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bazel / bazel / c55ec0f2cb3f5b44e5025bf9d3c5dc91d94db287 / . / third_party / grpc / src / core / ext / filters / client_channel / lb_policy / grpclb / grpclb.cc
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/*
*
* Copyright 2016 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
/// Implementation of the gRPC LB policy.
///
/// This policy takes as input a list of resolved addresses, which must
/// include at least one balancer address.
///
/// An internal channel (\a lb_channel_) is created for the addresses
/// from that are balancers. This channel behaves just like a regular
/// channel that uses pick_first to select from the list of balancer
/// addresses.
///
/// The first time the policy gets a request for a pick, a ping, or to exit
/// the idle state, \a StartPickingLocked() is called. This method is
/// responsible for instantiating the internal *streaming* call to the LB
/// server (whichever address pick_first chose). The call will be complete
/// when either the balancer sends status or when we cancel the call (e.g.,
/// because we are shutting down). In needed, we retry the call. If we
/// received at least one valid message from the server, a new call attempt
/// will be made immediately; otherwise, we apply back-off delays between
/// attempts.
///
/// We maintain an internal round_robin policy instance for distributing
/// requests across backends. Whenever we receive a new serverlist from
/// the balancer, we update the round_robin policy with the new list of
/// addresses. If we cannot communicate with the balancer on startup,
/// however, we may enter fallback mode, in which case we will populate
/// the RR policy's addresses from the backend addresses returned by the
/// resolver.
///
/// Once an RR policy instance is in place (and getting updated as described),
/// calls for a pick, a ping, or a cancellation will be serviced right
/// away by forwarding them to the RR instance. Any time there's no RR
/// policy available (i.e., right after the creation of the gRPCLB policy),
/// pick and ping requests are added to a list of pending picks and pings
/// to be flushed and serviced when the RR policy instance becomes available.
///
/// \see https://github.com/grpc/grpc/blob/master/doc/load-balancing.md for the
/// high level design and details.
// With the addition of a libuv endpoint, sockaddr.h now includes uv.h when
// using that endpoint. Because of various transitive includes in uv.h,
// including windows.h on Windows, uv.h must be included before other system
// headers. Therefore, sockaddr.h must always be included first.
#include <grpc/support/port_platform.h>
#include "src/core/lib/iomgr/sockaddr.h"
#include "src/core/lib/iomgr/socket_utils.h"
#include <inttypes.h>
#include <limits.h>
#include <string.h>
#include <grpc/byte_buffer_reader.h>
#include <grpc/grpc.h>
#include <grpc/support/alloc.h>
#include <grpc/support/string_util.h>
#include <grpc/support/time.h>
#include "src/core/ext/filters/client_channel/client_channel.h"
#include "src/core/ext/filters/client_channel/client_channel_factory.h"
#include "src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.h"
#include "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h"
#include "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h"
#include "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_client_stats.h"
#include "src/core/ext/filters/client_channel/lb_policy/grpclb/load_balancer_api.h"
#include "src/core/ext/filters/client_channel/lb_policy_factory.h"
#include "src/core/ext/filters/client_channel/lb_policy_registry.h"
#include "src/core/ext/filters/client_channel/parse_address.h"
#include "src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h"
#include "src/core/ext/filters/client_channel/server_address.h"
#include "src/core/ext/filters/client_channel/subchannel_index.h"
#include "src/core/lib/backoff/backoff.h"
#include "src/core/lib/channel/channel_args.h"
#include "src/core/lib/channel/channel_stack.h"
#include "src/core/lib/gpr/host_port.h"
#include "src/core/lib/gpr/string.h"
#include "src/core/lib/gprpp/manual_constructor.h"
#include "src/core/lib/gprpp/memory.h"
#include "src/core/lib/gprpp/mutex_lock.h"
#include "src/core/lib/gprpp/orphanable.h"
#include "src/core/lib/gprpp/ref_counted_ptr.h"
#include "src/core/lib/iomgr/combiner.h"
#include "src/core/lib/iomgr/sockaddr.h"
#include "src/core/lib/iomgr/sockaddr_utils.h"
#include "src/core/lib/iomgr/timer.h"
#include "src/core/lib/slice/slice_hash_table.h"
#include "src/core/lib/slice/slice_internal.h"
#include "src/core/lib/slice/slice_string_helpers.h"
#include "src/core/lib/surface/call.h"
#include "src/core/lib/surface/channel.h"
#include "src/core/lib/surface/channel_init.h"
#include "src/core/lib/transport/static_metadata.h"
#define GRPC_GRPCLB_INITIAL_CONNECT_BACKOFF_SECONDS 1
#define GRPC_GRPCLB_RECONNECT_BACKOFF_MULTIPLIER 1.6
#define GRPC_GRPCLB_RECONNECT_MAX_BACKOFF_SECONDS 120
#define GRPC_GRPCLB_RECONNECT_JITTER 0.2
#define GRPC_GRPCLB_DEFAULT_FALLBACK_TIMEOUT_MS 10000
#define GRPC_ARG_GRPCLB_ADDRESS_LB_TOKEN "grpc.grpclb_address_lb_token"
namespace grpc_core {
TraceFlag grpc_lb_glb_trace(false, "glb");
namespace {
constexpr char kGrpclb[] = "grpclb";
class GrpcLb : public LoadBalancingPolicy {
public:
explicit GrpcLb(const Args& args);
const char* name() const override { return kGrpclb; }
void UpdateLocked(const grpc_channel_args& args,
grpc_json* lb_config) override;
bool PickLocked(PickState* pick, grpc_error** error) override;
void CancelPickLocked(PickState* pick, grpc_error* error) override;
void CancelMatchingPicksLocked(uint32_t initial_metadata_flags_mask,
uint32_t initial_metadata_flags_eq,
grpc_error* error) override;
void NotifyOnStateChangeLocked(grpc_connectivity_state* state,
grpc_closure* closure) override;
grpc_connectivity_state CheckConnectivityLocked(
grpc_error** connectivity_error) override;
void HandOffPendingPicksLocked(LoadBalancingPolicy* new_policy) override;
void ExitIdleLocked() override;
void ResetBackoffLocked() override;
void FillChildRefsForChannelz(
channelz::ChildRefsList* child_subchannels,
channelz::ChildRefsList* child_channels) override;
private:
/// Linked list of pending pick requests. It stores all information needed to
/// eventually call (Round Robin's) pick() on them. They mainly stay pending
/// waiting for the RR policy to be created.
///
/// Note that when a pick is sent to the RR policy, we inject our own
/// on_complete callback, so that we can intercept the result before
/// invoking the original on_complete callback. This allows us to set the
/// LB token metadata and add client_stats to the call context.
/// See \a pending_pick_complete() for details.
struct PendingPick {
// The grpclb instance that created the wrapping. This instance is not
// owned; reference counts are untouched. It's used only for logging
// purposes.
GrpcLb* grpclb_policy;
// The original pick.
PickState* pick;
// Our on_complete closure and the original one.
grpc_closure on_complete;
grpc_closure* original_on_complete;
// Stats for client-side load reporting.
RefCountedPtr<GrpcLbClientStats> client_stats;
// Next pending pick.
PendingPick* next = nullptr;
};
/// Contains a call to the LB server and all the data related to the call.
class BalancerCallState : public InternallyRefCounted<BalancerCallState> {
public:
explicit BalancerCallState(
RefCountedPtr<LoadBalancingPolicy> parent_grpclb_policy);
// It's the caller's responsibility to ensure that Orphan() is called from
// inside the combiner.
void Orphan() override;
void StartQuery();
GrpcLbClientStats* client_stats() const { return client_stats_.get(); }
bool seen_initial_response() const { return seen_initial_response_; }
private:
// So Delete() can access our private dtor.
template <typename T>
friend void grpc_core::Delete(T*);
~BalancerCallState();
GrpcLb* grpclb_policy() const {
return static_cast<GrpcLb*>(grpclb_policy_.get());
}
void ScheduleNextClientLoadReportLocked();
void SendClientLoadReportLocked();
static bool LoadReportCountersAreZero(grpc_grpclb_request* request);
static void MaybeSendClientLoadReportLocked(void* arg, grpc_error* error);
static void ClientLoadReportDoneLocked(void* arg, grpc_error* error);
static void OnInitialRequestSentLocked(void* arg, grpc_error* error);
static void OnBalancerMessageReceivedLocked(void* arg, grpc_error* error);
static void OnBalancerStatusReceivedLocked(void* arg, grpc_error* error);
// The owning LB policy.
RefCountedPtr<LoadBalancingPolicy> grpclb_policy_;
// The streaming call to the LB server. Always non-NULL.
grpc_call* lb_call_ = nullptr;
// recv_initial_metadata
grpc_metadata_array lb_initial_metadata_recv_;
// send_message
grpc_byte_buffer* send_message_payload_ = nullptr;
grpc_closure lb_on_initial_request_sent_;
// recv_message
grpc_byte_buffer* recv_message_payload_ = nullptr;
grpc_closure lb_on_balancer_message_received_;
bool seen_initial_response_ = false;
// recv_trailing_metadata
grpc_closure lb_on_balancer_status_received_;
grpc_metadata_array lb_trailing_metadata_recv_;
grpc_status_code lb_call_status_;
grpc_slice lb_call_status_details_;
// The stats for client-side load reporting associated with this LB call.
// Created after the first serverlist is received.
