Replace usages of Unsafe.compareAndSwap(Int|Long)
This replaces them with Atomic(Integer|Long)FieldUpdater classes
respectively in Striped64 to allow it to be compiled for Android.
This removes one of the Android compilation failures but there
are some remaining so it will still not compile.
Change-Id: I225524aadfec15ae835f98ccc2ffbc180836c4a9
diff --git a/guava/src/com/google/common/cache/Striped64.java b/guava/src/com/google/common/cache/Striped64.java
index e045453..bb95eb9 100644
--- a/guava/src/com/google/common/cache/Striped64.java
+++ b/guava/src/com/google/common/cache/Striped64.java
@@ -12,6 +12,8 @@
package com.google.common.cache;
import java.util.Random;
+import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
+import java.util.concurrent.atomic.AtomicLongFieldUpdater;
/**
* A package-local class holding common representation and mechanics
@@ -91,29 +93,19 @@
* form of CAS here, if it were provided.
*/
static final class Cell {
+ @SuppressWarnings("UnusedDeclaration")
volatile long p0, p1, p2, p3, p4, p5, p6;
volatile long value;
+ @SuppressWarnings("UnusedDeclaration")
volatile long q0, q1, q2, q3, q4, q5, q6;
Cell(long x) { value = x; }
final boolean cas(long cmp, long val) {
- return UNSAFE.compareAndSwapLong(this, valueOffset, cmp, val);
+ return valueUpdater.compareAndSet(this, cmp, val);
}
- // Unsafe mechanics
- private static final sun.misc.Unsafe UNSAFE;
- private static final long valueOffset;
- static {
- try {
- UNSAFE = getUnsafe();
- Class<?> ak = Cell.class;
- valueOffset = UNSAFE.objectFieldOffset
- (ak.getDeclaredField("value"));
- } catch (Exception e) {
- throw new Error(e);
- }
- }
-
+ private static final AtomicLongFieldUpdater<Cell> valueUpdater =
+ AtomicLongFieldUpdater.newUpdater(Cell.class, "value");
}
/**
@@ -173,14 +165,14 @@
* CASes the base field.
*/
final boolean casBase(long cmp, long val) {
- return UNSAFE.compareAndSwapLong(this, baseOffset, cmp, val);
+ return baseUpdater.compareAndSet(this, cmp, val);
}
/**
* CASes the busy field from 0 to 1 to acquire lock.
*/
final boolean casBusy() {
- return UNSAFE.compareAndSwapInt(this, busyOffset, 0, 1);
+ return busyUpdater.compareAndSet(this, 0, 1);
}
/**
@@ -246,8 +238,7 @@
try {
if (cells == as) { // Expand table unless stale
Cell[] rs = new Cell[n << 1];
- for (int i = 0; i < n; ++i)
- rs[i] = as[i];
+ System.arraycopy(as, 0, rs, 0, n);
cells = rs;
}
} finally {
@@ -288,60 +279,15 @@
Cell[] as = cells;
base = initialValue;
if (as != null) {
- int n = as.length;
- for (int i = 0; i < n; ++i) {
- Cell a = as[i];
+ for (Cell a : as) {
if (a != null)
- a.value = initialValue;
+ a.value = initialValue;
}
}
}
- // Unsafe mechanics
- private static final sun.misc.Unsafe UNSAFE;
- private static final long baseOffset;
- private static final long busyOffset;
- static {
- try {
- UNSAFE = getUnsafe();
- Class<?> sk = Striped64.class;
- baseOffset = UNSAFE.objectFieldOffset
- (sk.getDeclaredField("base"));
- busyOffset = UNSAFE.objectFieldOffset
- (sk.getDeclaredField("busy"));
- } catch (Exception e) {
- throw new Error(e);
- }
- }
-
- /**
- * Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package.
- * Replace with a simple call to Unsafe.getUnsafe when integrating
- * into a jdk.
- *
- * @return a sun.misc.Unsafe
- */
- private static sun.misc.Unsafe getUnsafe() {
- try {
- return sun.misc.Unsafe.getUnsafe();
- } catch (SecurityException tryReflectionInstead) {}
- try {
- return java.security.AccessController.doPrivileged
- (new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
- public sun.misc.Unsafe run() throws Exception {
- Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class;
- for (java.lang.reflect.Field f : k.getDeclaredFields()) {
- f.setAccessible(true);
- Object x = f.get(null);
- if (k.isInstance(x))
- return k.cast(x);
- }
- throw new NoSuchFieldError("the Unsafe");
- }});
- } catch (java.security.PrivilegedActionException e) {
- throw new RuntimeException("Could not initialize intrinsics",
- e.getCause());
- }
- }
-
+ private static final AtomicLongFieldUpdater<Striped64> baseUpdater =
+ AtomicLongFieldUpdater.newUpdater(Striped64.class, "base");
+ private static final AtomicIntegerFieldUpdater<Striped64> busyUpdater =
+ AtomicIntegerFieldUpdater.newUpdater(Striped64.class, "busy");
}
