zsh: add tracing module

functions/tracing.zsh

@@ -0,0 +1,18 @@
+#!/bin/zsh
+
+function start_tracing {
+	zmodload zsh/zprof
+	zmodload zsh/datetime
+	setopt PROMPT_SUBST
+	PS4+='+$EPOCHREALTIME %N:%i> '
+	logfile=$(mktemp zsh_profile.XXXXXXXX)
+	echo "logging to $logfile"
+	exec 3>&2 2>$logfile
+	setopt XTRACE
+}
+
+function stop_tracing {
+	unsetopt XTRACE
+	exec 2>&3 3>&-
+	zprof | tee zprof_out.log | vimscratch -
+}