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/*
*
* Copyright 2014, 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/client_channel.h"
#include <stdio.h>
#include "src/core/channel/channel_args.h"
#include "src/core/channel/connected_channel.h"
#include "src/core/channel/metadata_buffer.h"
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/string.h>
#include <grpc/support/sync.h>
#include <grpc/support/useful.h>
/* Link back filter: passes up calls to the client channel, pushes down calls
down */
typedef struct { grpc_channel_element *back; } lb_channel_data;
typedef struct { grpc_call_element *back; } lb_call_data;
static void lb_call_op(grpc_call_element *elem, grpc_call_op *op) {
lb_call_data *calld = elem->call_data;
switch (op->dir) {
case GRPC_CALL_UP:
calld->back->filter->call_op(calld->back, op);
break;
case GRPC_CALL_DOWN:
grpc_call_next_op(elem, op);
break;
}
}
/* Currently we assume all channel operations should just be pushed up. */
static void lb_channel_op(grpc_channel_element *elem, grpc_channel_op *op) {
lb_channel_data *chand = elem->channel_data;
switch (op->dir) {
case GRPC_CALL_UP:
chand->back->filter->channel_op(chand->back, op);
break;
case GRPC_CALL_DOWN:
grpc_channel_next_op(elem, op);
break;
}
}
/* Constructor for call_data */
static void lb_init_call_elem(grpc_call_element *elem,
const void *server_transport_data) {}
/* Destructor for call_data */
static void lb_destroy_call_elem(grpc_call_element *elem) {}
/* Constructor for channel_data */
static void lb_init_channel_elem(grpc_channel_element *elem,
const grpc_channel_args *args,
grpc_mdctx *metadata_context, int is_first,
int is_last) {
GPR_ASSERT(is_first);
GPR_ASSERT(!is_last);
}
/* Destructor for channel_data */
static void lb_destroy_channel_elem(grpc_channel_element *elem) {}
static const grpc_channel_filter link_back_filter = {
lb_call_op, lb_channel_op,
sizeof(lb_call_data), lb_init_call_elem, lb_destroy_call_elem,
sizeof(lb_channel_data), lb_init_channel_elem, lb_destroy_channel_elem,
"clientchannel.linkback",
};
/* Client channel implementation */
typedef struct {
size_t inflight_requests;
grpc_channel_stack *channel_stack;
} child_entry;
typedef struct call_data call_data;
typedef struct {
/* protects children, child_count, child_capacity, active_child,
transport_setup_initiated
does not protect channel stacks held by children
transport_setup is assumed to be set once during construction */
gpr_mu mu;
/* the sending child (points somewhere in children, or NULL) */
child_entry *active_child;
/* vector of child channels */
child_entry *children;
size_t child_count;
size_t child_capacity;
/* calls waiting for a channel to be ready */
call_data **waiting_children;
size_t waiting_child_count;
size_t waiting_child_capacity;
/* transport setup for this channel */
grpc_transport_setup *transport_setup;
int transport_setup_initiated;
grpc_channel_args *args;
/* metadata cache */
grpc_mdelem *cancel_status;
} channel_data;
typedef enum {
CALL_CREATED,
CALL_WAITING,
CALL_ACTIVE,
CALL_CANCELLED
} call_state;
struct call_data {
/* owning element */
grpc_call_element *elem;
call_state state;
grpc_metadata_buffer pending_metadata;
gpr_timespec deadline;
union {
struct {
/* our child call stack */
grpc_call_stack *child_stack;
/* ... and the channel stack associated with it */
grpc_channel_stack *using_stack;
} active;
struct {
void (*on_complete)(void *user_data, grpc_op_error error);
void *on_complete_user_data;
gpr_uint32 start_flags;
} waiting;
} s;
};
static int prepare_activate(call_data *calld, child_entry *on_child) {
grpc_call_element *child_elem;
grpc_channel_stack *use_stack = on_child->channel_stack;
