Convert CorrelationContext entry keys and values to simple Strings (#…

…1363)

* convert CC entry keys and values to simple Strings

* fix broken javadoc

api/src/main/java/io/opentelemetry/correlationcontext/CorrelationContext.java

@@ -21,8 +21,8 @@
 import javax.annotation.concurrent.Immutable;
 
 /**
- * A map from {@link EntryKey} to {@link EntryValue} and {@link EntryMetadata} that can be used to
- * label anything that is associated with a specific operation.
+ * A map from {@link String} to {@link String} and {@link EntryMetadata} that can be used to label
+ * anything that is associated with a specific operation.
  *
  * <p>For example, {@code CorrelationContext}s can be used to label stats, log messages, or
  * debugging information.
@@ -41,14 +41,14 @@ public interface CorrelationContext {
   Collection<Entry> getEntries();
 
   /**
-   * Returns the {@code EntryValue} associated with the given {@code EntryKey}.
+   * Returns the {@code String} associated with the given key.
    *
    * @param entryKey entry key to return the value for.
-   * @return the {@code EntryValue} associated with the given {@code EntryKey}, or {@code null} if
-   *     no {@code Entry} with the given {@code entryKey} is in this {@code CorrelationContext}.
+   * @return the value associated with the given key, or {@code null} if no {@code Entry} with the
+   *     given {@code entryKey} is in this {@code CorrelationContext}.
    */
   @Nullable
-  EntryValue getEntryValue(EntryKey entryKey);
+  String getEntryValue(String entryKey);
 
   /**
    * Builder for the {@link CorrelationContext} class.
@@ -88,22 +88,22 @@ interface Builder {
     /**
      * Adds the key/value pair and metadata regardless of whether the key is present.
      *
-     * @param key the {@code EntryKey} which will be set.
-     * @param value the {@code EntryValue} to set for the given key.
+     * @param key the {@code String} key which will be set.
+     * @param value the {@code String} value to set for the given key.
      * @param entryMetadata the {@code EntryMetadata} associated with this {@link Entry}.
      * @return this
      * @since 0.1.0
      */
-    Builder put(EntryKey key, EntryValue value, EntryMetadata entryMetadata);
+    Builder put(String key, String value, EntryMetadata entryMetadata);
 
     /**
      * Removes the key if it exists.
      *
-     * @param key the {@code EntryKey} which will be removed.
+     * @param key the {@code String} key which will be removed.
      * @return this
      * @since 0.1.0
      */
-    Builder remove(EntryKey key);
+    Builder remove(String key);
 
     /**
      * Creates a {@code CorrelationContext} from this builder.

api/src/main/java/io/opentelemetry/correlationcontext/DefaultCorrelationContextManager.java

@@ -71,16 +71,15 @@ public CorrelationContext.Builder setNoParent() {
     }
 
     @Override
-    public CorrelationContext.Builder put(
-        EntryKey key, EntryValue value, EntryMetadata entryMetadata) {
+    public CorrelationContext.Builder put(String key, String value, EntryMetadata entryMetadata) {
       Utils.checkNotNull(key, "key");
       Utils.checkNotNull(value, "value");
       Utils.checkNotNull(entryMetadata, "entryMetadata");
       return this;
     }
 
     @Override
-    public CorrelationContext.Builder remove(EntryKey key) {
+    public CorrelationContext.Builder remove(String key) {
       Utils.checkNotNull(key, "key");
       return this;
     }

api/src/main/java/io/opentelemetry/correlationcontext/EmptyCorrelationContext.java

@@ -45,7 +45,7 @@ public Collection<Entry> getEntries() {
 
   @Nullable
   @Override
-  public EntryValue getEntryValue(EntryKey entryKey) {
+  public String getEntryValue(String entryKey) {
     return null;
   }
 

api/src/main/java/io/opentelemetry/correlationcontext/Entry.java

@@ -18,16 +18,31 @@
 
 import com.google.auto.value.AutoValue;
 import io.opentelemetry.correlationcontext.EntryMetadata.EntryTtl;
+import io.opentelemetry.internal.StringUtils;
+import io.opentelemetry.internal.Utils;
 import javax.annotation.concurrent.Immutable;
 
