From c45ee247ab5583a5bc85b0331d40ca71967c7aeb Mon Sep 17 00:00:00 2001
From: shortcipher3 <chris.jon.hall@gmail.com>
Date: Tue, 8 Sep 2020 22:25:09 -0600
Subject: [PATCH] Fixed application hanging for iris depth example when no face
 is in the input image

---
 mediapipe/calculators/util/non_max_suppression_calculator.cc   | 3 +++
 .../calculators/util/non_max_suppression_calculator.proto      | 3 +++
 .../modules/face_detection/face_detection_front_cpu.pbtxt      | 1 +
 3 files changed, 7 insertions(+)

diff --git a/mediapipe/calculators/util/non_max_suppression_calculator.cc b/mediapipe/calculators/util/non_max_suppression_calculator.cc
index 1ea1b3d6b..5721deba5 100644
--- a/mediapipe/calculators/util/non_max_suppression_calculator.cc
+++ b/mediapipe/calculators/util/non_max_suppression_calculator.cc
@@ -199,6 +199,9 @@ class NonMaxSuppressionCalculator : public CalculatorBase {
       if (options_.return_empty_detections()) {
         cc->Outputs().Index(0).Add(new Detections(), cc->InputTimestamp());
       }
+      if (options_.error_on_empty_detections()) {
+        return ::mediapipe::InternalError("NonMaxSuppression received empty detections, but detections are required for this pipeline.");
+       }
       return ::mediapipe::OkStatus();
     }
 
diff --git a/mediapipe/calculators/util/non_max_suppression_calculator.proto b/mediapipe/calculators/util/non_max_suppression_calculator.proto
index 5fa960497..f241f125c 100644
--- a/mediapipe/calculators/util/non_max_suppression_calculator.proto
+++ b/mediapipe/calculators/util/non_max_suppression_calculator.proto
@@ -58,6 +58,9 @@ message NonMaxSuppressionCalculatorOptions {
   // Whether to put empty detection vector in output stream.
   optional bool return_empty_detections = 5;
 
+  // Whether to throw an error on an empty input detection vector
+  optional bool error_on_empty_detections = 8;
+
   // Algorithms that can be used to apply non-maximum suppression.
   enum NmsAlgorithm {
     DEFAULT = 0;
diff --git a/mediapipe/modules/face_detection/face_detection_front_cpu.pbtxt b/mediapipe/modules/face_detection/face_detection_front_cpu.pbtxt
index fda86fc50..8644af112 100644
--- a/mediapipe/modules/face_detection/face_detection_front_cpu.pbtxt
+++ b/mediapipe/modules/face_detection/face_detection_front_cpu.pbtxt
@@ -128,6 +128,7 @@ node {
       min_suppression_threshold: 0.3
       overlap_type: INTERSECTION_OVER_UNION
       algorithm: WEIGHTED
+      error_on_empty_detections: true
     }
   }
 }