Begin work on biergarten data generator pipeline

pipeline/includes/work_queue.h

@@ -0,0 +1,63 @@
+#pragma once
+
+#include <condition_variable>
+#include <mutex>
+#include <optional>
+#include <queue>
+
+/// @brief Bounded thread-safe queue with blocking push/pop and shutdown.
+template <typename T> class WorkQueue {
+private:
+  std::queue<T> queue;
+  std::mutex mutex;
+  std::condition_variable cv_not_empty;
+  std::condition_variable cv_not_full;
+  size_t max_size;
+  bool shutdown = false;
+
+public:
+  /// @brief Creates a queue with fixed capacity.
+  explicit WorkQueue(size_t capacity) : max_size(capacity) {}
+
+  /// @brief Pushes an item, blocking while full unless shutdown is signaled.
+  bool push(T item) {
+    std::unique_lock<std::mutex> lock(mutex);
+    cv_not_full.wait(lock,
+                     [this] { return queue.size() < max_size || shutdown; });
+
+    if (shutdown)
+      return false;
+
+    queue.push(std::move(item));
+    cv_not_empty.notify_one();
+    return true;
+  }
+
+  /// @brief Pops an item, blocking while empty unless shutdown is signaled.
+  std::optional<T> pop() {
+    std::unique_lock<std::mutex> lock(mutex);
+    cv_not_empty.wait(lock, [this] { return !queue.empty() || shutdown; });
+
+    if (queue.empty())
+      return std::nullopt;
+
+    T item = std::move(queue.front());
+    queue.pop();
+    cv_not_full.notify_one();
+    return item;
+  }
+
+  /// @brief Signals queue shutdown and wakes all waiting producers/consumers.
+  void shutdown_queue() {
+    std::unique_lock<std::mutex> lock(mutex);
+    shutdown = true;
+    cv_not_empty.notify_all();
+    cv_not_full.notify_all();
+  }
+
+  /// @brief Returns current queue size.
+  size_t size() const {
+    std::lock_guard<std::mutex> lock(mutex);
+    return queue.size();
+  }
+};