if (calld->state == CALL_CANCELLED) return 0;
on_child->inflight_requests++;
/* no more access to calld->s.waiting allowed */
GPR_ASSERT(calld->state == CALL_WAITING);
calld->state = CALL_ACTIVE;
/* create a child stack, and record that we're using a particular channel
stack */
calld->s.active.child_stack = gpr_malloc(use_stack->call_stack_size);
calld->s.active.using_stack = use_stack;
grpc_call_stack_init(use_stack, NULL, calld->s.active.child_stack);
/* initialize the top level link back element */
child_elem = grpc_call_stack_element(calld->s.active.child_stack, 0);
GPR_ASSERT(child_elem->filter == &link_back_filter);
((lb_call_data *)child_elem->call_data)->back = calld->elem;
return 1;
}
static void do_nothing(void *ignored, grpc_op_error error) {}
static void complete_activate(call_data *calld, child_entry *on_child,
grpc_call_op *op) {
grpc_call_element *child_elem =
grpc_call_stack_element(calld->s.active.child_stack, 0);
GPR_ASSERT(calld->state == CALL_ACTIVE);
/* sending buffered metadata down the stack before the start call */
grpc_metadata_buffer_flush(&calld->pending_metadata, child_elem);
if (gpr_time_cmp(calld->deadline, gpr_inf_future) != 0) {
grpc_call_op dop;
dop.type = GRPC_SEND_DEADLINE;
dop.dir = GRPC_CALL_DOWN;
dop.flags = 0;
dop.data.deadline = calld->deadline;
dop.done_cb = do_nothing;
dop.user_data = NULL;
child_elem->filter->call_op(child_elem, &dop);
}
/* continue the start call down the stack, this nees to happen after metadata
are flushed*/
child_elem->filter->call_op(child_elem, op);
}
static void start_rpc(call_data *calld, channel_data *chand, grpc_call_op *op) {
gpr_mu_lock(&chand->mu);
if (calld->state == CALL_CANCELLED) {
gpr_mu_unlock(&chand->mu);
op->done_cb(op->user_data, GRPC_OP_ERROR);
return;
}
GPR_ASSERT(calld->state == CALL_CREATED);
calld->state = CALL_WAITING;
if (chand->active_child) {
/* channel is connected - use the connected stack */
if (prepare_activate(calld, chand->active_child)) {
gpr_mu_unlock(&chand->mu);
/* activate the request (pass it down) outside the lock */
complete_activate(calld, chand->active_child, op);
} else {
gpr_mu_unlock(&chand->mu);
}
} else {
/* check to see if we should initiate a connection (if we're not already),
but don't do so until outside the lock to avoid re-entrancy problems if
the callback is immediate */
int initiate_transport_setup = 0;
if (!chand->transport_setup_initiated) {
chand->transport_setup_initiated = 1;
initiate_transport_setup = 1;
}
/* add this call to the waiting set to be resumed once we have a child
channel stack, growing the waiting set if needed */
if (chand->waiting_child_count == chand->waiting_child_capacity) {
chand->waiting_child_capacity =
GPR_MAX(chand->waiting_child_capacity * 2, 8);
chand->waiting_children =
gpr_realloc(chand->waiting_children,
chand->waiting_child_capacity * sizeof(call_data *));
}
calld->s.waiting.on_complete = op->done_cb;
calld->s.waiting.on_complete_user_data = op->user_data;
calld->s.waiting.start_flags = op->flags;
chand->waiting_children[chand->waiting_child_count++] = calld;
gpr_mu_unlock(&chand->mu);
/* finally initiate transport setup if needed */
if (initiate_transport_setup) {
grpc_transport_setup_initiate(chand->transport_setup);
}
}
}
static void remove_waiting_child(channel_data *chand, call_data *calld) {
size_t new_count;
size_t i;
for (i = 0, new_count = 0; i < chand->waiting_child_count; i++) {
if (chand->waiting_children[i] == calld) continue;
chand->waiting_children[new_count++] = chand->waiting_children[i];
}
GPR_ASSERT(new_count == chand->waiting_child_count - 1 ||
new_count == chand->waiting_child_count);
chand->waiting_child_count = new_count;
