From 1fc754f054f9816b47b25b084e56f9488b024948 Mon Sep 17 00:00:00 2001
From: Nilton Vasques <nilton.vasques@gmail.com>
Date: Mon, 19 Jun 2023 10:58:44 -0300
Subject: [PATCH 1/2] Allow to create events/spans before the transaction start
 to compute queue time

---
 lib/elastic_apm/metrics/request_metrics.rb | 58 ++++++++++++++++++++++
 lib/elastic_apm/middleware.rb              | 19 +++++++
 lib/elastic_apm/span.rb                    |  5 +-
 lib/elastic_apm/transaction.rb             |  3 +-
 4 files changed, 81 insertions(+), 4 deletions(-)
 create mode 100644 lib/elastic_apm/metrics/request_metrics.rb

diff --git a/lib/elastic_apm/metrics/request_metrics.rb b/lib/elastic_apm/metrics/request_metrics.rb
new file mode 100644
index 000000000..366cdfd6e
--- /dev/null
+++ b/lib/elastic_apm/metrics/request_metrics.rb
@@ -0,0 +1,58 @@
+module ElasticAPM
+  class RequestMetrics
+    MILLISECONDS_CUTOFF = Time.new(2000, 1, 1).to_i * 1000
+    MICROSECONDS_CUTOFF = MILLISECONDS_CUTOFF * 1000
+    NANOSECONDS_CUTOFF = MICROSECONDS_CUTOFF * 1000
+
+    attr_reader :request_id, :size, :network_time
+
+    def initialize(env)
+      @request_id = env["HTTP_X_REQUEST_ID"]
+      @size = env["rack.input"].respond_to?(:size) ? env["rack.input"].size : 0
+      @network_time = env["puma.request_body_wait"].to_i
+      @request_start_header = env["HTTP_X_REQUEST_START"]
+    end
+
+    def started_at
+      if @request_start_header
+        # There are several variants of this header. We handle these:
+        #   - whole milliseconds (Heroku)
+        #   - whole microseconds (???)
+        #   - whole nanoseconds (Render)
+        #   - fractional seconds (NGINX)
+        #   - preceeding "t=" (NGINX)
+        value = @request_start_header.gsub(/[^0-9.]/, "").to_f
+
+        # `value` could be seconds, milliseconds, microseconds or nanoseconds.
+        # We use some arbitrary cutoffs to determine which one it is.
+
+        if value > NANOSECONDS_CUTOFF
+          Time.at(value / 1_000_000_000.0)
+        elsif value > MICROSECONDS_CUTOFF
+          Time.at(value / 1_000_000.0)
+        elsif value > MILLISECONDS_CUTOFF
+          Time.at(value / 1000.0)
+        else
+          Time.at(value)
+        end
+      end
+    end
+
+    def queue_time(now = Time.now)
+      return 0.0 if started_at.nil?
+
+      queue_time = ((now - started_at) * 1000).to_i
+
+      # Subtract the time Puma spent waiting on the request body, i.e. the network time. It's irrelevant to
+      # capacity-related queue time. Without this, slow clients and large request payloads will skew queue time.
+      queue_time -= network_time
+
+      # Safeguard against negative queue times (should not happen in practice)
+      (queue_time > 0) ? queue_time : 0
+    end
+
+    def queue_time_micros(now = Time.now)
+      (queue_time(now) * 1000).to_i
+    end
+  end
+end
diff --git a/lib/elastic_apm/middleware.rb b/lib/elastic_apm/middleware.rb
index 9e6aeb987..a6c166981 100644
--- a/lib/elastic_apm/middleware.rb
+++ b/lib/elastic_apm/middleware.rb
@@ -17,6 +17,7 @@
 
 #
 # frozen_string_literal: true
+require 'elastic_apm/metrics/request_metrics'
 
 module ElasticAPM
   # @api private
@@ -33,6 +34,8 @@ def call(env)
           transaction = start_transaction(env)
         end
 
+        register_queue_time(transaction, env) if transaction
+
         resp = @app.call env
       rescue InternalError
         raise # Don't report ElasticAPM errors
@@ -97,5 +100,21 @@ def running?
     def config
       @config ||= ElasticAPM.agent.config
     end
+
+    def register_queue_time(transaction, env)
+      request_metrics = RequestMetrics.new(env)
+      queue_time_micros = request_metrics.queue_time_micros
+      return if queue_time_micros.zero?
+
+      transaction.clock_start -= queue_time_micros
+      transaction.timestamp -= queue_time_micros # 350ms before
+
+      span = ElasticAPM.start_span 'Queue Time', 'queue', subtype: 'nginx', action: 'awaiting'
+
+      span.clock_start = transaction.clock_start
+      span.timestamp = transaction.timestamp
+
+      ElasticAPM.end_span(span)
+    end
   end
 end
diff --git a/lib/elastic_apm/span.rb b/lib/elastic_apm/span.rb
index a9b735c9f..2c8fa0ce8 100644
--- a/lib/elastic_apm/span.rb
+++ b/lib/elastic_apm/span.rb
@@ -84,7 +84,9 @@ def initialize(
       :outcome,
       :subtype,
       :trace_context,
-      :type
+      :type,
+      :clock_start,
+      :timestamp
     )
     attr_reader(
       :context,
@@ -93,7 +95,6 @@ def initialize(
       :sample_rate,
       :self_time,
       :stacktrace,
-      :timestamp,
       :transaction
     )
 
diff --git a/lib/elastic_apm/transaction.rb b/lib/elastic_apm/transaction.rb
index 23731fa65..332b4ff5d 100644
--- a/lib/elastic_apm/transaction.rb
+++ b/lib/elastic_apm/transaction.rb
@@ -87,7 +87,7 @@ def initialize(
     end
     # rubocop:enable Metrics/ParameterLists
 
-    attr_accessor :name, :type, :result, :outcome
+    attr_accessor :name, :type, :result, :outcome, :clock_start, :timestamp
 
     attr_reader(
       :breakdown_metrics,
@@ -101,7 +101,6 @@ def initialize(
       :sample_rate,
       :span_frames_min_duration,
       :started_spans,
-      :timestamp,
       :trace_context,
       :transaction_max_spans
     )

From 455bf3c1517710cbc00e9eb71713287d1ac0be0e Mon Sep 17 00:00:00 2001
From: Gustavo de Oliveira <gust.oliveira.ferreira@gmail.com>
Date: Wed, 28 Jan 2026 10:40:55 -0300
Subject: [PATCH 2/2] Trigger github actions