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More cleanup in client_channel code.

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pull/12297/head
Mark D. Roth 7 years ago
parent ca7084bced
commit b29296042a
1 changed files with 153 additions and 161 deletions
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  1. 314
      src/core/ext/filters/client_channel/client_channel.c

314
src/core/ext/filters/client_channel/client_channel.c
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@ -1016,13 +1016,11 @@ static void create_subchannel_call_locked(grpc_exec_ctx *exec_ctx,
GRPC_ERROR_UNREF(error); GRPC_ERROR_UNREF(error);
} }
static void subchannel_ready_locked(grpc_exec_ctx *exec_ctx, // Invoked when a pick is completed, on both success or failure.
grpc_call_element *elem, static void pick_done_locked(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
grpc_error *error) { grpc_error *error) {
call_data *calld = (call_data *)elem->call_data; call_data *calld = (call_data *)elem->call_data;
channel_data *chand = (channel_data *)elem->channel_data; channel_data *chand = (channel_data *)elem->channel_data;
grpc_polling_entity_del_from_pollset_set(exec_ctx, calld->pollent,
chand->interested_parties);
if (calld->connected_subchannel == NULL) { if (calld->connected_subchannel == NULL) {
// Failed to create subchannel. // Failed to create subchannel.
GRPC_ERROR_UNREF(calld->error); GRPC_ERROR_UNREF(calld->error);
@ -1044,12 +1042,116 @@ static void subchannel_ready_locked(grpc_exec_ctx *exec_ctx,
GRPC_ERROR_UNREF(error); GRPC_ERROR_UNREF(error);
} }
/** Return true if subchannel is available immediately (in which case // A wrapper around pick_done_locked() that is used in cases where
subchannel_ready_locked() should not be called), or false otherwise (in // either (a) the pick was deferred pending a resolver result or (b) the
which case subchannel_ready_locked() should be called when the subchannel // pick was done asynchronously. Removes the call's polling entity from
is available). */ // chand->interested_parties before invoking pick_done_locked().
static bool pick_subchannel_locked(grpc_exec_ctx *exec_ctx, static void async_pick_done_locked(grpc_exec_ctx *exec_ctx,
grpc_call_element *elem); grpc_call_element *elem, grpc_error *error) {
channel_data *chand = (channel_data *)elem->channel_data;
call_data *calld = (call_data *)elem->call_data;
grpc_polling_entity_del_from_pollset_set(exec_ctx, calld->pollent,
chand->interested_parties);
pick_done_locked(exec_ctx, elem, error);
}
// Note: This runs under the client_channel combiner, but will NOT be
// holding the call combiner.
static void pick_callback_cancel_locked(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
grpc_call_element *elem = (grpc_call_element *)arg;
channel_data *chand = (channel_data *)elem->channel_data;
call_data *calld = (call_data *)elem->call_data;
if (calld->lb_policy != NULL) {
if (GRPC_TRACER_ON(grpc_client_channel_trace)) {
gpr_log(GPR_DEBUG, "chand=%p calld=%p: cancelling pick from LB policy %p",
chand, calld, calld->lb_policy);
}
grpc_lb_policy_cancel_pick_locked(exec_ctx, calld->lb_policy,
&calld->connected_subchannel,
GRPC_ERROR_REF(error));
}
GRPC_CALL_STACK_UNREF(exec_ctx, calld->owning_call, "pick_callback_cancel");
}
// Callback invoked by grpc_lb_policy_pick_locked() for async picks.
// Unrefs the LB policy and invokes async_pick_done_locked().
static void pick_callback_done_locked(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
grpc_call_element *elem = (grpc_call_element *)arg;
channel_data *chand = (channel_data *)elem->channel_data;
call_data *calld = (call_data *)elem->call_data;
if (GRPC_TRACER_ON(grpc_client_channel_trace)) {
gpr_log(GPR_DEBUG, "chand=%p calld=%p: pick completed asynchronously",
chand, calld);
}
GPR_ASSERT(calld->lb_policy != NULL);
GRPC_LB_POLICY_UNREF(exec_ctx, calld->lb_policy, "pick_subchannel");
calld->lb_policy = NULL;
async_pick_done_locked(exec_ctx, elem, GRPC_ERROR_REF(error));
}
// Takes a ref to chand->lb_policy and calls grpc_lb_policy_pick_locked().
