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package io.grpc.internal;

import com.google.census.CensusContext;
import com.google.census.CensusContextFactory;
import com.google.census.MetricMap;
import com.google.census.TagKey;
import com.google.census.TagValue;

import java.nio.ByteBuffer;

public final class NoopCensusContextFactory extends CensusContextFactory {
  private static final ByteBuffer SERIALIZED_BYTES = ByteBuffer.allocate(0).asReadOnlyBuffer();
  private static final CensusContext DEFAULT_CONTEXT = new NoopCensusContext();
  private static final CensusContext.Builder BUILDER = new NoopContextBuilder();

  public static final CensusContextFactory INSTANCE = new NoopCensusContextFactory();

  private NoopCensusContextFactory() {
  }

  @Override
  public CensusContext deserialize(ByteBuffer buffer) {
    return DEFAULT_CONTEXT;
  }

  @Override
  public CensusContext getDefault() {
    return DEFAULT_CONTEXT;
  }

  private static class NoopCensusContext extends CensusContext {
    @Override
    public Builder builder() {
      return BUILDER;
    }

    @Override
    public CensusContext record(MetricMap metrics) {
      return DEFAULT_CONTEXT;
    }

    @Override
    public ByteBuffer serialize() {
      return SERIALIZED_BYTES;
    }
  }

  private static class NoopContextBuilder extends CensusContext.Builder {
    @Override
    public CensusContext.Builder set(TagKey key, TagValue value) {
      return this;
    }

    @Override
    public CensusContext build() {
      return DEFAULT_CONTEXT;
    }
  }
}

@@ -1900,26 +1900,22 @@
 c final 
-ByteBuffer
+byte%5B%5D
  SERIALI
@@ -1930,49 +1930,19 @@
 S = 
-ByteBuffer.allocate(0).asReadOnlyBuffer()
+new byte%5B0%5D
 ;%0A  
@@ -2722,32 +2722,68 @@
  return 
-SERIALIZED_BYTES
+ByteBuffer.wrap(SERIALIZED_BYTES).asReadOnlyBuffer()
 ;%0A    %7D%0A

fix a benign data race in NoopCensusContextFactory. (#2421)