perf: Add FilenameCache to cache compute_filename results

[HazAT]

Changed below autoresearch implementation to just have one universal FilenameCache.

---

Below is what autoresearch initially did.

⚡ Medium risk — class-level caches with invalidation

Part of #2901 (reduce memory allocations by ~53%)

Changes

Add class-level caches to StacktraceInterface for two expensive per-frame operations that repeat with identical inputs:

longest_load_path: Previously iterated $LOAD_PATH for every frame, creating many intermediate strings. Now cached by abs_path with automatic invalidation when $LOAD_PATH.size changes (e.g. after Bundler.require).

compute_filename: Many frames share identical abs_paths (same gem files appear in every exception). Results are cached in separate in_app/not_in_app hashes keyed by abs_path only, avoiding composite array keys. Cache invalidates on project_root or $LOAD_PATH changes.

Safety

Both caches are deterministic — same inputs always produce the same filename. The caches grow proportionally to the number of unique source files seen, which is naturally bounded in any application.

[cursor]

Cursor Bugbot has reviewed your changes and found 2 potential issues.

Bugbot Autofix prepared fixes for both issues found in the latest run.

• ✅ Fixed: Frame silently produces nil filename without cache
  • Made filename_cache a required keyword argument instead of defaulting to nil, so callers must provide a valid cache and will get an ArgumentError if they don't.
• ✅ Fixed: Dead project_root parameter in Frame constructor
  • Removed the unused project_root positional parameter from Frame.initialize since all filename computation is now delegated to FilenameCache.

Or push these changes by commenting:

@cursor push b9a3b54088

Preview (b9a3b54088)

diff --git a/sentry-ruby/lib/sentry/interfaces/stacktrace.rb b/sentry-ruby/lib/sentry/interfaces/stacktrace.rb
--- a/sentry-ruby/lib/sentry/interfaces/stacktrace.rb
+++ b/sentry-ruby/lib/sentry/interfaces/stacktrace.rb
@@ -27,7 +27,7 @@
       attr_accessor :abs_path, :context_line, :function, :in_app, :filename,
                   :lineno, :module, :pre_context, :post_context, :vars
 
-      def initialize(project_root, line, strip_backtrace_load_path = true, filename_cache: nil)
+      def initialize(line, strip_backtrace_load_path: true, filename_cache:)
         @strip_backtrace_load_path = strip_backtrace_load_path
         @filename_cache = filename_cache
 

diff --git a/sentry-ruby/lib/sentry/interfaces/stacktrace_builder.rb b/sentry-ruby/lib/sentry/interfaces/stacktrace_builder.rb
--- a/sentry-ruby/lib/sentry/interfaces/stacktrace_builder.rb
+++ b/sentry-ruby/lib/sentry/interfaces/stacktrace_builder.rb
@@ -90,7 +90,7 @@
     private
 
     def convert_parsed_line_into_frame(line)
-      frame = StacktraceInterface::Frame.new(project_root, line, strip_backtrace_load_path, filename_cache: @filename_cache)
+      frame = StacktraceInterface::Frame.new(line, strip_backtrace_load_path: strip_backtrace_load_path, filename_cache: @filename_cache)
       frame.set_context(linecache, context_lines) if context_lines
       frame
     end

diff --git a/sentry-ruby/spec/sentry/interfaces/stacktrace_spec.rb b/sentry-ruby/spec/sentry/interfaces/stacktrace_spec.rb
--- a/sentry-ruby/spec/sentry/interfaces/stacktrace_spec.rb
+++ b/sentry-ruby/spec/sentry/interfaces/stacktrace_spec.rb
@@ -15,14 +15,14 @@
     let(:filename_cache) { Sentry::FilenameCache.new(configuration.project_root) }
 
     it "initializes a Frame with the correct info from the given Backtrace::Line object" do
-      first_frame = Sentry::StacktraceInterface::Frame.new(configuration.project_root, lines.first, true, filename_cache: filename_cache)
+      first_frame = Sentry::StacktraceInterface::Frame.new(lines.first, strip_backtrace_load_path: true, filename_cache: filename_cache)
 
       expect(first_frame.filename).to match(/base.rb/)
       expect(first_frame.in_app).to eq(false)
       expect(first_frame.function).to eq("save")
       expect(first_frame.lineno).to eq(10)
 
-      second_frame = Sentry::StacktraceInterface::Frame.new(configuration.project_root, lines.last, true, filename_cache: filename_cache)
+      second_frame = Sentry::StacktraceInterface::Frame.new(lines.last, strip_backtrace_load_path: true, filename_cache: filename_cache)
 
       expect(second_frame.filename).to match(/post.rb/)
       expect(second_frame.in_app).to eq(true)
@@ -31,11 +31,11 @@
     end
 
     it "does not strip load path when strip_backtrace_load_path is false" do
-      first_frame = Sentry::StacktraceInterface::Frame.new(configuration.project_root, lines.first, false, filename_cache: filename_cache)
+      first_frame = Sentry::StacktraceInterface::Frame.new(lines.first, strip_backtrace_load_path: false, filename_cache: filename_cache)
       expect(first_frame.filename).to eq(first_frame.abs_path)
       expect(first_frame.filename).to eq(raw_lines.first.split(':').first)
 
-      second_frame = Sentry::StacktraceInterface::Frame.new(configuration.project_root, lines.last, false, filename_cache: filename_cache)
+      second_frame = Sentry::StacktraceInterface::Frame.new(lines.last, strip_backtrace_load_path: false, filename_cache: filename_cache)
       expect(second_frame.filename).to eq(second_frame.abs_path)
       expect(second_frame.filename).to eq(raw_lines.last.split(':').first)
     end

diff --git a/sentry-ruby/spec/sentry/transport_spec.rb b/sentry-ruby/spec/sentry/transport_spec.rb
--- a/sentry-ruby/spec/sentry/transport_spec.rb
+++ b/sentry-ruby/spec/sentry/transport_spec.rb
@@ -341,9 +341,8 @@
           new_stacktrace = Sentry::StacktraceInterface.new(
             frames: frame_list_size.times.map do |zero_based_index|
               Sentry::StacktraceInterface::Frame.new(
-                "/fake/path",
                 Sentry::Backtrace::Line.parse("app.rb:#{zero_based_index + 1}:in `/'", in_app_pattern),
-                true,
+                strip_backtrace_load_path: true,
                 filename_cache: Sentry::FilenameCache.new("/fake/path")
               )
             end,

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