// If the pick was completed synchronously, unrefs the LB policy and
// returns true.
static bool pick_callback_start_locked(grpc_exec_ctx *exec_ctx,
grpc_call_element *elem) {
channel_data *chand = (channel_data *)elem->channel_data;
call_data *calld = (call_data *)elem->call_data;
if (GRPC_TRACER_ON(grpc_client_channel_trace)) {
gpr_log(GPR_DEBUG, "chand=%p calld=%p: starting pick on lb_policy=%p",
chand, calld, chand->lb_policy);
}
apply_service_config_to_call_locked(exec_ctx, elem);
// If the application explicitly set wait_for_ready, use that.
// Otherwise, if the service config specified a value for this
// method, use that.
uint32_t initial_metadata_flags =
calld->initial_metadata_batch->payload->send_initial_metadata
.send_initial_metadata_flags;
const bool wait_for_ready_set_from_api =
initial_metadata_flags &
GRPC_INITIAL_METADATA_WAIT_FOR_READY_EXPLICITLY_SET;
const bool wait_for_ready_set_from_service_config =
calld->method_params != NULL &&
calld->method_params->wait_for_ready != WAIT_FOR_READY_UNSET;
if (!wait_for_ready_set_from_api && wait_for_ready_set_from_service_config) {
if (calld->method_params->wait_for_ready == WAIT_FOR_READY_TRUE) {
initial_metadata_flags |= GRPC_INITIAL_METADATA_WAIT_FOR_READY;
} else {
initial_metadata_flags &= ~GRPC_INITIAL_METADATA_WAIT_FOR_READY;
}
}
const grpc_lb_policy_pick_args inputs = {
calld->initial_metadata_batch->payload->send_initial_metadata
.send_initial_metadata,
initial_metadata_flags, &calld->lb_token_mdelem};
// Keep a ref to the LB policy in calld while the pick is pending.
GRPC_LB_POLICY_REF(chand->lb_policy, "pick_subchannel");
calld->lb_policy = chand->lb_policy;
GRPC_CLOSURE_INIT(&calld->lb_pick_closure, pick_callback_done_locked, elem,
grpc_combiner_scheduler(chand->combiner));
const bool pick_done = grpc_lb_policy_pick_locked(
exec_ctx, chand->lb_policy, &inputs, &calld->connected_subchannel,
calld->subchannel_call_context, NULL, &calld->lb_pick_closure);
if (pick_done) {
/* synchronous grpc_lb_policy_pick call. Unref the LB policy. */
if (GRPC_TRACER_ON(grpc_client_channel_trace)) {
gpr_log(GPR_DEBUG, "chand=%p calld=%p: pick completed synchronously",
chand, calld);
}
GRPC_LB_POLICY_UNREF(exec_ctx, calld->lb_policy, "pick_subchannel");
calld->lb_policy = NULL;
} else {
GRPC_CALL_STACK_REF(calld->owning_call, "pick_callback_cancel");
grpc_call_combiner_set_notify_on_cancel(
exec_ctx, calld->call_combiner,
GRPC_CLOSURE_INIT(&calld->lb_pick_cancel_closure,
pick_callback_cancel_locked, elem,
grpc_combiner_scheduler(chand->combiner)));
}
return pick_done;
}
typedef struct { typedef struct {
grpc_call_element *elem; grpc_call_element *elem;
@ -1069,17 +1171,17 @@ static void pick_after_resolver_result_cancel_locked(grpc_exec_ctx *exec_ctx,
gpr_free(args); gpr_free(args);
return; return;
} }
args->finished = true;
grpc_call_element *elem = args->elem;
channel_data *chand = (channel_data *)elem->channel_data;
call_data *calld = (call_data *)elem->call_data;
// If we don't yet have a resolver result, then a closure for // If we don't yet have a resolver result, then a closure for
// pick_after_resolver_result_done_locked() will have been added to // pick_after_resolver_result_done_locked() will have been added to
// chand->waiting_for_resolver_result_closures, and it may not be invoked // chand->waiting_for_resolver_result_closures, and it may not be invoked
// until after this call has been destroyed. We mark the operation as // until after this call has been destroyed. We mark the operation as
// finished, so that when pick_after_resolver_result_done_locked() // finished, so that when pick_after_resolver_result_done_locked()
// is called, it will be a no-op. We also immediately invoke // is called, it will be a no-op. We also immediately invoke
// subchannel_ready_locked() to propagate the error back to the caller. // async_pick_done_locked() to propagate the error back to the caller.
