1 files changed, 52 insertions, 0 deletions
diff --git a/src/librbd/asio/ContextWQ.h b/src/librbd/asio/ContextWQ.h
new file mode 100644
index 000000000..85c254161
--- /dev/null
+++ b/src/librbd/asio/ContextWQ.h
@@ -0,0 +1,52 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#ifndef CEPH_LIBRBD_ASIO_CONTEXT_WQ_H
+#define CEPH_LIBRBD_ASIO_CONTEXT_WQ_H
+
+#include "include/common_fwd.h"
+#include "include/Context.h"
+#include <atomic>
+#include <memory>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/io_context_strand.hpp>
+#include <boost/asio/post.hpp>
+
+namespace librbd {
+namespace asio {
+
+class ContextWQ {
+public:
+  explicit ContextWQ(CephContext* cct, boost::asio::io_context& io_context);
+  ~ContextWQ();
+
+  void drain();
+
+  void queue(Context *ctx, int r = 0) {
+    ++m_queued_ops;
+
+    // ensure all legacy ContextWQ users are dispatched sequentially for
+    // backwards compatibility (i.e. might not be concurrent thread-safe)
+    boost::asio::post(*m_strand, [this, ctx, r]() {
+      ctx->complete(r);
+
+      ceph_assert(m_queued_ops > 0);
+      --m_queued_ops;
+    });
+  }
+
+private:
+  CephContext* m_cct;
+  boost::asio::io_context& m_io_context;
+  std::unique_ptr<boost::asio::io_context::strand> m_strand;
+
+  std::atomic<uint64_t> m_queued_ops;
+
+  void drain_handler(Context* ctx);
+
+};
+
+} // namespace asio
+} // namespace librbd
+
+#endif // CEPH_LIBRBD_ASIO_CONTEXT_WQ_H