[NO-TICKET] Remove profiler support for Ruby 2.3 and 2.4

ext/datadog_profiling_native_extension/NativeExtensionDesign.md

@@ -28,7 +28,7 @@ documentation.**
 The profiling native extension is (and must always be) designed to **not cause failures** during gem installation, even
 if some features, Ruby versions, or operating systems are not supported.
 
-E.g. the extension must not break installation on Ruby 2.1 (or the oldest Ruby version we support at the time) on 64-bit ARM macOS,
+E.g. the extension must not break installation on Ruby 2.5 (or the oldest Ruby version we support at the time) on 64-bit ARM macOS,
 even if at run time it will effectively do nothing for such a setup.
 
 We have a CI setup to help validate this, but this is really important to keep in mind when adding to or changing the

ext/datadog_profiling_native_extension/extconf.rb

@@ -126,7 +126,7 @@ def add_compiler_flag(flag)
   # have_library 'pthread'
   # have_func 'pthread_getcpuclockid'
   # ```
-  # but a) it broke the build on Windows, b) on older Ruby versions (2.2 and below) and c) It's slower to build
+  # but it's slower to build
   # so instead we just assume that we have the function we need on Linux, and nowhere else
   $defs << '-DHAVE_PTHREAD_GETCPUCLOCKID'
 end
@@ -163,6 +163,11 @@ def add_compiler_flag(flag)
 # On older Rubies, there was no jit_return member on the rb_control_frame_t struct
 $defs << '-DNO_JIT_RETURN' if RUBY_VERSION < '3.1'
 
+# On older Rubies, rb_gc_force_recycle allowed to free objects in a way that
+# would be invisible to free tracepoints, finalizers and without cleaning
+# obj_to_id_tbl mappings.
+$defs << '-DHAVE_WORKING_RB_GC_FORCE_RECYCLE' if RUBY_VERSION < '3.1'
+
 # On older Rubies, we need to use a backported version of this function. See private_vm_api_access.h for details.
 $defs << '-DUSE_BACKPORTED_RB_PROFILE_FRAME_METHOD_NAME' if RUBY_VERSION < '3'
 
@@ -175,34 +180,15 @@ def add_compiler_flag(flag)
 # On older Rubies, objects would not move
 $defs << '-DNO_T_MOVED' if RUBY_VERSION < '2.7'
 
+# On older Rubies, there was no RUBY_SEEN_OBJ_ID flag
+$defs << '-DNO_SEEN_OBJ_ID_FLAG' if RUBY_VERSION < '2.7'
+
 # On older Rubies, rb_global_vm_lock_struct did not include the owner field
 $defs << '-DNO_GVL_OWNER' if RUBY_VERSION < '2.6'
 
 # On older Rubies, there was no thread->invoke_arg
 $defs << '-DNO_THREAD_INVOKE_ARG' if RUBY_VERSION < '2.6'
 
-# On older Rubies, we need to use rb_thread_t instead of rb_execution_context_t
-$defs << '-DUSE_THREAD_INSTEAD_OF_EXECUTION_CONTEXT' if RUBY_VERSION < '2.5'
-
-# On older Rubies, extensions can't use GET_VM()
-$defs << '-DNO_GET_VM' if RUBY_VERSION < '2.5'
-
-# On older Rubies...
-if RUBY_VERSION < '2.4'
-  # ...we need to use RUBY_VM_NORMAL_ISEQ_P instead of VM_FRAME_RUBYFRAME_P
-  $defs << '-DUSE_ISEQ_P_INSTEAD_OF_RUBYFRAME_P'
-  # ...we use a legacy copy of rb_vm_frame_method_entry
-  $defs << '-DUSE_LEGACY_RB_VM_FRAME_METHOD_ENTRY'
-end
-
-# On older Rubies, rb_gc_force_recycle allowed to free objects in a way that
-# would be invisible to free tracepoints, finalizers and without cleaning
-# obj_to_id_tbl mappings.
-$defs << '-DHAVE_WORKING_RB_GC_FORCE_RECYCLE' if RUBY_VERSION < '3.1'
-
-# On older Rubies, there was no RUBY_SEEN_OBJ_ID flag
-$defs << '-DNO_SEEN_OBJ_ID_FLAG' if RUBY_VERSION < '2.7'
-
 # If we got here, libdatadog is available and loaded
 ENV['PKG_CONFIG_PATH'] = "#{ENV['PKG_CONFIG_PATH']}:#{Libdatadog.pkgconfig_folder}"
 Logging.message("[datadog] PKG_CONFIG_PATH set to #{ENV['PKG_CONFIG_PATH'].inspect}\n")

