src/core/channel/channel_stack.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.
 *     * Neither the name of Google Inc. nor the names of its
 * 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,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include "src/core/channel/channel_stack.h"
#include <grpc/support/log.h>

#include <stdlib.h>
#include <string.h>

int grpc_trace_channel = 0;

/* Memory layouts.

   Channel stack is laid out as: {
     grpc_channel_stack stk;
     padding to GPR_MAX_ALIGNMENT
     grpc_channel_element[stk.count];
     per-filter memory, aligned to GPR_MAX_ALIGNMENT
   }

   Call stack is laid out as: {
     grpc_call_stack stk;
     padding to GPR_MAX_ALIGNMENT
     grpc_call_element[stk.count];
     per-filter memory, aligned to GPR_MAX_ALIGNMENT
   } */

/* Given a size, round up to the next multiple of sizeof(void*) */
#define ROUND_UP_TO_ALIGNMENT_SIZE(x) \
  (((x) + GPR_MAX_ALIGNMENT - 1u) & ~(GPR_MAX_ALIGNMENT - 1u))

size_t
grpc_channel_stack_size (const grpc_channel_filter ** filters, size_t filter_count)
{
  /* always need the header, and size for the channel elements */
  size_t size = ROUND_UP_TO_ALIGNMENT_SIZE (sizeof (grpc_channel_stack)) + ROUND_UP_TO_ALIGNMENT_SIZE (filter_count * sizeof (grpc_channel_element));
  size_t i;

  GPR_ASSERT ((GPR_MAX_ALIGNMENT & (GPR_MAX_ALIGNMENT - 1)) == 0 && "GPR_MAX_ALIGNMENT must be a power of two");

  /* add the size for each filter */
  for (i = 0; i < filter_count; i++)
    {
      size += ROUND_UP_TO_ALIGNMENT_SIZE (filters[i]->sizeof_channel_data);
    }

  return size;
}

#define CHANNEL_ELEMS_FROM_STACK(stk)                                   \
  ((grpc_channel_element *)((char *)(stk) + ROUND_UP_TO_ALIGNMENT_SIZE( \
                                                sizeof(grpc_channel_stack))))

#define CALL_ELEMS_FROM_STACK(stk)       \
  ((grpc_call_element *)((char *)(stk) + \
                         ROUND_UP_TO_ALIGNMENT_SIZE(sizeof(grpc_call_stack))))

grpc_channel_element *
grpc_channel_stack_element (grpc_channel_stack * channel_stack, size_t index)
{
  return CHANNEL_ELEMS_FROM_STACK (channel_stack) + index;
}

grpc_channel_element *
grpc_channel_stack_last_element (grpc_channel_stack * channel_stack)
{
  return grpc_channel_stack_element (channel_stack, channel_stack->count - 1);
}

grpc_call_element *
grpc_call_stack_element (grpc_call_stack * call_stack, size_t index)
{
  return CALL_ELEMS_FROM_STACK (call_stack) + index;
}

void
grpc_channel_stack_init (grpc_exec_ctx * exec_ctx, const grpc_channel_filter ** filters, size_t filter_count, grpc_channel * master, const grpc_channel_args * args, grpc_mdctx * metadata_context, grpc_channel_stack * stack)
{
  size_t call_size = ROUND_UP_TO_ALIGNMENT_SIZE (sizeof (grpc_call_stack)) + ROUND_UP_TO_ALIGNMENT_SIZE (filter_count * sizeof (grpc_call_element));
  grpc_channel_element *elems;
  char *user_data;
  size_t i;

  stack->count = filter_count;
  elems = CHANNEL_ELEMS_FROM_STACK (stack);
  user_data = ((char *) elems) + ROUND_UP_TO_ALIGNMENT_SIZE (filter_count * sizeof (grpc_channel_element));

  /* init per-filter data */
  for (i = 0; i < filter_count; i++)
    {
      elems[i].filter = filters[i];
      elems[i].channel_data = user_data;
      elems[i].filter->init_channel_elem (&elems[i], master, args, metadata_context, i == 0, i == (exec_ctx, filter_count - 1));
      user_data += ROUND_UP_TO_ALIGNMENT_SIZE (filters[i]->sizeof_channel_data);
      call_size += ROUND_UP_TO_ALIGNMENT_SIZE (filters[i]->sizeof_call_data);
    }

