Bug 906230 - Add HardwareUtils.isLowMemoryPlatform() (r=kats)

mobile/android/base/util/HardwareUtils.java

@@ -12,15 +12,34 @@ import android.os.Build;
 import android.util.Log;
 import android.view.ViewConfiguration;
 
+import java.io.RandomAccessFile;
+import java.io.IOException;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
 public final class HardwareUtils {
     private static final String LOGTAG = "GeckoHardwareUtils";
 
+    // Minimum memory threshold for a device to be considered
+    // a low memory platform (see sIsLowMemoryPlatform). This value
+    // has be in sync with Gecko's equivalent threshold (defined in
+    // xpcom/base/nsMemoryImpl.cpp) and should only be used in cases
+    // where we can't depend on Gecko to be up and running e.g. show/hide
+    // reading list capabilities in HomePager.
+    private static final int LOW_MEMORY_THRESHOLD_KB = 384 * 1024;
+
+    private static final String PROC_MEMINFO_FILE = "/proc/meminfo";
+
+    private static final Pattern PROC_MEMTOTAL_FORMAT =
+          Pattern.compile("^MemTotal:[ \t]*([0-9]*)[ \t]kB");
+
     private static Context sContext;
 
     private static Boolean sIsLargeTablet;
     private static Boolean sIsSmallTablet;
     private static Boolean sIsTelevision;
     private static Boolean sHasMenuButton;
+    private static Boolean sIsLowMemoryPlatform;
 
     private HardwareUtils() {
     }
@@ -73,4 +92,43 @@ public final class HardwareUtils {
         }
         return sHasMenuButton;
     }
+
+    public static boolean isLowMemoryPlatform() {
+        if (sIsLowMemoryPlatform == null) {
+            RandomAccessFile fileReader = null;
+            try {
+                fileReader = new RandomAccessFile(PROC_MEMINFO_FILE, "r");
+
+                // Defaults to false
+                long totalMem = LOW_MEMORY_THRESHOLD_KB;
+
+                String line = null;
+                while ((line = fileReader.readLine()) != null) {
+                    final Matcher matcher = PROC_MEMTOTAL_FORMAT.matcher(line);
+                    if (matcher.find()) {
+                        totalMem = Long.parseLong(matcher.group(1));
+                        break;
+                    }
+                }
+
+                sIsLowMemoryPlatform = (totalMem < LOW_MEMORY_THRESHOLD_KB);
+            } catch (IOException e) {
+                // Fallback to false if we fail to read meminfo
+                // for some reason.
+                Log.w(LOGTAG, "Could not read " + PROC_MEMINFO_FILE + "." +
+                              "Falling back to isLowMemoryPlatform = false", e);
+                sIsLowMemoryPlatform = false;
+            } finally {
+                if (fileReader != null) {
+                    try {
+                        fileReader.close();
+                    } catch (IOException e) {
+                        // Do nothing
+                    }
+                }
+            }
+        }
+
+        return sIsLowMemoryPlatform;
+    }
 }

xpcom/base/nsMemoryImpl.cpp

@@ -15,6 +15,11 @@
 
 #ifdef ANDROID
 #include <stdio.h>
+
+// Minimum memory threshold for a device to be considered
+// a low memory platform. This value has be in sync with
+// Java's equivalent threshold, defined in
+// mobile/android/base/util/HardwareUtils.java
 #define LOW_MEMORY_THRESHOLD_KB (384 * 1024)
 #endif