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#ifndef GRPC_CORE_LIB_CHANNEL_DEADLINE_FILTER_H
#define GRPC_CORE_LIB_CHANNEL_DEADLINE_FILTER_H

#include "src/core/lib/channel/channel_stack.h"
#include "src/core/lib/iomgr/timer.h"

typedef enum grpc_deadline_timer_state {
  GRPC_DEADLINE_STATE_INITIAL,
  GRPC_DEADLINE_STATE_PENDING,
  GRPC_DEADLINE_STATE_FINISHED
} grpc_deadline_timer_state;

// State used for filters that enforce call deadlines.
// Must be the first field in the filter's call_data.
typedef struct grpc_deadline_state {
  // We take a reference to the call stack for the timer callback.
  grpc_call_stack* call_stack;
  gpr_atm timer_state;
  grpc_timer timer;
  grpc_closure timer_callback;
  // Closure to invoke when the call is complete.
  // We use this to cancel the timer.
  grpc_closure on_complete;
  // The original on_complete closure, which we chain to after our own
  // closure is invoked.
  grpc_closure* next_on_complete;
} grpc_deadline_state;

//
// NOTE: All of these functions require that the first field in
// elem->call_data is a grpc_deadline_state.
//

void grpc_deadline_state_init(grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
                              grpc_call_stack* call_stack);
void grpc_deadline_state_destroy(grpc_exec_ctx* exec_ctx,
                                 grpc_call_element* elem);

// Starts the timer with the specified deadline.
// Should be called from the filter's init_call_elem() method.
void grpc_deadline_state_start(grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
                               gpr_timespec deadline);

// Cancels the existing timer and starts a new one with new_deadline.
//
// Note: It is generally safe to call this with an earlier deadline
// value than the current one, but not the reverse.  No checks are done
// to ensure that the timer callback is not invoked while it is in the
// process of being reset, which means that attempting to increase the
// deadline may result in the timer being called twice.
void grpc_deadline_state_reset(grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
                               gpr_timespec new_deadline);

// To be called from the client-side filter's start_transport_stream_op()
// method.  Ensures that the deadline timer is cancelled when the call
// is completed.
//
// Note: It is the caller's responsibility to chain to the next filter if
// necessary after this function returns.
void grpc_deadline_state_client_start_transport_stream_op(
    grpc_exec_ctx* exec_ctx, grpc_call_element* elem,
    grpc_transport_stream_op* op);

// Deadline filters for direct client channels and server channels.
// Note: Deadlines for non-direct client channels are handled by the
// client_channel filter.
extern const grpc_channel_filter grpc_client_deadline_filter;
extern const grpc_channel_filter grpc_server_deadline_filter;

#endif /* GRPC_CORE_LIB_CHANNEL_DEADLINE_FILTER_H */