  GPR_ASSERT (user_data > (char *) stack);
  GPR_ASSERT ((gpr_uintptr) (user_data - (char *) stack) == grpc_channel_stack_size (filters, filter_count));

  stack->call_stack_size = call_size;
}

void
grpc_channel_stack_destroy (grpc_exec_ctx * exec_ctx, grpc_channel_stack * stack)
{
  grpc_channel_element *channel_elems = CHANNEL_ELEMS_FROM_STACK (stack);
  size_t count = stack->count;
  size_t i;

  /* destroy per-filter data */
  for (i = 0; i < count; i++)
    {
      channel_elems[i].filter->destroy_channel_elem (exec_ctx, &channel_elems[i]);
    }
}

void
grpc_call_stack_init (grpc_exec_ctx * exec_ctx, grpc_channel_stack * channel_stack, const void *transport_server_data, grpc_transport_stream_op * initial_op, grpc_call_stack * call_stack)
{
  grpc_channel_element *channel_elems = CHANNEL_ELEMS_FROM_STACK (channel_stack);
  size_t count = channel_stack->count;
  grpc_call_element *call_elems;
  char *user_data;
  size_t i;

  call_stack->count = count;
  call_elems = CALL_ELEMS_FROM_STACK (call_stack);
  user_data = ((char *) call_elems) + ROUND_UP_TO_ALIGNMENT_SIZE (count * sizeof (grpc_call_element));

  /* init per-filter data */
  for (i = 0; i < count; i++)
    {
      call_elems[i].filter = channel_elems[i].filter;
      call_elems[i].channel_data = channel_elems[i].channel_data;
      call_elems[i].call_data = user_data;
      call_elems[i].filter->init_call_elem (exec_ctx, &call_elems[i], transport_server_data, initial_op);
      user_data += ROUND_UP_TO_ALIGNMENT_SIZE (call_elems[i].filter->sizeof_call_data);
    }
}

void
grpc_call_stack_destroy (grpc_exec_ctx * exec_ctx, grpc_call_stack * stack)
{
  grpc_call_element *elems = CALL_ELEMS_FROM_STACK (stack);
  size_t count = stack->count;
  size_t i;

  /* destroy per-filter data */
  for (i = 0; i < count; i++)
    {
      elems[i].filter->destroy_call_elem (exec_ctx, &elems[i]);
    }
}

void
grpc_call_next_op (grpc_exec_ctx * exec_ctx, grpc_call_element * elem, grpc_transport_stream_op * op)
{
  grpc_call_element *next_elem = elem + 1;
  next_elem->filter->start_transport_stream_op (exec_ctx, next_elem, op);
}

char *
grpc_call_next_get_peer (grpc_exec_ctx * exec_ctx, grpc_call_element * elem)
{
  grpc_call_element *next_elem = elem + 1;
  return next_elem->filter->get_peer (exec_ctx, next_elem);
}

void
grpc_channel_next_op (grpc_exec_ctx * exec_ctx, grpc_channel_element * elem, grpc_transport_op * op)
{
  grpc_channel_element *next_elem = elem + 1;
  next_elem->filter->start_transport_op (exec_ctx, next_elem, op);
}

grpc_channel_stack *
grpc_channel_stack_from_top_element (grpc_channel_element * elem)
{
  return (grpc_channel_stack *) ((char *) (elem) - ROUND_UP_TO_ALIGNMENT_SIZE (sizeof (grpc_channel_stack)));
}

grpc_call_stack *
grpc_call_stack_from_top_element (grpc_call_element * elem)
{
  return (grpc_call_stack *) ((char *) (elem) - ROUND_UP_TO_ALIGNMENT_SIZE (sizeof (grpc_call_stack)));
}

void
grpc_call_element_send_cancel (grpc_exec_ctx * exec_ctx, grpc_call_element * cur_elem)
{
  grpc_transport_stream_op op;
  memset (&op, 0, sizeof (op));
  op.cancel_with_status = GRPC_STATUS_CANCELLED;
  grpc_call_next_op (exec_ctx, cur_elem, &op);
}