WIP precompile task for firefox

.github/workflows/ci.yml

@@ -12,6 +12,7 @@ jobs:
           - "2.7"
           - "3.0"
           - "3.1"
+          - "3.2"
     steps:
     - uses: actions/checkout@v3
     - name: Set up Ruby ${{ matrix.ruby }}
@@ -20,7 +21,6 @@ jobs:
         ruby-version: ${{ matrix.ruby }}
     - name: Build
       run: |
-        gem install bundler
         bundle install --jobs 4 --retry 3
     - name: Test on ${{ matrix.ruby }}
       run: |

Gemfile

@@ -6,6 +6,7 @@ gemspec
 # Specify the same dependency sources as the application Gemfile
 gem("activesupport", "~> 5.2")
 gem("railties", "~> 5.2")
+gem("vernier", "~> 0.4.0") if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new("3.2.1")
 
 gem("google-cloud-storage", "~> 1.21")
 gem("rubocop", require: false)

Gemfile.lock

@@ -179,6 +179,7 @@ GEM
       thread_safe (~> 0.1)
     uber (0.1.0)
     unicode-display_width (2.1.0)
+    vernier (0.4.0)
     webrick (1.7.0)
 
 PLATFORMS
@@ -197,6 +198,7 @@ DEPENDENCIES
   rubocop
   rubocop-performance
   rubocop-shopify
+  vernier (~> 0.4.0)
 
 BUNDLED WITH
    2.4.18

README.md

@@ -76,12 +76,14 @@ Rails.application.config.app_profiler.profile_header = "X-Profile"
 
 | Key | Value | Notes |
 | --- | ----- | ----- |
-| profile/mode | Supported profiling modes: `cpu`, `wall`, `object`. | Use `profile` in (1), and `mode` in (2). |
+| profile/mode | Supported profiling modes: `cpu`, `wall`, `object` for stackprof. | Use `profile` in (1), and `mode` in (2). Vernier backend only supports `wall` and `retained` at present time|
 | async | Upload profile in a background thread. When this is set, profile redirect headers are not present in the response.
 | interval | Sampling interval in microseconds. | |
 | ignore_gc | Ignore garbage collection frames | |
 | autoredirect | Redirect request automatically to Speedscope's page after profiling. | |
 | context | Directory within the specified bucket in the selected storage where raw profile data should be written. | Only supported in (2). Defaults to `Rails.env` if not specified. |
+| backend | Profiler to use, either `stackprof` or `vernier`. Defaults to `stackprof`. Note that Vernier requires Ruby 3.2.1+ |
+
 
 Note that the `autoredirect` feature can be turned on for all requests by doing the following:
 
@@ -280,11 +282,16 @@ report = AppProfiler.run(mode: :cpu) do
   # ...
 end
 
-report.view # opens the profile locally in speedscope.
+report.view # opens the profile locally in speedscope or firefox profiler, as appropriate
 ```
 
 Profile files can be found locally in your rails app at `tmp/app_profiler/*.json`.
 
+**Note** In development, if using the SpeedscopeRemoteViewer for stackprof
+or if using Vernier, a route for `/app_profiler` will be added to the application.
+If using Vernier, a route for `/from-url` is also added. These will be handled
+in middlewares, before any application routing logic. There is a small chance
+that these could shadow existing routes in the application.
 
 ## Storage backends
 
@@ -312,6 +319,22 @@ Note that in `development` and `test` modes the file isn't uploaded. Instead, it
 Rails.application.config.app_profiler.middleware_action = AppProfiler::Middleware::UploadAction
 ```
 