}
static void cancel_rpc(grpc_call_element *elem, grpc_call_op *op) {
call_data *calld = elem->call_data;
channel_data *chand = elem->channel_data;
grpc_call_element *child_elem;
grpc_call_op finish_op;
gpr_mu_lock(&chand->mu);
switch (calld->state) {
case CALL_ACTIVE:
child_elem = grpc_call_stack_element(calld->s.active.child_stack, 0);
gpr_mu_unlock(&chand->mu);
child_elem->filter->call_op(child_elem, op);
return; /* early out */
case CALL_WAITING:
remove_waiting_child(chand, calld);
calld->s.waiting.on_complete(calld->s.waiting.on_complete_user_data,
GRPC_OP_ERROR);
/* fallthrough intended */
case CALL_CREATED:
calld->state = CALL_CANCELLED;
gpr_mu_unlock(&chand->mu);
/* send up a synthesized status */
finish_op.type = GRPC_RECV_METADATA;
finish_op.dir = GRPC_CALL_UP;
finish_op.flags = 0;
finish_op.data.metadata = grpc_mdelem_ref(chand->cancel_status);
finish_op.done_cb = do_nothing;
finish_op.user_data = NULL;
grpc_call_next_op(elem, &finish_op);
/* send up a finish */
finish_op.type = GRPC_RECV_FINISH;
finish_op.dir = GRPC_CALL_UP;
finish_op.flags = 0;
finish_op.done_cb = do_nothing;
finish_op.user_data = NULL;
grpc_call_next_op(elem, &finish_op);
return; /* early out */
case CALL_CANCELLED:
gpr_mu_unlock(&chand->mu);
return; /* early out */
}
gpr_log(GPR_ERROR, "should never reach here");
abort();
}
static void call_op(grpc_call_element *elem, grpc_call_op *op) {
call_data *calld = elem->call_data;
channel_data *chand = elem->channel_data;
grpc_call_element *child_elem;
GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
switch (op->type) {
case GRPC_SEND_METADATA:
grpc_metadata_buffer_queue(&calld->pending_metadata, op);
break;
case GRPC_SEND_DEADLINE:
calld->deadline = op->data.deadline;
op->done_cb(op->user_data, GRPC_OP_OK);
break;
case GRPC_SEND_START:
/* filter out the start event to find which child to send on */
start_rpc(calld, chand, op);
break;
case GRPC_CANCEL_OP:
cancel_rpc(elem, op);
break;
default:
switch (op->dir) {
case GRPC_CALL_UP:
grpc_call_next_op(elem, op);
break;
case GRPC_CALL_DOWN:
child_elem = grpc_call_stack_element(calld->s.active.child_stack, 0);
GPR_ASSERT(calld->state == CALL_ACTIVE);
child_elem->filter->call_op(child_elem, op);
break;
}
break;
}
}
static void broadcast_channel_op_down(grpc_channel_element *elem,
grpc_channel_op *op) {
channel_data *chand = elem->channel_data;
grpc_channel_element *child_elem;
grpc_channel_stack **children;
size_t child_count;
size_t i;
/* copy the current set of children, and mark them all as having an inflight
request */
gpr_mu_lock(&chand->mu);
child_count = chand->child_count;
children = gpr_malloc(sizeof(grpc_channel_stack *) * child_count);
for (i = 0; i < child_count; i++) {
children[i] = chand->children[i].channel_stack;
chand->children[i].inflight_requests++;
}
gpr_mu_unlock(&chand->mu);
/* send the message down */
for (i = 0; i < child_count; i++) {
child_elem = grpc_channel_stack_element(children[i], 0);
if (op->type == GRPC_CHANNEL_GOAWAY) {
gpr_slice_ref(op->data.goaway.message);
}
child_elem->filter->channel_op(child_elem, op);
}
if (op->type == GRPC_CHANNEL_GOAWAY) {
gpr_slice_unref(op->data.goaway.message);
}
/* unmark the inflight requests */
gpr_mu_lock(&chand->mu);
for (i = 0; i < child_count; i++) {
chand->children[i].inflight_requests--;
}
gpr_mu_unlock(&chand->mu);
gpr_free(children);
}
static void channel_op(grpc_channel_element *elem, grpc_channel_op *op) {
GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
switch (op->type) {
default:
switch (op->dir) {
case GRPC_CALL_UP:
grpc_channel_next_op(elem, op);
break;
case GRPC_CALL_DOWN:
broadcast_channel_op_down(elem, op);
