import com.google.common.collect.Collections2;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Sets;
-import java.lang.ref.SoftReference;
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
import java.util.Collections;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
-import java.util.concurrent.ThreadFactory;
-import java.util.concurrent.atomic.AtomicReference;
+import javax.annotation.concurrent.GuardedBy;
import org.opendaylight.controller.config.util.capability.Capability;
import org.opendaylight.controller.config.util.capability.ModuleListener;
import org.opendaylight.controller.config.util.capability.YangModuleCapability;
import org.opendaylight.yangtools.yang.model.api.SchemaContextProvider;
import org.opendaylight.yangtools.yang.model.repo.api.YangTextSchemaSource;
import org.opendaylight.yangtools.yang.model.repo.spi.SchemaSourceProvider;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
public class YangStoreService implements YangStoreContext {
- private static final Logger LOG = LoggerFactory.getLogger(YangStoreService.class);
+ private final SchemaSourceProvider<YangTextSchemaSource> sourceProvider;
+ private final ExecutorService notificationExecutor = Executors.newSingleThreadExecutor(
+ new ThreadFactoryBuilder().setDaemon(true).setNameFormat("yangstore-capability-notifications").build());
/**
- * This is a rather interesting locking model. We need to guard against both the
- * cache expiring from GC and being invalidated by schema context change. The
- * context can change while we are doing processing, so we do not want to block
- * it, so no synchronization can happen on the methods.
- *
- * So what we are doing is the following:
- *
- * We synchronize with GC as usual, using a SoftReference.
- *
- * The atomic reference is used to synchronize with {@link #refresh(org.opendaylight.yangtools.sal.binding.generator.util.BindingRuntimeContext)}, e.g. when
- * refresh happens, it will push a SoftReference(null), e.g. simulate the GC. Now
- * that may happen while the getter is already busy acting on the old schema context,
- * so it needs to understand that a refresh has happened and retry. To do that, it
- * attempts a CAS operation -- if it fails, in knows that the SoftReference has
- * been replaced and thus it needs to retry.
- *
- * Note that {@link #getYangStoreSnapshot()} will still use synchronize() internally
- * to stop multiple threads doing the same work.
+ * Guarded by explicit lock to allow for properly synchronizing the initial notification and modification
+ * of the listener set.
*/
- private final AtomicReference<SoftReference<YangStoreSnapshot>> ref =
- new AtomicReference<>(new SoftReference<YangStoreSnapshot>(null));
-
- private final AtomicReference<SoftReference<BindingRuntimeContext>> refBindingContext =
- new AtomicReference<>(new SoftReference<BindingRuntimeContext>(null));
-
- private final SchemaSourceProvider<YangTextSchemaSource> sourceProvider;
-
- private final ExecutorService notificationExecutor = Executors.newSingleThreadExecutor(new ThreadFactory() {
- @Override
- public Thread newThread(final Runnable r) {
- return new Thread(r, "yangstore-capability-notifications");
- }
- });
+ @GuardedBy("listeners")
+ private final Set<ModuleListener> listeners = new HashSet<>();
- private final Set<ModuleListener> listeners = Collections.synchronizedSet(new HashSet<ModuleListener>());
+ /**
+ * This is the latest snapshot. Some of its state is always initialized, but the MXBean maps potentially cause
+ * recomputation. Accessing those two specific methods needs to re-check whether the snapshot has changed
+ * asynchronously and retry if it didi.
