[Do not merge] Initial prototype for context-prop overhaul.

api/src/main/java/io/opentelemetry/context/Context.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2019, OpenTelemetry 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.opentelemetry.context;
+
+public final class Context {
+  private final io.grpc.Context ctx;
+
+  private Context(io.grpc.Context ctx) {
+    this.ctx = ctx;
+  }
+
+  public static Context current() {
+    return new Context(io.grpc.Context.current());
+  }
+
+  public static Scope setCurrent(Context ctx) {
+    return new ScopeImpl(ctx);
+  }
+
+  public static <T> Context.Key<T> createKey(String name) {
+    return new Key<T>(io.grpc.Context.<T>key(name));
+  }
+
+  public <T> T getValue(Context.Key<T> key) {
+    return key.key().get(ctx);
+  }
+
+  public <T> Context setValue(Context.Key<T> key, T value) {
+    return new Context(ctx.withValue(key.key(), value));
+  }
+
+  public static final class Key<T> {
+    io.grpc.Context.Key<T> key;
+
+    private Key(io.grpc.Context.Key<T> key) {
+      this.key = key;
+    }
+
+    io.grpc.Context.Key<T> key() {
+      return key;
+    }
+  }
+
+  static final class ScopeImpl implements Scope {
+    private final io.grpc.Context ctx;
+    private final io.grpc.Context prevCtx;
+
+    public ScopeImpl(Context ctx) {
+      this.ctx = ctx.ctx;
+      this.prevCtx = ctx.ctx.attach();
+    }
+
+    @Override
+    public void close() {
+      ctx.detach(prevCtx);
+    }
+  }
+}

api/src/main/java/io/opentelemetry/context/propagation/HttpExtractor.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2019, OpenTelemetry 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.opentelemetry.context.propagation;
+
+import io.opentelemetry.context.Context;
+import javax.annotation.Nullable;
+
+public interface HttpExtractor {
+  <C> Context extract(Context ctx, Getter<C> getter);
+
+  interface Getter<C> {
+    @Nullable
+    String get(C carrier, String key);
+  }
+}

api/src/main/java/io/opentelemetry/context/propagation/HttpInjector.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2019, OpenTelemetry 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.opentelemetry.context.propagation;
+
+import io.opentelemetry.context.Context;
+
+public interface HttpInjector {
+  <C> void inject(Context ctx, C carrier, Setter<C> setter);
+
+  interface Setter<C> {
+    void put(C carrier, String key, String value);
+  }
+}

api/src/main/java/io/opentelemetry/distributedcontext/BaggageManager.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2019, OpenTelemetry 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.opentelemetry.distributedcontext;
+
+import io.opentelemetry.context.Context;
+import io.opentelemetry.context.propagation.HttpExtractor;
+import io.opentelemetry.context.propagation.HttpInjector;
+
+public interface BaggageManager {
+  public Context setValue(Context ctx, String key, String value);
+
+  public String getValue(Context ctx, String key);
+
+  public void removeValue(Context ctx, String key);
+
+  public void clear(Context ctx);
+
+  public HttpInjector getHttpInjector();
+
+  public HttpExtractor getHttpExtractor();
+}

api/src/main/java/io/opentelemetry/distributedcontext/CorrelationsManager.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2019, OpenTelemetry 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.opentelemetry.distributedcontext;
+
+import io.opentelemetry.context.Context;
+import io.opentelemetry.context.propagation.HttpExtractor;
+import io.opentelemetry.context.propagation.HttpInjector;
+import java.util.List;
+
+public interface CorrelationsManager {
+  public Context setValue(Context ctx, CorrelationLabel label, HopLimit hopLimit);
+
+  public Context setValues(Context ctx, List<CorrelationLabel> labels, HopLimit hopLimit);
+
+  public interface CorrelationLabel {
+    public String key();
+
+    public String value();
+  }
+
+  public enum HopLimit {
+    NO_PROPAGATION,
+    UNLIMITED_PROPAGATION
+  }
+
+  public HttpInjector getHttpInjector();
+
+  public HttpExtractor getHttpExtractor();
+}