1.1 --- a/src/jdk/nashorn/internal/runtime/GlobalConstants.java Thu Nov 06 13:15:52 2014 +0100
1.2 +++ b/src/jdk/nashorn/internal/runtime/GlobalConstants.java Thu Nov 06 17:06:56 2014 +0100
1.3 @@ -31,12 +31,14 @@
1.4 import static jdk.nashorn.internal.runtime.UnwarrantedOptimismException.INVALID_PROGRAM_POINT;
1.5 import static jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor.getProgramPoint;
1.6 import static jdk.nashorn.internal.runtime.logging.DebugLogger.quote;
1.7 +
1.8 import java.lang.invoke.MethodHandle;
1.9 import java.lang.invoke.MethodHandles;
1.10 import java.lang.invoke.SwitchPoint;
1.11 import java.util.Arrays;
1.12 import java.util.HashMap;
1.13 import java.util.Map;
1.14 +import java.util.concurrent.atomic.AtomicBoolean;
1.15 import java.util.logging.Level;
1.16 import jdk.internal.dynalink.CallSiteDescriptor;
1.17 import jdk.internal.dynalink.DynamicLinker;
1.18 @@ -50,7 +52,7 @@
1.19 import jdk.nashorn.internal.runtime.logging.Logger;
1.20
1.21 /**
1.22 - * Each global owns one of these. This is basically table of accessors
1.23 + * Each context owns one of these. This is basically table of accessors
1.24 * for global properties. A global constant is evaluated to a MethodHandle.constant
1.25 * for faster access and to avoid walking to proto chain looking for it.
1.26 *
1.27 @@ -67,12 +69,19 @@
1.28 * reregister the switchpoint. Set twice or more - don't try again forever, or we'd
1.29 * just end up relinking our way into megamorphisism.
1.30 *
1.31 + * Also it has to be noted that this kind of linking creates a coupling between a Global
1.32 + * and the call sites in compiled code belonging to the Context. For this reason, the
1.33 + * linkage becomes incorrect as soon as the Context has more than one Global. The
1.34 + * {@link #invalidateForever()} is invoked by the Context to invalidate all linkages and
1.35 + * turn off the functionality of this object as soon as the Context's {@link Context#newGlobal()} is invoked
1.36 + * for second time.
1.37 + *
1.38 * We can extend this to ScriptObjects in general (GLOBAL_ONLY=false), which requires
1.39 * a receiver guard on the constant getter, but it currently leaks memory and its benefits
1.40 * have not yet been investigated property.
1.41 *
1.42 - * As long as all Globals share the same constant instance, we need synchronization
1.43 - * whenever we access the instance.
1.44 + * As long as all Globals in a Context share the same GlobalConstants instance, we need synchronization
1.45 + * whenever we access it.
1.46 */
1.47 @Logger(name="const")
1.48 public final class GlobalConstants implements Loggable {
1.49 @@ -82,7 +91,7 @@
1.50 * Script objects require a receiver guard, which is memory intensive, so this is currently
1.51 * disabled. We might implement a weak reference based approach to this later.
1.52 */
1.53 - private static final boolean GLOBAL_ONLY = true;
1.54 + public static final boolean GLOBAL_ONLY = true;
1.55
1.56 private static final MethodHandles.Lookup LOOKUP = MethodHandles.lookup();
1.57
1.58 @@ -98,6 +107,8 @@
1.59 */
1.60 private final Map<String, Access> map = new HashMap<>();
1.61
1.62 + private final AtomicBoolean invalidatedForever = new AtomicBoolean(false);
1.63 +
1.64 /**
1.65 * Constructor - used only by global
1.66 * @param log logger, or null if none
1.67 @@ -216,10 +227,34 @@
1.68 * the same class for a new global, but the builtins and global scoped variables
1.69 * will have changed.
