We use `totalMetrics` with a `startTimeInNanos` and a call to `postIngest` to track the 'total time' that ingest is running for a given document. You can imagine it's a little stopwatch that we start and stop. Unfortunately, I think we're stopping the stopwatch just a little too soon, on the start side, we include the time spent transforming the document into an `IngestDocument`, but we do not include the (non-negligible) time transforming from an `IngestDocument` after the pipeline logic has run.

That is, the call to `sourceAsMap` is included:

https://github.com/elastic/elasticsearch/blob/d03664f84f15dcfcb900cf2d43121ca9d89bdda8/server/src/main/java/org/elasticsearch/ingest/IngestService.java#L905

But the call to `source` is not:

https://github.com/elastic/elasticsearch/blob/d03664f84f15dcfcb900cf2d43121ca9d89bdda8/server/src/main/java/org/elasticsearch/ingest/IngestService.java#L948

The consequence of this is that the `total` ingest stats doesn't actually reflect the true time spent in ingest code:

```
GET _nodes/stats?filter_path=nodes.*.ingest
{
  "nodes" : {
    "Aysm6ztIRne2ES5ktyuqtw" : {
      "ingest" : {
        "total" : {
          "count" : 1,
          "time_in_millis" : 110, <--- this should be a little higher than it is
```
server/src/main/java/org/elasticsearch/ingest/IngestService.java
}
        
        
        
        
        ingestClusterStateListeners.forEach(consumer -> consumer.accept(state));
        IngestMetadata newIngestMetadata = state.getMetadata().custom(IngestMetadata.TYPE);
        if (newIngestMetadata == null) {
            return;
        }
        try {
            innerUpdatePipelines(newIngestMetadata);
        } catch (ElasticsearchParseException e) {
            logger.warn("failed to update ingest pipelines", e);
        }
    }
    synchronized void innerUpdatePipelines(IngestMetadata newIngestMetadata) {
        Map<String, PipelineHolder> existingPipelines = this.pipelines;
        
        Map<String, PipelineHolder> newPipelines = null;
        List<ElasticsearchParseException> exceptions = null;
        
        
        for (PipelineConfiguration newConfiguration : newIngestMetadata.getPipelines().values()) {
            PipelineHolder previous = existingPipelines.get(newConfiguration.getId());
            if (previous != null && previous.configuration.equals(newConfiguration)) {
                continue;
            }
            if (newPipelines == null) {
                newPipelines = new HashMap<>(existingPipelines);