Extract logic about current state in internal class. (#1381)

5 files changed, 34 insertions, 77 deletions

diff --git a/impl_core/src/main/java/io/opencensus/implcore/tags/CurrentTaggingState.java b/impl_core/src/main/java/io/opencensus/implcore/tags/CurrentTaggingState.java
deleted file mode 100644
index 8be055bb..00000000
--- a/impl_core/src/main/java/io/opencensus/implcore/tags/CurrentTaggingState.java
+++ /dev/null
@@ -1,55 +0,0 @@
-/*
- * Copyright 2017, OpenCensus Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package io.opencensus.implcore.tags;
-
-import static com.google.common.base.Preconditions.checkNotNull;
-
-import com.google.common.base.Preconditions;
-import io.opencensus.tags.TaggingState;
-import io.opencensus.tags.TagsComponent;
-import javax.annotation.concurrent.GuardedBy;
-import javax.annotation.concurrent.ThreadSafe;
-
-/**
- * The current {@link TaggingState} for a {@link TagsComponent}.
- *
- * <p>This class allows different tagging classes to share the state in a thread-safe way.
- */
-@ThreadSafe
-public final class CurrentTaggingState {
-
-  @GuardedBy("this")
-  private TaggingState currentState = TaggingState.ENABLED;
-
-  @GuardedBy("this")
-  private boolean isRead;
-
-  public synchronized TaggingState get() {
-    isRead = true;
-    return getInternal();
-  }
-
-  public synchronized TaggingState getInternal() {
-    return currentState;
-  }
-
-  // Sets current state to the given state.
-  synchronized void set(TaggingState state) {
-    Preconditions.checkState(!isRead, "State was already read, cannot set state.");
-    currentState = checkNotNull(state, "state");
-  }
-}
diff --git a/impl_core/src/main/java/io/opencensus/implcore/tags/TaggerImpl.java b/impl_core/src/main/java/io/opencensus/implcore/tags/TaggerImpl.java
index 0159ddbe..9f3a5429 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/tags/TaggerImpl.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/tags/TaggerImpl.java
@@ -17,13 +17,14 @@
 package io.opencensus.implcore.tags;
 
 import io.opencensus.common.Scope;
+import io.opencensus.implcore.internal.CurrentState;
+import io.opencensus.implcore.internal.CurrentState.State;
 import io.opencensus.implcore.internal.NoopScope;
 import io.opencensus.tags.InternalUtils;
 import io.opencensus.tags.Tag;
 import io.opencensus.tags.TagContext;
 import io.opencensus.tags.TagContextBuilder;
 import io.opencensus.tags.Tagger;
-import io.opencensus.tags.TaggingState;
 import java.util.Iterator;
 
 public final class TaggerImpl extends Tagger {
@@ -31,9 +32,9 @@ public final class TaggerImpl extends Tagger {
   // withTagContext(...) always puts a TagContextImpl into scope, even if the argument is another
   // TagContext subclass.
 
-  private final CurrentTaggingState state;
+  private final CurrentState state;
 
-  TaggerImpl(CurrentTaggingState state) {
+  TaggerImpl(CurrentState state) {
     this.state = state;
   }
 
@@ -44,35 +45,35 @@ public final class TaggerImpl extends Tagger {
 
   @Override
   public TagContextImpl getCurrentTagContext() {
-    return state.getInternal() == TaggingState.DISABLED
+    return state.getInternal() == State.DISABLED
         ? TagContextImpl.EMPTY
         : toTagContextImpl(CurrentTagContextUtils.getCurrentTagContext());
   }
 
   @Override
   public TagContextBuilder emptyBuilder() {
-    return state.getInternal() == TaggingState.DISABLED
+    return state.getInternal() == State.DISABLED
         ? NoopTagContextBuilder.INSTANCE
         : new TagContextBuilderImpl();
   }
 
   @Override
   public TagContextBuilder currentBuilder() {
-    return state.getInternal() == TaggingState.DISABLED
+    return state.getInternal() == State.DISABLED
         ? NoopTagContextBuilder.INSTANCE
         : toBuilder(CurrentTagContextUtils.getCurrentTagContext());
   }
 
   @Override
   public TagContextBuilder toBuilder(TagContext tags) {
-    return state.getInternal() == TaggingState.DISABLED
+    return state.getInternal() == State.DISABLED
         ? NoopTagContextBuilder.INSTANCE
         : toTagContextBuilderImpl(tags);
   }
 
   @Override
   public Scope withTagContext(TagContext tags) {
-    return state.getInternal() == TaggingState.DISABLED
+    return state.getInternal() == State.DISABLED
         ? NoopScope.getInstance()
         : CurrentTagContextUtils.withTagContext(toTagContextImpl(tags));
   }
diff --git a/impl_core/src/main/java/io/opencensus/implcore/tags/TagsComponentImplBase.java b/impl_core/src/main/java/io/opencensus/implcore/tags/TagsComponentImplBase.java
index c05f2fa8..88c31bae 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/tags/TagsComponentImplBase.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/tags/TagsComponentImplBase.java
@@ -18,6 +18,8 @@ package io.opencensus.implcore.tags;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
+import io.opencensus.implcore.internal.CurrentState;
+import io.opencensus.implcore.internal.CurrentState.State;
 import io.opencensus.implcore.tags.propagation.TagPropagationComponentImpl;
 import io.opencensus.tags.Tagger;
 import io.opencensus.tags.TaggingState;
@@ -26,13 +28,14 @@ import io.opencensus.tags.propagation.TagPropagationComponent;
 