RefCountedPtr<GrpcLbClientStats> client_stats_;
grpc_millis client_stats_report_interval_ = 0;
grpc_timer client_load_report_timer_;
bool client_load_report_timer_callback_pending_ = false;
bool last_client_load_report_counters_were_zero_ = false;
bool client_load_report_is_due_ = false;
// The closure used for either the load report timer or the callback for
// completion of sending the load report.
grpc_closure client_load_report_closure_;
};
~GrpcLb();
void ShutdownLocked() override;
// Helper function used in ctor and UpdateLocked().
void ProcessChannelArgsLocked(const grpc_channel_args& args);
// Methods for dealing with the balancer channel and call.
void StartPickingLocked();
void StartBalancerCallLocked();
static void OnFallbackTimerLocked(void* arg, grpc_error* error);
void StartBalancerCallRetryTimerLocked();
static void OnBalancerCallRetryTimerLocked(void* arg, grpc_error* error);
static void OnBalancerChannelConnectivityChangedLocked(void* arg,
grpc_error* error);
// Pending pick methods.
static void PendingPickSetMetadataAndContext(PendingPick* pp);
PendingPick* PendingPickCreate(PickState* pick);
void AddPendingPick(PendingPick* pp);
static void OnPendingPickComplete(void* arg, grpc_error* error);
// Methods for dealing with the RR policy.
void CreateOrUpdateRoundRobinPolicyLocked();
grpc_channel_args* CreateRoundRobinPolicyArgsLocked();
void CreateRoundRobinPolicyLocked(const Args& args);
bool PickFromRoundRobinPolicyLocked(bool force_async, PendingPick* pp,
grpc_error** error);
void UpdateConnectivityStateFromRoundRobinPolicyLocked(
grpc_error* rr_state_error);
static void OnRoundRobinConnectivityChangedLocked(void* arg,
grpc_error* error);
static void OnRoundRobinRequestReresolutionLocked(void* arg,
grpc_error* error);
// Who the client is trying to communicate with.
const char* server_name_ = nullptr;
// Current channel args from the resolver.
grpc_channel_args* args_ = nullptr;
// Internal state.
bool started_picking_ = false;
bool shutting_down_ = false;
grpc_connectivity_state_tracker state_tracker_;
// The channel for communicating with the LB server.
grpc_channel* lb_channel_ = nullptr;
// Mutex to protect the channel to the LB server. This is used when
// processing a channelz request.
gpr_mu lb_channel_mu_;
grpc_connectivity_state lb_channel_connectivity_;
grpc_closure lb_channel_on_connectivity_changed_;
// Are we already watching the LB channel's connectivity?
bool watching_lb_channel_ = false;
// Response generator to inject address updates into lb_channel_.
RefCountedPtr<FakeResolverResponseGenerator> response_generator_;
// The data associated with the current LB call. It holds a ref to this LB
// policy. It's initialized every time we query for backends. It's reset to
// NULL whenever the current LB call is no longer needed (e.g., the LB policy
// is shutting down, or the LB call has ended). A non-NULL lb_calld_ always
// contains a non-NULL lb_call_.
OrphanablePtr<BalancerCallState> lb_calld_;
// Timeout in milliseconds for the LB call. 0 means no deadline.
int lb_call_timeout_ms_ = 0;
// Balancer call retry state.
BackOff lb_call_backoff_;
bool retry_timer_callback_pending_ = false;
grpc_timer lb_call_retry_timer_;
grpc_closure lb_on_call_retry_;
// The deserialized response from the balancer. May be nullptr until one
// such response has arrived.
grpc_grpclb_serverlist* serverlist_ = nullptr;
// Index into serverlist for next pick.
// If the server at this index is a drop, we return a drop.
// Otherwise, we delegate to the RR policy.
size_t serverlist_index_ = 0;
// Timeout in milliseconds for before using fallback backend addresses.
// 0 means not using fallback.
int lb_fallback_timeout_ms_ = 0;
// The backend addresses from the resolver.
UniquePtr<ServerAddressList> fallback_backend_addresses_;
// Fallback timer.
bool fallback_timer_callback_pending_ = false;
grpc_timer lb_fallback_timer_;
grpc_closure lb_on_fallback_;
// Pending picks that are waiting on the RR policy's connectivity.
PendingPick* pending_picks_ = nullptr;
// The RR policy to use for the backends.
OrphanablePtr<LoadBalancingPolicy> rr_policy_;
grpc_connectivity_state rr_connectivity_state_;
grpc_closure on_rr_connectivity_changed_;
grpc_closure on_rr_request_reresolution_;
};
//
// serverlist parsing code
//
// vtable for LB token channel arg.
void* lb_token_copy(void* token) {
return token == nullptr
? nullptr
: (void*)GRPC_MDELEM_REF(grpc_mdelem{(uintptr_t)token}).payload;
}
void lb_token_destroy(void* token) {
if (token != nullptr) {
GRPC_MDELEM_UNREF(grpc_mdelem{(uintptr_t)token});
}
}
int lb_token_cmp(void* token1, void* token2) {
// Always indicate a match, since we don't want this channel arg to
// affect the subchannel's key in the index.
return 0;
}
const grpc_arg_pointer_vtable lb_token_arg_vtable = {
lb_token_copy, lb_token_destroy, lb_token_cmp};
bool IsServerValid(const grpc_grpclb_server* server, size_t idx, bool log) {
if (server->drop) return false;
const grpc_grpclb_ip_address* ip = &server->ip_address;
if (GPR_UNLIKELY(server->port >> 16 != 0)) {
if (log) {
gpr_log(GPR_ERROR,
"Invalid port '%d' at index %lu of serverlist. Ignoring.",
server->port, (unsigned long)idx);
}
return false;
}
if (GPR_UNLIKELY(ip->size != 4 && ip->size != 16)) {
if (log) {
gpr_log(GPR_ERROR,
"Expected IP to be 4 or 16 bytes, got %d at index %lu of "
"serverlist. Ignoring",
ip->size, (unsigned long)idx);
}
return false;
}
return true;
}
void ParseServer(const grpc_grpclb_server* server,
grpc_resolved_address* addr) {
memset(addr, 0, sizeof(*addr));
if (server->drop) return;
const uint16_t netorder_port = grpc_htons((uint16_t)server->port);
/* the addresses are given in binary format (a in(6)_addr struct) in
* server->ip_address.bytes. */
const grpc_grpclb_ip_address* ip = &server->ip_address;
if (ip->size == 4) {
addr->len = static_cast<socklen_t>(sizeof(grpc_sockaddr_in));
grpc_sockaddr_in* addr4 = reinterpret_cast<grpc_sockaddr_in*>(&addr->addr);
addr4->sin_family = GRPC_AF_INET;
memcpy(&addr4->sin_addr, ip->bytes, ip->size);
addr4->sin_port = netorder_port;
} else if (ip->size == 16) {
addr->len = static_cast<socklen_t>(sizeof(grpc_sockaddr_in6));
grpc_sockaddr_in6* addr6 = (grpc_sockaddr_in6*)&addr->addr;
addr6->sin6_family = GRPC_AF_INET6;
memcpy(&addr6->sin6_addr, ip->bytes, ip->size);
addr6->sin6_port = netorder_port;
}
}
// Returns addresses extracted from \a serverlist.
ServerAddressList ProcessServerlist(const grpc_grpclb_serverlist* serverlist) {
ServerAddressList addresses;
for (size_t i = 0; i < serverlist->num_servers; ++i) {
const grpc_grpclb_server* server = serverlist->servers[i];
if (!IsServerValid(serverlist->servers[i], i, false)) continue;
// Address processing.
grpc_resolved_address addr;
ParseServer(server, &addr);
// LB token processing.
grpc_mdelem lb_token;
if (server->has_load_balance_token) {
const size_t lb_token_max_length =
GPR_ARRAY_SIZE(server->load_balance_token);
const size_t lb_token_length =
strnlen(server->load_balance_token, lb_token_max_length);
grpc_slice lb_token_mdstr = grpc_slice_from_copied_buffer(
server->load_balance_token, lb_token_length);
lb_token = grpc_mdelem_from_slices(GRPC_MDSTR_LB_TOKEN, lb_token_mdstr);
} else {
char* uri = grpc_sockaddr_to_uri(&addr);
gpr_log(GPR_INFO,
"Missing LB token for backend address '%s'. The empty token will "
"be used instead",
uri);
gpr_free(uri);
lb_token = GRPC_MDELEM_LB_TOKEN_EMPTY;
}
// Add address.
grpc_arg arg = grpc_channel_arg_pointer_create(
const_cast<char*>(GRPC_ARG_GRPCLB_ADDRESS_LB_TOKEN),
(void*)lb_token.payload, &lb_token_arg_vtable);
grpc_channel_args* args = grpc_channel_args_copy_and_add(nullptr, &arg, 1);
addresses.emplace_back(addr, args);
// Clean up.
GRPC_MDELEM_UNREF(lb_token);
}
return addresses;
}
//
// GrpcLb::BalancerCallState
//
GrpcLb::BalancerCallState::BalancerCallState(
RefCountedPtr<LoadBalancingPolicy> parent_grpclb_policy)
: InternallyRefCounted<BalancerCallState>(&grpc_lb_glb_trace),
grpclb_policy_(std::move(parent_grpclb_policy)) {
GPR_ASSERT(grpclb_policy_ != nullptr);
GPR_ASSERT(!grpclb_policy()->shutting_down_);
// Init the LB call. Note that the LB call will progress every time there's
// activity in grpclb_policy_->interested_parties(), which is comprised of
// the polling entities from client_channel.