1.70 */
1.71 - public synchronized void invalidateAll() {
1.72 - log.info("New global created - invalidating all constant callsites without increasing invocation count.");
1.73 - for (final Access acc : map.values()) {
1.74 - acc.invalidateUncounted();
1.75 + public void invalidateAll() {
1.76 + if (!invalidatedForever.get()) {
1.77 + log.info("New global created - invalidating all constant callsites without increasing invocation count.");
1.78 + synchronized (this) {
1.79 + for (final Access acc : map.values()) {
1.80 + acc.invalidateUncounted();
1.81 + }
1.82 + }
1.83 + }
1.84 + }
1.85 +
1.86 + /**
1.87 + * To avoid an expensive global guard "is this the same global", similar to the
1.88 + * receiver guard on the ScriptObject level, we invalidate all getters when the
1.89 + * second Global is created by the Context owning this instance. After this
1.90 + * method is invoked, this GlobalConstants instance will both invalidate all the
1.91 + * switch points it produced, and it will stop handing out new method handles
1.92 + * altogether.
1.93 + */
1.94 + public void invalidateForever() {
1.95 + if (invalidatedForever.compareAndSet(false, true)) {
1.96 + log.info("New global created - invalidating all constant callsites.");
1.97 + synchronized (this) {
1.98 + for (final Access acc : map.values()) {
1.99 + acc.invalidateForever();
1.100 + }
1.101 + map.clear();
1.102 + }
1.103 }
1.104 }
1.105
1.106 @@ -251,7 +286,7 @@
1.107 return obj;
1.108 }
1.109
1.110 - private synchronized Access getOrCreateSwitchPoint(final String name) {
1.111 + private Access getOrCreateSwitchPoint(final String name) {
1.112 Access acc = map.get(name);
1.113 if (acc != null) {
1.114 return acc;
1.115 @@ -267,9 +302,13 @@
1.116 * @param name name of property
1.117 */
1.118 void delete(final String name) {
1.119 - final Access acc = map.get(name);
1.120 - if (acc != null) {
1.121 - acc.invalidateForever();
1.122 + if (!invalidatedForever.get()) {
1.123 + synchronized (this) {
1.124 + final Access acc = map.get(name);
1.125 + if (acc != null) {
1.126 + acc.invalidateForever();
1.127 + }
1.128 + }
1.129 }
1.130 }
1.131
1.132 @@ -313,45 +352,45 @@
1.133 *
1.134 * @return null if failed to set up constant linkage
1.135 */
1.136 - synchronized GuardedInvocation findSetMethod(final FindProperty find, final ScriptObject receiver, final GuardedInvocation inv, final CallSiteDescriptor desc, final LinkRequest request) {
1.137 - if (GLOBAL_ONLY && !isGlobalSetter(receiver, find)) {
1.138 + GuardedInvocation findSetMethod(final FindProperty find, final ScriptObject receiver, final GuardedInvocation inv, final CallSiteDescriptor desc, final LinkRequest request) {
1.139 + if (invalidatedForever.get() || (GLOBAL_ONLY && !isGlobalSetter(receiver, find))) {
1.140 return null;
1.141 }
1.142
1.143 final String name = desc.getNameToken(CallSiteDescriptor.NAME_OPERAND);
1.144
1.145 - final Access acc = getOrCreateSwitchPoint(name);
1.146 + synchronized (this) {
1.147 + final Access acc = getOrCreateSwitchPoint(name);
1.148
1.149 - if (log.isEnabled()) {
1.150 - log.fine("Trying to link constant SETTER ", acc);
1.151 + if (log.isEnabled()) {
1.152 + log.fine("Trying to link constant SETTER ", acc);
1.153 + }
1.154 +
1.155 + if (!acc.mayRetry() || invalidatedForever.get()) {