args->finished = true;
grpc_call_element *elem = args->elem;
channel_data *chand = (channel_data *)elem->channel_data;
call_data *calld = (call_data *)elem->call_data;
if (GRPC_TRACER_ON(grpc_client_channel_trace)) { if (GRPC_TRACER_ON(grpc_client_channel_trace)) {
gpr_log(GPR_DEBUG, gpr_log(GPR_DEBUG,
"chand=%p calld=%p: cancelling pick waiting for resolver result", "chand=%p calld=%p: cancelling pick waiting for resolver result",
@ -1087,12 +1189,12 @@ static void pick_after_resolver_result_cancel_locked(grpc_exec_ctx *exec_ctx,
} }
// Note: Although we are not in the call combiner here, we are // Note: Although we are not in the call combiner here, we are
// basically stealing the call combiner from the pending pick, so // basically stealing the call combiner from the pending pick, so
// it's safe to call subchannel_ready_locked() here -- we are // it's safe to call async_pick_done_locked() here -- we are
// essentially calling it here instead of calling it in // essentially calling it here instead of calling it in
// pick_after_resolver_result_done_locked(). // pick_after_resolver_result_done_locked().
subchannel_ready_locked(exec_ctx, elem, async_pick_done_locked(exec_ctx, elem,
GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING( GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
"Pick cancelled", &error, 1)); "Pick cancelled", &error, 1));
} }
static void pick_after_resolver_result_done_locked(grpc_exec_ctx *exec_ctx, static void pick_after_resolver_result_done_locked(grpc_exec_ctx *exec_ctx,
@ -1117,14 +1219,19 @@ static void pick_after_resolver_result_done_locked(grpc_exec_ctx *exec_ctx,
gpr_log(GPR_DEBUG, "chand=%p calld=%p: resolver failed to return data", gpr_log(GPR_DEBUG, "chand=%p calld=%p: resolver failed to return data",
chand, calld); chand, calld);
} }
subchannel_ready_locked(exec_ctx, elem, GRPC_ERROR_REF(error)); async_pick_done_locked(exec_ctx, elem, GRPC_ERROR_REF(error));
} else { } else {
if (GRPC_TRACER_ON(grpc_client_channel_trace)) { if (GRPC_TRACER_ON(grpc_client_channel_trace)) {
gpr_log(GPR_DEBUG, "chand=%p calld=%p: resolver returned, doing pick", gpr_log(GPR_DEBUG, "chand=%p calld=%p: resolver returned, doing pick",
chand, calld); chand, calld);
} }
if (pick_subchannel_locked(exec_ctx, elem)) { if (pick_callback_start_locked(exec_ctx, elem)) {
subchannel_ready_locked(exec_ctx, elem, GRPC_ERROR_NONE); // Even if the LB policy returns a result synchronously, we have
// already added our polling entity to chand->interested_parties
// in order to wait for the resolver result, so we need to
// remove it here. Therefore, we call async_pick_done_locked()
// instead of pick_done_locked().
async_pick_done_locked(exec_ctx, elem, GRPC_ERROR_NONE);
} }
} }
} }
@ -1152,154 +1259,38 @@ static void pick_after_resolver_result_start_locked(grpc_exec_ctx *exec_ctx,
grpc_combiner_scheduler(chand->combiner))); grpc_combiner_scheduler(chand->combiner)));
} }
// Note: This runs under the client_channel combiner, but will NOT be static void start_pick_locked(grpc_exec_ctx *exec_ctx, void *arg,
// holding the call combiner. grpc_error *ignored) {
static void pick_callback_cancel_locked(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
grpc_call_element *elem = (grpc_call_element *)arg;
channel_data *chand = (channel_data *)elem->channel_data;
call_data *calld = (call_data *)elem->call_data;
if (error != GRPC_ERROR_NONE && calld->lb_policy != NULL) {
if (GRPC_TRACER_ON(grpc_client_channel_trace)) {
gpr_log(GPR_DEBUG, "chand=%p calld=%p: cancelling pick from LB policy %p",
chand, calld, calld->lb_policy);
}
grpc_lb_policy_cancel_pick_locked(exec_ctx, calld->lb_policy,
&calld->connected_subchannel,
GRPC_ERROR_REF(error));
}
GRPC_CALL_STACK_UNREF(exec_ctx, calld->owning_call, "pick_callback_cancel");
}
// Callback invoked by grpc_lb_policy_pick_locked() for async picks.
