Create 'implicit context' when plugin pushes frames

This allows plugins to properly append
the cause for events that use the transaction
system and fires the events after the frame
has been closed.

src/main/java/org/spongepowered/common/event/tracking/PhaseContext.java

@@ -82,6 +82,7 @@ public class PhaseContext<P extends PhaseContext<P>> implements PhaseStateProxy<
     private boolean allowsEntityEvents = true;
     private boolean allowsBulkBlockCaptures = true; // Defaults to allow block captures
     private boolean allowsBulkEntityCaptures = true;
+    private boolean requiresImplicitPhase = false;
     @Nullable Deque<CauseStackManager.StackFrame> usedFrame;
 
     private @Nullable Object source;
@@ -378,6 +379,15 @@ public Optional<ServerLocation> containerLocation() {
         return Optional.empty();
     }
 
+    public final boolean requiresImplicitPhase() {
+        return this.requiresImplicitPhase;
+    }
+
+    protected P requiresImplicitPhase(final boolean requiresImplicitPhase) {
+        this.requiresImplicitPhase = requiresImplicitPhase;
+        return (P) this;
+    }
+
     protected boolean isRunaway(final PhaseContext<?> phaseContext) {
         return phaseContext.getClass() == this.getClass();
     }

src/main/java/org/spongepowered/common/event/tracking/PhaseTracker.java

@@ -55,6 +55,7 @@
 import org.spongepowered.common.applaunch.config.core.SpongeConfigs;
 import org.spongepowered.common.event.cause.entity.SpongeSpawnTypes;
 import org.spongepowered.common.event.tracking.phase.general.GeneralPhase;
+import org.spongepowered.common.event.tracking.phase.plugin.PluginPhase;
 import org.spongepowered.common.event.tracking.phase.tick.TickPhase;
 import org.spongepowered.common.launch.Launch;
 import org.spongepowered.common.util.Constants;
@@ -568,6 +569,10 @@ public Object peekCause() {
 
     @Override
     public StackFrame pushCauseFrame() {
+        return this.pushCauseFrame0(false);
+    }
+
+    public StackFrame pushCauseFrame0(final boolean skipImplicitPhaseCreation) {
         this.enforceMainThread();
         // Ensure duplicate causes will be correctly sized.
         final int size = this.cause.size();
@@ -596,14 +601,35 @@ public StackFrame pushCauseFrame() {
             // were created.
             frame.stackDebug = new Exception();
         }
+        if (!skipImplicitPhaseCreation && this.getPhaseContext().requiresImplicitPhase()) {
+            frame.implicitContext = PluginPhase.State.PLUGIN.createPhaseContext(this).buildAndSwitch();
+        }
         return frame;
     }
 
     @Override
     public void popCauseFrame(final StackFrame oldFrame) {
         Objects.requireNonNull(oldFrame, "oldFrame");
         this.enforceMainThread();
-        final @Nullable SpongeCauseStackFrame frame = this.frames.peek();
+        @Nullable SpongeCauseStackFrame frame = this.frames.peek();
+        if (frame != oldFrame) {
+            // If implicit context is present, we need to
+            // first close it as it might have pushed new frames.
+            // This is an implementation detail so the caller has
+            // no knowledge of this context, so it can't close it
+            // by itself and instead closes the outer frame.
+            if (((SpongeCauseStackFrame) oldFrame).implicitContext != null) {
+                ((SpongeCauseStackFrame) oldFrame).implicitContext.close();
+                ((SpongeCauseStackFrame) oldFrame).implicitContext = null;
+                frame = this.frames.peek();
+            }
+        } else if (frame.implicitContext != null) {
+            // See above, no frames to close here.
+            // Fast path to avoid casting.
+            frame.implicitContext.close();
+            frame.implicitContext = null;
+        }
+
         if (frame != oldFrame) {
             // If the given frame is not the top frame then some form of
             // corruption of the stack has occurred and we do our best to correct
@@ -763,7 +789,7 @@ private void checkProviders() {
         // except for this method call-point.
         for (final Iterator<PhaseContext<@NonNull ?>> iterator = this.phaseContextProviders.descendingIterator(); iterator.hasNext(); ) {
             final PhaseContext<@NonNull ?> context = iterator.next();
-            final StackFrame frame = this.pushCauseFrame(); // these should auto close
+            final StackFrame frame = this.pushCauseFrame0(true); // these should auto close
             context.getFrameModifier().accept(frame); // The frame will be auto closed by the phase context
         }
         // Clear the list since everything is now loaded.