 /**
- * {@link EntryKey} paired with a {@link EntryValue}.
+ * String-String key-value pair, along with {@link EntryMetadata}.
  *
  * @since 0.1.0
  */
 @Immutable
 @AutoValue
 public abstract class Entry {
+  /**
+   * The maximum length for an entry key name. The value is {@value #MAX_KEY_LENGTH}.
+   *
+   * @since 0.1.0
+   */
+  public static final int MAX_KEY_LENGTH = 255;
+
+  /**
+   * The maximum length for a entry value. The value is {@value #MAX_VALUE_LENGTH}.
+   *
+   * @since 0.1.0
+   */
+  public static final int MAX_VALUE_LENGTH = 255;
 
   /** Default propagation metadata - unlimited propagation. */
   public static final EntryMetadata METADATA_UNLIMITED_PROPAGATION =
@@ -44,7 +59,9 @@ public abstract class Entry {
    * @return a {@code Entry}.
    * @since 0.1.0
    */
-  public static Entry create(EntryKey key, EntryValue value, EntryMetadata entryMetadata) {
+  public static Entry create(String key, String value, EntryMetadata entryMetadata) {
+    Utils.checkArgument(keyIsValid(key), "Invalid entry key name: %s", key);
+    Utils.checkArgument(isValueValid(value), "Invalid entry value: %s", value);
     return new AutoValue_Entry(key, value, entryMetadata);
   }
 
@@ -54,15 +71,15 @@ public static Entry create(EntryKey key, EntryValue value, EntryMetadata entryMe
    * @return the entry's key.
    * @since 0.1.0
    */
-  public abstract EntryKey getKey();
+  public abstract String getKey();
 
   /**
    * Returns the entry's value.
    *
    * @return the entry's value.
    * @since 0.1.0
    */
-  public abstract EntryValue getValue();
+  public abstract String getValue();
 
   /**
    * Returns the {@link EntryMetadata} associated with this {@link Entry}.
@@ -71,4 +88,26 @@ public static Entry create(EntryKey key, EntryValue value, EntryMetadata entryMe
    * @since 0.1.0
    */
   public abstract EntryMetadata getEntryMetadata();
+
+  /**
+   * Determines whether the given {@code String} is a valid entry key.
+   *
+   * @param name the entry key name to be validated.
+   * @return whether the name is valid.
+   */
+  private static boolean keyIsValid(String name) {
+    return !name.isEmpty()
+        && name.length() <= MAX_KEY_LENGTH
+        && StringUtils.isPrintableString(name);
+  }
+
+  /**
+   * Determines whether the given {@code String} is a valid entry value.
+   *
+   * @param value the entry value to be validated.
+   * @return whether the value is valid.
+   */
+  private static boolean isValueValid(String value) {
+    return value.length() <= MAX_VALUE_LENGTH && StringUtils.isPrintableString(value);
+  }
 }

api/src/main/java/io/opentelemetry/correlationcontext/package-info.java

@@ -21,10 +21,9 @@
  * to label anything that is associated with a specific operation. For example, the {@code
  * opentelemetry.stats} package labels all stats with the current entries.
  *
- * <p>{@link io.opentelemetry.correlationcontext.Entry Entrys} are key-value pairs. The {@link
- * io.opentelemetry.correlationcontext.EntryKey keys} and {@link
- * io.opentelemetry.correlationcontext.EntryValue values} are wrapped {@code String}s. They are
- * stored as a map in a {@link io.opentelemetry.correlationcontext.CorrelationContext}.
+ * <p>{@link io.opentelemetry.correlationcontext.Entry Entrys} are key-value pairs of {@link
+ * java.lang.String}s. They are stored as a map in a {@link
+ * io.opentelemetry.correlationcontext.CorrelationContext}.
  *
  * <p>Note that entries are independent of the tracing data that is propagated in the {@code
  * io.grpc.Context}, such as trace ID.

api/src/test/java/io/opentelemetry/correlationcontext/DefaultCorrelationContextManagerTest.java

@@ -33,8 +33,8 @@
 public final class DefaultCorrelationContextManagerTest {
   private static final CorrelationContextManager defaultCorrelationContextManager =
       DefaultCorrelationContextManager.getInstance();
-  private static final EntryKey KEY = EntryKey.create("key");
-  private static final EntryValue VALUE = EntryValue.create("value");
+  private static final String KEY = "key";
+  private static final String VALUE = "value";
 
   private static final CorrelationContext DIST_CONTEXT =
       new CorrelationContext() {
@@ -46,7 +46,7 @@ public Collection<Entry> getEntries() {
         }
 
         @Override
-        public EntryValue getEntryValue(EntryKey entryKey) {
+        public String getEntryValue(String entryKey) {
           return VALUE;
         }
       };