break;
}
break;
}
}
static void error_bad_on_complete(void *arg, grpc_op_error error) {
gpr_log(GPR_ERROR,
"Waiting finished but not started? Bad on_complete callback");
abort();
}
/* Constructor for call_data */
static void init_call_elem(grpc_call_element *elem,
const void *server_transport_data) {
call_data *calld = elem->call_data;
GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
GPR_ASSERT(server_transport_data == NULL);
calld->elem = elem;
calld->state = CALL_CREATED;
calld->deadline = gpr_inf_future;
calld->s.waiting.on_complete = error_bad_on_complete;
calld->s.waiting.on_complete_user_data = NULL;
grpc_metadata_buffer_init(&calld->pending_metadata);
}
/* Destructor for call_data */
static void destroy_call_elem(grpc_call_element *elem) {
call_data *calld = elem->call_data;
channel_data *chand = elem->channel_data;
size_t i;
/* if the metadata buffer is not flushed, destroy it here. */
grpc_metadata_buffer_destroy(&calld->pending_metadata, GRPC_OP_OK);
/* if the call got activated, we need to destroy the child stack also, and
remove it from the in-flight requests tracked by the child_entry we
picked */
if (calld->state == CALL_ACTIVE) {
grpc_call_stack_destroy(calld->s.active.child_stack);
gpr_free(calld->s.active.child_stack);
gpr_mu_lock(&chand->mu);
for (i = 0; i < chand->child_count; i++) {
if (chand->children[i].channel_stack == calld->s.active.using_stack) {
chand->children[i].inflight_requests--;
/* TODO(ctiller): garbage collect channels that are not active
and have no inflight requests */
}
}
gpr_mu_unlock(&chand->mu);
}
}
/* Constructor for channel_data */
static void init_channel_elem(grpc_channel_element *elem,
const grpc_channel_args *args,
grpc_mdctx *metadata_context, int is_first,
int is_last) {
channel_data *chand = elem->channel_data;
char temp[16];
GPR_ASSERT(!is_first);
GPR_ASSERT(is_last);
GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
gpr_mu_init(&chand->mu);
chand->active_child = NULL;
chand->children = NULL;
chand->child_count = 0;
chand->child_capacity = 0;
chand->waiting_children = NULL;
chand->waiting_child_count = 0;
chand->waiting_child_capacity = 0;
chand->transport_setup = NULL;
chand->transport_setup_initiated = 0;
chand->args = grpc_channel_args_copy(args);
sprintf(temp, "%d", GRPC_STATUS_CANCELLED);
chand->cancel_status =
grpc_mdelem_from_strings(metadata_context, "grpc-status", temp);
}
/* Destructor for channel_data */
static void destroy_channel_elem(grpc_channel_element *elem) {
channel_data *chand = elem->channel_data;
size_t i;
grpc_transport_setup_cancel(chand->transport_setup);
for (i = 0; i < chand->child_count; i++) {
GPR_ASSERT(chand->children[i].inflight_requests == 0);
grpc_channel_stack_destroy(chand->children[i].channel_stack);
gpr_free(chand->children[i].channel_stack);
}
grpc_channel_args_destroy(chand->args);
grpc_mdelem_unref(chand->cancel_status);
gpr_mu_destroy(&chand->mu);
GPR_ASSERT(chand->waiting_child_count == 0);
gpr_free(chand->waiting_children);
gpr_free(chand->children);
}
const grpc_channel_filter grpc_client_channel_filter = {
call_op, channel_op,
sizeof(call_data), init_call_elem, destroy_call_elem,
sizeof(channel_data), init_channel_elem, destroy_channel_elem,
"clientchannel",
};
grpc_transport_setup_result grpc_client_channel_transport_setup_complete(
grpc_channel_stack *channel_stack, grpc_transport *transport,
grpc_channel_filter const **channel_filters, size_t num_channel_filters,
grpc_mdctx *mdctx) {
/* we just got a new transport: lets create a child channel stack for it */
grpc_channel_element *elem = grpc_channel_stack_last_element(channel_stack);
channel_data *chand = elem->channel_data;
