socket_windows.h

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#ifndef GRPC_INTERNAL_CORE_IOMGR_SOCKET_WINDOWS_H
#define GRPC_INTERNAL_CORE_IOMGR_SOCKET_WINDOWS_H

#include <windows.h>

#include <grpc/support/sync.h>
#include <grpc/support/atm.h>

/* This holds the data for an outstanding read or write on a socket.
   The mutex to protect the concurrent access to that data is the one
   inside the winsocket wrapper. */
typedef struct grpc_winsocket_callback_info {
  /* This is supposed to be a WSAOVERLAPPED, but in order to get that
     definition, we need to include ws2tcpip.h, which needs to be included
     from the top, otherwise it'll clash with a previous inclusion of
     windows.h that in turns includes winsock.h. If anyone knows a way
     to do it properly, feel free to send a patch. */
  OVERLAPPED overlapped;
  /* The callback information for the pending operation. May be empty if the
     caller hasn't registered a callback yet. */
  void(*cb)(void *opaque, int success);
  void *opaque;
  /* A boolean to describe if the IO Completion Port got a notification for
     that operation. This will happen if the operation completed before the
     called had time to register a callback. We could avoid that behavior
     altogether by forcing the caller to always register its callback before
     proceeding queue an operation, but it is frequent for an IO Completion
     Port to trigger quickly. This way we avoid a context switch for calling
     the callback. We also simplify the read / write operations to avoid having
     to hold a mutex for a long amount of time. */
  int has_pending_iocp;
  /* The results of the overlapped operation. */
  DWORD bytes_transfered;
  int wsa_error;
  /* A boolean indicating that we started an operation. */
  int outstanding;
} grpc_winsocket_callback_info;

/* This is a wrapper to a Windows socket. A socket can have one outstanding
   read, and one outstanding write. Doing an asynchronous accept means waiting
   for a read operation. Doing an asynchronous connect means waiting for a
   write operation. These are completely arbitrary ties between the operation
   and the kind of event, because we can have one overlapped per pending
   operation, whichever its nature is. So we could have more dedicated pending
   operation callbacks for connect and listen. But given the scope of listen
   and accept, we don't need to go to that extent and waste memory. Also, this
   is closer to what happens in posix world. */
typedef struct grpc_winsocket {
  SOCKET socket;

  grpc_winsocket_callback_info write_info;
  grpc_winsocket_callback_info read_info;

  gpr_mu state_mu;

  /* You can't add the same socket twice to the same IO Completion Port.
     This prevents that. */
  int added_to_iocp;
  /* A boolean to indicate that the caller has abandoned that socket, but
     there is a pending operation that the IO Completion Port will have to
     wait for. The socket will be collected at that time. */
  int orphan;
} grpc_winsocket;

/* Create a wrapped windows handle. This takes ownership of it, meaning that
   it will be responsible for closing it. */
grpc_winsocket *grpc_winsocket_create(SOCKET socket);

/* Initiate an asynchronous shutdown of the socket. Will call off any pending
   operation to cancel them. Returns the number of callbacks that got setup. */
int grpc_winsocket_shutdown(grpc_winsocket *socket);

/* Abandon a socket. */
void grpc_winsocket_orphan(grpc_winsocket *socket);

/* Destroy a socket. Should only be called by the IO Completion Port thread,
   or by grpc_winsocket_orphan if there's no pending operation. */
void grpc_winsocket_destroy(grpc_winsocket *socket);

#endif  /* GRPC_INTERNAL_CORE_IOMGR_SOCKET_WINDOWS_H */