[GitHub] [incubator-druid] esevastyanov commented on a change in pull request #8157: Enum of ResponseContext keys

[GitBox <gi...@apache.org>]

esevastyanov commented on a change in pull request #8157: Enum of ResponseContext keys
URL: https://github.com/apache/incubator-druid/pull/8157#discussion_r309659574
 
 

 ##########
 File path: processing/src/main/java/org/apache/druid/query/context/ResponseContext.java
 ##########
 @@ -76,56 +253,158 @@ public static ResponseContext createEmpty()
     return DefaultResponseContext.createEmpty();
   }
 
-  protected abstract Map<String, Object> getDelegate();
+  /**
+   * Deserializes a string into {@link ResponseContext} using given {@link ObjectMapper}.
+   * @throws IllegalStateException if one of the deserialized map keys has not been registered.
+   */
+  public static ResponseContext deserialize(String responseContext, ObjectMapper objectMapper) throws IOException
+  {
+    final Map<String, Object> keyNameToObjects = objectMapper.readValue(
+        responseContext,
+        JacksonUtils.TYPE_REFERENCE_MAP_STRING_OBJECT
+    );
+    final ResponseContext context = ResponseContext.createEmpty();
+    keyNameToObjects.forEach((keyName, value) -> {
+      final BaseKey key = Key.keyOf(keyName);
+      context.add(key, value);
+    });
+    return context;
+  }
+
+  protected abstract Map<BaseKey, Object> getDelegate();
 
-  public Object put(String key, Object value)
+  /**
+   * Associates the specified object with the specified key.
+   * @throws IllegalStateException if the key has not been registered.
+   */
+  public Object put(BaseKey key, Object value)
   {
-    return getDelegate().put(key, value);
+    final BaseKey registeredKey = Key.keyOf(key.getName());
+    return getDelegate().put(registeredKey, value);
   }
 
-  public Object get(String key)
+  public Object get(BaseKey key)
   {
     return getDelegate().get(key);
   }
 
-  public Object remove(String key)
+  public Object remove(BaseKey key)
   {
     return getDelegate().remove(key);
   }
 
-  public void putAll(Map<? extends String, ?> m)
+  /**
+   * Adds (merges) a new value associated with a key to an old value.
+   * See merge function of a context key for a specific implementation.
+   * @throws IllegalStateException if the key has not been registered.
+   */
+  public Object add(BaseKey key, Object value)
   {
-    getDelegate().putAll(m);
+    final BaseKey registeredKey = Key.keyOf(key.getName());
+    return getDelegate().merge(registeredKey, value, key.getMergeFunction());
   }
 
-  public void putAll(ResponseContext responseContext)
+  /**
+   * Merges a response context into the current.
+   * @throws IllegalStateException If a key of the {@code responseContext} has not been registered.
+   */
+  public void merge(ResponseContext responseContext)
   {
-    getDelegate().putAll(responseContext.getDelegate());
+    responseContext.getDelegate().forEach((key, newValue) -> {
+      if (newValue != null) {
+        add(key, newValue);
+      }
+    });
   }
 
-  public int size()
+  /**
+   * Serializes the context given that the resulting string length is less than the provided limit.
+   * This method tries to remove some elements from context collections if it's needed to satisfy the limit.
+   * The resulting string might be correctly deserialized to {@link ResponseContext}.
+   */
+  public SerializationResult serializeWith(ObjectMapper objectMapper, int maxCharsNumber) throws JsonProcessingException
   {
-    return getDelegate().size();
+    final String fullSerializedString = objectMapper.writeValueAsString(getDelegate());
+    if (fullSerializedString.length() <= maxCharsNumber) {
+      return new SerializationResult(fullSerializedString, fullSerializedString);
+    } else {
+      // Indicates that the context is truncated during serialization.
+      add(Key.TRUNCATED, true);
+      final ObjectNode contextJsonNode = objectMapper.valueToTree(getDelegate());
+      final ArrayList<Map.Entry<String, JsonNode>> sortedNodesByLength = Lists.newArrayList(contextJsonNode.fields());
+      final Comparator<Map.Entry<String, JsonNode>> valueLengthReversedComparator =
+          Comparator.comparing((Map.Entry<String, JsonNode> e) -> e.getValue().toString().length()).reversed();
+      sortedNodesByLength.sort(valueLengthReversedComparator);
+      int needToRemoveCharsNumber = fullSerializedString.length() - maxCharsNumber;
+      // In general, the complexity of this block is O(n*m*log(m)) where n - context size, m - context's array size
+      for (Map.Entry<String, JsonNode> e : sortedNodesByLength) {
 
 Review comment:
   looks nice. updated

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