grpc_channel_element *lb_elem;
grpc_channel_stack *child_stack;
size_t num_child_filters = 2 + num_channel_filters;
grpc_channel_filter const **child_filters;
grpc_transport_setup_result result;
child_entry *child_ent;
call_data **waiting_children;
size_t waiting_child_count;
size_t i;
grpc_call_op *call_ops;
/* build the child filter stack */
child_filters = gpr_malloc(sizeof(grpc_channel_filter *) * num_child_filters);
/* we always need a link back filter to get back to the connected channel */
child_filters[0] = &link_back_filter;
for (i = 0; i < num_channel_filters; i++) {
child_filters[i + 1] = channel_filters[i];
}
/* and we always need a connected channel to talk to the transport */
child_filters[num_child_filters - 1] = &grpc_connected_channel_filter;
GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
/* BEGIN LOCKING CHANNEL */
gpr_mu_lock(&chand->mu);
chand->transport_setup_initiated = 0;
if (chand->child_count == chand->child_capacity) {
/* realloc will invalidate chand->active_child, but it's reset in the next
stanza anyway */
chand->child_capacity =
GPR_MAX(2 * chand->child_capacity, chand->child_capacity + 2);
chand->children = gpr_realloc(chand->children,
sizeof(child_entry) * chand->child_capacity);
}
/* build up the child stack */
child_stack =
gpr_malloc(grpc_channel_stack_size(child_filters, num_child_filters));
grpc_channel_stack_init(child_filters, num_child_filters, chand->args, mdctx,
child_stack);
lb_elem = grpc_channel_stack_element(child_stack, 0);
GPR_ASSERT(lb_elem->filter == &link_back_filter);
((lb_channel_data *)lb_elem->channel_data)->back = elem;
result = grpc_connected_channel_bind_transport(child_stack, transport);
child_ent = &chand->children[chand->child_count++];
child_ent->channel_stack = child_stack;
child_ent->inflight_requests = 0;
chand->active_child = child_ent;
/* capture the waiting children - we'll activate them outside the lock
to avoid re-entrancy problems */
waiting_children = chand->waiting_children;
waiting_child_count = chand->waiting_child_count;
/* bumping up inflight_requests here avoids taking a lock per rpc below */
chand->waiting_children = NULL;
chand->waiting_child_count = 0;
chand->waiting_child_capacity = 0;
call_ops = gpr_malloc(sizeof(grpc_call_op) * waiting_child_count);
for (i = 0; i < waiting_child_count; i++) {
call_ops[i].type = GRPC_SEND_START;
call_ops[i].dir = GRPC_CALL_DOWN;
call_ops[i].flags = waiting_children[i]->s.waiting.start_flags;
call_ops[i].done_cb = waiting_children[i]->s.waiting.on_complete;
call_ops[i].user_data =
waiting_children[i]->s.waiting.on_complete_user_data;
if (!prepare_activate(waiting_children[i], child_ent)) {
waiting_children[i] = NULL;
call_ops[i].done_cb(call_ops[i].user_data, GRPC_OP_ERROR);
}
}
/* END LOCKING CHANNEL */
gpr_mu_unlock(&chand->mu);
/* activate any pending operations - this is safe to do as we guarantee one
and only one write operation per request at the surface api - if we lose
that guarantee we need to do some curly locking here */
for (i = 0; i < waiting_child_count; i++) {
if (waiting_children[i]) {
complete_activate(waiting_children[i], child_ent, &call_ops[i]);
}
}
gpr_free(waiting_children);
gpr_free(call_ops);
gpr_free(child_filters);
return result;
}
void grpc_client_channel_set_transport_setup(grpc_channel_stack *channel_stack,
grpc_transport_setup *setup) {
/* post construction initialization: set the transport setup pointer */
grpc_channel_element *elem = grpc_channel_stack_last_element(channel_stack);
channel_data *chand = elem->channel_data;
GPR_ASSERT(!chand->transport_setup);
chand->transport_setup = setup;
}
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