// Unrefs the LB policy and invokes subchannel_ready_locked().
static void pick_callback_done_locked(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
grpc_call_element *elem = (grpc_call_element *)arg; grpc_call_element *elem = (grpc_call_element *)arg;
channel_data *chand = (channel_data *)elem->channel_data;
call_data *calld = (call_data *)elem->call_data; call_data *calld = (call_data *)elem->call_data;
if (GRPC_TRACER_ON(grpc_client_channel_trace)) {
gpr_log(GPR_DEBUG, "chand=%p calld=%p: pick completed asynchronously",
chand, calld);
}
GPR_ASSERT(calld->lb_policy != NULL);
GRPC_LB_POLICY_UNREF(exec_ctx, calld->lb_policy, "pick_subchannel");
calld->lb_policy = NULL;
subchannel_ready_locked(exec_ctx, elem, GRPC_ERROR_REF(error));
}
// Takes a ref to chand->lb_policy and calls grpc_lb_policy_pick_locked().
// If the pick was completed synchronously, unrefs the LB policy and
// returns true.
static bool pick_callback_start_locked(grpc_exec_ctx *exec_ctx,
grpc_call_element *elem,
const grpc_lb_policy_pick_args *inputs) {
channel_data *chand = (channel_data *)elem->channel_data; channel_data *chand = (channel_data *)elem->channel_data;
call_data *calld = (call_data *)elem->call_data; GPR_ASSERT(calld->connected_subchannel == NULL);
if (GRPC_TRACER_ON(grpc_client_channel_trace)) { if (chand->lb_policy != NULL) {
gpr_log(GPR_DEBUG, "chand=%p calld=%p: starting pick on lb_policy=%p", // We already have an LB policy, so ask it for a pick.
chand, calld, chand->lb_policy); if (pick_callback_start_locked(exec_ctx, elem)) {
} // Pick completed synchronously.
// Keep a ref to the LB policy in calld while the pick is pending. pick_done_locked(exec_ctx, elem, GRPC_ERROR_NONE);
GRPC_LB_POLICY_REF(chand->lb_policy, "pick_subchannel"); return;
calld->lb_policy = chand->lb_policy;
GRPC_CLOSURE_INIT(&calld->lb_pick_closure, pick_callback_done_locked, elem,
grpc_combiner_scheduler(chand->combiner));
const bool pick_done = grpc_lb_policy_pick_locked(
exec_ctx, chand->lb_policy, inputs, &calld->connected_subchannel,
calld->subchannel_call_context, NULL, &calld->lb_pick_closure);
if (pick_done) {
/* synchronous grpc_lb_policy_pick call. Unref the LB policy. */
if (GRPC_TRACER_ON(grpc_client_channel_trace)) {
gpr_log(GPR_DEBUG, "chand=%p calld=%p: pick completed synchronously",
chand, calld);
} }
GRPC_LB_POLICY_UNREF(exec_ctx, calld->lb_policy, "pick_subchannel");
calld->lb_policy = NULL;
} else { } else {
GRPC_CALL_STACK_REF(calld->owning_call, "pick_callback_cancel"); // We do not yet have an LB policy, so wait for a resolver result.
grpc_call_combiner_set_notify_on_cancel( if (chand->resolver == NULL) {
exec_ctx, calld->call_combiner, pick_done_locked(exec_ctx, elem,
GRPC_CLOSURE_INIT(&calld->lb_pick_cancel_closure, GRPC_ERROR_CREATE_FROM_STATIC_STRING("Disconnected"));
pick_callback_cancel_locked, elem, return;
grpc_combiner_scheduler(chand->combiner)));
}
return pick_done;
}
static bool pick_subchannel_locked(grpc_exec_ctx *exec_ctx,
grpc_call_element *elem) {
GPR_TIMER_BEGIN("pick_subchannel", 0);
channel_data *chand = (channel_data *)elem->channel_data;
call_data *calld = (call_data *)elem->call_data;
bool pick_done = false;
if (chand->lb_policy != NULL) {
apply_service_config_to_call_locked(exec_ctx, elem);
// If the application explicitly set wait_for_ready, use that.