1.156 + if (log.isEnabled()) {
1.157 + log.fine("*** SET: Giving up on " + quote(name) + " - retry count has exceeded " + DynamicLinker.getLinkedCallSiteLocation());
1.158 + }
1.159 + return null;
1.160 + }
1.161 +
1.162 + if (acc.hasBeenInvalidated()) {
1.163 + log.info("New chance for " + acc);
1.164 + acc.newSwitchPoint();
1.165 + }
1.166 +
1.167 + assert !acc.hasBeenInvalidated();
1.168 +
1.169 + // if we haven't given up on this symbol, add a switchpoint invalidation filter to the receiver parameter
1.170 + final MethodHandle target = inv.getInvocation();
1.171 + final Class<?> receiverType = target.type().parameterType(0);
1.172 + final MethodHandle boundInvalidator = MH.bindTo(INVALIDATE_SP, this);
1.173 + final MethodHandle invalidator = MH.asType(boundInvalidator, boundInvalidator.type().changeParameterType(0, receiverType).changeReturnType(receiverType));
1.174 + final MethodHandle mh = MH.filterArguments(inv.getInvocation(), 0, MH.insertArguments(invalidator, 1, acc));
1.175 +
1.176 + assert inv.getSwitchPoints() == null : Arrays.asList(inv.getSwitchPoints());
1.177 + log.info("Linked setter " + quote(name) + " " + acc.getSwitchPoint());
1.178 + return new GuardedInvocation(mh, inv.getGuard(), acc.getSwitchPoint(), inv.getException());
1.179 }
1.180 -
1.181 - if (!acc.mayRetry()) {
1.182 - if (log.isEnabled()) {
1.183 - log.fine("*** SET: Giving up on " + quote(name) + " - retry count has exceeded " + DynamicLinker.getLinkedCallSiteLocation());
1.184 - }
1.185 - return null;
1.186 - }
1.187 -
1.188 - assert acc.mayRetry();
1.189 -
1.190 - if (acc.hasBeenInvalidated()) {
1.191 - log.info("New chance for " + acc);
1.192 - acc.newSwitchPoint();
1.193 - }
1.194 -
1.195 - assert !acc.hasBeenInvalidated();
1.196 -
1.197 - // if we haven't given up on this symbol, add a switchpoint invalidation filter to the receiver parameter
1.198 - final MethodHandle target = inv.getInvocation();
1.199 - final Class<?> receiverType = target.type().parameterType(0);
1.200 - final MethodHandle boundInvalidator = MH.bindTo(INVALIDATE_SP, this);
1.201 - final MethodHandle invalidator = MH.asType(boundInvalidator, boundInvalidator.type().changeParameterType(0, receiverType).changeReturnType(receiverType));
1.202 - final MethodHandle mh = MH.filterArguments(inv.getInvocation(), 0, MH.insertArguments(invalidator, 1, acc));
1.203 -
1.204 - assert inv.getSwitchPoints() == null : Arrays.asList(inv.getSwitchPoints());
1.205 - log.info("Linked setter " + quote(name) + " " + acc.getSwitchPoint());
1.206 - return new GuardedInvocation(mh, inv.getGuard(), acc.getSwitchPoint(), inv.getException());
1.207 }
1.208
1.209 /**
1.210 @@ -380,11 +419,11 @@
1.211 *
1.212 * @return resulting getter, or null if failed to create constant
1.213 */
1.214 - synchronized GuardedInvocation findGetMethod(final FindProperty find, final ScriptObject receiver, final CallSiteDescriptor desc) {
1.215 + GuardedInvocation findGetMethod(final FindProperty find, final ScriptObject receiver, final CallSiteDescriptor desc) {
1.216 // Only use constant getter for fast scope access, because the receiver may change between invocations
1.217 // for slow-scope and non-scope callsites.
1.218 // Also return null for user accessor properties as they may have side effects.
