations under the License.
 
 __purr_start_stream() {
-	echo "$PURR_THREAD_START" >>$purr_background_handler_cache
+	echo "$PURR_THREAD_START" >$thread_io_pipe
 }
 
 __purr_thread_stop_stream() {
-	echo "$PURR_THREAD_STOP" >>$purr_background_handler_cache
+	echo "$PURR_THREAD_STOP" >$thread_io_pipe
 }
 
 __purr_cleanup() {
 	local dir_name=$1
 
 	# Send a message to the background threads that they need to die.
-	if [ -f $purr_background_handler_cache ]; then
-		echo "$PURR_THREAD_CLEANUP" >>$purr_background_handler_cache
+	if [ -p $thread_io_pipe ]; then
+		echo "$PURR_THREAD_CLEANUP" >$thread_io_pipe
 	fi
 
 	# Delete all of the cached state files.

src/threads/thread_setup.sh

@@ -70,9 +70,9 @@ __purr_create_files() {
 	purr_preview_command_cache="$dir_name/preview-command-cache.purr"
 	/usr/bin/touch $purr_preview_command_cache
 
-	# File to communicate with the background handler.
-	purr_background_handler_cache="$dir_name/background-handler-IO.purr"
-	/usr/bin/touch $purr_background_handler_cache
+	# Pipe to communicate with the background handler.
+	thread_io_pipe=$dir_name/thread_io_pipe
+	mkfifo $thread_io_pipe
 
 	# File to communicate what the accept command intent was.
 	purr_accept_command_cache="$dir_name/purr_accept_command_cache.purr"

src/ui/ui_strings.sh

@@ -150,5 +150,5 @@ set_header_serial="echo \"$stream_serial_msg\" >| $purr_stream_header_cache;"
 hint_preview_window="top,70%,nohidden,wrap,+200/2"
 hint_preview_window_hidden="top,70%,hidden,wrap,+200/2"
 
-start_stream="echo \"$PURR_THREAD_START\" >> $purr_background_handler_cache;"
-stop_stream="echo \"$PURR_THREAD_STOP\" >> $purr_background_handler_cache;"
+start_stream="echo \"$PURR_THREAD_START\" >$thread_io_pipe;"
+stop_stream="echo \"$PURR_THREAD_STOP\" >$thread_io_pipe;"

tests/validators/file_validator.sh

@@ -27,13 +27,6 @@ validate_runtime_purr_files() {
 	grep -q -- "Verbose" $dir_name/stream-header.purr
 	echo "Input stream is verbose."
 
-	# Is the handler processing IO?
-	if [ -s $dir_name/background-handler-IO.purr ]; then
-		return 1
-	else
-		echo "Thread IO working."
-	fi
-
 	# Did we start on the instruction preview? And it is visible?
 	grep -q -- "instruction" $dir_name/preview-command-cache.purr
 	grep -q -- "nohidden" $dir_name/preview-visibility-cache.purr
@@ -57,10 +50,6 @@ validate_runtime_purr_files() {
 validate_exit_time_purr_files() {
 	dir_name=$1
 
-	# Has the handler been told to clean up?
-	grep -q -- "purr_thread_cleanup" $dir_name/background-handler-IO.purr
-	echo "Threads are in cleanup."
-
 	# Did the handler actually do clean up?
 	if [ ! -f $dir_name/verbose-input-cache.purr ]; then
 		echo "Threads did actually cleanup."