*/
public interface CloseTracked<T extends CloseTracked<T>> {
+ /**
+ * This returns the allocation context as {@link StackTraceElement}s. NB that
+ * this is a relatively <b>EXPENSIVE</b> operation! You should only ever call
+ * this when you really need to, e.g. when you actually produce output for
+ * humans, but not too early.
+ */
+ // TODO When we're on Java 9, then instead return a StackWalker.StackFrame[] here?
@Nullable StackTraceElement[] getAllocationContextStackTrace();
CloseTracked<T> getRealCloseTracked();
*/
public class CloseTrackedTrait<T extends CloseTracked<T>> implements CloseTracked<T> {
+ // NB: It's important that we keep a Throwable here, and not directly the StackTraceElement[] !
+ // This is because creating a new Throwable() is a lot less expensive in terms of runtime overhead
+ // than actually calling its getStackTrace(), which we can delay until we really need to.
+ // see also e.g. https://stackoverflow.com/a/26122232/421602
private final @Nullable Throwable allocationContext;
private final CloseTrackedRegistry<T> closeTrackedRegistry;
private final CloseTracked<T> realCloseTracked;
public CloseTrackedTrait(CloseTrackedRegistry<T> transactionChainRegistry, CloseTracked<T> realCloseTracked) {
if (transactionChainRegistry.isDebugContextEnabled()) {
- this.allocationContext = new Throwable("allocated at");
+ // NB: We're NOT doing the (expensive) getStackTrace() here just yet (only below)
+ // TODO When we're on Java 9, then instead use the new java.lang.StackWalker API..
+ this.allocationContext = new Throwable();
} else {
this.allocationContext = null;
}
}
@Override
+ @Nullable
public StackTraceElement[] getAllocationContextStackTrace() {
return allocationContext != null ? allocationContext.getStackTrace() : null;
}