8079205: CallSite dependency tracking is broken after sun.misc.Cleaner became automatically cleared
Reviewed-by: roland, psandoz, plevart, kbarrett, jrose
--- a/jdk/src/java.base/share/classes/java/lang/invoke/CallSite.java Thu May 14 12:05:33 2015 -0700
+++ b/jdk/src/java.base/share/classes/java/lang/invoke/CallSite.java Fri May 15 19:23:27 2015 +0300
@@ -27,8 +27,6 @@
import static java.lang.invoke.MethodHandleStatics.*;
import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
-import java.lang.reflect.Field;
-import sun.misc.Cleaner;
/**
* A {@code CallSite} is a holder for a variable {@link MethodHandle},
@@ -138,47 +136,9 @@
/**
* {@code CallSite} dependency context.
- * VM uses context class to store nmethod dependencies on the call site target.
- * Can be in 2 states: (a) null; or (b) {@code Cleaner} instance pointing to some Class instance.
- * Lazily initialized when CallSite instance is linked to some indy call site or VM needs
- * it to store dependencies. As a corollary, "null" context means there are no dependencies
- * registered yet. {@code Cleaner} is used in 2 roles:
- * (a) context class access for VM;
- * (b) stale context class cleanup.
- * {@code Cleaner} holds the context class until cleanup action is finished (see {@code PhantomReference}).
- * Though it's impossible to get the context class using {@code Reference.get()}, VM extracts it directly
- * from {@code Reference.referent} field.
- */
- private volatile Cleaner context = null;
-
- /**
- * Default context.
- * VM uses it to initialize non-linked CallSite context.
+ * JVM uses CallSite.context to store nmethod dependencies on the call site target.
*/
- private static class DefaultContext {}
- private static final Cleaner DEFAULT_CONTEXT = makeContext(DefaultContext.class, null);
-
- private static Cleaner makeContext(Class<?> referent, final CallSite holder) {
- return Cleaner.create(referent,
- new Runnable() {
- @Override public void run() {
- MethodHandleNatives.invalidateDependentNMethods(holder);
- }
- });
- }
-
- /** Initialize context class used for nmethod dependency tracking */
- /*package-private*/
- void initContext(Class<?> newContext) {
- // If there are concurrent actions, exactly one succeeds.
- if (context == null) {
- UNSAFE.compareAndSwapObject(this, CONTEXT_OFFSET, /*expected=*/null, makeContext(newContext, this));
- // No need to care about failed CAS attempt.
- // Since initContext is called from indy call site linkage in newContext class, there's no risk
- // that the context class becomes dead while corresponding context cleaner is alive (causing cleanup
- // action in the wrong context).
- }
- }
+ private final MethodHandleNatives.CallSiteContext context = MethodHandleNatives.CallSiteContext.make(this);
/**
* Returns the type of this call site's target.
--- a/jdk/src/java.base/share/classes/java/lang/invoke/MethodHandleNatives.java Thu May 14 12:05:33 2015 -0700
+++ b/jdk/src/java.base/share/classes/java/lang/invoke/MethodHandleNatives.java Fri May 15 19:23:27 2015 +0300
@@ -30,6 +30,7 @@
import static java.lang.invoke.MethodHandleNatives.Constants.*;
import static java.lang.invoke.MethodHandleStatics.*;
import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
+import sun.misc.Cleaner;
/**
* The JVM interface for the method handles package is all here.
@@ -61,8 +62,27 @@
static native void setCallSiteTargetNormal(CallSite site, MethodHandle target);
static native void setCallSiteTargetVolatile(CallSite site, MethodHandle target);
- /** Invalidate CallSite context: clean up dependent nmethods and reset call site context to initial state (null). */
- static native void invalidateDependentNMethods(CallSite site);
+ /** Represents a context to track nmethod dependencies on CallSite instance target. */
+ static class CallSiteContext implements Runnable {
+ //@Injected JVM_nmethodBucket* vmdependencies;
+
+ static CallSiteContext make(CallSite cs) {
+ final CallSiteContext newContext = new CallSiteContext();
+ // Cleaner is attached to CallSite instance and it clears native structures allocated for CallSite context.
+ // Though the CallSite can become unreachable, its Context is retained by the Cleaner instance (which is
+ // referenced from Cleaner class) until cleanup is performed.
+ Cleaner.create(cs, newContext);
+ return newContext;
+ }
+
+ @Override
+ public void run() {
+ MethodHandleNatives.clearCallSiteContext(this);
+ }
+ }
+
+ /** Invalidate all recorded nmethods. */
+ private static native void clearCallSiteContext(CallSiteContext context);
private static native void registerNatives();
static {
@@ -235,7 +255,6 @@
return Invokers.linkToTargetMethod(type);
} else {
appendixResult[0] = callSite;
- callSite.initContext(caller);
return Invokers.linkToCallSiteMethod(type);
}
}