GPR_ASSERT(grpclb_policy()->server_name_ != nullptr);
GPR_ASSERT(grpclb_policy()->server_name_[0] != '\0');
const grpc_millis deadline =
grpclb_policy()->lb_call_timeout_ms_ == 0
? GRPC_MILLIS_INF_FUTURE
: ExecCtx::Get()->Now() + grpclb_policy()->lb_call_timeout_ms_;
lb_call_ = grpc_channel_create_pollset_set_call(
grpclb_policy()->lb_channel_, nullptr, GRPC_PROPAGATE_DEFAULTS,
grpclb_policy_->interested_parties(),
GRPC_MDSTR_SLASH_GRPC_DOT_LB_DOT_V1_DOT_LOADBALANCER_SLASH_BALANCELOAD,
nullptr, deadline, nullptr);
// Init the LB call request payload.
grpc_grpclb_request* request =
grpc_grpclb_request_create(grpclb_policy()->server_name_);
grpc_slice request_payload_slice = grpc_grpclb_request_encode(request);
send_message_payload_ =
grpc_raw_byte_buffer_create(&request_payload_slice, 1);
grpc_slice_unref_internal(request_payload_slice);
grpc_grpclb_request_destroy(request);
// Init other data associated with the LB call.
grpc_metadata_array_init(&lb_initial_metadata_recv_);
grpc_metadata_array_init(&lb_trailing_metadata_recv_);
GRPC_CLOSURE_INIT(&lb_on_initial_request_sent_, OnInitialRequestSentLocked,
this, grpc_combiner_scheduler(grpclb_policy()->combiner()));
GRPC_CLOSURE_INIT(&lb_on_balancer_message_received_,
OnBalancerMessageReceivedLocked, this,
grpc_combiner_scheduler(grpclb_policy()->combiner()));
GRPC_CLOSURE_INIT(&lb_on_balancer_status_received_,
OnBalancerStatusReceivedLocked, this,
grpc_combiner_scheduler(grpclb_policy()->combiner()));
}
GrpcLb::BalancerCallState::~BalancerCallState() {
GPR_ASSERT(lb_call_ != nullptr);
grpc_call_unref(lb_call_);
grpc_metadata_array_destroy(&lb_initial_metadata_recv_);
grpc_metadata_array_destroy(&lb_trailing_metadata_recv_);
grpc_byte_buffer_destroy(send_message_payload_);
grpc_byte_buffer_destroy(recv_message_payload_);
grpc_slice_unref_internal(lb_call_status_details_);
}
void GrpcLb::BalancerCallState::Orphan() {
GPR_ASSERT(lb_call_ != nullptr);
// If we are here because grpclb_policy wants to cancel the call,
// lb_on_balancer_status_received_ will complete the cancellation and clean
// up. Otherwise, we are here because grpclb_policy has to orphan a failed
// call, then the following cancellation will be a no-op.
grpc_call_cancel(lb_call_, nullptr);
if (client_load_report_timer_callback_pending_) {
grpc_timer_cancel(&client_load_report_timer_);
}
// Note that the initial ref is hold by lb_on_balancer_status_received_
// instead of the caller of this function. So the corresponding unref happens
// in lb_on_balancer_status_received_ instead of here.
}
void GrpcLb::BalancerCallState::StartQuery() {
GPR_ASSERT(lb_call_ != nullptr);
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO, "[grpclb %p] lb_calld=%p: Starting LB call %p",
grpclb_policy_.get(), this, lb_call_);
}
// Create the ops.
grpc_call_error call_error;
grpc_op ops[3];
memset(ops, 0, sizeof(ops));
// Op: send initial metadata.
grpc_op* op = ops;
op->op = GRPC_OP_SEND_INITIAL_METADATA;
op->data.send_initial_metadata.count = 0;
op->flags = 0;
op->reserved = nullptr;
op++;
// Op: send request message.
GPR_ASSERT(send_message_payload_ != nullptr);
op->op = GRPC_OP_SEND_MESSAGE;
op->data.send_message.send_message = send_message_payload_;
op->flags = 0;
op->reserved = nullptr;
op++;
// TODO(roth): We currently track this ref manually. Once the
// ClosureRef API is ready, we should pass the RefCountedPtr<> along
// with the callback.
auto self = Ref(DEBUG_LOCATION, "on_initial_request_sent");
self.release();
call_error = grpc_call_start_batch_and_execute(
lb_call_, ops, (size_t)(op - ops), &lb_on_initial_request_sent_);
GPR_ASSERT(GRPC_CALL_OK == call_error);
// Op: recv initial metadata.
op = ops;
op->op = GRPC_OP_RECV_INITIAL_METADATA;
op->data.recv_initial_metadata.recv_initial_metadata =
&lb_initial_metadata_recv_;
op->flags = 0;
op->reserved = nullptr;
op++;
// Op: recv response.
op->op = GRPC_OP_RECV_MESSAGE;
op->data.recv_message.recv_message = &recv_message_payload_;
op->flags = 0;
op->reserved = nullptr;
op++;
// TODO(roth): We currently track this ref manually. Once the
// ClosureRef API is ready, we should pass the RefCountedPtr<> along
// with the callback.
self = Ref(DEBUG_LOCATION, "on_message_received");
self.release();
call_error = grpc_call_start_batch_and_execute(
lb_call_, ops, (size_t)(op - ops), &lb_on_balancer_message_received_);
GPR_ASSERT(GRPC_CALL_OK == call_error);
// Op: recv server status.
op = ops;
op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
op->data.recv_status_on_client.trailing_metadata =
&lb_trailing_metadata_recv_;
op->data.recv_status_on_client.status = &lb_call_status_;
op->data.recv_status_on_client.status_details = &lb_call_status_details_;
op->flags = 0;
op->reserved = nullptr;
op++;
// This callback signals the end of the LB call, so it relies on the initial
// ref instead of a new ref. When it's invoked, it's the initial ref that is
// unreffed.
call_error = grpc_call_start_batch_and_execute(
lb_call_, ops, (size_t)(op - ops), &lb_on_balancer_status_received_);
GPR_ASSERT(GRPC_CALL_OK == call_error);
};
void GrpcLb::BalancerCallState::ScheduleNextClientLoadReportLocked() {
const grpc_millis next_client_load_report_time =
ExecCtx::Get()->Now() + client_stats_report_interval_;
GRPC_CLOSURE_INIT(&client_load_report_closure_,
MaybeSendClientLoadReportLocked, this,
grpc_combiner_scheduler(grpclb_policy()->combiner()));
grpc_timer_init(&client_load_report_timer_, next_client_load_report_time,
&client_load_report_closure_);
client_load_report_timer_callback_pending_ = true;
}
void GrpcLb::BalancerCallState::MaybeSendClientLoadReportLocked(
void* arg, grpc_error* error) {
BalancerCallState* lb_calld = static_cast<BalancerCallState*>(arg);
GrpcLb* grpclb_policy = lb_calld->grpclb_policy();
lb_calld->client_load_report_timer_callback_pending_ = false;
if (error != GRPC_ERROR_NONE || lb_calld != grpclb_policy->lb_calld_.get()) {
lb_calld->Unref(DEBUG_LOCATION, "client_load_report");
return;
}
// If we've already sent the initial request, then we can go ahead and send
// the load report. Otherwise, we need to wait until the initial request has
// been sent to send this (see OnInitialRequestSentLocked()).
if (lb_calld->send_message_payload_ == nullptr) {
lb_calld->SendClientLoadReportLocked();
} else {
lb_calld->client_load_report_is_due_ = true;
}
}
bool GrpcLb::BalancerCallState::LoadReportCountersAreZero(
grpc_grpclb_request* request) {
GrpcLbClientStats::DroppedCallCounts* drop_entries =
static_cast<GrpcLbClientStats::DroppedCallCounts*>(
request->client_stats.calls_finished_with_drop.arg);
return request->client_stats.num_calls_started == 0 &&
request->client_stats.num_calls_finished == 0 &&
request->client_stats.num_calls_finished_with_client_failed_to_send ==
0 &&
request->client_stats.num_calls_finished_known_received == 0 &&
(drop_entries == nullptr || drop_entries->size() == 0);
}
void GrpcLb::BalancerCallState::SendClientLoadReportLocked() {
// Construct message payload.
GPR_ASSERT(send_message_payload_ == nullptr);
grpc_grpclb_request* request =
grpc_grpclb_load_report_request_create_locked(client_stats_.get());
// Skip client load report if the counters were all zero in the last
// report and they are still zero in this one.
if (LoadReportCountersAreZero(request)) {
if (last_client_load_report_counters_were_zero_) {
grpc_grpclb_request_destroy(request);
ScheduleNextClientLoadReportLocked();
return;
}
last_client_load_report_counters_were_zero_ = true;
} else {
last_client_load_report_counters_were_zero_ = false;
}
grpc_slice request_payload_slice = grpc_grpclb_request_encode(request);
send_message_payload_ =
grpc_raw_byte_buffer_create(&request_payload_slice, 1);
grpc_slice_unref_internal(request_payload_slice);
grpc_grpclb_request_destroy(request);
// Send the report.
grpc_op op;
memset(&op, 0, sizeof(op));
op.op = GRPC_OP_SEND_MESSAGE;
op.data.send_message.send_message = send_message_payload_;
GRPC_CLOSURE_INIT(&client_load_report_closure_, ClientLoadReportDoneLocked,
this, grpc_combiner_scheduler(grpclb_policy()->combiner()));
grpc_call_error call_error = grpc_call_start_batch_and_execute(
lb_call_, &op, 1, &client_load_report_closure_);
if (GPR_UNLIKELY(call_error != GRPC_CALL_OK)) {
gpr_log(GPR_ERROR,
"[grpclb %p] lb_calld=%p call_error=%d sending client load report",
grpclb_policy_.get(), this, call_error);
GPR_ASSERT(GRPC_CALL_OK == call_error);
}
}
void GrpcLb::BalancerCallState::ClientLoadReportDoneLocked(void* arg,
grpc_error* error) {
BalancerCallState* lb_calld = static_cast<BalancerCallState*>(arg);
GrpcLb* grpclb_policy = lb_calld->grpclb_policy();
grpc_byte_buffer_destroy(lb_calld->send_message_payload_);
lb_calld->send_message_payload_ = nullptr;
if (error != GRPC_ERROR_NONE || lb_calld != grpclb_policy->lb_calld_.get()) {
lb_calld->Unref(DEBUG_LOCATION, "client_load_report");
return;
}
lb_calld->ScheduleNextClientLoadReportLocked();
}
void GrpcLb::BalancerCallState::OnInitialRequestSentLocked(void* arg,
grpc_error* error) {
BalancerCallState* lb_calld = static_cast<BalancerCallState*>(arg);
grpc_byte_buffer_destroy(lb_calld->send_message_payload_);
lb_calld->send_message_payload_ = nullptr;
// If we attempted to send a client load report before the initial request was
// sent (and this lb_calld is still in use), send the load report now.
