pollset_kick_posix.h

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#ifndef GRPC_INTERNAL_CORE_IOMGR_POLLSET_KICK_POSIX_H
#define GRPC_INTERNAL_CORE_IOMGR_POLLSET_KICK_POSIX_H

#include "src/core/iomgr/wakeup_fd_posix.h"
#include <grpc/support/sync.h>

/* pollset kicking allows breaking a thread out of polling work for
   a given pollset.
   writing a byte to a pipe is used as a posix-ly portable base
   mechanism, and eventfds are utilized on Linux for better performance. */

typedef struct grpc_kick_fd_info {
  grpc_wakeup_fd_info wakeup_fd;
  /* used for polling list and free list */
  struct grpc_kick_fd_info *next;
  /* only used when polling */
  struct grpc_kick_fd_info *prev;
} grpc_kick_fd_info;

typedef struct grpc_pollset_kick_state {
  gpr_mu mu;
  int kicked;
  struct grpc_kick_fd_info fd_list;
} grpc_pollset_kick_state;

#define GRPC_POLLSET_KICK_GET_FD(kick_fd_info) \
  GRPC_WAKEUP_FD_GET_READ_FD(&(kick_fd_info)->wakeup_fd)

/* This is an abstraction around the typical pipe mechanism for waking up a
   thread sitting in a poll() style call. */

void grpc_pollset_kick_global_init(void);
void grpc_pollset_kick_global_destroy(void);

void grpc_pollset_kick_init(grpc_pollset_kick_state *kick_state);
void grpc_pollset_kick_destroy(grpc_pollset_kick_state *kick_state);

/* Guarantees a pure posix implementation rather than a specialized one, if
 * applicable. Intended for testing. */
void grpc_pollset_kick_global_init_fallback_fd(void);

/* Must be called before entering poll(). If return value is NULL, this consumed
   an existing kick. Otherwise the return value is an FD to add to the poll set.
 */
grpc_kick_fd_info *grpc_pollset_kick_pre_poll(
    grpc_pollset_kick_state *kick_state);

/* Consume an existing kick. Must be called after poll returns that the fd was
   readable, and before calling kick_post_poll. */
void grpc_pollset_kick_consume(grpc_pollset_kick_state *kick_state,
                               grpc_kick_fd_info *fd_info);

/* Must be called after pre_poll, and after consume if applicable */
void grpc_pollset_kick_post_poll(grpc_pollset_kick_state *kick_state,
                                 grpc_kick_fd_info *fd_info);

/* Actually kick */
void grpc_pollset_kick_kick(grpc_pollset_kick_state *kick_state);

#endif /* GRPC_INTERNAL_CORE_IOMGR_POLLSET_KICK_POSIX_H */