// Otherwise, if the service config specified a value for this
// method, use that.
uint32_t initial_metadata_flags =
calld->initial_metadata_batch->payload->send_initial_metadata
.send_initial_metadata_flags;
const bool wait_for_ready_set_from_api =
initial_metadata_flags &
GRPC_INITIAL_METADATA_WAIT_FOR_READY_EXPLICITLY_SET;
const bool wait_for_ready_set_from_service_config =
calld->method_params != NULL &&
calld->method_params->wait_for_ready != WAIT_FOR_READY_UNSET;
if (!wait_for_ready_set_from_api &&
wait_for_ready_set_from_service_config) {
if (calld->method_params->wait_for_ready == WAIT_FOR_READY_TRUE) {
initial_metadata_flags |= GRPC_INITIAL_METADATA_WAIT_FOR_READY;
} else {
initial_metadata_flags &= ~GRPC_INITIAL_METADATA_WAIT_FOR_READY;
}
} }
const grpc_lb_policy_pick_args inputs = {
calld->initial_metadata_batch->payload->send_initial_metadata
.send_initial_metadata,
initial_metadata_flags, &calld->lb_token_mdelem};
pick_done = pick_callback_start_locked(exec_ctx, elem, &inputs);
} else if (chand->resolver != NULL) {
if (!chand->started_resolving) { if (!chand->started_resolving) {
start_resolving_locked(exec_ctx, chand); start_resolving_locked(exec_ctx, chand);
} }
pick_after_resolver_result_start_locked(exec_ctx, elem); pick_after_resolver_result_start_locked(exec_ctx, elem);
} else {
subchannel_ready_locked(
exec_ctx, elem, GRPC_ERROR_CREATE_FROM_STATIC_STRING("Disconnected"));
}
GPR_TIMER_END("pick_subchannel", 0);
return pick_done;
}
static void start_pick_locked(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error_ignored) {
GPR_TIMER_BEGIN("start_pick_locked", 0);
grpc_call_element *elem = (grpc_call_element *)arg;
call_data *calld = (call_data *)elem->call_data;
channel_data *chand = (channel_data *)elem->channel_data;
GPR_ASSERT(calld->connected_subchannel == NULL);
if (pick_subchannel_locked(exec_ctx, elem)) {
// Pick was returned synchronously.
if (calld->connected_subchannel == NULL) {
GRPC_ERROR_UNREF(calld->error);
calld->error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
"Call dropped by load balancing policy");
waiting_for_pick_batches_fail(exec_ctx, elem,
GRPC_ERROR_REF(calld->error));
} else {
// Create subchannel call.
create_subchannel_call_locked(exec_ctx, elem, GRPC_ERROR_NONE);
}
} else {
// Pick will be done asynchronously. Add the call's polling entity to
// the channel's interested_parties, so that I/O for the resolver
// and LB policy can be done under it.
grpc_polling_entity_add_to_pollset_set(exec_ctx, calld->pollent,
chand->interested_parties);
} }
GPR_TIMER_END("start_pick_locked", 0); // We need to wait for either a resolver result or for an async result
// from the LB policy. Add the polling entity from call_data to the
// channel_data's interested_parties, so that the I/O of the LB policy
// and resolver can be done under it. The polling entity will be
// removed in async_pick_done_locked().
grpc_polling_entity_add_to_pollset_set(exec_ctx, calld->pollent,
chand->interested_parties);
} }
static void on_complete(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) { static void on_complete(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
@ -1394,7 +1385,8 @@ static void cc_start_transport_stream_op_batch(
// combiner to start a pick. // combiner to start a pick.
if (batch->send_initial_metadata) { if (batch->send_initial_metadata) {
if (GRPC_TRACER_ON(grpc_client_channel_trace)) { if (GRPC_TRACER_ON(grpc_client_channel_trace)) {
gpr_log(GPR_DEBUG, "chand=%p calld=%p: entering combiner", chand, calld); gpr_log(GPR_DEBUG, "chand=%p calld=%p: entering client_channel combiner",
chand, calld);
} }
GRPC_CLOSURE_SCHED( GRPC_CLOSURE_SCHED(
exec_ctx, exec_ctx,

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