if (lb_calld->client_load_report_is_due_ &&
lb_calld == lb_calld->grpclb_policy()->lb_calld_.get()) {
lb_calld->SendClientLoadReportLocked();
lb_calld->client_load_report_is_due_ = false;
}
lb_calld->Unref(DEBUG_LOCATION, "on_initial_request_sent");
}
void GrpcLb::BalancerCallState::OnBalancerMessageReceivedLocked(
void* arg, grpc_error* error) {
BalancerCallState* lb_calld = static_cast<BalancerCallState*>(arg);
GrpcLb* grpclb_policy = lb_calld->grpclb_policy();
// Null payload means the LB call was cancelled.
if (lb_calld != grpclb_policy->lb_calld_.get() ||
lb_calld->recv_message_payload_ == nullptr) {
lb_calld->Unref(DEBUG_LOCATION, "on_message_received");
return;
}
grpc_byte_buffer_reader bbr;
grpc_byte_buffer_reader_init(&bbr, lb_calld->recv_message_payload_);
grpc_slice response_slice = grpc_byte_buffer_reader_readall(&bbr);
grpc_byte_buffer_reader_destroy(&bbr);
grpc_byte_buffer_destroy(lb_calld->recv_message_payload_);
lb_calld->recv_message_payload_ = nullptr;
grpc_grpclb_initial_response* initial_response;
grpc_grpclb_serverlist* serverlist;
if (!lb_calld->seen_initial_response_ &&
(initial_response = grpc_grpclb_initial_response_parse(response_slice)) !=
nullptr) {
// Have NOT seen initial response, look for initial response.
if (initial_response->has_client_stats_report_interval) {
lb_calld->client_stats_report_interval_ = GPR_MAX(
GPR_MS_PER_SEC, grpc_grpclb_duration_to_millis(
&initial_response->client_stats_report_interval));
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO,
"[grpclb %p] lb_calld=%p: Received initial LB response "
"message; client load reporting interval = %" PRId64
" milliseconds",
grpclb_policy, lb_calld,
lb_calld->client_stats_report_interval_);
}
} else if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO,
"[grpclb %p] lb_calld=%p: Received initial LB response message; "
"client load reporting NOT enabled",
grpclb_policy, lb_calld);
}
grpc_grpclb_initial_response_destroy(initial_response);
lb_calld->seen_initial_response_ = true;
} else if ((serverlist = grpc_grpclb_response_parse_serverlist(
response_slice)) != nullptr) {
// Have seen initial response, look for serverlist.
GPR_ASSERT(lb_calld->lb_call_ != nullptr);
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO,
"[grpclb %p] lb_calld=%p: Serverlist with %" PRIuPTR
" servers received",
grpclb_policy, lb_calld, serverlist->num_servers);
for (size_t i = 0; i < serverlist->num_servers; ++i) {
grpc_resolved_address addr;
ParseServer(serverlist->servers[i], &addr);
char* ipport;
grpc_sockaddr_to_string(&ipport, &addr, false);
gpr_log(GPR_INFO,
"[grpclb %p] lb_calld=%p: Serverlist[%" PRIuPTR "]: %s",
grpclb_policy, lb_calld, i, ipport);
gpr_free(ipport);
}
}
// Start sending client load report only after we start using the
// serverlist returned from the current LB call.
if (lb_calld->client_stats_report_interval_ > 0 &&
lb_calld->client_stats_ == nullptr) {
lb_calld->client_stats_.reset(New<GrpcLbClientStats>());
// TODO(roth): We currently track this ref manually. Once the
// ClosureRef API is ready, we should pass the RefCountedPtr<> along
// with the callback.
auto self = lb_calld->Ref(DEBUG_LOCATION, "client_load_report");
self.release();
lb_calld->ScheduleNextClientLoadReportLocked();
}
// Check if the serverlist differs from the previous one.
if (grpc_grpclb_serverlist_equals(grpclb_policy->serverlist_, serverlist)) {
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO,
"[grpclb %p] lb_calld=%p: Incoming server list identical to "
"current, ignoring.",
grpclb_policy, lb_calld);
}
grpc_grpclb_destroy_serverlist(serverlist);
} else { // New serverlist.
if (grpclb_policy->serverlist_ != nullptr) {
// Dispose of the old serverlist.
grpc_grpclb_destroy_serverlist(grpclb_policy->serverlist_);
} else {
// Dispose of the fallback.
grpclb_policy->fallback_backend_addresses_.reset();
if (grpclb_policy->fallback_timer_callback_pending_) {
grpc_timer_cancel(&grpclb_policy->lb_fallback_timer_);
}
}
// Update the serverlist in the GrpcLb instance. This serverlist
// instance will be destroyed either upon the next update or when the
// GrpcLb instance is destroyed.
grpclb_policy->serverlist_ = serverlist;
grpclb_policy->serverlist_index_ = 0;
grpclb_policy->CreateOrUpdateRoundRobinPolicyLocked();
}
} else {
// No valid initial response or serverlist found.
char* response_slice_str =
grpc_dump_slice(response_slice, GPR_DUMP_ASCII | GPR_DUMP_HEX);
gpr_log(GPR_ERROR,
"[grpclb %p] lb_calld=%p: Invalid LB response received: '%s'. "
"Ignoring.",
grpclb_policy, lb_calld, response_slice_str);
gpr_free(response_slice_str);
}
grpc_slice_unref_internal(response_slice);
if (!grpclb_policy->shutting_down_) {
// Keep listening for serverlist updates.
grpc_op op;
memset(&op, 0, sizeof(op));
op.op = GRPC_OP_RECV_MESSAGE;
op.data.recv_message.recv_message = &lb_calld->recv_message_payload_;
op.flags = 0;
op.reserved = nullptr;
// Reuse the "OnBalancerMessageReceivedLocked" ref taken in StartQuery().
const grpc_call_error call_error = grpc_call_start_batch_and_execute(
lb_calld->lb_call_, &op, 1,
&lb_calld->lb_on_balancer_message_received_);
GPR_ASSERT(GRPC_CALL_OK == call_error);
} else {
lb_calld->Unref(DEBUG_LOCATION, "on_message_received+grpclb_shutdown");
}
}
void GrpcLb::BalancerCallState::OnBalancerStatusReceivedLocked(
void* arg, grpc_error* error) {
BalancerCallState* lb_calld = static_cast<BalancerCallState*>(arg);
GrpcLb* grpclb_policy = lb_calld->grpclb_policy();
GPR_ASSERT(lb_calld->lb_call_ != nullptr);
if (grpc_lb_glb_trace.enabled()) {
char* status_details =
grpc_slice_to_c_string(lb_calld->lb_call_status_details_);
gpr_log(GPR_INFO,
"[grpclb %p] lb_calld=%p: Status from LB server received. "
"Status = %d, details = '%s', (lb_call: %p), error '%s'",
grpclb_policy, lb_calld, lb_calld->lb_call_status_, status_details,
lb_calld->lb_call_, grpc_error_string(error));
gpr_free(status_details);
}
grpclb_policy->TryReresolutionLocked(&grpc_lb_glb_trace, GRPC_ERROR_NONE);
// If this lb_calld is still in use, this call ended because of a failure so
// we want to retry connecting. Otherwise, we have deliberately ended this
// call and no further action is required.
if (lb_calld == grpclb_policy->lb_calld_.get()) {
grpclb_policy->lb_calld_.reset();
GPR_ASSERT(!grpclb_policy->shutting_down_);
if (lb_calld->seen_initial_response_) {
// If we lose connection to the LB server, reset the backoff and restart
// the LB call immediately.
grpclb_policy->lb_call_backoff_.Reset();
grpclb_policy->StartBalancerCallLocked();
} else {
// If this LB call fails establishing any connection to the LB server,
// retry later.
grpclb_policy->StartBalancerCallRetryTimerLocked();
}
}
lb_calld->Unref(DEBUG_LOCATION, "lb_call_ended");
}
//
// helper code for creating balancer channel
//
ServerAddressList ExtractBalancerAddresses(const ServerAddressList& addresses) {
ServerAddressList balancer_addresses;
for (size_t i = 0; i < addresses.size(); ++i) {
if (addresses[i].IsBalancer()) {
// Strip out the is_balancer channel arg, since we don't want to
// recursively use the grpclb policy in the channel used to talk to
// the balancers. Note that we do NOT strip out the balancer_name
// channel arg, since we need that to set the authority correctly
// to talk to the balancers.
static const char* args_to_remove[] = {
GRPC_ARG_ADDRESS_IS_BALANCER,
};
balancer_addresses.emplace_back(
addresses[i].address(),
grpc_channel_args_copy_and_remove(addresses[i].args(), args_to_remove,
GPR_ARRAY_SIZE(args_to_remove)));
}
}
return balancer_addresses;
}
/* Returns the channel args for the LB channel, used to create a bidirectional
* stream for the reception of load balancing updates.
*
* Inputs:
* - \a addresses: corresponding to the balancers.
* - \a response_generator: in order to propagate updates from the resolver
* above the grpclb policy.
* - \a args: other args inherited from the grpclb policy. */
grpc_channel_args* BuildBalancerChannelArgs(
const ServerAddressList& addresses,
FakeResolverResponseGenerator* response_generator,
const grpc_channel_args* args) {
ServerAddressList balancer_addresses = ExtractBalancerAddresses(addresses);
// Channel args to remove.
static const char* args_to_remove[] = {
// LB policy name, since we want to use the default (pick_first) in
// the LB channel.
GRPC_ARG_LB_POLICY_NAME,
// The channel arg for the server URI, since that will be different for
// the LB channel than for the parent channel. The client channel
// factory will re-add this arg with the right value.