ext/datadog_profiling_native_extension/native_extension_helpers.rb

@@ -86,7 +86,6 @@ def self.unsupported_reason
             on_macos? ||
             on_unknown_os? ||
             on_unsupported_cpu_arch? ||
-            on_unsupported_ruby_version? ||
             expected_to_use_mjit_but_mjit_is_disabled? ||
             libdatadog_not_available? ||
             libdatadog_not_usable?
@@ -260,15 +259,6 @@ def self.pkg_config_missing?(command: $PKGCONFIG) # rubocop:disable Style/Global
           architecture_not_supported unless RUBY_PLATFORM.start_with?('x86_64', 'aarch64', 'arm64')
         end
 
-        private_class_method def self.on_unsupported_ruby_version?
-          ruby_version_not_supported = explain_issue(
-            'the profiler only supports Ruby 2.3 or newer.',
-            suggested: UPGRADE_RUBY,
-          )
-
-          ruby_version_not_supported if RUBY_VERSION.start_with?('2.1.', '2.2.')
-        end
-
         # On some Rubies, we require the mjit header to be present. If Ruby was installed without MJIT support, we also skip
         # building the extension.
         private_class_method def self.expected_to_use_mjit_but_mjit_is_disabled?

ext/datadog_profiling_native_extension/private_vm_api_access.c

@@ -129,12 +129,7 @@ bool is_current_thread_holding_the_gvl(void) {
   }
 #else
   current_gvl_owner gvl_owner(void) {
-    rb_vm_t *vm =
-      #ifndef NO_GET_VM
-        GET_VM();
-      #else
-        thread_struct_from_object(rb_thread_current())->vm;
-      #endif
+    rb_vm_t *vm = GET_VM();
 
     // BIG Issue: Ruby < 2.6 did not have the owner field. The really nice thing about the owner field is that it's
     // "atomic" -- when a thread sets it, it "declares" two things in a single step
@@ -163,7 +158,7 @@ bool is_current_thread_holding_the_gvl(void) {
     //
     // Thus an incorrect `is_current_thread_holding_the_gvl` result may lead to issues inside `rb_postponed_job_register_one`.
     //
-    // For this reason we currently do not enable the new Ruby profiler on Ruby 2.5 and below by default, and we print a
+    // For this reason we currently do not enable the new Ruby profiler on Ruby 2.5 by default, and we print a
     // warning when customers force-enable it.
     bool gvl_acquired = vm->gvl.acquired != 0;
     rb_thread_t *current_owner = vm->running_thread;
@@ -213,12 +208,7 @@ uint64_t native_thread_id_for(VALUE thread) {
 // Returns the stack depth by using the same approach as rb_profile_frames and backtrace_each: get the positions
 // of the end and current frame pointers and subtracting them.
 ptrdiff_t stack_depth_for(VALUE thread) {
-  #ifndef USE_THREAD_INSTEAD_OF_EXECUTION_CONTEXT // Modern Rubies
-    const rb_execution_context_t *ec = thread_struct_from_object(thread)->ec;
-  #else // Ruby < 2.5
-    const rb_thread_t *ec = thread_struct_from_object(thread);
-  #endif
-
+  const rb_execution_context_t *ec = thread_struct_from_object(thread)->ec;
   const rb_control_frame_t *cfp = ec->cfp, *end_cfp = RUBY_VM_END_CONTROL_FRAME(ec);
 
