## Summary `Prometheus::Client::Formats::Text.marshal` raises `NoMethodError` as soon as the registry holds a `Prometheus::Client::Summary` with an observation. `Prometheus::Client::Push#add` and `#replace` render the registry with it, so a summary cannot be pushed to a Pushgateway at all. The gem's own `Rack::Collector` registers a summary (`http_request_duration_seconds`, [`collector.rb` lines 42 to 45](https://gitlab.com/gitlab-org/ruby/gems/prometheus-client-mmap/-/blob/b4cf84ba58dcba3ec8c74e5004bc552d1a1834f9/lib/prometheus/client/rack/collector.rb#L42-45)), so its registry fails the same way once it has recorded a request. #77 reported this and was closed for inactivity on 2026-08-18. It still fails with the released 1.6.1 and on `master` (b4cf84ba), so I'm opening a new issue for it. The summary case was also raised in a comment on #75; !299 handles the histogram half of #75 and leaves the summary out, because it needs a change to `Summary` itself. ## Steps to reproduce With prometheus-client-mmap 1.6.1, and with `master` at b4cf84ba, on Ruby 3.4.11: ```ruby require 'prometheus/client' require 'prometheus/client/formats/text' require 'prometheus/client/push' registry = Prometheus::Client::Registry.new summary = registry.summary(:request_seconds, 'Request time') summary.observe({ route: 'x' }, 0.5) summary.observe({ route: 'x' }, 0.25) puts Prometheus::Client::Formats::Text.marshal(registry) # or: Prometheus::Client::Push.new(job: 'example').add(registry) ``` It fails the same way with the default value class (`MmapedValue`) and with `SimpleValue`. ## Current behavior ```plaintext NoMethodError: undefined method 'map' for an instance of Float lib/prometheus/client/formats/text.rb:61:in 'Prometheus::Client::Formats::Text.summary' lib/prometheus/client/formats/text.rb:52:in 'Prometheus::Client::Formats::Text.representation' lib/prometheus/client/formats/text.rb:20:in 'block (2 levels) in Prometheus::Client::Formats::Text.marshal' ``` `Push#add` raises the same error before it sends anything. ## Expected behavior The text format carries the summary's sum and count, the two samples `Formats::Text.marshal_multiprocess` already produces for the same summary (`request_seconds_sum{route="x"} 0.75` and `request_seconds_count{route="x"} 2`): ```plaintext # HELP request_seconds Request time # TYPE request_seconds summary request_seconds_sum{route="x"} 0.75 request_seconds_count{route="x"} 2.0 ``` The gem computes no quantiles (`Summary::Value` never stores any), so there are no `quantile` samples, as in `marshal_multiprocess`. ## Cause `Summary#values` maps each label set to `value.sum`, the value object of the sum alone ([`summary.rb` lines 53 to 60](https://gitlab.com/gitlab-org/ruby/gems/prometheus-client-mmap/-/blob/b4cf84ba58dcba3ec8c74e5004bc552d1a1834f9/lib/prometheus/client/summary.rb#L53-60)). `Formats::Text.summary` then calls `value.get.map`, `value.get.sum` and `value.get.total` on that object ([`text.rb` lines 60 to 68](https://gitlab.com/gitlab-org/ruby/gems/prometheus-client-mmap/-/blob/b4cf84ba58dcba3ec8c74e5004bc552d1a1834f9/lib/prometheus/client/formats/text.rb#L60-68)), but its `get` is the sum as a `Float`. The count lives in `Summary::Value#total`, which `values` never hands out, so the format cannot reach it. The format spec does not catch it because it renders a double: the summary there is a `Hash` of quantiles stubbed to answer `sum` and `total` ([`text_spec.rb` lines 9 to 13](https://gitlab.com/gitlab-org/ruby/gems/prometheus-client-mmap/-/blob/b4cf84ba58dcba3ec8c74e5004bc552d1a1834f9/spec/prometheus/client/formats/text_spec.rb#L9-13)), a shape `Summary` never produces. The `#get` and `#values` examples in `summary_spec.rb` are skipped with `xdescribe` ([lines 21 to 55](https://gitlab.com/gitlab-org/ruby/gems/prometheus-client-mmap/-/blob/b4cf84ba58dcba3ec8c74e5004bc552d1a1834f9/spec/prometheus/client/summary_spec.rb#L21-55)). The README's summary example also shows `summary.get` returning quantiles ([`README.md` lines 197 to 199](https://gitlab.com/gitlab-org/ruby/gems/prometheus-client-mmap/-/blob/b4cf84ba58dcba3ec8c74e5004bc552d1a1834f9/README.md#L197-199)), while it returns the sum. ## Possible fix - `Summary#values` returns each label set's `Summary::Value`, and `Summary::Value` gets a `get` that returns the sum, so `summary.get(labels)` and `summary.values[labels].get` keep returning the same number as today. - `Formats::Text.summary` emits `<name>_sum` from `value.sum.get` and `<name>_count` from `value.total.get`. - The format spec renders a real `Summary` instead of the double, the push spec pushes a registry holding one, and the README example shows what `get` returns. I tried the first two points in memory on `master`: the text format then gives the output above, and a Pushgateway 1.11.4 accepts the push and serves `request_seconds_sum` and `request_seconds_count` for the job. I'd like to work on this.