fd_posix.h

/*
 *
 * Copyright 2015, Google Inc.
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 * modification, are permitted provided that the following conditions are
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 *
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 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
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#ifndef GRPC_INTERNAL_CORE_IOMGR_FD_POSIX_H
#define GRPC_INTERNAL_CORE_IOMGR_FD_POSIX_H

#include "src/core/iomgr/iomgr.h"
#include "src/core/iomgr/pollset.h"
#include <grpc/support/atm.h>
#include <grpc/support/sync.h>
#include <grpc/support/time.h>

typedef struct {
  grpc_iomgr_cb_func cb;
  void *cb_arg;
} grpc_iomgr_closure;

typedef struct grpc_fd grpc_fd;

typedef struct grpc_fd_watcher {
  struct grpc_fd_watcher *next;
  struct grpc_fd_watcher *prev;
  grpc_pollset *pollset;
  grpc_fd *fd;
} grpc_fd_watcher;

struct grpc_fd {
  int fd;
  /* refst format:
       bit0:   1=active/0=orphaned
       bit1-n: refcount
     meaning that mostly we ref by two to avoid altering the orphaned bit,
     and just unref by 1 when we're ready to flag the object as orphaned */
  gpr_atm refst;

  gpr_mu set_state_mu;
  gpr_atm shutdown;

  gpr_mu watcher_mu;
  grpc_fd_watcher watcher_root;

  gpr_atm readst;
  gpr_atm writest;

  grpc_iomgr_cb_func on_done;
  void *on_done_user_data;
  struct grpc_fd *freelist_next;
};

/* Create a wrapped file descriptor.
   Requires fd is a non-blocking file descriptor.
   This takes ownership of closing fd. */
grpc_fd *grpc_fd_create(int fd);

/* Releases fd to be asynchronously destroyed.
   on_done is called when the underlying file descriptor is definitely close()d.
   If on_done is NULL, no callback will be made.
   Requires: *fd initialized; no outstanding notify_on_read or
   notify_on_write. */
void grpc_fd_orphan(grpc_fd *fd, grpc_iomgr_cb_func on_done, void *user_data);

/* Begin polling on an fd.
   Registers that the given pollset is interested in this fd - so that if read
   or writability interest changes, the pollset can be kicked to pick up that
   new interest.
   Return value is:
     (fd_needs_read? read_mask : 0) | (fd_needs_write? write_mask : 0)
   i.e. a combination of read_mask and write_mask determined by the fd's current
   interest in said events.
   Polling strategies that do not need to alter their behavior depending on the
   fd's current interest (such as epoll) do not need to call this function. */
gpr_uint32 grpc_fd_begin_poll(grpc_fd *fd, grpc_pollset *pollset,
                              gpr_uint32 read_mask, gpr_uint32 write_mask,
                              grpc_fd_watcher *rec);
/* Complete polling previously started with grpc_fd_begin_poll */
void grpc_fd_end_poll(grpc_fd_watcher *rec);

/* Return 1 if this fd is orphaned, 0 otherwise */
int grpc_fd_is_orphaned(grpc_fd *fd);

/* Cause any current callbacks to error out with GRPC_CALLBACK_CANCELLED. */
void grpc_fd_shutdown(grpc_fd *fd);

/* Register read interest, causing read_cb to be called once when fd becomes
   readable, on deadline specified by deadline, or on shutdown triggered by
   grpc_fd_shutdown.
   read_cb will be called with read_cb_arg when *fd becomes readable.
   read_cb is Called with status of GRPC_CALLBACK_SUCCESS if readable,
   GRPC_CALLBACK_TIMED_OUT if the call timed out,
   and CANCELLED if the call was cancelled.

   Requires:This method must not be called before the read_cb for any previous
   call runs. Edge triggered events are used whenever they are supported by the
   underlying platform. This means that users must drain fd in read_cb before
   calling notify_on_read again. Users are also expected to handle spurious
   events, i.e read_cb is called while nothing can be readable from fd  */
void grpc_fd_notify_on_read(grpc_fd *fd, grpc_iomgr_closure *closure);

/* Exactly the same semantics as above, except based on writable events.  */
void grpc_fd_notify_on_write(grpc_fd *fd, grpc_iomgr_closure *closure);

/* Notification from the poller to an fd that it has become readable or
   writable.
   If allow_synchronous_callback is 1, allow running the fd callback inline
   in this callstack, otherwise register an asynchronous callback and return */
void grpc_fd_become_readable(grpc_fd *fd, int allow_synchronous_callback);
void grpc_fd_become_writable(grpc_fd *fd, int allow_synchronous_callback);

/* Reference counting for fds */
void grpc_fd_ref(grpc_fd *fd);
void grpc_fd_unref(grpc_fd *fd);

void grpc_fd_global_init(void);
void grpc_fd_global_shutdown(void);

#endif  /* GRPC_INTERNAL_CORE_IOMGR_FD_POSIX_H */