+ */
+ private volatile YangStoreSnapshot snap;
public YangStoreService(final SchemaContextProvider schemaContextProvider,
final SchemaSourceProvider<YangTextSchemaSource> sourceProvider) {
this.sourceProvider = sourceProvider;
}
- synchronized YangStoreContext getYangStoreSnapshot() {
- SoftReference<YangStoreSnapshot> r = ref.get();
- YangStoreSnapshot ret = r.get();
-
- while (ret == null) {
- // We need to be compute a new value
- // TODO sourceProvider is not a snapshot
- ret = new YangStoreSnapshot(refBindingContext.get().get(), sourceProvider);
-
- if (!ref.compareAndSet(r, new SoftReference<>(ret))) {
- LOG.debug("Concurrent refresh detected, recomputing snapshot");
- r = ref.get();
- ret = null;
- }
- }
-
- return ret;
- }
-
public YangStoreContext getCurrentSnapshot() {
- return getYangStoreSnapshot();
+ return snap;
}
@Deprecated
@Override
public Map<String, Map<String, ModuleMXBeanEntry>> getModuleMXBeanEntryMap() {
- return getYangStoreSnapshot().getModuleMXBeanEntryMap();
+ Map<String, Map<String, ModuleMXBeanEntry>> ret;
+ YangStoreSnapshot snapshot;
+
+ do {
+ snapshot = snap;
+ ret = snapshot.getModuleMXBeanEntryMap();
+ } while (!snapshot.equals(snap));
+
+ return ret;
}
@Override
public Map<QName, Map<String, ModuleMXBeanEntry>> getQNamesToIdentitiesToModuleMXBeanEntries() {
- return getYangStoreSnapshot().getQNamesToIdentitiesToModuleMXBeanEntries();
+ Map<QName, Map<String, ModuleMXBeanEntry>> ret;
+ YangStoreSnapshot snapshot;
+
+ do {
+ snapshot = snap;
+ ret = snapshot.getQNamesToIdentitiesToModuleMXBeanEntries();
+ } while (!snapshot.equals(snap));
+
+ return ret;
}
@Override
public Set<Module> getModules() {
- return getYangStoreSnapshot().getModules();
+ return snap.getModules();
}
@Override
public String getModuleSource(final ModuleIdentifier moduleIdentifier) {
- return getYangStoreSnapshot().getModuleSource(moduleIdentifier);
+ return snap.getModuleSource(moduleIdentifier);
}
@Override
public EnumResolver getEnumResolver() {
- return getYangStoreSnapshot().getEnumResolver();
+ return snap.getEnumResolver();
}
public void refresh(final BindingRuntimeContext runtimeContext) {
- final YangStoreSnapshot previous = ref.get().get();
- ref.set(new SoftReference<YangStoreSnapshot>(null));
- refBindingContext.set(new SoftReference<>(runtimeContext));
- notificationExecutor.submit(new CapabilityChangeNotifier(previous));
+ final YangStoreSnapshot next = new YangStoreSnapshot(runtimeContext, sourceProvider);
+ final YangStoreSnapshot previous = snap;
+ snap = next;
+ notificationExecutor.submit(new Runnable() {
+ @Override
+ public void run() {
+ notifyListeners(previous, next);
+ }
+ });
}
public AutoCloseable registerModuleListener(final ModuleListener listener) {
- YangStoreContext context = ref.get().get();
+ final YangStoreContext context = snap;
- if (context == null) {
- context = getYangStoreSnapshot();
+ synchronized (listeners) {
+ if (context != null) {
+ listener.onCapabilitiesChanged(toCapabilities(context.getModules(), context), Collections.<Capability>emptySet());
+ }
+ this.listeners.add(listener);
}
- this.listeners.add(listener);
- listener.onCapabilitiesChanged(toCapabilities(context.getModules(), context), Collections.<Capability>emptySet());
-
return new AutoCloseable() {
@Override
public void close() {
- YangStoreService.this.listeners.remove(listener);
+ synchronized (listeners) {
+ listeners.remove(listener);
+ }
}
};
}
+ void notifyListeners(final YangStoreSnapshot previous, final YangStoreSnapshot current) {
+ final Set<Module> prevModules = previous.getModules();
+ final Set<Module> currModules = current.getModules();
+ final Set<Module> removed = Sets.difference(prevModules, currModules);
+ final Set<Module> added = Sets.difference(currModules, prevModules);
+
+ final Set<Capability> addedCaps = toCapabilities(added, current);
+ final Set<Capability> removedCaps = toCapabilities(removed, current);
+
+ synchronized (listeners) {
+ for (final ModuleListener listener : listeners) {
+ listener.onCapabilitiesChanged(addedCaps, removedCaps);
+ }
+ }
+ }
+
private static Set<Capability> toCapabilities(final Set<Module> modules, final YangStoreContext current) {
return ImmutableSet.copyOf(Collections2.transform(modules, new Function<Module, Capability>() {
@Override
}
}));
}
-
- private final class CapabilityChangeNotifier implements Runnable {
-
- private final YangStoreSnapshot previous;
-
- public CapabilityChangeNotifier(final YangStoreSnapshot previous) {
- this.previous = previous;
- }
-
- @Override
- public void run() {
- final YangStoreContext current = getYangStoreSnapshot();
-
- if (!current.equals(previous)) {
- final Set<Module> prevModules = previous.getModules();
- final Set<Module> currModules = current.getModules();
- final Set<Module> removed = Sets.difference(prevModules, currModules);
- final Set<Module> added = Sets.difference(currModules, prevModules);
-
- final Set<Capability> addedCaps = toCapabilities(added, current);
- final Set<Capability> removedCaps = toCapabilities(removed, current);
-
- for (final ModuleListener listener : listeners) {
- listener.onCapabilitiesChanged(addedCaps, removedCaps);
- }
- }
- }
-
- }
}
Code Review / controller.git / blobdiff