GRPC_ARG_SERVER_URI,
// The resolved addresses, which will be generated by the name resolver
// used in the LB channel. Note that the LB channel will use the fake
// resolver, so this won't actually generate a query to DNS (or some
// other name service). However, the addresses returned by the fake
// resolver will have is_balancer=false, whereas our own addresses have
// is_balancer=true. We need the LB channel to return addresses with
// is_balancer=false so that it does not wind up recursively using the
// grpclb LB policy, as per the special case logic in client_channel.c.
GRPC_ARG_SERVER_ADDRESS_LIST,
// The fake resolver response generator, because we are replacing it
// with the one from the grpclb policy, used to propagate updates to
// the LB channel.
GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR,
// The LB channel should use the authority indicated by the target
// authority table (see \a grpc_lb_policy_grpclb_modify_lb_channel_args),
// as opposed to the authority from the parent channel.
GRPC_ARG_DEFAULT_AUTHORITY,
// Just as for \a GRPC_ARG_DEFAULT_AUTHORITY, the LB channel should be
// treated as a stand-alone channel and not inherit this argument from the
// args of the parent channel.
GRPC_SSL_TARGET_NAME_OVERRIDE_ARG,
};
// Channel args to add.
const grpc_arg args_to_add[] = {
// New address list.
// Note that we pass these in both when creating the LB channel
// and via the fake resolver. The latter is what actually gets used.
CreateServerAddressListChannelArg(&balancer_addresses),
// The fake resolver response generator, which we use to inject
// address updates into the LB channel.
grpc_core::FakeResolverResponseGenerator::MakeChannelArg(
response_generator),
// A channel arg indicating the target is a grpclb load balancer.
grpc_channel_arg_integer_create(
const_cast<char*>(GRPC_ARG_ADDRESS_IS_GRPCLB_LOAD_BALANCER), 1),
// A channel arg indicating this is an internal channels, aka it is
// owned by components in Core, not by the user application.
grpc_channel_arg_integer_create(
const_cast<char*>(GRPC_ARG_CHANNELZ_CHANNEL_IS_INTERNAL_CHANNEL), 1),
};
// Construct channel args.
grpc_channel_args* new_args = grpc_channel_args_copy_and_add_and_remove(
args, args_to_remove, GPR_ARRAY_SIZE(args_to_remove), args_to_add,
GPR_ARRAY_SIZE(args_to_add));
// Make any necessary modifications for security.
return grpc_lb_policy_grpclb_modify_lb_channel_args(new_args);
}
//
// ctor and dtor
//
GrpcLb::GrpcLb(const LoadBalancingPolicy::Args& args)
: LoadBalancingPolicy(args),
response_generator_(MakeRefCounted<FakeResolverResponseGenerator>()),
lb_call_backoff_(
BackOff::Options()
.set_initial_backoff(GRPC_GRPCLB_INITIAL_CONNECT_BACKOFF_SECONDS *
1000)
.set_multiplier(GRPC_GRPCLB_RECONNECT_BACKOFF_MULTIPLIER)
.set_jitter(GRPC_GRPCLB_RECONNECT_JITTER)
.set_max_backoff(GRPC_GRPCLB_RECONNECT_MAX_BACKOFF_SECONDS *
1000)) {
// Initialization.
gpr_mu_init(&lb_channel_mu_);
grpc_subchannel_index_ref();
GRPC_CLOSURE_INIT(&lb_channel_on_connectivity_changed_,
&GrpcLb::OnBalancerChannelConnectivityChangedLocked, this,
grpc_combiner_scheduler(args.combiner));
GRPC_CLOSURE_INIT(&on_rr_connectivity_changed_,
&GrpcLb::OnRoundRobinConnectivityChangedLocked, this,
grpc_combiner_scheduler(args.combiner));
GRPC_CLOSURE_INIT(&on_rr_request_reresolution_,
&GrpcLb::OnRoundRobinRequestReresolutionLocked, this,
grpc_combiner_scheduler(args.combiner));
grpc_connectivity_state_init(&state_tracker_, GRPC_CHANNEL_IDLE, "grpclb");
// Record server name.
const grpc_arg* arg = grpc_channel_args_find(args.args, GRPC_ARG_SERVER_URI);
const char* server_uri = grpc_channel_arg_get_string(arg);
GPR_ASSERT(server_uri != nullptr);
grpc_uri* uri = grpc_uri_parse(server_uri, true);
GPR_ASSERT(uri->path[0] != '\0');
server_name_ = gpr_strdup(uri->path[0] == '/' ? uri->path + 1 : uri->path);
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO,
"[grpclb %p] Will use '%s' as the server name for LB request.",
this, server_name_);
}
grpc_uri_destroy(uri);
// Record LB call timeout.
arg = grpc_channel_args_find(args.args, GRPC_ARG_GRPCLB_CALL_TIMEOUT_MS);
lb_call_timeout_ms_ = grpc_channel_arg_get_integer(arg, {0, 0, INT_MAX});
// Record fallback timeout.
arg = grpc_channel_args_find(args.args, GRPC_ARG_GRPCLB_FALLBACK_TIMEOUT_MS);
lb_fallback_timeout_ms_ = grpc_channel_arg_get_integer(
arg, {GRPC_GRPCLB_DEFAULT_FALLBACK_TIMEOUT_MS, 0, INT_MAX});
// Process channel args.
ProcessChannelArgsLocked(*args.args);
}
GrpcLb::~GrpcLb() {
GPR_ASSERT(pending_picks_ == nullptr);
gpr_mu_destroy(&lb_channel_mu_);
gpr_free((void*)server_name_);
grpc_channel_args_destroy(args_);
grpc_connectivity_state_destroy(&state_tracker_);
if (serverlist_ != nullptr) {
grpc_grpclb_destroy_serverlist(serverlist_);
}
grpc_subchannel_index_unref();
}
void GrpcLb::ShutdownLocked() {
grpc_error* error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("Channel shutdown");
shutting_down_ = true;
lb_calld_.reset();
if (retry_timer_callback_pending_) {
grpc_timer_cancel(&lb_call_retry_timer_);
}
if (fallback_timer_callback_pending_) {
grpc_timer_cancel(&lb_fallback_timer_);
}
rr_policy_.reset();
TryReresolutionLocked(&grpc_lb_glb_trace, GRPC_ERROR_CANCELLED);
// We destroy the LB channel here instead of in our destructor because
// destroying the channel triggers a last callback to
// OnBalancerChannelConnectivityChangedLocked(), and we need to be
// alive when that callback is invoked.
if (lb_channel_ != nullptr) {
gpr_mu_lock(&lb_channel_mu_);
grpc_channel_destroy(lb_channel_);
lb_channel_ = nullptr;
gpr_mu_unlock(&lb_channel_mu_);
}
grpc_connectivity_state_set(&state_tracker_, GRPC_CHANNEL_SHUTDOWN,
GRPC_ERROR_REF(error), "grpclb_shutdown");
// Clear pending picks.
PendingPick* pp;
while ((pp = pending_picks_) != nullptr) {
pending_picks_ = pp->next;
pp->pick->connected_subchannel.reset();
// Note: pp is deleted in this callback.
GRPC_CLOSURE_SCHED(&pp->on_complete, GRPC_ERROR_REF(error));
}
GRPC_ERROR_UNREF(error);
}
//
// public methods
//
void GrpcLb::HandOffPendingPicksLocked(LoadBalancingPolicy* new_policy) {
PendingPick* pp;
while ((pp = pending_picks_) != nullptr) {
pending_picks_ = pp->next;
pp->pick->on_complete = pp->original_on_complete;
grpc_error* error = GRPC_ERROR_NONE;
if (new_policy->PickLocked(pp->pick, &error)) {
// Synchronous return; schedule closure.
GRPC_CLOSURE_SCHED(pp->pick->on_complete, error);
}
Delete(pp);
}
}
// Cancel a specific pending pick.
//
// A grpclb pick progresses as follows:
// - If there's a Round Robin policy (rr_policy_) available, it'll be
// handed over to the RR policy (in CreateRoundRobinPolicyLocked()). From
// that point onwards, it'll be RR's responsibility. For cancellations, that
// implies the pick needs also be cancelled by the RR instance.
// - Otherwise, without an RR instance, picks stay pending at this policy's
// level (grpclb), inside the pending_picks_ list. To cancel these,
// we invoke the completion closure and set the pick's connected
// subchannel to nullptr right here.
void GrpcLb::CancelPickLocked(PickState* pick, grpc_error* error) {
PendingPick* pp = pending_picks_;
pending_picks_ = nullptr;
while (pp != nullptr) {
PendingPick* next = pp->next;
if (pp->pick == pick) {
pick->connected_subchannel.reset();
// Note: pp is deleted in this callback.
GRPC_CLOSURE_SCHED(&pp->on_complete,
GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
"Pick Cancelled", &error, 1));
} else {
pp->next = pending_picks_;
pending_picks_ = pp;
}
pp = next;
}
if (rr_policy_ != nullptr) {
rr_policy_->CancelPickLocked(pick, GRPC_ERROR_REF(error));
}
GRPC_ERROR_UNREF(error);
}
// Cancel all pending picks.
//
// A grpclb pick progresses as follows:
// - If there's a Round Robin policy (rr_policy_) available, it'll be
// handed over to the RR policy (in CreateRoundRobinPolicyLocked()). From
// that point onwards, it'll be RR's responsibility. For cancellations, that
// implies the pick needs also be cancelled by the RR instance.
// - Otherwise, without an RR instance, picks stay pending at this policy's
// level (grpclb), inside the pending_picks_ list. To cancel these,
// we invoke the completion closure and set the pick's connected
// subchannel to nullptr right here.
void GrpcLb::CancelMatchingPicksLocked(uint32_t initial_metadata_flags_mask,
uint32_t initial_metadata_flags_eq,
grpc_error* error) {
PendingPick* pp = pending_picks_;
pending_picks_ = nullptr;
while (pp != nullptr) {
PendingPick* next = pp->next;
if ((*pp->pick->initial_metadata_flags & initial_metadata_flags_mask) ==
initial_metadata_flags_eq) {
// Note: pp is deleted in this callback.
