src/core/transport/transport.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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 * in the documentation and/or other materials provided with the
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#ifndef GRPC_INTERNAL_CORE_TRANSPORT_TRANSPORT_H
#define GRPC_INTERNAL_CORE_TRANSPORT_TRANSPORT_H

#include <stddef.h>

#include "src/core/iomgr/pollset.h"
#include "src/core/iomgr/pollset_set.h"
#include "src/core/transport/stream_op.h"
#include "src/core/channel/context.h"

/* forward declarations */
typedef struct grpc_transport grpc_transport;

/* grpc_stream doesn't actually exist. It's used as a typesafe
   opaque pointer for whatever data the transport wants to track
   for a stream. */
typedef struct grpc_stream grpc_stream;

/* Represents the send/recv closed state of a stream. */
typedef enum grpc_stream_state {
  /* the stream is open for sends and receives */
  GRPC_STREAM_OPEN,
  /* the stream is closed for sends, but may still receive data */
  GRPC_STREAM_SEND_CLOSED,
  /* the stream is closed for receives, but may still send data */
  GRPC_STREAM_RECV_CLOSED,
  /* the stream is closed for both sends and receives */
  GRPC_STREAM_CLOSED
} grpc_stream_state;

/* Transport stream op: a set of operations to perform on a transport
   against a single stream */
typedef struct grpc_transport_stream_op {
  grpc_iomgr_closure *on_consumed;

  grpc_stream_op_buffer *send_ops;
  int is_last_send;
  grpc_iomgr_closure *on_done_send;

  grpc_stream_op_buffer *recv_ops;
  grpc_stream_state *recv_state;
  /** The number of bytes this peer is currently prepared to receive.

      Bytes offered are used to replenish per-stream flow control windows.
      Offers are not retractable: if 5 bytes are offered and no bytes are read,
        a later offer of 3 bytes still implies that 5 have been offered. */
  gpr_uint32 max_recv_bytes;
  grpc_iomgr_closure *on_done_recv;

  grpc_pollset *bind_pollset;

  grpc_status_code cancel_with_status;

  /* Indexes correspond to grpc_context_index enum values */
  grpc_call_context_element *context;
} grpc_transport_stream_op;

/** Transport op: a set of operations to perform on a transport as a whole */
typedef struct grpc_transport_op {
  /** called when processing of this op is done */
  grpc_iomgr_closure *on_consumed;
  /** connectivity monitoring */
  grpc_iomgr_closure *on_connectivity_state_change;
  grpc_connectivity_state *connectivity_state;
  /** should the transport be disconnected */
  int disconnect;
  /** should we send a goaway?
      after a goaway is sent, once there are no more active calls on
      the transport, the transport should disconnect */
  int send_goaway;
  /** what should the goaway contain? */
  grpc_status_code goaway_status;
  gpr_slice *goaway_message;
  /** set the callback for accepting new streams;
      this is a permanent callback, unlike the other one-shot closures */
  void (*set_accept_stream)(void *user_data, grpc_transport *transport,
                            const void *server_data);
  void *set_accept_stream_user_data;
  /** add this transport to a pollset */
  grpc_pollset *bind_pollset;
  /** send a ping, call this back if not NULL */
  grpc_iomgr_closure *send_ping;
} grpc_transport_op;

/* Returns the amount of memory required to store a grpc_stream for this
   transport */
size_t grpc_transport_stream_size(grpc_transport *transport);

/* Initialize transport data for a stream.

   Returns 0 on success, any other (transport-defined) value for failure.

   Arguments:
     transport   - the transport on which to create this stream
     stream      - a pointer to uninitialized memory to initialize
     server_data - either NULL for a client initiated stream, or a pointer
                   supplied from the accept_stream callback function */
int grpc_transport_init_stream(grpc_transport *transport, grpc_stream *stream,
                               const void *server_data,
                               grpc_transport_stream_op *initial_op);

/* Destroy transport data for a stream.

   Requires: a recv_batch with final_state == GRPC_STREAM_CLOSED has been
   received by the up-layer. Must not be called in the same call stack as
   recv_frame.

   Arguments:
     transport - the transport on which to create this stream
     stream    - the grpc_stream to destroy (memory is still owned by the
                 caller, but any child memory must be cleaned up) */
void grpc_transport_destroy_stream(grpc_transport *transport,
                                   grpc_stream *stream);

void grpc_transport_stream_op_finish_with_failure(grpc_transport_stream_op *op);

void grpc_transport_stream_op_add_cancellation(grpc_transport_stream_op *op,
                                               grpc_status_code status,
                                               grpc_mdstr *message);

char *grpc_transport_stream_op_string(grpc_transport_stream_op *op);

/* Send a batch of operations on a transport

   Takes ownership of any objects contained in ops.

   Arguments:
     transport - the transport on which to initiate the stream
     stream    - the stream on which to send the operations. This must be
                 non-NULL and previously initialized by the same transport.
     op        - a grpc_transport_stream_op specifying the op to perform */
void grpc_transport_perform_stream_op(grpc_transport *transport,
                                      grpc_stream *stream,
                                      grpc_transport_stream_op *op);

void grpc_transport_perform_op(grpc_transport *transport,
                               grpc_transport_op *op);

/* Send a ping on a transport

   Calls cb with user data when a response is received. */
void grpc_transport_ping(grpc_transport *transport, grpc_iomgr_closure *cb);

/* Advise peer of pending connection termination. */
void grpc_transport_goaway(grpc_transport *transport, grpc_status_code status,
                           gpr_slice debug_data);

/* Close a transport. Aborts all open streams. */
void grpc_transport_close(grpc_transport *transport);

/* Destroy the transport */
void grpc_transport_destroy(grpc_transport *transport);

#endif /* GRPC_INTERNAL_CORE_TRANSPORT_TRANSPORT_H */