private Family prepareSketches()

in src/main/java/org/apache/datasketches/server/MergeHandler.java [140:201]
45 lines of code
19 McCabe index (conditional complexity)

  private Family prepareSketches(final JsonArray sources, Family family, final String dst, final ArrayList<MergeEntry> sketchList) {
    final HashSet<String> namedSet = new HashSet<>();

    // TODO: Check for sketch value types with distinct counting?
    //       Less obvious how to handle serialized sketch input in that case

    // add destination if one exists just in case it's also listed as a source
    if (dst != null) {
      namedSet.add(dst);
    }

    for (final JsonElement elmt : sources) {
      if (elmt.isJsonPrimitive()) {
        // check family
        final String key = elmt.getAsString();
        final SketchStorage.SketchEntry entry = sketches.getSketch(key);
        if (entry == null || (family != null && family != entry.family_)) {
          throw new SketchesException("Input sketches must exist and be of the same family as the target");
        }

        // add to set, save family if we didn't have one yet
        if (!namedSet.contains(key)) {
          namedSet.add(key);
          if (family == null) {
            family = entry.family_;
          }

          // if we have a theta Union we need to get the result first
          if (entry.family_ == Family.UNION) {
            sketchList.add(new MergeEntry(key, ((Union) entry.sketch_).getResult()));
          } else {
            sketchList.add(new MergeEntry(key, entry.sketch_));
          }
        }
      } else { // is JsonObject
        // need special handling for theta as we store Unions?
        final JsonObject sourceObj = elmt.getAsJsonObject();
        if (!sourceObj.has(SketchConstants.QUERY_FAMILY_FIELD)
            || !sourceObj.has(SketchConstants.QUERY_DATA_FIELD)) {
          throw new SketchesException("Base64 sketch used as merge input must specify both \""
              + SketchConstants.QUERY_FAMILY_FIELD + "\" and \"" + SketchConstants.QUERY_DATA_FIELD + "\"");
        }

        final Family skFamily = familyFromString(sourceObj.get(SketchConstants.QUERY_FAMILY_FIELD).getAsString());
        final String skString = sourceObj.get(SketchConstants.QUERY_DATA_FIELD).getAsString();
        if (skString == null || (family != null
            && ((family != Family.UNION && family != skFamily) || (family == Family.UNION && skFamily != Family.QUICKSELECT)))) {
          throw new SketchesException("Input sketches must exist and be of the same family as the target");
        }

        // add to list, save family if we didn't have one yet
        // use hashcode of sketch as name -- we'll later create a needless lock but cleaner than conditional locking
        final Object sketch = deserializeSketch(skFamily, skString);
        sketchList.add(new MergeEntry(Integer.toString(sketch.hashCode()), sketch));
        if (family == null) {
          family = skFamily;
        }
      }
    }

    return family;
  }