 /** Base implementation of {@link TagsComponent}. */
 public class TagsComponentImplBase extends TagsComponent {
+  private static final State DEFAULT_STATE = State.ENABLED;
 
-  // The TaggingState shared between the TagsComponent, Tagger, and TagPropagationComponent
-  private final CurrentTaggingState state = new CurrentTaggingState();
+  // The State shared between the TagsComponent, Tagger, and TagPropagationComponent
+  private final CurrentState currentState = new CurrentState(DEFAULT_STATE);
 
-  private final Tagger tagger = new TaggerImpl(state);
+  private final Tagger tagger = new TaggerImpl(currentState);
   private final TagPropagationComponent tagPropagationComponent =
-      new TagPropagationComponentImpl(state);
+      new TagPropagationComponentImpl(currentState);
 
   @Override
   public Tagger getTagger() {
@@ -46,12 +49,20 @@ public class TagsComponentImplBase extends TagsComponent {
 
   @Override
   public TaggingState getState() {
-    return state.get();
+    return stateToTaggingState(currentState.get());
   }
 
   @Override
   @Deprecated
   public void setState(TaggingState newState) {
-    state.set(checkNotNull(newState, "newState"));
+    currentState.set(taggingStateToState(checkNotNull(newState, "newState")));
+  }
+
+  private static State taggingStateToState(TaggingState taggingState) {
+    return taggingState == TaggingState.ENABLED ? State.ENABLED : State.DISABLED;
+  }
+
+  private static TaggingState stateToTaggingState(State state) {
+    return state == State.ENABLED ? TaggingState.ENABLED : TaggingState.DISABLED;
   }
 }
diff --git a/impl_core/src/main/java/io/opencensus/implcore/tags/propagation/TagContextBinarySerializerImpl.java b/impl_core/src/main/java/io/opencensus/implcore/tags/propagation/TagContextBinarySerializerImpl.java
index 781cdff0..5a25da5b 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/tags/propagation/TagContextBinarySerializerImpl.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/tags/propagation/TagContextBinarySerializerImpl.java
@@ -16,10 +16,10 @@
 
 package io.opencensus.implcore.tags.propagation;
 
-import io.opencensus.implcore.tags.CurrentTaggingState;
+import io.opencensus.implcore.internal.CurrentState;
+import io.opencensus.implcore.internal.CurrentState.State;
 import io.opencensus.implcore.tags.TagContextImpl;
 import io.opencensus.tags.TagContext;
-import io.opencensus.tags.TaggingState;
 import io.opencensus.tags.propagation.TagContextBinarySerializer;
 import io.opencensus.tags.propagation.TagContextDeserializationException;
 import io.opencensus.tags.propagation.TagContextSerializationException;
@@ -27,22 +27,22 @@ import io.opencensus.tags.propagation.TagContextSerializationException;
 final class TagContextBinarySerializerImpl extends TagContextBinarySerializer {
   private static final byte[] EMPTY_BYTE_ARRAY = {};
 
-  private final CurrentTaggingState state;
+  private final CurrentState state;
 
-  TagContextBinarySerializerImpl(CurrentTaggingState state) {
+  TagContextBinarySerializerImpl(CurrentState state) {
     this.state = state;
   }
 
   @Override
   public byte[] toByteArray(TagContext tags) throws TagContextSerializationException {
-    return state.getInternal() == TaggingState.DISABLED
+    return state.getInternal() == State.DISABLED
         ? EMPTY_BYTE_ARRAY
         : SerializationUtils.serializeBinary(tags);
   }
 
   @Override
   public TagContext fromByteArray(byte[] bytes) throws TagContextDeserializationException {
-    return state.getInternal() == TaggingState.DISABLED
+    return state.getInternal() == State.DISABLED
         ? TagContextImpl.EMPTY
         : SerializationUtils.deserializeBinary(bytes);
   }
diff --git a/impl_core/src/main/java/io/opencensus/implcore/tags/propagation/TagPropagationComponentImpl.java b/impl_core/src/main/java/io/opencensus/implcore/tags/propagation/TagPropagationComponentImpl.java
index 5def0758..42ada755 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/tags/propagation/TagPropagationComponentImpl.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/tags/propagation/TagPropagationComponentImpl.java
@@ -16,14 +16,14 @@
 
 package io.opencensus.implcore.tags.propagation;
 
-import io.opencensus.implcore.tags.CurrentTaggingState;
+import io.opencensus.implcore.internal.CurrentState;
 import io.opencensus.tags.propagation.TagContextBinarySerializer;
 import io.opencensus.tags.propagation.TagPropagationComponent;
 
 public final class TagPropagationComponentImpl extends TagPropagationComponent {
   private final TagContextBinarySerializer tagContextBinarySerializer;
 
-  public TagPropagationComponentImpl(CurrentTaggingState state) {
+  public TagPropagationComponentImpl(CurrentState state) {
     tagContextBinarySerializer = new TagContextBinarySerializerImpl(state);
   }