commit 89e363d9079fcb84ab9724234bac8d11f36355d0
author Maciej Żenczykowski <maze@google.com> Wed Dec 21 23:09:50 2022 +0000
committer Maciej Żenczykowski <maze@google.com> Wed Dec 21 23:12:37 2022 +0000
tree d0347f6c547a6c4d9a67bddd4799743e241b9d7e
parent f219efb1240b886c727c3e77e032997c62d3f9db

switch BpfBitmap key from U32 to S32

Since this is an array from 32 bit int to 64 bit int,
the S32/U32 distinction doesn't matter before we hit
a bitmap with 2 billion entries, ie. 128 billion bits,
taking up 16GiB of RAM...

But S32 is a native java int, while U32 requires long.

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I5b06e80e801e007bafb18693647d968cba905c36

staticlibs/device/com/android/net/module/util/BpfBitmap.java

diff --git a/staticlibs/device/com/android/net/module/util/BpfBitmap.java b/staticlibs/device/com/android/net/module/util/BpfBitmap.java
index 0c8bb37..d2a5b65 100644
--- a/staticlibs/device/com/android/net/module/util/BpfBitmap.java
+++ b/staticlibs/device/com/android/net/module/util/BpfBitmap.java
@@ -27,7 +27,7 @@
  *
  */
 public class BpfBitmap {
-    private BpfMap<Struct.U32, Struct.S64> mBpfMap;
+    private BpfMap<Struct.S32, Struct.S64> mBpfMap;
 
     /**
      * Create a BpfBitmap map wrapper with "path" of filesystem.
@@ -35,8 +35,8 @@
      * @param path The path of the BPF map.
      */
     public BpfBitmap(@NonNull String path) throws ErrnoException {
-        mBpfMap = new BpfMap<Struct.U32, Struct.S64>(path, BpfMap.BPF_F_RDWR,
-                Struct.U32.class, Struct.S64.class);
+        mBpfMap = new BpfMap<Struct.S32, Struct.S64>(path, BpfMap.BPF_F_RDWR,
+                Struct.S32.class, Struct.S64.class);
     }
 
     /**
@@ -44,7 +44,7 @@
      *
      * @param key The key in the map corresponding to the value to return.
      */
-    private long getBpfMapValue(Struct.U32 key) throws ErrnoException  {
+    private long getBpfMapValue(Struct.S32 key) throws ErrnoException  {
         Struct.S64 curVal = mBpfMap.getValue(key);
         if (curVal != null) {
             return curVal.val;
@@ -61,7 +61,7 @@
     public boolean get(int index) throws ErrnoException  {
         if (index < 0) return false;
 
-        Struct.U32 key = new Struct.U32(index >> 6);
+        Struct.S32 key = new Struct.S32(index >> 6);
         return ((getBpfMapValue(key) >>> (index & 63)) & 1L) != 0;
     }
 
@@ -92,7 +92,7 @@
     public void set(int index, boolean set) throws ErrnoException {
         if (index < 0) throw new IllegalArgumentException("Index out of bounds.");
 
-        Struct.U32 key = new Struct.U32(index >> 6);
+        Struct.S32 key = new Struct.S32(index >> 6);
         long mask = (1L << (index & 63));
         long val = getBpfMapValue(key);
         if (set) val |= mask; else val &= ~mask;
@@ -114,7 +114,7 @@
      * Checks if all bitmap values are 0.
      */
     public boolean isEmpty() throws ErrnoException {
-        Struct.U32 key = mBpfMap.getFirstKey();
+        Struct.S32 key = mBpfMap.getFirstKey();
         while (key != null) {
             if (getBpfMapValue(key) != 0) {
                 return false;