GRPC_CLOSURE_SCHED(&pp->on_complete,
GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
"Pick Cancelled", &error, 1));
} else {
pp->next = pending_picks_;
pending_picks_ = pp;
}
pp = next;
}
if (rr_policy_ != nullptr) {
rr_policy_->CancelMatchingPicksLocked(initial_metadata_flags_mask,
initial_metadata_flags_eq,
GRPC_ERROR_REF(error));
}
GRPC_ERROR_UNREF(error);
}
void GrpcLb::ExitIdleLocked() {
if (!started_picking_) {
StartPickingLocked();
}
}
void GrpcLb::ResetBackoffLocked() {
if (lb_channel_ != nullptr) {
grpc_channel_reset_connect_backoff(lb_channel_);
}
if (rr_policy_ != nullptr) {
rr_policy_->ResetBackoffLocked();
}
}
bool GrpcLb::PickLocked(PickState* pick, grpc_error** error) {
PendingPick* pp = PendingPickCreate(pick);
bool pick_done = false;
if (rr_policy_ != nullptr) {
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO, "[grpclb %p] about to PICK from RR %p", this,
rr_policy_.get());
}
pick_done =
PickFromRoundRobinPolicyLocked(false /* force_async */, pp, error);
} else { // rr_policy_ == NULL
if (pick->on_complete == nullptr) {
*error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
"No pick result available but synchronous result required.");
pick_done = true;
} else {
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO,
"[grpclb %p] No RR policy. Adding to grpclb's pending picks",
this);
}
AddPendingPick(pp);
if (!started_picking_) {
StartPickingLocked();
}
pick_done = false;
}
}
return pick_done;
}
void GrpcLb::FillChildRefsForChannelz(
channelz::ChildRefsList* child_subchannels,
channelz::ChildRefsList* child_channels) {
// delegate to the RoundRobin to fill the children subchannels.
rr_policy_->FillChildRefsForChannelz(child_subchannels, child_channels);
MutexLock lock(&lb_channel_mu_);
if (lb_channel_ != nullptr) {
grpc_core::channelz::ChannelNode* channel_node =
grpc_channel_get_channelz_node(lb_channel_);
if (channel_node != nullptr) {
child_channels->push_back(channel_node->uuid());
}
}
}
grpc_connectivity_state GrpcLb::CheckConnectivityLocked(
grpc_error** connectivity_error) {
return grpc_connectivity_state_get(&state_tracker_, connectivity_error);
}
void GrpcLb::NotifyOnStateChangeLocked(grpc_connectivity_state* current,
grpc_closure* notify) {
grpc_connectivity_state_notify_on_state_change(&state_tracker_, current,
notify);
}
// Returns the backend addresses extracted from the given addresses.
UniquePtr<ServerAddressList> ExtractBackendAddresses(
const ServerAddressList& addresses) {
void* lb_token = (void*)GRPC_MDELEM_LB_TOKEN_EMPTY.payload;
grpc_arg arg = grpc_channel_arg_pointer_create(
const_cast<char*>(GRPC_ARG_GRPCLB_ADDRESS_LB_TOKEN), lb_token,
&lb_token_arg_vtable);
auto backend_addresses = MakeUnique<ServerAddressList>();
for (size_t i = 0; i < addresses.size(); ++i) {
if (!addresses[i].IsBalancer()) {
backend_addresses->emplace_back(
addresses[i].address(),
grpc_channel_args_copy_and_add(addresses[i].args(), &arg, 1));
}
}
return backend_addresses;
}
void GrpcLb::ProcessChannelArgsLocked(const grpc_channel_args& args) {
const ServerAddressList* addresses = FindServerAddressListChannelArg(&args);
if (addresses == nullptr) {
// Ignore this update.
gpr_log(
GPR_ERROR,
"[grpclb %p] No valid LB addresses channel arg in update, ignoring.",
this);
return;
}
// Update fallback address list.
fallback_backend_addresses_ = ExtractBackendAddresses(*addresses);
// Make sure that GRPC_ARG_LB_POLICY_NAME is set in channel args,
// since we use this to trigger the client_load_reporting filter.
static const char* args_to_remove[] = {GRPC_ARG_LB_POLICY_NAME};
grpc_arg new_arg = grpc_channel_arg_string_create(
(char*)GRPC_ARG_LB_POLICY_NAME, (char*)"grpclb");
grpc_channel_args_destroy(args_);
args_ = grpc_channel_args_copy_and_add_and_remove(
&args, args_to_remove, GPR_ARRAY_SIZE(args_to_remove), &new_arg, 1);
// Construct args for balancer channel.
grpc_channel_args* lb_channel_args =
BuildBalancerChannelArgs(*addresses, response_generator_.get(), &args);
// Create balancer channel if needed.
if (lb_channel_ == nullptr) {
char* uri_str;
gpr_asprintf(&uri_str, "fake:///%s", server_name_);
gpr_mu_lock(&lb_channel_mu_);
lb_channel_ = grpc_client_channel_factory_create_channel(
client_channel_factory(), uri_str,
GRPC_CLIENT_CHANNEL_TYPE_LOAD_BALANCING, lb_channel_args);
gpr_mu_unlock(&lb_channel_mu_);
GPR_ASSERT(lb_channel_ != nullptr);
gpr_free(uri_str);
}
// Propagate updates to the LB channel (pick_first) through the fake
// resolver.
response_generator_->SetResponse(lb_channel_args);
grpc_channel_args_destroy(lb_channel_args);
}
void GrpcLb::UpdateLocked(const grpc_channel_args& args, grpc_json* lb_config) {
ProcessChannelArgsLocked(args);
// Update the existing RR policy.
if (rr_policy_ != nullptr) CreateOrUpdateRoundRobinPolicyLocked();
// Start watching the LB channel connectivity for connection, if not
// already doing so.
if (!watching_lb_channel_) {
lb_channel_connectivity_ = grpc_channel_check_connectivity_state(
lb_channel_, true /* try to connect */);
grpc_channel_element* client_channel_elem = grpc_channel_stack_last_element(
grpc_channel_get_channel_stack(lb_channel_));
GPR_ASSERT(client_channel_elem->filter == &grpc_client_channel_filter);
watching_lb_channel_ = true;
// TODO(roth): We currently track this ref manually. Once the
// ClosureRef API is ready, we should pass the RefCountedPtr<> along
// with the callback.
auto self = Ref(DEBUG_LOCATION, "watch_lb_channel_connectivity");
self.release();
grpc_client_channel_watch_connectivity_state(
client_channel_elem,
grpc_polling_entity_create_from_pollset_set(interested_parties()),
&lb_channel_connectivity_, &lb_channel_on_connectivity_changed_,
nullptr);
}
}
//
// code for balancer channel and call
//
void GrpcLb::StartPickingLocked() {
// Start a timer to fall back.
if (lb_fallback_timeout_ms_ > 0 && serverlist_ == nullptr &&
!fallback_timer_callback_pending_) {
grpc_millis deadline = ExecCtx::Get()->Now() + lb_fallback_timeout_ms_;
// TODO(roth): We currently track this ref manually. Once the
// ClosureRef API is ready, we should pass the RefCountedPtr<> along
// with the callback.
auto self = Ref(DEBUG_LOCATION, "on_fallback_timer");
self.release();
GRPC_CLOSURE_INIT(&lb_on_fallback_, &GrpcLb::OnFallbackTimerLocked, this,
grpc_combiner_scheduler(combiner()));
fallback_timer_callback_pending_ = true;
grpc_timer_init(&lb_fallback_timer_, deadline, &lb_on_fallback_);
}
started_picking_ = true;
StartBalancerCallLocked();
}
void GrpcLb::StartBalancerCallLocked() {
GPR_ASSERT(lb_channel_ != nullptr);
if (shutting_down_) return;
// Init the LB call data.
GPR_ASSERT(lb_calld_ == nullptr);
lb_calld_ = MakeOrphanable<BalancerCallState>(Ref());
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO,
"[grpclb %p] Query for backends (lb_channel: %p, lb_calld: %p)",
this, lb_channel_, lb_calld_.get());
}
lb_calld_->StartQuery();
}
void GrpcLb::OnFallbackTimerLocked(void* arg, grpc_error* error) {
GrpcLb* grpclb_policy = static_cast<GrpcLb*>(arg);
grpclb_policy->fallback_timer_callback_pending_ = false;
// If we receive a serverlist after the timer fires but before this callback
// actually runs, don't fall back.
if (grpclb_policy->serverlist_ == nullptr && !grpclb_policy->shutting_down_ &&
error == GRPC_ERROR_NONE) {
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO,
"[grpclb %p] Falling back to use backends from resolver",
grpclb_policy);
}
GPR_ASSERT(grpclb_policy->fallback_backend_addresses_ != nullptr);
grpclb_policy->CreateOrUpdateRoundRobinPolicyLocked();
}
grpclb_policy->Unref(DEBUG_LOCATION, "on_fallback_timer");
}
void GrpcLb::StartBalancerCallRetryTimerLocked() {
grpc_millis next_try = lb_call_backoff_.NextAttemptTime();
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO, "[grpclb %p] Connection to LB server lost...", this);
grpc_millis timeout = next_try - ExecCtx::Get()->Now();
if (timeout > 0) {
gpr_log(GPR_INFO, "[grpclb %p] ... retry_timer_active in %" PRId64 "ms.",
this, timeout);
} else {
gpr_log(GPR_INFO, "[grpclb %p] ... retry_timer_active immediately.",
this);
}
}
// TODO(roth): We currently track this ref manually. Once the
// ClosureRef API is ready, we should pass the RefCountedPtr<> along
// with the callback.