+## Profiler backends
+
+It is possible to configure AppProfiler to use the [`vernier`](https://github.com/jhawthorn/vernier) or [`stackprof`](https://github.com/tmm1/stackprof). To use `vernier`, it must be added separately in the application Gemfile.
+
+The backend can be selected dynamically at runtime using the `backend` parameter. The default backend to use when this parameter is not specified can be configured with:
+
+```ruby
+AppProfiler.backend = AppProfiler::StackprofBackend # or AppProfiler::VernierBackend
+# OR
+Rails.application.config.app_profiler.backend = AppProfiler::StackprofBackend # or AppProfiler::VernierBackend
+```
+
+By default, the stackprof backend will be used.
+
+In local development, changing the backend will change whether the profile is viewed in speedscope or firefox-profiler.
+
 ## Running tests
 
 ```

Rakefile

@@ -3,6 +3,8 @@
 require "bundler/gem_tasks"
 require "rake/testtask"
 
+load "lib/tasks/firefox_profiler_compile.rake"
+
 Rake::TestTask.new(:test) do |t|
   t.libs << "test"
   t.libs << "lib"

dev.yml

@@ -3,7 +3,7 @@ name: app-profiler
 type: ruby
 
 up:
-  - ruby: 3.1.2
+  - ruby: 3.2.1
   - bundler
 
 commands:

lib/app_profiler.rb

@@ -9,6 +9,9 @@ module AppProfiler
   class ConfigurationError < StandardError
   end
 
+  class BackendError < StandardError
+  end
+
   DefaultProfileFormatter = proc do |upload|
     "#{AppProfiler.speedscope_host}#profileURL=#{upload.url}"
   end
@@ -25,15 +28,16 @@ module Storage
 
   module Viewer
     autoload :BaseViewer, "app_profiler/viewer/base_viewer"
-    autoload :SpeedscopeViewer, "app_profiler/viewer/speedscope_viewer"
-    autoload :SpeedscopeRemoteViewer, "app_profiler/viewer/speedscope_remote_viewer"
+    autoload :SpeedscopeViewer, "app_profiler/viewer/speedscope"
+    autoload :SpeedscopeRemoteViewer, "app_profiler/viewer/remote/speedscope"
+    autoload :FirefoxRemoteViewer, "app_profiler/viewer/remote/firefox"
   end
 
   require "app_profiler/middleware"
   require "app_profiler/parameters"
   require "app_profiler/request_parameters"
-  require "app_profiler/profiler"
   require "app_profiler/profile"
+  require "app_profiler/backend"
   require "app_profiler/server"
 
   mattr_accessor :logger, default: Logger.new($stdout)
@@ -48,8 +52,10 @@ module Viewer
   mattr_reader   :profile_url_formatter,
     default: DefaultProfileFormatter
 
+  mattr_accessor :gecko_viewer_package, default: "https://github.com/tenderlove/profiler#v0.0.2"
   mattr_accessor :storage, default: Storage::FileStorage
-  mattr_accessor :viewer, default: Viewer::SpeedscopeViewer
+  mattr_accessor :viewer, default: Viewer::SpeedscopeViewer # DEPRECATED
+  mattr_accessor :speedscope_viewer, default: Viewer::SpeedscopeViewer
   mattr_accessor :middleware, default: Middleware
   mattr_accessor :server, default: Server
   mattr_accessor :upload_queue_max_length, default: 10
@@ -60,17 +66,73 @@ module Viewer
   mattr_reader :after_process_queue, default: nil
 
   class << self
-    def run(*args, &block)
-      Profiler.run(*args, &block)
+    def run(*args, backend: nil, **kwargs, &block)
+      orig_backend = self.backend
+      begin
+        self.backend = backend if backend
+        profiler.run(*args, **kwargs, &block)
+      rescue BackendError
+        yield
+      end
+    ensure
+      AppProfiler.backend = orig_backend
     end
 
     def start(*args)
-      Profiler.start(*args)
+      profiler.start(*args)
     end
 
     def stop
-      Profiler.stop
-      Profiler.results
+      profiler.stop
+      profiler.results
+    end
+
+    def running?
+      @backend&.running?
+    end
+
+    def profiler
+      @backend ||= backend.new
+    end
+
+    def backend=(new_backend)
+      new_profiler_backend = if new_backend.is_a?(String)
+        backend_for(new_backend)
+      elsif new_backend&.< Backend
+        new_backend
+      else
+        raise BackendError, "unsupportend backend type #{new_backend.class}"
+      end
+
+      if running?
+        raise BackendError,
+          "cannot change backend to #{new_backend::NAME} while #{backend::NAME} backend is running"
+      end
+
+      return if @profiler_backend == new_backend
+
+      clear
+      @profiler_backend = new_profiler_backend
+    end
+
+    def backend_for(backend_name)
