Allocator takes size as an int instead of a long.

Motivation:
We don't want to support buffers larger than what can be addressed with an int.
This ensures we won't run into trouble with the max IO size on various operating systems.

buffer/src/main/java/io/netty/buffer/b2/Allocator.java

@@ -43,7 +43,7 @@ public interface Allocator extends AutoCloseable {
      * @param size The size of {@link Buf} to allocate.
      * @return The newly allocated {@link Buf}.
      */
-    Buf allocate(long size);
+    Buf allocate(int size);
 
     /**
      * Allocate a {@link Buf} of the given size in bytes. This method may throw an {@link OutOfMemoryError} if there is
@@ -55,7 +55,7 @@ public interface Allocator extends AutoCloseable {
      * @param order The default byte order used by the accessor methods that don't have an explicit byte order.
      * @return The newly allocated {@link Buf}.
      */
-    default Buf allocate(long size, ByteOrder order) {
+    default Buf allocate(int size, ByteOrder order) {
         return allocate(size).order(order);
     }
 
@@ -71,7 +71,7 @@ public interface Allocator extends AutoCloseable {
         var man = MemoryManager.getHeapMemoryManager();
         return new Allocator() {
             @Override
-            public Buf allocate(long size) {
+            public Buf allocate(int size) {
                 checkSize(size);
                 return man.allocateConfined(size, man.drop(), null);
             }
@@ -82,7 +82,7 @@ public interface Allocator extends AutoCloseable {
         var man = MemoryManager.getNativeMemoryManager();
         return new Allocator() {
             @Override
-            public Buf allocate(long size) {
+            public Buf allocate(int size) {
                 checkSize(size);
                 return man.allocateConfined(size, man.drop(), null);
             }
@@ -93,7 +93,7 @@ public interface Allocator extends AutoCloseable {
         var man = MemoryManager.getNativeMemoryManager();
         return new Allocator() {
             @Override
-            public Buf allocate(long size) {
+            public Buf allocate(int size) {
                 checkSize(size);
                 return man.allocateConfined(size, man.drop(), Statics.CLEANER);
             }

buffer/src/main/java/io/netty/buffer/b2/SizeClassedMemoryPool.java

@@ -36,7 +36,7 @@ class SizeClassedMemoryPool implements Allocator, Drop<Buf> {
     }
 
     @Override
-    public Buf allocate(long size) {
+    public Buf allocate(int size) {
         Allocator.checkSize(size);
         var sizeClassPool = getSizeClassPool(size);
         Send<Buf> send = sizeClassPool.poll();

buffer/src/test/java/io/netty/buffer/b2/CompositeBufTest.java

@@ -47,8 +47,8 @@ public class CompositeBufTest extends BufTest {
                     var b = secondAllocator.get();
                     return new Allocator() {
                         @Override
-                        public Buf allocate(long size) {
-                            long half = size / 2;
+                        public Buf allocate(int size) {
+                            int half = size / 2;
                             try (Buf firstHalf = a.allocate(half);
                                  Buf secondHalf = b.allocate(size - half)) {
                                 return Buf.compose(firstHalf, secondHalf);

buffer/src/test/java/io/netty/buffer/b2/DirectBufWithCleanerTest.java

@@ -44,7 +44,7 @@ public class DirectBufWithCleanerTest extends DirectBufTest {
         assertThat(sum, lessThan(totalAllocated));
     }
 
-    protected void allocateAndForget(Allocator allocator, long size) {
+    protected void allocateAndForget(Allocator allocator, int size) {
         allocator.allocate(size);
     }
 }