implemented RAM detection function

lib/launcher/python/mchandler.py

@@ -1,4 +1,4 @@
-import os
+import os, psutil
 
 # java -Xmx$RAM$ -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M -Djava.library.path=$NATIVES$ -cp $LIBRARIES$ net.minecraft.launchwrapper.Launch --username $USERNAME$ --version 1.7.10-Forge10.13.4.1614-1.7.10 --gameDir $GAMEDIR$ --assetsDir $ASSETS$ --assetIndex 1.7.10 --uuid $UUID$ --accessToken $ACCESSTOKEN$ --userProperties {} --userType mojang --width $WINDOWWIDTH$ --height $WINDOWHEIGHT$ --tweakClass cpw.mods.fml.common.launcher.FMLTweaker
 # $RAM$ the amount of RAM with postfix (k, M, G ...)
@@ -13,7 +13,7 @@ import os
 game_properties = {
     "window width": "1366",
     "window height": "768",
-    "ram": autoram(),
+    "ram": "4G",
     "username": None,
     "uuid": None,
     "access token": None,
@@ -27,9 +27,21 @@ command = None
 
 full_command = None
 
-def autoram():
-    return "4G"
-    # TODO: detect available RAM
+def autoram(minram, maxram, balance):
+    ram_available = psutil.virtual_memory().available
+    # not enough memory
+    if ram_available < minram:
+        # TODO: raise an exception
+        return -1
+    # plenty of memory
+    elif ram_available > maxram+balance:
+        return maxram
+    # enough memory but we do not want to occupy all
+    elif float(ram_available)*float(maxram)/float(maxram+balance) > minram:
+        return int(float(ram_available)*float(maxram)/float(maxram+balance))
+    # barely enough memory
+    elif ram_available > minram or ram_available == minram:
+        return ram_available
 
 def launch():
     global command