[PROF-12841] Fix profiler not identifying executables with gems they belong to

**What does this PR do?**

This PR fixes the profiler's "code provenance" metadata to include
the paths to gem executables (if any).

This ensures that, when e.g. starting `puma` via `bin/puma` or
`bundle exec puma`, we still identify the puma executable as
belonging to the `puma` gem.

**Motivation:**

The "code provenance" is used to power the "Only My Code" feature
that shows up in multiple places in the profiler UX, and so we want
it to be as accurate as possible.

**Additional Notes:**

N/A

**How to test the change?**

This change includes test coverage. It can also be tested easily
by running

```bash
DD_PROFILING_ENABLED=true DD_SERVICE=test-provenance bundle exec ddprofrb exec pry -e "sleep 1; exit"
```

and checking that `bin/pry` is correctly categorized as belonging
to the `pry` gem in the Datadog UX.

Author: ivoanjo

Steepfile

@@ -224,6 +224,7 @@ target :datadog do
   # References `RubyVM::YJIT`, which does not have type information.
   ignore 'lib/datadog/core/environment/yjit.rb'
 
+  library 'bundler'
   library 'pathname'
   library 'cgi'
   library 'logger', 'monitor'

lib/datadog/profiling/collectors/code_provenance.rb

@@ -22,6 +22,7 @@ def initialize(
           @libraries_by_path = {}
           @seen_files = Set.new
           @seen_libraries = Set.new
+          @executable_paths = [Gem.bindir, (Bundler.bin_path.to_s if defined?(Bundler))].uniq.compact.freeze
 
           record_library(
             Library.new(
@@ -51,7 +52,8 @@ def generate_json
           :libraries_by_name,
           :libraries_by_path,
           :seen_files,
-          :seen_libraries
+          :seen_libraries,
+          :executable_paths
 
         def record_library(library)
           libraries_by_name[library.name] = library
@@ -79,13 +81,20 @@ def record_loaded_specs(loaded_specs)
           loaded_specs.each do |spec|
             next if libraries_by_name.key?(spec.name)
 
+            extra_paths = [(spec.extension_dir if spec.extensions.any?)]
+            spec.executables&.each do |executable|
+              executable_paths.each do |path|
+                extra_paths << File.join(path, executable)
+              end
+            end
+
             record_library(
               Library.new(
                 kind: "library",
                 name: spec.name,
                 version: spec.version,
                 path: spec.gem_dir,
-                extra_paths: [(spec.extension_dir if spec.extensions.any?)],
+                extra_paths: extra_paths,
               )
             )
             recorded_library = true
@@ -119,7 +128,7 @@ class Library
           attr_reader :kind, :name, :version
 
           def initialize(kind:, name:, version:, path:, extra_paths:)
-            extra_paths = Array(extra_paths).reject { |p| p.nil? || p.empty? }.map { |p| p.dup.freeze }
+            extra_paths = Array(extra_paths).compact.reject(&:empty?).map { |p| p.dup.freeze }
             @kind = kind.freeze
             @name = name.dup.freeze
             @version = version.to_s.dup.freeze

sig/datadog/profiling/collectors/code_provenance.rbs

@@ -12,6 +12,7 @@ module Datadog
         attr_reader libraries_by_path: Hash[String, Library]
         attr_reader seen_files: Set[String]
         attr_reader seen_libraries: Set[Library]
+        attr_reader executable_paths: Array[String]
 
         def record_library: (Library) -> void
         def sort_libraries_by_longest_path_first: () -> void

spec/datadog/profiling/collectors/code_provenance_spec.rb

@@ -32,11 +32,16 @@
           kind: "library",
           name: "datadog",
           version: Datadog::VERSION::STRING,
-          paths: contain_exactly(start_with("/"), include("extensions").and(include(RUBY_PLATFORM))),
+          paths: contain_exactly(
+            start_with("/"),
+            include("extensions").and(include(RUBY_PLATFORM)),
+            "#{Gem.bindir}/ddprofrb",
+            "#{Bundler.bin_path}/ddprofrb",
+          ),
         },
         {
           kind: "library",
-          name: "rspec-core",
+          name: "rspec",
           version: start_with("3."), # This will one day need to be bumped for RSpec 4
           paths: contain_exactly(start_with("/")),
         },
@@ -59,6 +64,20 @@
       )
     end
 
+    it "includes the executables for gems with executables" do
+      refresh
+
+      expect(generate_result.find { |it| it[:name] == "rspec-core" }.fetch(:paths)).to contain_exactly(
+        Gem.loaded_specs.fetch("rspec-core").gem_dir,
+        "#{Gem.bindir}/rspec",
+        "#{Bundler.bin_path}/rspec",
+      )
+
+      # Sanity checks
+      expect(Gem.bindir).to start_with("/")
+      expect(Bundler.bin_path.to_s).to start_with("/")
+    end
+
     it "records the correct path for datadog" do
       refresh
 
@@ -78,13 +97,15 @@
             version: "not_loaded_version",
             gem_dir: "/not_loaded/",
             extensions: [],
+            executables: [],
           ),
           instance_double(
             Gem::Specification,
             name: "is_loaded",
             version: "is_loaded_version",
             gem_dir: "/is_loaded/",
             extensions: [],
+            executables: [],
           )
         ],
       )
@@ -131,13 +152,15 @@
               version: "1.2.3",
               gem_dir: "/dd-trace-rb",
               extensions: [],
+              executables: [],
             ),
             instance_double(
               Gem::Specification,
               name: "byebug",
               version: "4.5.6",
               gem_dir: "/dd-trace-rb/vendor/bundle/ruby/2.7.0/gems/byebug-11.1.3",
               extensions: [],
+              executables: [],
             )
           ],
         )

vendor/rbs/bundler/0/bundler.rbs

@@ -0,0 +1,3 @@
+module Bundler
+  def self.bin_path: () -> Pathname
+end

vendor/rbs/gem/0/gem.rbs

@@ -16,4 +16,5 @@ class Gem::BasicSpecification
   def gem_dir: () -> String
   def extension_dir: () -> String
   def extensions: () -> Array[String]
+  def executables: () -> Array[String]?
 end