   if (end_cfp == NULL) return 0;
@@ -253,12 +243,7 @@ void ddtrace_thread_list(VALUE result_array) {
     rb_ractor_t *current_ractor = ddtrace_get_ractor();
     ccan_list_for_each(&current_ractor->threads.set, thread, lt_node) {
   #else
-    rb_vm_t *vm =
-      #ifndef NO_GET_VM
-        GET_VM();
-      #else
-        thread_struct_from_object(rb_thread_current())->vm;
-      #endif
+    rb_vm_t *vm = GET_VM();
     list_for_each(&vm->living_threads, thread, vmlt_node) {
   #endif
       switch (thread->status) {
@@ -394,13 +379,6 @@ calc_lineno(const rb_iseq_t *iseq, const VALUE *pc)
 // * Add thread argument
 // * Add is_ruby_frame argument
 // * Removed `if (lines)` tests -- require/assume that like `buff`, `lines` is always specified
-// * Support Ruby < 2.5 by using rb_thread_t instead of rb_execution_context_t (which did not exist and was just
-//   part of rb_thread_t)
-// * Support Ruby < 2.4 by using `RUBY_VM_NORMAL_ISEQ_P(cfp->iseq)` instead of `VM_FRAME_RUBYFRAME_P(cfp)`.
-//   Given that the Ruby 2.3 version of `rb_profile_frames` did not support native methods and thus did not need this
-//   check, how did I figure out what to replace it with? I did it by looking at other places in the VM code where the
-//   code looks exactly the same but Ruby 2.4 uses `VM_FRAME_RUBYFRAME_P` whereas Ruby 2.3 used `RUBY_VM_NORMAL_ISEQ_P`.
-//   Examples of these are `errinfo_place` in `eval.c`, `rb_vm_get_ruby_level_next_cfp` (among others) in `vm.c`, etc.
 // * Skip dummy frame that shows up in main thread
 // * Add `end_cfp == NULL` and `end_cfp <= cfp` safety checks. These are used in a bunch of places in
 //   `vm_backtrace.c` (`backtrace_each`, `backtrace_size`, `rb_ec_partial_backtrace_object`) but are conspicuously
@@ -449,11 +427,7 @@ int ddtrace_rb_profile_frames(VALUE thread, int start, int limit, VALUE *buff, i
     // Modified from upstream: Instead of using `GET_EC` to collect info from the current thread,
     // support sampling any thread (including the current) passed as an argument
     rb_thread_t *th = thread_struct_from_object(thread);
-    #ifndef USE_THREAD_INSTEAD_OF_EXECUTION_CONTEXT // Modern Rubies
-      const rb_execution_context_t *ec = th->ec;
-    #else // Ruby < 2.5
-      const rb_thread_t *ec = th;
-    #endif
+    const rb_execution_context_t *ec = th->ec;
     const rb_control_frame_t *cfp = ec->cfp, *end_cfp = RUBY_VM_END_CONTROL_FRAME(ec);
     #ifndef NO_JIT_RETURN
       const rb_control_frame_t *top = cfp;
@@ -499,11 +473,7 @@ int ddtrace_rb_profile_frames(VALUE thread, int start, int limit, VALUE *buff, i
           // rb_profile_frames does not do this check, but `backtrace_each` (`vm_backtrace.c`) does. This frame is not
           // exposed by the Ruby backtrace APIs and for now we want to match its behavior 1:1
         }
-#ifndef USE_ISEQ_P_INSTEAD_OF_RUBYFRAME_P // Modern Rubies
         else if (VM_FRAME_RUBYFRAME_P(cfp)) {
-#else // Ruby < 2.4
-        else if (RUBY_VM_NORMAL_ISEQ_P(cfp->iseq)) {
-#endif
             if (start > 0) {
                 start--;
                 continue;
@@ -719,51 +689,27 @@ check_method_entry(VALUE obj, int can_be_svar)
     }
 }
 
-#ifndef USE_LEGACY_RB_VM_FRAME_METHOD_ENTRY
-  // Taken from upstream vm_insnhelper.c at commit 5f10bd634fb6ae8f74a4ea730176233b0ca96954 (March 2022, Ruby 3.2 trunk)
-  // Copyright (C) 2007 Koichi Sasada
-  // to support our custom rb_profile_frames (see above)
-  //
-  // While older Rubies may have this function, the symbol is not exported which leads to dynamic loader issues, e.g.
-  // `dyld: lazy symbol binding failed: Symbol not found: _rb_vm_frame_method_entry`.
-  //
-  // Modifications: None
-  MJIT_STATIC const rb_callable_method_entry_t *
-  rb_vm_frame_method_entry(const rb_control_frame_t *cfp)
-  {
-      const VALUE *ep = cfp->ep;
-      rb_callable_method_entry_t *me;
-
-      while (!VM_ENV_LOCAL_P(ep)) {
-          if ((me = check_method_entry(ep[VM_ENV_DATA_INDEX_ME_CREF], FALSE)) != NULL) return me;
-          ep = VM_ENV_PREV_EP(ep);
-      }
-
-      return check_method_entry(ep[VM_ENV_DATA_INDEX_ME_CREF], TRUE);
-  }
-#else
-  // Taken from upstream vm_insnhelper.c at commit 556e9f726e2b80f6088982c6b43abfe68bfad591 (October 2018, ruby_2_3 branch)
-  // Copyright (C) 2007 Koichi Sasada
-  // to support our custom rb_profile_frames (see above)
-  //
-  // Quite a few macros in this function changed after Ruby 2.3. Rather than trying to fix the Ruby 3.2 version to work
-  // with 2.3 constants, I decided to import the Ruby 2.3 version.
-  //
-  // Modifications: None
-  const rb_callable_method_entry_t *
-  rb_vm_frame_method_entry(const rb_control_frame_t *cfp)
-  {
-      VALUE *ep = cfp->ep;
-      rb_callable_method_entry_t *me;
+// Taken from upstream vm_insnhelper.c at commit 5f10bd634fb6ae8f74a4ea730176233b0ca96954 (March 2022, Ruby 3.2 trunk)
+// Copyright (C) 2007 Koichi Sasada
+// to support our custom rb_profile_frames (see above)
+//
+// While older Rubies may have this function, the symbol is not exported which leads to dynamic loader issues, e.g.
+// `dyld: lazy symbol binding failed: Symbol not found: _rb_vm_frame_method_entry`.
+//
+// Modifications: None
+MJIT_STATIC const rb_callable_method_entry_t *
+rb_vm_frame_method_entry(const rb_control_frame_t *cfp)
+{
+    const VALUE *ep = cfp->ep;
+    rb_callable_method_entry_t *me;
 
