Enable ram_percentage on macos

scripts/ram_percentage.sh

@@ -6,11 +6,66 @@ source "$CURRENT_DIR/helpers.sh"
 
 ram_percentage_format="%3.1f%%"
 
+# macos vm_stat sample
+# Mach Virtual Memory Statistics: (page size of 4096 bytes)
+# Pages free:                               91122.
+# Pages active:                           1492064.
+# Pages inactive:                         1471069.
+# Pages speculative:                        25487.
+# Pages throttled:                              0.
+# Pages wired down:                        866263.
+# Pages purgeable:                         106819.
+# "Translation faults":                 757779378.
+# Pages copy-on-write:                   88220937.
+# Pages zero filled:                    286952409.
+# Pages reactivated:                       535355.
+# Pages purged:                           1462986.
+# File-backed pages:                       710060.
+# Anonymous pages:                        2278560.
+# Pages stored in compressor:              612786.
+# Pages occupied by compressor:            248063.
+# Decompressions:                         1400918.
+# Compressions:                           2034985.
+# Pageins:                                5227063.
+# Pageouts:                                  1998.
+# Swapins:                                1319876.
+# Swapouts:                               1402641.
+
+sum_macos_vm_stats() {
+  cat - \
+  | perl -pe "s/^[^\d]*([\d]*)\./\1/g"  \
+  | awk '{ print $1 * 4096 }' \
+  | awk '{ a += $1 } END { print a }' 
+}
+
 print_ram_percentage() {
   ram_percentage_format=$(get_tmux_option "@ram_percentage_format" "$ram_percentage_format")
 
   if command_exists "free"; then
     free | awk -v format="$ram_percentage_format" '$1 == "Mem:" {printf(format, 100*$3/$2)}'
+  elif command_exists "vm_stat"; then
+    # page size of 4096 bytes
+    stats=$(vm_stat)
+
+    used_and_cached=$(echo "$stats" \
+      | grep -E "(Pages active|Pages inactive|Pages speculative|Pages wired down|Pages occupied by compressor)" \
+      | sum_macos_vm_stats \
+    )
+
+    cached=$(echo "$stats" \
+      | grep -E "(Pages purgeable|File-backed pages)" \
+      | sum_macos_vm_stats \
+    )
+
+    free=$(echo "$stats" \
+      | grep -E "(Pages free)" \
+      | sum_macos_vm_stats \
+    )
+
+    used=$(($used_and_cached - $cached))
+    total=$(($used_and_cached + $free))
+
+    echo "$used $total" | awk -v format="$ram_percentage_format" '{printf(format, 100*$1/$2)}'
   fi
 }