src/core/lib/channel/connected_channel.c

/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */

#include "src/core/lib/channel/connected_channel.h"

#include <stdarg.h>
#include <stdio.h>
#include <string.h>

#include <grpc/byte_buffer.h>
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/slice_buffer.h>
#include "src/core/lib/profiling/timers.h"
#include "src/core/lib/support/string.h"
#include "src/core/lib/transport/transport.h"

#define MAX_BUFFER_LENGTH 8192

typedef struct connected_channel_channel_data {
  grpc_transport *transport;
} channel_data;

typedef struct connected_channel_call_data { void *unused; } call_data;

/* We perform a small hack to locate transport data alongside the connected
   channel data in call allocations, to allow everything to be pulled in minimal
   cache line requests */
#define TRANSPORT_STREAM_FROM_CALL_DATA(calld) ((grpc_stream *)((calld) + 1))
#define CALL_DATA_FROM_TRANSPORT_STREAM(transport_stream) \
  (((call_data *)(transport_stream)) - 1)

/* Intercept a call operation and either push it directly up or translate it
   into transport stream operations */
static void con_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
                                          grpc_call_element *elem,
                                          grpc_transport_stream_op *op) {
  call_data *calld = elem->call_data;
  channel_data *chand = elem->channel_data;
  GRPC_CALL_LOG_OP(GPR_INFO, elem, op);

  grpc_transport_perform_stream_op(exec_ctx, chand->transport,
                                   TRANSPORT_STREAM_FROM_CALL_DATA(calld), op);
}

static void con_start_transport_op(grpc_exec_ctx *exec_ctx,
                                   grpc_channel_element *elem,
                                   grpc_transport_op *op) {
  channel_data *chand = elem->channel_data;
  grpc_transport_perform_op(exec_ctx, chand->transport, op);
}

/* Constructor for call_data */
static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
                           grpc_call_element_args *args) {
  call_data *calld = elem->call_data;
  channel_data *chand = elem->channel_data;
  int r;

  r = grpc_transport_init_stream(
      exec_ctx, chand->transport, TRANSPORT_STREAM_FROM_CALL_DATA(calld),
      &args->call_stack->refcount, args->server_transport_data);
  GPR_ASSERT(r == 0);
}

static void set_pollset_or_pollset_set(grpc_exec_ctx *exec_ctx,
                                       grpc_call_element *elem,
                                       grpc_polling_entity *pollent) {
  call_data *calld = elem->call_data;
  channel_data *chand = elem->channel_data;
  grpc_transport_set_pops(exec_ctx, chand->transport,
                          TRANSPORT_STREAM_FROM_CALL_DATA(calld), pollent);
}

/* Destructor for call_data */
static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
                              const grpc_call_final_info *final_info,
                              void *and_free_memory) {
  call_data *calld = elem->call_data;
  channel_data *chand = elem->channel_data;
  grpc_transport_destroy_stream(exec_ctx, chand->transport,
                                TRANSPORT_STREAM_FROM_CALL_DATA(calld),
                                and_free_memory);
}

/* Constructor for channel_data */
static void init_channel_elem(grpc_exec_ctx *exec_ctx,
                              grpc_channel_element *elem,
                              grpc_channel_element_args *args) {
  channel_data *cd = (channel_data *)elem->channel_data;
  GPR_ASSERT(args->is_last);
  cd->transport = NULL;
}

/* Destructor for channel_data */
static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
                                 grpc_channel_element *elem) {
  channel_data *cd = (channel_data *)elem->channel_data;
  grpc_transport_destroy(exec_ctx, cd->transport);
}

static char *con_get_peer(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
  channel_data *chand = elem->channel_data;
  return grpc_transport_get_peer(exec_ctx, chand->transport);
}

static const grpc_channel_filter connected_channel_filter = {
    con_start_transport_stream_op,
    con_start_transport_op,
    sizeof(call_data),
    init_call_elem,
    set_pollset_or_pollset_set,
    destroy_call_elem,
    sizeof(channel_data),
    init_channel_elem,
    destroy_channel_elem,
    con_get_peer,
    "connected",
};

static void bind_transport(grpc_channel_stack *channel_stack,
                           grpc_channel_element *elem, void *t) {
  channel_data *cd = (channel_data *)elem->channel_data;
  GPR_ASSERT(elem->filter == &connected_channel_filter);
  GPR_ASSERT(cd->transport == NULL);
  cd->transport = t;

  /* HACK(ctiller): increase call stack size for the channel to make space
     for channel data. We need a cleaner (but performant) way to do this,
     and I'm not sure what that is yet.
     This is only "safe" because call stacks place no additional data after
     the last call element, and the last call element MUST be the connected
     channel. */
  channel_stack->call_stack_size += grpc_transport_stream_size(t);
}

bool grpc_add_connected_filter(grpc_channel_stack_builder *builder,
                               void *arg_must_be_null) {
  GPR_ASSERT(arg_must_be_null == NULL);
  grpc_transport *t = grpc_channel_stack_builder_get_transport(builder);
  GPR_ASSERT(t != NULL);
  return grpc_channel_stack_builder_append_filter(
      builder, &connected_channel_filter, bind_transport, t);
}

grpc_stream *grpc_connected_channel_get_stream(grpc_call_element *elem) {
  call_data *calld = elem->call_data;
  return TRANSPORT_STREAM_FROM_CALL_DATA(calld);
}