-      while (!VM_EP_LEP_P(ep)) {
-          if ((me = check_method_entry(ep[-1], FALSE)) != NULL) return me;
-          ep = VM_EP_PREV_EP(ep);
-      }
+    while (!VM_ENV_LOCAL_P(ep)) {
+        if ((me = check_method_entry(ep[VM_ENV_DATA_INDEX_ME_CREF], FALSE)) != NULL) return me;
+        ep = VM_ENV_PREV_EP(ep);
+    }
 
-      return check_method_entry(ep[-1], TRUE);
-  }
-#endif // USE_LEGACY_RB_VM_FRAME_METHOD_ENTRY
+    return check_method_entry(ep[VM_ENV_DATA_INDEX_ME_CREF], TRUE);
+}
 #endif // RUBY_MJIT_HEADER
 
 #ifndef NO_RACTORS
@@ -880,13 +826,6 @@ static inline int ddtrace_imemo_type(VALUE imemo) {
 // This is used to workaround a VM bug. See "handle_sampling_signal" in "collectors_cpu_and_wall_time_worker" for details.
 #ifdef NO_POSTPONED_TRIGGER
   void *objspace_ptr_for_gc_finalize_deferred_workaround(void) {
-    rb_vm_t *vm =
-      #ifndef NO_GET_VM // TODO: Inline GET_VM below once we drop support in dd-trace-rb 2.x for < Ruby 2.5
-        GET_VM();
-      #else
-        thread_struct_from_object(rb_thread_current())->vm;
-      #endif
-
-    return vm->objspace;
+    return GET_VM()->objspace;
   }
 #endif

ext/datadog_profiling_native_extension/ruby_helpers.h

@@ -16,11 +16,6 @@ static inline VALUE process_pending_interruptions(DDTRACE_UNUSED VALUE _) {
   return Qnil;
 }
 
-// RB_UNLIKELY is not supported on Ruby 2.3
-#ifndef RB_UNLIKELY
-  #define RB_UNLIKELY(x) x
-#endif
-
 // Calls process_pending_interruptions BUT "rescues" any exceptions to be raised, returning them instead as
 // a non-zero `pending_exception`.
 //

integration/apps/rack/app/acme.rb

@@ -90,8 +90,7 @@ def detailed_check(request)
         [200, { 'content-type' => 'application/json'}, [JSON.pretty_generate(
           webserver_process: $PROGRAM_NAME,
           profiler_available: Datadog::Profiling.start_if_enabled,
-          # NOTE: Threads can't be named on Ruby 2.1 and 2.2
-          profiler_threads: ((Thread.list.map(&:name).select { |it| it && it.include?('Profiling') }) unless RUBY_VERSION < '2.3')
+          profiler_threads: Thread.list.map(&:name).select { |it| it && it.include?('Profiling') },
         )], "\n"]
       end
     end

integration/apps/rack/app/resque_background_job.rb

@@ -29,8 +29,7 @@ def self.perform(key, value)
       value: value,
       resque_process: $PROGRAM_NAME,
       profiler_available: Datadog::Profiling.start_if_enabled,
-      # NOTE: Threads can't be named on Ruby 2.1 and 2.2
-      profiler_threads: ((Thread.list.map(&:name).select { |it| it && it.include?('Profiling') }) unless RUBY_VERSION < '2.3')
+      profiler_threads: Thread.list.map(&:name).select { |it| it && it.include?('Profiling') },
     ))
   end
 end

