add commands for osx

metrics/memory.sh

@@ -1,5 +1,21 @@
 #!/bin/sh
 
-collect () {
-  echo $(free | awk '/buffers\/cache/{print $4/($3+$4) * 100.0;}')
-}
+if [ $OS_TYPE == "osx" ]; then
+
+  # FIXME: total_memory leaks out
+  total_memory=$(sysctl -n hw.memsize)
+
+  collect () {
+    echo $(vm_stat | awk -v total_memory=$total_memory \
+              'BEGIN {FS="   *"; pages=0}
+               /Pages (free|inactive|speculative)/ {pages+=$2}
+               END {printf "%.2f", 100 - (pages * 4096) / total_memory * 100.0}')
+  }
+
+else
+
+  collect () {
+    echo $(free | awk '/buffers\/cache/{printf "%.2f", $4 / ($3 + $4) * 100.0}')
+  }
+
+fi

metrics/swap.sh

@@ -1,5 +1,15 @@
 #!/bin/sh
 
-collect () {
-  echo $(free | awk '/Swap/{print $3/$2 * 100.0;}')
-}
+if [ $OS_TYPE == "osx" ]; then
+
+  collect () {
+    echo $(sysctl -n vm.swapusage | awk '{printf "%.2f", $6 / $3 * 100.0}')
+  }
+
+else
+
+  collect () {
+    echo $(free | awk '/Swap/{printf "%.2f", $3/$2 * 100.0;}')
+  }
+
+fi