[Feature Request] Add capability for reading statistics from search phase results processors

[martin-gaievski]

Is your feature request related to a problem? Please describe

Existing API for retrieving search pipeline stats does not have data for search phase results processors.

Here is sample response for GET _nodes/stats/search_pipeline request:

{
  "_nodes": {
    "total": 6,
    "successful": 6,
    "failed": 0
  },
  "cluster_name": "opensearch-infra-stack-martin-30a-lb4-939274133793-us-east-1",
  "nodes": {
    "OIx5MQRkSkS6PKFPJ4IfKQ": {
      "timestamp": 1741558432570,
      "name": "ip-10-0-5-178.ec2.internal",
      "transport_address": "10.0.5.178:9300",
      "host": "10.0.5.178",
      "ip": "10.0.5.178:9300",
      "roles": [
        "cluster_manager"
      ],
      "attributes": {
        "shard_indexing_pressure_enabled": "true"
      },
      "search_pipeline": {
        "total_request": {
          "count": 0,
          "time_in_millis": 0,
          "current": 0,
          "failed": 0
        },
        "total_response": {
          "count": 0,
          "time_in_millis": 0,
          "current": 0,
          "failed": 0
        },
        "pipelines": {
          "norm-pipeline": {
            "request": {
              "count": 0,
              "time_in_millis": 0,
              "current": 0,
              "failed": 0
            },
            "response": {
              "count": 0,
              "time_in_millis": 0,
              "current": 0,
              "failed": 0
            },
            "request_processors": [],
            "response_processors": []
          }
        }
      }
    },
    "cxC2D7ljTpKjeQhFqYyuQw": {
      "timestamp": 1741558432568,
      "name": "ip-10-0-4-50.ec2.internal",
      "transport_address": "10.0.4.50:9300",
      "host": "10.0.4.50",
      "ip": "10.0.4.50:9300",
      "roles": [
        "data",
        "ingest"
      ],
      "attributes": {
        "shard_indexing_pressure_enabled": "true"
      },
      "search_pipeline": {
        "total_request": {
          "count": 0,
          "time_in_millis": 0,
          "current": 0,
          "failed": 0
        },
        "total_response": {
          "count": 0,
          "time_in_millis": 0,
          "current": 0,
          "failed": 0
        },
        "pipelines": {
          "norm-pipeline": {
            "request": {
              "count": 0,
              "time_in_millis": 0,
              "current": 0,
              "failed": 0
            },
            "response": {
              "count": 0,
              "time_in_millis": 0,
              "current": 0,
              "failed": 0
            },
            "request_processors": [],
            "response_processors": []
          }
        }
      }
    },
    "Zde2tzuFSfSZtXDMtYrZ2g": {
      "timestamp": 1741558432571,
      "name": "ip-10-0-4-235.ec2.internal",
      "transport_address": "10.0.4.235:9300",
      "host": "10.0.4.235",
      "ip": "10.0.4.235:9300",
      "roles": [
        "cluster_manager"
      ],
      "attributes": {
        "shard_indexing_pressure_enabled": "true"
      },
      "search_pipeline": {
        "total_request": {
          "count": 0,
          "time_in_millis": 0,
          "current": 0,
          "failed": 0
        },
        "total_response": {
          "count": 0,
          "time_in_millis": 0,
          "current": 0,
          "failed": 0
        },
        "pipelines": {
          "norm-pipeline": {
            "request": {
              "count": 0,
              "time_in_millis": 0,
              "current": 0,
              "failed": 0
            },
            "response": {
              "count": 0,
              "time_in_millis": 0,
              "current": 0,
              "failed": 0
            },
            "request_processors": [],
            "response_processors": []
          }
        }
      }
    },
    "XgCFz5L1STe8NOGvvugUSQ": {
      "timestamp": 1741558432568,
      "name": "ip-10-0-5-220.ec2.internal",
      "transport_address": "10.0.5.220:9300",
      "host": "10.0.5.220",
      "ip": "10.0.5.220:9300",
      "roles": [
        "data",
        "ingest"
      ],
      "attributes": {
        "shard_indexing_pressure_enabled": "true"
      },
      "search_pipeline": {
        "total_request": {
          "count": 0,
          "time_in_millis": 0,
          "current": 0,
          "failed": 0
        },
        "total_response": {
          "count": 0,
          "time_in_millis": 0,
          "current": 0,
          "failed": 0
        },
        "pipelines": {
          "norm-pipeline": {
            "request": {
              "count": 0,
              "time_in_millis": 0,
              "current": 0,
              "failed": 0
            },
            "response": {
              "count": 0,
              "time_in_millis": 0,
              "current": 0,
              "failed": 0
            },
            "request_processors": [],
            "response_processors": []
          }
        }
      }
    },
    "xxW5HwaXTKuIGVI04L6ZGw": {
      "timestamp": 1741558432569,
      "name": "ip-10-0-3-71.ec2.internal",
      "transport_address": "10.0.3.71:9300",
      "host": "10.0.3.71",
      "ip": "10.0.3.71:9300",
      "roles": [
        "data",
        "ingest"
      ],
      "attributes": {
        "shard_indexing_pressure_enabled": "true"
      },
      "search_pipeline": {
        "total_request": {
          "count": 0,
          "time_in_millis": 0,
          "current": 0,
          "failed": 0
        },
        "total_response": {
          "count": 0,
          "time_in_millis": 0,
          "current": 0,
          "failed": 0
        },
        "pipelines": {
          "norm-pipeline": {
            "request": {
              "count": 0,
              "time_in_millis": 0,
              "current": 0,
              "failed": 0
            },
            "response": {
              "count": 0,
              "time_in_millis": 0,
              "current": 0,
              "failed": 0
            },
            "request_processors": [],
            "response_processors": []
          }
        }
      }
    },
    "lU-npuC1QDyKvFujVXdZHQ": {
      "timestamp": 1741558432569,
      "name": "seed",
      "transport_address": "10.0.5.254:9300",
      "host": "10.0.5.254",
      "ip": "10.0.5.254:9300",
      "roles": [
        "cluster_manager"
      ],
      "attributes": {
        "shard_indexing_pressure_enabled": "true"
      },
      "search_pipeline": {
        "total_request": {
          "count": 0,
          "time_in_millis": 0,
          "current": 0,
          "failed": 0
        },
        "total_response": {
          "count": 0,
          "time_in_millis": 0,
          "current": 0,
          "failed": 0
        },
        "pipelines": {
          "norm-pipeline": {
            "request": {
              "count": 0,
              "time_in_millis": 0,
              "current": 0,
              "failed": 0
            },
            "response": {
              "count": 0,
              "time_in_millis": 0,
              "current": 0,
              "failed": 0
            },
            "request_processors": [],
            "response_processors": []
          }
        }
      }
    }
  }
}

Describe the solution you'd like

Include section for search phase results processor to existing API response. Information can be similar to what is collected for request and response processors: count, time, number of currently running and failed executions.

Related component

Search

Describe alternatives you've considered

No response

Additional context

No response

[mch2]

Thanks @martin-gaievski we see you have linked a PR already so assigning to you.