+      if defined?(AppProfiler::VernierBackend::NAME) &&
+          backend_name == AppProfiler::VernierBackend::NAME
+        AppProfiler::VernierBackend
+      elsif backend_name == AppProfiler::StackprofBackend::NAME
+        AppProfiler::StackprofBackend
+      else
+        raise BackendError, "unknown backend #{backend_name}"
+      end
+    end
+
+    def backend
+      @profiler_backend ||= DefaultBackend
+    end
+
+    def clear
+      @backend.stop if @backend&.running?
+      @backend = nil
     end
 
     def profile_header=(profile_header)
@@ -120,6 +182,17 @@ def profile_url(upload)
 
       AppProfiler.profile_url_formatter.call(upload)
     end
+
+    # DEPRECATIONS
+    def viewer
+      ActiveSupport::Deprecation.warn("viewer is deprecated, use speedscope_viewer instead")
+      @viewer
+    end
+
+    def viewer=(viewer)
+      ActiveSupport::Deprecation.warn("viewer= is deprecated, use speedscope_viewer= instead")
+      @viewer = viewer
+    end
   end
 
   require "app_profiler/railtie" if defined?(Rails::Railtie)

lib/app_profiler/backend.rb

@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+module AppProfiler
+  class Backend
+    def run(params = {}, &block)
+      raise NotImplementedError
+    end
+
+    def start(params = {})
+      raise NotImplementedError
+    end
+
+    def stop
+      raise NotImplementedError
+    end
+
+    def results
+      raise NotImplementedError
+    end
+
+    def running?
+      raise NotImplementedError
+    end
+
+    class << self
+      def run_lock
+        @run_lock ||= Mutex.new
+      end
+    end
+
+    protected
+
+    def acquire_run_lock
+      self.class.run_lock.try_lock
+    end
+
+    def release_run_lock
+      self.class.run_lock.unlock
+    rescue ThreadError
+      AppProfiler.logger.warn("[AppProfiler] run lock not released as it was never acquired")
+    end
+  end
+
+  autoload :StackprofBackend, "app_profiler/backend/stackprof"
+  autoload :VernierBackend, "app_profiler/backend/vernier"
+  DefaultBackend = AppProfiler::StackprofBackend
+end

lib/app_profiler/backend/stackprof.rb

@@ -0,0 +1,93 @@
+# frozen_string_literal: true
+
+require "stackprof"
+
+module AppProfiler
+  class StackprofBackend < Backend
+    NAME = "stackprof"
+    DEFAULTS = {
+      mode: :cpu,
+      raw: true,
+    }.freeze
+
+    AVAILABLE_MODES = [
+      :wall,
+      :cpu,
+      :object,
+    ].freeze
+
+    def run(params = {})
+      started = start(params)
+
+      yield
+
+      return unless started
+
+      stop
+      results
+    ensure
+      # Only stop the profiler if profiling was started in this context.
+      stop if started
+    end
+
+    def start(params = {})
+      # Do not start the profiler if StackProf was started somewhere else.
+      return false if running?
+      return false unless acquire_run_lock
+
+      clear
+
+      ::StackProf.start(**DEFAULTS, **params)
+    rescue => error
+      AppProfiler.logger.info(
+        "[Profiler] failed to start the profiler error_class=#{error.class} error_message=#{error.message}"
+      )
+      release_run_lock
+      # This is a boolean instead of nil because StackProf#start returns a
+      # boolean as well.
+      false
+    end
+
+    def stop
+      ::StackProf.stop
+    ensure
+      release_run_lock
+    end
+
+    def results
+      stackprof_profile = backend_results
+
+      return unless stackprof_profile
+
+      AppProfiler::AbstractProfile.from_stackprof(stackprof_profile)
+    rescue => error
+      AppProfiler.logger.info(
+        "[Profiler] failed to obtain the profile error_class=#{error.class} error_message=#{error.message}"
+      )
+      nil
+    end
+
+    def running?
+      ::StackProf.running?
+    end
+
+    private
+
+    def backend_results
+      ::StackProf.results
+    end
+
+    # Clears the previous profiling session.
+    #
+    # StackProf will attempt to reuse frames from the previous profiling
+    # session if the results are not collected. This is usually called before
+    # StackProf#start is invoked to ensure that new profiling sessions do
+    # not reuse previous frames if they exist.
+    #
+    # Ref: https://github.com/tmm1/stackprof/blob/0ded6c/ext/stackprof/stackprof.c#L118-L123
+    #
+    def clear
+      backend_results
+    end
+  end
+end