Read/write loop test working

uring.h

@@ -0,0 +1,64 @@
+#pragma once
+
+#include <liburing.h>
+#include <cstdint>
+#include <functional>
+#include <vector>
+
+namespace uring {
+
+// Not thread safe. Instantiate one per thread instead.
+class URing {
+ public:
+  URing(uint32_t num_entries);
+  ~URing();
+
+  // TODO: write/writev don't work for files because they always use offset 0
+  void write(int fd, const void *buf, size_t count,
+             const std::function<void(int32_t res)> &callback);
+  void writev(int fd, const std::vector<iovec> &vecs,
+              const std::function<void(int32_t res)> &callback);
+  void pwritev(int fd, const std::vector<iovec> &vecs, off_t offset,
+               const std::function<void(int32_t res)> &callback);
+
+  // TODO: read/readv don't work for files because they always use offset 0
+  void read(int fd, const void *buf, size_t count,
+            const std::function<void(int32_t res)> &callback);
+  void readv(int fd, const std::vector<iovec> &vecs,
+             const std::function<void(int32_t res)> &callback);
+  void preadv(int fd, const std::vector<iovec> &vecs, off_t offset,
+              const std::function<void(int32_t res)> &callback);
+
+  // Submit all operations queued since the last Submit(). They must all be in
+  // a valid state when this is called.
+  void Submit();
+
+  // Wait for one operation to complete and synchronously call its callback.
+  void Wait();
+
+  // If an operation is complete, synchronously call its callback and return
+  // true.
+  bool Try();
+
+ private:
+  io_uring ring_;
+  int ring_fd_;
+
+  struct Entry {
+    Entry *free_next;
+    std::vector<iovec> vecs;
+    std::function<void(int32_t)> callback;
+  };
+
+  std::vector<Entry> entries_;
+  Entry *free_head_ = nullptr;
+
+  Entry *GetEntry(const std::function<void(int32_t res)> &callback);
+  void PutEntry(Entry *entry, int32_t res);
+
+  io_uring_sqe *GetSQE();
+
+  void ProcessCQE(io_uring_cqe *cqe);
+};
+
+}  // namespace uring