auto self = Ref(DEBUG_LOCATION, "on_balancer_call_retry_timer");
self.release();
GRPC_CLOSURE_INIT(&lb_on_call_retry_, &GrpcLb::OnBalancerCallRetryTimerLocked,
this, grpc_combiner_scheduler(combiner()));
retry_timer_callback_pending_ = true;
grpc_timer_init(&lb_call_retry_timer_, next_try, &lb_on_call_retry_);
}
void GrpcLb::OnBalancerCallRetryTimerLocked(void* arg, grpc_error* error) {
GrpcLb* grpclb_policy = static_cast<GrpcLb*>(arg);
grpclb_policy->retry_timer_callback_pending_ = false;
if (!grpclb_policy->shutting_down_ && error == GRPC_ERROR_NONE &&
grpclb_policy->lb_calld_ == nullptr) {
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO, "[grpclb %p] Restarting call to LB server",
grpclb_policy);
}
grpclb_policy->StartBalancerCallLocked();
}
grpclb_policy->Unref(DEBUG_LOCATION, "on_balancer_call_retry_timer");
}
// Invoked as part of the update process. It continues watching the LB channel
// until it shuts down or becomes READY. It's invoked even if the LB channel
// stayed READY throughout the update (for example if the update is identical).
void GrpcLb::OnBalancerChannelConnectivityChangedLocked(void* arg,
grpc_error* error) {
GrpcLb* grpclb_policy = static_cast<GrpcLb*>(arg);
if (grpclb_policy->shutting_down_) goto done;
// Re-initialize the lb_call. This should also take care of updating the
// embedded RR policy. Note that the current RR policy, if any, will stay in
// effect until an update from the new lb_call is received.
switch (grpclb_policy->lb_channel_connectivity_) {
case GRPC_CHANNEL_CONNECTING:
case GRPC_CHANNEL_TRANSIENT_FAILURE: {
// Keep watching the LB channel.
grpc_channel_element* client_channel_elem =
grpc_channel_stack_last_element(
grpc_channel_get_channel_stack(grpclb_policy->lb_channel_));
GPR_ASSERT(client_channel_elem->filter == &grpc_client_channel_filter);
grpc_client_channel_watch_connectivity_state(
client_channel_elem,
grpc_polling_entity_create_from_pollset_set(
grpclb_policy->interested_parties()),
&grpclb_policy->lb_channel_connectivity_,
&grpclb_policy->lb_channel_on_connectivity_changed_, nullptr);
break;
}
// The LB channel may be IDLE because it's shut down before the update.
// Restart the LB call to kick the LB channel into gear.
case GRPC_CHANNEL_IDLE:
case GRPC_CHANNEL_READY:
grpclb_policy->lb_calld_.reset();
if (grpclb_policy->started_picking_) {
if (grpclb_policy->retry_timer_callback_pending_) {
grpc_timer_cancel(&grpclb_policy->lb_call_retry_timer_);
}
grpclb_policy->lb_call_backoff_.Reset();
grpclb_policy->StartBalancerCallLocked();
}
// fallthrough
case GRPC_CHANNEL_SHUTDOWN:
done:
grpclb_policy->watching_lb_channel_ = false;
grpclb_policy->Unref(DEBUG_LOCATION,
"watch_lb_channel_connectivity_cb_shutdown");
}
}
//
// PendingPick
//
// Adds lb_token of selected subchannel (address) to the call's initial
// metadata.
grpc_error* AddLbTokenToInitialMetadata(
grpc_mdelem lb_token, grpc_linked_mdelem* lb_token_mdelem_storage,
grpc_metadata_batch* initial_metadata) {
GPR_ASSERT(lb_token_mdelem_storage != nullptr);
GPR_ASSERT(!GRPC_MDISNULL(lb_token));
return grpc_metadata_batch_add_tail(initial_metadata, lb_token_mdelem_storage,
lb_token);
}
// Destroy function used when embedding client stats in call context.
void DestroyClientStats(void* arg) {
static_cast<GrpcLbClientStats*>(arg)->Unref();
}
void GrpcLb::PendingPickSetMetadataAndContext(PendingPick* pp) {
// If connected_subchannel is nullptr, no pick has been made by the RR
// policy (e.g., all addresses failed to connect). There won't be any
// LB token available.
if (pp->pick->connected_subchannel != nullptr) {
const grpc_arg* arg =
grpc_channel_args_find(pp->pick->connected_subchannel->args(),
GRPC_ARG_GRPCLB_ADDRESS_LB_TOKEN);
if (arg != nullptr) {
grpc_mdelem lb_token = {
reinterpret_cast<uintptr_t>(arg->value.pointer.p)};
AddLbTokenToInitialMetadata(GRPC_MDELEM_REF(lb_token),
&pp->pick->lb_token_mdelem_storage,
pp->pick->initial_metadata);
} else {
gpr_log(GPR_ERROR,
"[grpclb %p] No LB token for connected subchannel pick %p",
pp->grpclb_policy, pp->pick);
abort();
}
// Pass on client stats via context. Passes ownership of the reference.
if (pp->client_stats != nullptr) {
pp->pick->subchannel_call_context[GRPC_GRPCLB_CLIENT_STATS].value =
pp->client_stats.release();
pp->pick->subchannel_call_context[GRPC_GRPCLB_CLIENT_STATS].destroy =
DestroyClientStats;
}
} else {
pp->client_stats.reset();
}
}
/* The \a on_complete closure passed as part of the pick requires keeping a
* reference to its associated round robin instance. We wrap this closure in
* order to unref the round robin instance upon its invocation */
void GrpcLb::OnPendingPickComplete(void* arg, grpc_error* error) {
PendingPick* pp = static_cast<PendingPick*>(arg);
PendingPickSetMetadataAndContext(pp);
GRPC_CLOSURE_SCHED(pp->original_on_complete, GRPC_ERROR_REF(error));
Delete(pp);
}
GrpcLb::PendingPick* GrpcLb::PendingPickCreate(PickState* pick) {
PendingPick* pp = New<PendingPick>();
pp->grpclb_policy = this;
pp->pick = pick;
GRPC_CLOSURE_INIT(&pp->on_complete, &GrpcLb::OnPendingPickComplete, pp,
grpc_schedule_on_exec_ctx);
pp->original_on_complete = pick->on_complete;
pick->on_complete = &pp->on_complete;
return pp;
}
void GrpcLb::AddPendingPick(PendingPick* pp) {
pp->next = pending_picks_;
pending_picks_ = pp;
}
//
// code for interacting with the RR policy
//
// Performs a pick over \a rr_policy_. Given that a pick can return
// immediately (ignoring its completion callback), we need to perform the
// cleanups this callback would otherwise be responsible for.
// If \a force_async is true, then we will manually schedule the
// completion callback even if the pick is available immediately.
bool GrpcLb::PickFromRoundRobinPolicyLocked(bool force_async, PendingPick* pp,
grpc_error** error) {
// Check for drops if we are not using fallback backend addresses.
if (serverlist_ != nullptr && serverlist_->num_servers > 0) {
// Look at the index into the serverlist to see if we should drop this call.
grpc_grpclb_server* server = serverlist_->servers[serverlist_index_++];
if (serverlist_index_ == serverlist_->num_servers) {
serverlist_index_ = 0; // Wrap-around.
}
if (server->drop) {
// Update client load reporting stats to indicate the number of
// dropped calls. Note that we have to do this here instead of in
// the client_load_reporting filter, because we do not create a
// subchannel call (and therefore no client_load_reporting filter)
// for dropped calls.
if (lb_calld_ != nullptr && lb_calld_->client_stats() != nullptr) {
lb_calld_->client_stats()->AddCallDroppedLocked(
server->load_balance_token);
}
if (force_async) {
GRPC_CLOSURE_SCHED(pp->original_on_complete, GRPC_ERROR_NONE);
Delete(pp);
return false;
}
Delete(pp);
return true;
}
}
// Set client_stats.
if (lb_calld_ != nullptr && lb_calld_->client_stats() != nullptr) {
pp->client_stats = lb_calld_->client_stats()->Ref();
}
// Pick via the RR policy.
bool pick_done = rr_policy_->PickLocked(pp->pick, error);
if (pick_done) {
PendingPickSetMetadataAndContext(pp);
if (force_async) {
GRPC_CLOSURE_SCHED(pp->original_on_complete, *error);
*error = GRPC_ERROR_NONE;
pick_done = false;
}
Delete(pp);
}
// else, the pending pick will be registered and taken care of by the
// pending pick list inside the RR policy. Eventually,
// OnPendingPickComplete() will be called, which will (among other
// things) add the LB token to the call's initial metadata.
return pick_done;
}
void GrpcLb::CreateRoundRobinPolicyLocked(const Args& args) {
GPR_ASSERT(rr_policy_ == nullptr);
rr_policy_ = LoadBalancingPolicyRegistry::CreateLoadBalancingPolicy(
"round_robin", args);
if (GPR_UNLIKELY(rr_policy_ == nullptr)) {
gpr_log(GPR_ERROR, "[grpclb %p] Failure creating a RoundRobin policy",
this);
return;
}
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO, "[grpclb %p] Created new RR policy %p", this,
rr_policy_.get());
}
// TODO(roth): We currently track this ref manually. Once the new
// ClosureRef API is done, pass the RefCountedPtr<> along with the closure.
auto self = Ref(DEBUG_LOCATION, "on_rr_reresolution_requested");
self.release();
rr_policy_->SetReresolutionClosureLocked(&on_rr_request_reresolution_);
grpc_error* rr_state_error = nullptr;
rr_connectivity_state_ = rr_policy_->CheckConnectivityLocked(&rr_state_error);
// Connectivity state is a function of the RR policy updated/created.
UpdateConnectivityStateFromRoundRobinPolicyLocked(rr_state_error);
// Add the gRPC LB's interested_parties pollset_set to that of the newly
// created RR policy. This will make the RR policy progress upon activity on
// gRPC LB, which in turn is tied to the application's call.
grpc_pollset_set_add_pollset_set(rr_policy_->interested_parties(),
interested_parties());
// Subscribe to changes to the connectivity of the new RR.