src/main/java/org/spongepowered/common/event/tracking/SpongeCauseStackFrame.java

@@ -43,6 +43,7 @@ public final class SpongeCauseStackFrame implements CauseStackManager.StackFrame
     private final Map<EventContextKey<?>, Object> storedContext;
     int old_min_depth;
     int lastCauseSize;
+    @Nullable PhaseContext<?> implicitContext = null;
 
     @Nullable Exception stackDebug = null;
 
@@ -58,6 +59,7 @@ public void clear() {
         this.storedContext.clear();
         this.lastCauseSize = -1;
         this.old_min_depth = -1;
+        this.implicitContext = null;
         this.stackDebug = null;
     }
 

src/main/java/org/spongepowered/common/event/tracking/phase/general/CommandPhaseContext.java

@@ -47,6 +47,7 @@ public class CommandPhaseContext extends GeneralPhaseContext<CommandPhaseContext
 
     CommandPhaseContext(final IPhaseState<CommandPhaseContext> state, final PhaseTracker tracker) {
         super(state, tracker);
+        this.requiresImplicitPhase(true);
     }
 
     @Override

src/main/java/org/spongepowered/common/event/tracking/phase/plugin/BasicPluginState.java

@@ -26,6 +26,7 @@
 
 import org.spongepowered.api.event.CauseStackManager;
 import org.spongepowered.common.event.tracking.PhaseTracker;
+import org.spongepowered.common.event.tracking.TrackingUtil;
 
 import java.util.function.BiConsumer;
 
@@ -51,6 +52,6 @@ public BiConsumer<CauseStackManager.StackFrame, BasicPluginContext> getFrameModi
 
     @Override
     public void unwind(final BasicPluginContext phaseContext) {
-
+        TrackingUtil.processBlockCaptures(phaseContext);
     }
 }

src/main/java/org/spongepowered/common/event/tracking/phase/plugin/DelayedTaskPhaseState.java

@@ -70,6 +70,7 @@ public static class Context extends PluginPhaseContext<Context> {
 
         public Context(final IPhaseState<Context> phaseState, final PhaseTracker tracker) {
             super(phaseState, tracker);
+            this.requiresImplicitPhase(false);
         }
 
         public Context container(final PluginContainer container) {

src/main/java/org/spongepowered/common/event/tracking/phase/plugin/PluginPhase.java

@@ -34,6 +34,7 @@ public static final class State {
         public static final IPhaseState<VolumeStreamApplicationState.Context> VOLUME_STREAM_APPLICATION = new VolumeStreamApplicationState();
         public static final IPhaseState<BasicPluginContext> SCHEDULED_TASK = new ScheduledTaskPhaseState();
         public static final IPhaseState<DelayedTaskPhaseState.Context> DELAYED_TASK = new DelayedTaskPhaseState();
+        public static final IPhaseState<BasicPluginContext> PLUGIN = new BasicPluginState();
 
         private State() {
         }

src/main/java/org/spongepowered/common/event/tracking/phase/plugin/PluginPhaseContext.java

@@ -42,6 +42,7 @@ public class PluginPhaseContext<P extends PluginPhaseContext<P>> extends PhaseCo
 
     protected PluginPhaseContext(final IPhaseState<P> phaseState, final PhaseTracker tracker) {
         super(phaseState, tracker);
+        this.requiresImplicitPhase(true);
     }
 
     @Override