tset

mediadb (20260419+25) unstable; urgency=critical

  * Fix preview render queue lock-up where an exception thrown during 

    FFmpeg initialization would jump the stack and skip the lock release 

    on the `inflight_mutex_`, permanently deadlocking duplicate preview 

    requests with a "timeout waiting for in-flight preview" error.

 -- Jan Koester <jan.koester@tuxist.de>  Sun, 19 Apr 2026 14:00:00 +0200

mediadb (20260419+24) unstable; urgency=critical

  * Fix broken cluster fetch and index replication operations on startup: Add 

        inflight_.insert(key);

    }

    struct InflightGuard {

        PreviewService* self;

        std::string key;

        ~InflightGuard() {

            std::lock_guard<std::mutex> lk(self->inflight_mutex_);

            self->inflight_.erase(key);

            self->inflight_cv_.notify_all();

        }

    } inflight_guard{this, key};

    // Acquire render semaphore with timeout — limits concurrent FFmpeg

    // processes to avoid overloading the CPU.

    if (!render_sem_.try_acquire_for(std::chrono::seconds(30))) {

        {

            std::lock_guard<std::mutex> lk(inflight_mutex_);

            inflight_.erase(key);

        }

        inflight_cv_.notify_all();

        error_out = "preview render queue full (semaphore timeout)";

        return nullptr;

    }

    struct SemGuard {

        PreviewService* self;

        ~SemGuard() { self->render_sem_.release(); }

    } sem_guard{this};

    // Run FFmpeg on the io_pool with a timeout.  This prevents a stuck

    // FFmpeg render from blocking the HTTP worker thread indefinitely.

    // Captures are by value so the lambda is safe if we return on timeout.

    });

    auto status = fut.wait_for(std::chrono::seconds(60));

    render_sem_.release();

    if (status == std::future_status::timeout) {

        {

            std::lock_guard<std::mutex> lk(inflight_mutex_);

            inflight_.erase(key);

        }

        inflight_cv_.notify_all();

        error_out = "preview render timed out after 60s";

        return nullptr;

    }

    auto [result, render_err] = fut.get();

    error_out = std::move(render_err);

    {

        std::lock_guard<std::mutex> lk(inflight_mutex_);

        inflight_.erase(key);

    }

    inflight_cv_.notify_all();

    if (!result.has_value()) {

        return nullptr;

    }