// TODO(roth): We currently track this ref manually. Once the new
// ClosureRef API is done, pass the RefCountedPtr<> along with the closure.
self = Ref(DEBUG_LOCATION, "on_rr_connectivity_changed");
self.release();
rr_policy_->NotifyOnStateChangeLocked(&rr_connectivity_state_,
&on_rr_connectivity_changed_);
rr_policy_->ExitIdleLocked();
// Send pending picks to RR policy.
PendingPick* pp;
while ((pp = pending_picks_)) {
pending_picks_ = pp->next;
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO,
"[grpclb %p] Pending pick about to (async) PICK from RR %p", this,
rr_policy_.get());
}
grpc_error* error = GRPC_ERROR_NONE;
PickFromRoundRobinPolicyLocked(true /* force_async */, pp, &error);
}
}
grpc_channel_args* GrpcLb::CreateRoundRobinPolicyArgsLocked() {
ServerAddressList tmp_addresses;
ServerAddressList* addresses = &tmp_addresses;
bool is_backend_from_grpclb_load_balancer = false;
if (serverlist_ != nullptr) {
tmp_addresses = ProcessServerlist(serverlist_);
is_backend_from_grpclb_load_balancer = true;
} else {
// If CreateOrUpdateRoundRobinPolicyLocked() is invoked when we haven't
// received any serverlist from the balancer, we use the fallback backends
// returned by the resolver. Note that the fallback backend list may be
// empty, in which case the new round_robin policy will keep the requested
// picks pending.
GPR_ASSERT(fallback_backend_addresses_ != nullptr);
addresses = fallback_backend_addresses_.get();
}
GPR_ASSERT(addresses != nullptr);
// Replace the server address list in the channel args that we pass down to
// the subchannel.
static const char* keys_to_remove[] = {GRPC_ARG_SERVER_ADDRESS_LIST};
grpc_arg args_to_add[3] = {
CreateServerAddressListChannelArg(addresses),
// A channel arg indicating if the target is a backend inferred from a
// grpclb load balancer.
grpc_channel_arg_integer_create(
const_cast<char*>(
GRPC_ARG_ADDRESS_IS_BACKEND_FROM_GRPCLB_LOAD_BALANCER),
is_backend_from_grpclb_load_balancer),
};
size_t num_args_to_add = 2;
if (is_backend_from_grpclb_load_balancer) {
args_to_add[2] = grpc_channel_arg_integer_create(
const_cast<char*>(GRPC_ARG_INHIBIT_HEALTH_CHECKING), 1);
++num_args_to_add;
}
grpc_channel_args* args = grpc_channel_args_copy_and_add_and_remove(
args_, keys_to_remove, GPR_ARRAY_SIZE(keys_to_remove), args_to_add,
num_args_to_add);
return args;
}
void GrpcLb::CreateOrUpdateRoundRobinPolicyLocked() {
if (shutting_down_) return;
grpc_channel_args* args = CreateRoundRobinPolicyArgsLocked();
GPR_ASSERT(args != nullptr);
if (rr_policy_ != nullptr) {
if (grpc_lb_glb_trace.enabled()) {
gpr_log(GPR_INFO, "[grpclb %p] Updating RR policy %p", this,
rr_policy_.get());
}
rr_policy_->UpdateLocked(*args, nullptr);
} else {
LoadBalancingPolicy::Args lb_policy_args;
lb_policy_args.combiner = combiner();
lb_policy_args.client_channel_factory = client_channel_factory();
lb_policy_args.args = args;
CreateRoundRobinPolicyLocked(lb_policy_args);
}
grpc_channel_args_destroy(args);
}
void GrpcLb::OnRoundRobinRequestReresolutionLocked(void* arg,
grpc_error* error) {
GrpcLb* grpclb_policy = static_cast<GrpcLb*>(arg);
if (grpclb_policy->shutting_down_ || error != GRPC_ERROR_NONE) {
grpclb_policy->Unref(DEBUG_LOCATION, "on_rr_reresolution_requested");
return;
}
if (grpc_lb_glb_trace.enabled()) {
gpr_log(
GPR_INFO,
"[grpclb %p] Re-resolution requested from the internal RR policy (%p).",
grpclb_policy, grpclb_policy->rr_policy_.get());
}
// If we are talking to a balancer, we expect to get updated addresses form
// the balancer, so we can ignore the re-resolution request from the RR
// policy. Otherwise, handle the re-resolution request using the
// grpclb policy's original re-resolution closure.
if (grpclb_policy->lb_calld_ == nullptr ||
!grpclb_policy->lb_calld_->seen_initial_response()) {
grpclb_policy->TryReresolutionLocked(&grpc_lb_glb_trace, GRPC_ERROR_NONE);
}
// Give back the wrapper closure to the RR policy.
grpclb_policy->rr_policy_->SetReresolutionClosureLocked(
&grpclb_policy->on_rr_request_reresolution_);
}
void GrpcLb::UpdateConnectivityStateFromRoundRobinPolicyLocked(
grpc_error* rr_state_error) {
const grpc_connectivity_state curr_glb_state =
grpc_connectivity_state_check(&state_tracker_);
/* The new connectivity status is a function of the previous one and the new
* input coming from the status of the RR policy.
*
* current state (grpclb's)
* |
* v || I | C | R | TF | SD | <- new state (RR's)
* ===++====+=====+=====+======+======+
* I || I | C | R | [I] | [I] |
* ---++----+-----+-----+------+------+
* C || I | C | R | [C] | [C] |
* ---++----+-----+-----+------+------+
* R || I | C | R | [R] | [R] |
* ---++----+-----+-----+------+------+
* TF || I | C | R | [TF] | [TF] |
* ---++----+-----+-----+------+------+
* SD || NA | NA | NA | NA | NA | (*)
* ---++----+-----+-----+------+------+
*
* A [STATE] indicates that the old RR policy is kept. In those cases, STATE
* is the current state of grpclb, which is left untouched.
*
* In summary, if the new state is TRANSIENT_FAILURE or SHUTDOWN, stick to
* the previous RR instance.
*
* Note that the status is never updated to SHUTDOWN as a result of calling
* this function. Only glb_shutdown() has the power to set that state.
*
* (*) This function mustn't be called during shutting down. */
GPR_ASSERT(curr_glb_state != GRPC_CHANNEL_SHUTDOWN);
switch (rr_connectivity_state_) {
case GRPC_CHANNEL_TRANSIENT_FAILURE:
case GRPC_CHANNEL_SHUTDOWN:
GPR_ASSERT(rr_state_error != GRPC_ERROR_NONE);
break;
case GRPC_CHANNEL_IDLE:
case GRPC_CHANNEL_CONNECTING:
case GRPC_CHANNEL_READY:
GPR_ASSERT(rr_state_error == GRPC_ERROR_NONE);
}
if (grpc_lb_glb_trace.enabled()) {
gpr_log(
GPR_INFO,
"[grpclb %p] Setting grpclb's state to %s from new RR policy %p state.",
this, grpc_connectivity_state_name(rr_connectivity_state_),
rr_policy_.get());
}
grpc_connectivity_state_set(&state_tracker_, rr_connectivity_state_,
rr_state_error,
"update_lb_connectivity_status_locked");
}
void GrpcLb::OnRoundRobinConnectivityChangedLocked(void* arg,
grpc_error* error) {
GrpcLb* grpclb_policy = static_cast<GrpcLb*>(arg);
if (grpclb_policy->shutting_down_) {
grpclb_policy->Unref(DEBUG_LOCATION, "on_rr_connectivity_changed");
return;
}
grpclb_policy->UpdateConnectivityStateFromRoundRobinPolicyLocked(
GRPC_ERROR_REF(error));
// Resubscribe. Reuse the "on_rr_connectivity_changed" ref.
grpclb_policy->rr_policy_->NotifyOnStateChangeLocked(
&grpclb_policy->rr_connectivity_state_,
&grpclb_policy->on_rr_connectivity_changed_);
}
//
// factory
//
class GrpcLbFactory : public LoadBalancingPolicyFactory {
public:
OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
const LoadBalancingPolicy::Args& args) const override {
/* Count the number of gRPC-LB addresses. There must be at least one. */
const ServerAddressList* addresses =
FindServerAddressListChannelArg(args.args);
if (addresses == nullptr) return nullptr;
bool found_balancer = false;
for (size_t i = 0; i < addresses->size(); ++i) {
if ((*addresses)[i].IsBalancer()) {
found_balancer = true;
break;
}
}
if (!found_balancer) return nullptr;
return OrphanablePtr<LoadBalancingPolicy>(New<GrpcLb>(args));
}
const char* name() const override { return kGrpclb; }
};
} // namespace
} // namespace grpc_core
//
// Plugin registration
//
namespace {
// Only add client_load_reporting filter if the grpclb LB policy is used.
bool maybe_add_client_load_reporting_filter(grpc_channel_stack_builder* builder,
void* arg) {
const grpc_channel_args* args =
grpc_channel_stack_builder_get_channel_arguments(builder);
const grpc_arg* channel_arg =
grpc_channel_args_find(args, GRPC_ARG_LB_POLICY_NAME);
if (channel_arg != nullptr && channel_arg->type == GRPC_ARG_STRING &&
strcmp(channel_arg->value.string, "grpclb") == 0) {
return grpc_channel_stack_builder_append_filter(
builder, (const grpc_channel_filter*)arg, nullptr, nullptr);
}
return true;
}
} // namespace
void grpc_lb_policy_grpclb_init() {
grpc_core::LoadBalancingPolicyRegistry::Builder::
RegisterLoadBalancingPolicyFactory(
grpc_core::UniquePtr<grpc_core::LoadBalancingPolicyFactory>(
grpc_core::New<grpc_core::GrpcLbFactory>()));
grpc_channel_init_register_stage(GRPC_CLIENT_SUBCHANNEL,
GRPC_CHANNEL_INIT_BUILTIN_PRIORITY,
maybe_add_client_load_reporting_filter,
(void*)&grpc_client_load_reporting_filter);
}
void grpc_lb_policy_grpclb_shutdown() {}