1.219 - if (!NashornCallSiteDescriptor.isFastScope(desc)
1.220 + if (invalidatedForever.get() || !NashornCallSiteDescriptor.isFastScope(desc)
1.221 || (GLOBAL_ONLY && !find.getOwner().isGlobal())
1.222 || find.getProperty() instanceof UserAccessorProperty) {
1.223 return null;
1.224 @@ -395,51 +434,53 @@
1.225 final Class<?> retType = desc.getMethodType().returnType();
1.226 final String name = desc.getNameToken(CallSiteDescriptor.NAME_OPERAND);
1.227
1.228 - final Access acc = getOrCreateSwitchPoint(name);
1.229 + synchronized (this) {
1.230 + final Access acc = getOrCreateSwitchPoint(name);
1.231
1.232 - log.fine("Starting to look up object value " + name);
1.233 - final Object c = find.getObjectValue();
1.234 + log.fine("Starting to look up object value " + name);
1.235 + final Object c = find.getObjectValue();
1.236
1.237 - if (log.isEnabled()) {
1.238 - log.fine("Trying to link constant GETTER " + acc + " value = " + c);
1.239 + if (log.isEnabled()) {
1.240 + log.fine("Trying to link constant GETTER " + acc + " value = " + c);
1.241 + }
1.242 +
1.243 + if (acc.hasBeenInvalidated() || acc.guardFailed() || invalidatedForever.get()) {
1.244 + if (log.isEnabled()) {
1.245 + log.info("*** GET: Giving up on " + quote(name) + " - retry count has exceeded " + DynamicLinker.getLinkedCallSiteLocation());
1.246 + }
1.247 + return null;
1.248 + }
1.249 +
1.250 + final MethodHandle cmh = constantGetter(c);
1.251 +
1.252 + MethodHandle mh;
1.253 + MethodHandle guard;
1.254 +
1.255 + if (isOptimistic) {
1.256 + if (JSType.getAccessorTypeIndex(cmh.type().returnType()) <= JSType.getAccessorTypeIndex(retType)) {
1.257 + //widen return type - this is pessimistic, so it will always work
1.258 + mh = MH.asType(cmh, cmh.type().changeReturnType(retType));
1.259 + } else {
1.260 + //immediately invalidate - we asked for a too wide constant as a narrower one
1.261 + mh = MH.dropArguments(MH.insertArguments(JSType.THROW_UNWARRANTED.methodHandle(), 0, c, programPoint), 0, Object.class);
1.262 + }
1.263 + } else {
1.264 + //pessimistic return type filter
1.265 + mh = Lookup.filterReturnType(cmh, retType);
1.266 + }
1.267 +
1.268 + if (find.getOwner().isGlobal()) {
1.269 + guard = null;
1.270 + } else {
1.271 + guard = MH.insertArguments(RECEIVER_GUARD, 0, acc, receiver);
1.272 + }
1.273 +
1.274 + if (log.isEnabled()) {
1.275 + log.info("Linked getter " + quote(name) + " as MethodHandle.constant() -> " + c + " " + acc.getSwitchPoint());
1.276 + mh = MethodHandleFactory.addDebugPrintout(log, Level.FINE, mh, "get const " + acc);
1.277 + }
1.278 +
1.279 + return new GuardedInvocation(mh, guard, acc.getSwitchPoint(), null);
1.280 }
1.281 -
1.282 - if (acc.hasBeenInvalidated() || acc.guardFailed()) {
1.283 - if (log.isEnabled()) {
1.284 - log.info("*** GET: Giving up on " + quote(name) + " - retry count has exceeded " + DynamicLinker.getLinkedCallSiteLocation());
1.285 - }
1.286 - return null;
1.287 - }
1.288 -
1.289 - final MethodHandle cmh = constantGetter(c);
1.290 -
1.291 - MethodHandle mh;
1.292 - MethodHandle guard;
1.293 -
1.294 - if (isOptimistic) {
1.295 - if (JSType.getAccessorTypeIndex(cmh.type().returnType()) <= JSType.getAccessorTypeIndex(retType)) {
1.296 - //widen return type - this is pessimistic, so it will always work
1.297 - mh = MH.asType(cmh, cmh.type().changeReturnType(retType));
1.298 - } else {
1.299 - //immediately invalidate - we asked for a too wide constant as a narrower one
1.300 - mh = MH.dropArguments(MH.insertArguments(JSType.THROW_UNWARRANTED.methodHandle(), 0, c, programPoint), 0, Object.class);
1.301 - }
1.302 - } else {
1.303 - //pessimistic return type filter
1.304 - mh = Lookup.filterReturnType(cmh, retType);
1.305 - }
1.306 -
1.307 - if (find.getOwner().isGlobal()) {
1.308 - guard = null;
1.309 - } else {
1.310 - guard = MH.insertArguments(RECEIVER_GUARD, 0, acc, receiver);
1.311 - }
1.312 -
1.313 - if (log.isEnabled()) {
1.314 - log.info("Linked getter " + quote(name) + " as MethodHandle.constant() -> " + c + " " + acc.getSwitchPoint());
1.315 - mh = MethodHandleFactory.addDebugPrintout(log, Level.FINE, mh, "get const " + acc);
1.316 - }
1.317 -
1.318 - return new GuardedInvocation(mh, guard, acc.getSwitchPoint(), null);
1.319 }
1.320 }
