CubicSDR/docs/plans/smart-pointers.md

Plan: Replace Raw new/delete with Smart Pointers

CubicSDR is a cross-platform Software-Defined Radio application (C++14, wxWidgets, OpenGL). This plan covers replacing raw new/delete allocations with std::unique_ptr and fixing memory leaks in src/CubicSDR.cpp.

See also: RECOMMENDATIONS.md | PLAN.md | Threading Model

Last Updated: 2026-07-23

Current State

In src/CubicSDR.cpp:

• 8 raw new std::thread(...) allocations (lines 390, 393, 397, 405, 617, 794, 843, 1164)
• 6 raw new WorkerThread() allocations (lines 340, 355, 358, 374, 400, 1157)
• 15 raw delete operations (lines 506-530, 775, 804, 1148, 1153, 1188, 1194)
• 4 confirmed memory leaks:
  • m_glContextAttributes (line 225) — never deleted
  • confName wxString (line 562) — never freed
  • modPath wxString (line 579) — never freed
  • appframe (line 404) — never explicitly deleted
• t_SDREnum overwritten (lines 617, 794) without joining/deleting the old thread

Implementation Plan

Phase 1: Declare smart pointer members

In src/CubicSDR.h, change declarations from:

std::thread *t_SDR;
SDRThread *sdrThread;

to:

std::unique_ptr<std::thread> t_SDR;
std::unique_ptr<SDRThread> sdrThread;

Apply to all thread and worker object pointers:

• t_SDR, t_PostSDR, t_SpectrumVisual, t_DemodVisual, t_SDREnum, t_Rig
• sdrThread, sdrPostThread, spectrumVisualThread, demodVisualThread, sdrEnum, rigThread
• m_glContext (PrimaryGLContext*)

Phase 2: Update allocations

Replace all new calls with std::make_unique:

// Before:
t_SDR = new std::thread(&SDRThread::threadMain, sdrThread);
// After:
t_SDR = std::make_unique<std::thread>(&SDRThread::threadMain, sdrThread);

Phase 3: Remove all manual delete calls

Smart pointers handle cleanup automatically. Remove all 15 delete operations.

Phase 4: Fix memory leaks

• m_glContextAttributes: wrap in std::unique_ptr<wxGLContextAttrs> or delete in OnExit().
• confName/modPath (lines 562, 579): change from raw new wxString to stack-allocated wxString or std::unique_ptr.

Phase 5: Fix t_SDREnum overwrite

Before overwriting t_SDREnum, join the existing thread:

if (t_SDREnum && t_SDREnum->joinable()) {
    t_SDREnum->join();
}
t_SDREnum = std::make_unique<std::thread>(...);

Design Considerations: Join vs. Detach

When replacing raw new/delete with smart pointers, each thread must be evaluated for correct shutdown semantics:

• Join before delete — Use when the thread's work must complete before destruction (e.g., t_SDR, t_DemodVisual). The current code joins before deleting, so std::unique_ptr with explicit join() preserves existing behavior.
• Detach — Use when the thread is a background worker that should outlive the owning scope. If any thread is detached, it must not be held by a unique_ptr that joins on destruction — use a detached raw pointer or std::thread stored separately.
• Exception safety — std::unique_ptr destructor calls delete (not join). For threads that must be joined, always call join() explicitly before the unique_ptr goes out of scope. Consider a RAII wrapper that joins in the destructor if this pattern is needed in multiple places.

Review each thread allocation in CubicSDR.cpp and document the chosen semantics (join or detach) in a code comment at the declaration site.

Verification Criteria

• Zero raw new std::thread(...) or new WorkerThread(...) allocations remain in CubicSDR.cpp.
• Zero manual delete calls for thread or worker objects remain.
• No memory leaks detected under repeated startup/shutdown cycles (verify with AddressSanitizer or Valgrind if available).
• All 4 confirmed memory leaks are fixed.
• t_SDREnum overwrite is guarded by a join check.
• Build succeeds and application starts/closes cleanly.

Rollback Strategy

If smart pointer changes cause crashes (e.g., a thread joined twice, or a use-after-free):

1. git revert the commit.
2. The original raw new/delete code is functional — the revert is safe.
3. If only specific phases cause issues, revert to the last working phase (e.g., keep Phase 1 declarations but revert Phase 2 allocations).

Files to Modify

File	Action
src/CubicSDR.h	Change pointer declarations to smart pointers
src/CubicSDR.cpp	Update allocations, remove deletes, fix leaks