integration/apps/rack/app/sidekiq_background_job.rb

@@ -27,8 +27,7 @@ def perform(key, value)
       value: value,
       sidekiq_process: $PROGRAM_NAME,
       profiler_available: Datadog::Profiling.start_if_enabled,
-      # NOTE: Threads can't be named on Ruby 2.1 and 2.2
-      profiler_threads: ((Thread.list.map(&:name).select { |it| it && it.include?('Profiling') }) unless RUBY_VERSION < '2.3')
+      profiler_threads: Thread.list.map(&:name).select { |it| it && it.include?('Profiling') },
     ))
   end
 end

integration/apps/rack/spec/integration/basic_spec.rb

@@ -11,7 +11,7 @@
     it { is_expected.to be_a_kind_of(Net::HTTPOK) }
   end
 
-  let(:expected_profiler_available) { RUBY_VERSION >= '2.3' }
+  let(:expected_profiler_available) { true }
 
   let(:expected_profiler_threads) do
     expected_profiler_available ? contain_exactly(

integration/apps/rails-five/config/initializers/resque.rb

@@ -1,4 +1,3 @@
 require 'resque'
 
 Resque.redis = ENV['REDIS_URL']
-# Resque.redis = 'redis:6379' # Ruby 2.2 compatibility

integration/apps/rails-seven/config/initializers/resque.rb

@@ -1,4 +1,3 @@
 require 'resque'
 
 Resque.redis = ENV['REDIS_URL']
-# Resque.redis = 'redis:6379' # Ruby 2.2 compatibility

integration/apps/rails-seven/spec/integration/basic_spec.rb

@@ -14,7 +14,7 @@
 
     let(:json_result) { JSON.parse(subject.body, symbolize_names: true) }
 
-    let(:expected_profiler_available) { RUBY_VERSION >= '2.3' }
+    let(:expected_profiler_available) { true }
 
     let(:expected_profiler_threads) do
       expected_profiler_available ? contain_exactly(

integration/apps/rails-six/config/initializers/resque.rb

@@ -1,4 +1,3 @@
 require 'resque'
 
 Resque.redis = ENV['REDIS_URL']
-# Resque.redis = 'redis:6379' # Ruby 2.2 compatibility

integration/apps/rails-six/spec/integration/basic_spec.rb

@@ -14,7 +14,7 @@
 
     let(:json_result) { JSON.parse(subject.body, symbolize_names: true) }
 
-    let(:expected_profiler_available) { RUBY_VERSION >= '2.3' }
+    let(:expected_profiler_available) { true }
 
     let(:expected_profiler_threads) do
       expected_profiler_available ? contain_exactly(

integration/apps/sinatra2-classic/Gemfile

@@ -17,5 +17,5 @@ gem 'pry-byebug'
 # gem 'ruby-prof'
 gem 'rspec'
 gem 'rspec-wait'
-gem 'webrick' if RUBY_VERSION >= '2.3' # Older Rubies can just use the built-in version of webrick
+gem 'webrick'
 gem 'rackup'

integration/apps/sinatra2-classic/app/acme.rb

@@ -37,12 +37,7 @@
     JSON.generate(
       webserver_process: $PROGRAM_NAME,
       profiler_available: Datadog::Profiling.start_if_enabled,
-      # NOTE: Threads can't be named on Ruby 2.1 and 2.2
-      profiler_threads: (unless RUBY_VERSION < '2.3'
-                           (Thread.list.map(&:name).select do |it|
-                              it && it.include?('Profiling')
-                            end)
-                         end)
+      profiler_threads: Thread.list.map(&:name).select { |it| it && it.include?('Profiling') },
     )
   ]
 end

integration/apps/sinatra2-classic/spec/integration/basic_spec.rb

@@ -11,7 +11,7 @@
     it { is_expected.to be_a_kind_of(Net::HTTPOK) }
   end
 
-  let(:expected_profiler_available) { RUBY_VERSION >= '2.3' }
+  let(:expected_profiler_available) { true }
 
   let(:expected_profiler_threads) do
     expected_profiler_available ? contain_exactly(

integration/apps/sinatra2-modular/Gemfile

@@ -13,10 +13,7 @@ gem 'datadog', *Datadog::DemoEnv.gem_spec('datadog')
 
 # Development
 gem 'pry-byebug'
-# gem 'pry-stack_explorer', platform: :ruby
-# gem 'rbtrace'
-# gem 'ruby-prof'
 gem 'rspec'
 gem 'rspec-wait'
-gem 'webrick' if RUBY_VERSION >= '2.3' # Older Rubies can just use the built-in version of webrick
+gem 'webrick'
 gem 'rackup'