/* * * 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 #include "src/core/lib/iomgr/sockaddr.h" #include "src/core/lib/iomgr/socket_utils.h" #include #include #include #include #include #include #include #include #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/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/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 namespace grpc_core { TraceFlag grpc_lb_glb_trace(false, "glb"); namespace { class GrpcLb : public LoadBalancingPolicy { public: GrpcLb(const grpc_lb_addresses* addresses, const Args& args); void UpdateLocked(const grpc_channel_args& args) 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(ChildRefsList* child_subchannels, 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; // The LB token associated with the pick. This is set via user_data in // the pick. grpc_mdelem lb_token; // Stats for client-side load reporting. RefCountedPtr 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 InternallyRefCountedWithTracing { public: explicit BalancerCallState( RefCountedPtr 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 friend void grpc_core::Delete(T*); ~BalancerCallState(); GrpcLb* grpclb_policy() const { return static_cast(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 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 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 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 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. grpc_lb_addresses* fallback_backend_addresses_ = nullptr; // 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 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 tokens in grpc_lb_addresses 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) { if (token1 > token2) return 1; if (token1 < token2) return -1; return 0; } const grpc_lb_user_data_vtable lb_token_vtable = { lb_token_copy, lb_token_destroy, lb_token_cmp}; // Returns the backend addresses extracted from the given addresses. grpc_lb_addresses* ExtractBackendAddresses(const grpc_lb_addresses* addresses) { // First pass: count the number of backend addresses. size_t num_backends = 0; for (size_t i = 0; i < addresses->num_addresses; ++i) { if (!addresses->addresses[i].is_balancer) { ++num_backends; } } // Second pass: actually populate the addresses and (empty) LB tokens. grpc_lb_addresses* backend_addresses = grpc_lb_addresses_create(num_backends, &lb_token_vtable); size_t num_copied = 0; for (size_t i = 0; i < addresses->num_addresses; ++i) { if (addresses->addresses[i].is_balancer) continue; const grpc_resolved_address* addr = &addresses->addresses[i].address; grpc_lb_addresses_set_address(backend_addresses, num_copied, &addr->addr, addr->len, false /* is_balancer */, nullptr /* balancer_name */, (void*)GRPC_MDELEM_LB_TOKEN_EMPTY.payload); ++num_copied; } return backend_addresses; } 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(sizeof(grpc_sockaddr_in)); grpc_sockaddr_in* addr4 = reinterpret_cast(&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(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. grpc_lb_addresses* ProcessServerlist(const grpc_grpclb_serverlist* serverlist) { size_t num_valid = 0; /* first pass: count how many are valid in order to allocate the necessary * memory in a single block */ for (size_t i = 0; i < serverlist->num_servers; ++i) { if (IsServerValid(serverlist->servers[i], i, true)) ++num_valid; } grpc_lb_addresses* lb_addresses = grpc_lb_addresses_create(num_valid, &lb_token_vtable); /* second pass: actually populate the addresses and LB tokens (aka user data * to the outside world) to be read by the RR policy during its creation. * Given that the validity tests are very cheap, they are performed again * instead of marking the valid ones during the first pass, as this would * incurr in an allocation due to the arbitrary number of server */ size_t addr_idx = 0; for (size_t sl_idx = 0; sl_idx < serverlist->num_servers; ++sl_idx) { const grpc_grpclb_server* server = serverlist->servers[sl_idx]; if (!IsServerValid(serverlist->servers[sl_idx], sl_idx, false)) continue; GPR_ASSERT(addr_idx < num_valid); /* address processing */ grpc_resolved_address addr; ParseServer(server, &addr); /* lb token processing */ void* user_data; 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); user_data = (void*)grpc_mdelem_from_slices(GRPC_MDSTR_LB_TOKEN, lb_token_mdstr) .payload; } 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); user_data = (void*)GRPC_MDELEM_LB_TOKEN_EMPTY.payload; } grpc_lb_addresses_set_address(lb_addresses, addr_idx, &addr.addr, addr.len, false /* is_balancer */, nullptr /* balancer_name */, user_data); ++addr_idx; } GPR_ASSERT(addr_idx == num_valid); return lb_addresses; } // // GrpcLb::BalancerCallState // GrpcLb::BalancerCallState::BalancerCallState( RefCountedPtr parent_grpclb_policy) : InternallyRefCountedWithTracing(&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] Starting LB call (lb_calld: %p, 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(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( 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] call_error=%d", grpclb_policy_.get(), call_error); GPR_ASSERT(GRPC_CALL_OK == call_error); } } void GrpcLb::BalancerCallState::ClientLoadReportDoneLocked(void* arg, grpc_error* error) { BalancerCallState* lb_calld = static_cast(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(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(arg); GrpcLb* grpclb_policy = lb_calld->grpclb_policy(); // Empty 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] Received initial LB response message; " "client load reporting interval = %" PRId64 " milliseconds", grpclb_policy, lb_calld->client_stats_report_interval_); } } else if (grpc_lb_glb_trace.enabled()) { gpr_log(GPR_INFO, "[grpclb %p] Received initial LB response message; client load " "reporting NOT enabled", grpclb_policy); } 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] Serverlist with %" PRIuPTR " servers received", grpclb_policy, 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] Serverlist[%" PRIuPTR "]: %s", grpclb_policy, i, ipport); gpr_free(ipport); } } /* update serverlist */ if (serverlist->num_servers > 0) { // 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()); // 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(); } if (grpc_grpclb_serverlist_equals(grpclb_policy->serverlist_, serverlist)) { if (grpc_lb_glb_trace.enabled()) { gpr_log(GPR_INFO, "[grpclb %p] Incoming server list identical to current, " "ignoring.", grpclb_policy); } 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 { /* or dispose of the fallback */ grpc_lb_addresses_destroy(grpclb_policy->fallback_backend_addresses_); grpclb_policy->fallback_backend_addresses_ = nullptr; if (grpclb_policy->fallback_timer_callback_pending_) { grpc_timer_cancel(&grpclb_policy->lb_fallback_timer_); } } // and update the copy 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 { if (grpc_lb_glb_trace.enabled()) { gpr_log(GPR_INFO, "[grpclb %p] Received empty server list, ignoring.", grpclb_policy); } grpc_grpclb_destroy_serverlist(serverlist); } } else { // No valid initial response or serverlist found. gpr_log(GPR_ERROR, "[grpclb %p] Invalid LB response received: '%s'. Ignoring.", grpclb_policy, grpc_dump_slice(response_slice, GPR_DUMP_ASCII | GPR_DUMP_HEX)); } 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(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] Status from LB server received. Status = %d, details " "= '%s', (lb_calld: %p, lb_call: %p), error '%s'", grpclb_policy, lb_calld->lb_call_status_, status_details, lb_calld, 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 // grpc_lb_addresses* ExtractBalancerAddresses( const grpc_lb_addresses* addresses) { size_t num_grpclb_addrs = 0; for (size_t i = 0; i < addresses->num_addresses; ++i) { if (addresses->addresses[i].is_balancer) ++num_grpclb_addrs; } // There must be at least one balancer address, or else the // client_channel would not have chosen this LB policy. GPR_ASSERT(num_grpclb_addrs > 0); grpc_lb_addresses* lb_addresses = grpc_lb_addresses_create(num_grpclb_addrs, nullptr); size_t lb_addresses_idx = 0; for (size_t i = 0; i < addresses->num_addresses; ++i) { if (!addresses->addresses[i].is_balancer) continue; if (GPR_UNLIKELY(addresses->addresses[i].user_data != nullptr)) { gpr_log(GPR_ERROR, "This LB policy doesn't support user data. It will be ignored"); } grpc_lb_addresses_set_address( lb_addresses, lb_addresses_idx++, addresses->addresses[i].address.addr, addresses->addresses[i].address.len, false /* is balancer */, addresses->addresses[i].balancer_name, nullptr /* user data */); } GPR_ASSERT(num_grpclb_addrs == lb_addresses_idx); return lb_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 grpc_lb_addresses* addresses, FakeResolverResponseGenerator* response_generator, const grpc_channel_args* args) { grpc_lb_addresses* lb_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_LB_ADDRESSES, // 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 LB addresses. // Note that we pass these in both when creating the LB channel // and via the fake resolver. The latter is what actually gets used. grpc_lb_addresses_create_channel_arg(lb_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(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(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. new_args = grpc_lb_policy_grpclb_modify_lb_channel_args(new_args); // Clean up. grpc_lb_addresses_destroy(lb_addresses); return new_args; } // // ctor and dtor // GrpcLb::GrpcLb(const grpc_lb_addresses* addresses, const LoadBalancingPolicy::Args& args) : LoadBalancingPolicy(args), response_generator_(MakeRefCounted()), 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_); } if (fallback_backend_addresses_ != nullptr) { grpc_lb_addresses_destroy(fallback_backend_addresses_); } 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; pp->pick->user_data = nullptr; 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(ChildRefsList* child_subchannels, ChildRefsList* child_channels) { // delegate to the RoundRobin to fill the children subchannels. rr_policy_->FillChildRefsForChannelz(child_subchannels, child_channels); mu_guard guard(&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); } void GrpcLb::ProcessChannelArgsLocked(const grpc_channel_args& args) { const grpc_arg* arg = grpc_channel_args_find(&args, GRPC_ARG_LB_ADDRESSES); if (GPR_UNLIKELY(arg == nullptr || arg->type != GRPC_ARG_POINTER)) { // Ignore this update. gpr_log( GPR_ERROR, "[grpclb %p] No valid LB addresses channel arg in update, ignoring.", this); return; } const grpc_lb_addresses* addresses = static_cast(arg->value.pointer.p); // Update fallback address list. if (fallback_backend_addresses_ != nullptr) { grpc_lb_addresses_destroy(fallback_backend_addresses_); } 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) { ProcessChannelArgsLocked(args); // If fallback is configured and the RR policy already exists, update // it with the new fallback addresses. if (lb_fallback_timeout_ms_ > 0 && 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(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(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(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(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(); } // Fall through. 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(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 * user_data/token available */ if (pp->pick->connected_subchannel != nullptr) { if (GPR_LIKELY(!GRPC_MDISNULL(pp->lb_token))) { AddLbTokenToInitialMetadata(GRPC_MDELEM_REF(pp->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(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(); 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) { // 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 and user_data. if (lb_calld_ != nullptr && lb_calld_->client_stats() != nullptr) { pp->client_stats = lb_calld_->client_stats()->Ref(); } GPR_ASSERT(pp->pick->user_data == nullptr); pp->pick->user_data = (void**)&pp->lb_token; // 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; } // 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() { grpc_lb_addresses* addresses; bool is_backend_from_grpclb_load_balancer = false; if (serverlist_ != nullptr) { GPR_ASSERT(serverlist_->num_servers > 0); 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 = grpc_lb_addresses_copy(fallback_backend_addresses_); } GPR_ASSERT(addresses != nullptr); // Replace the LB addresses in the channel args that we pass down to // the subchannel. static const char* keys_to_remove[] = {GRPC_ARG_LB_ADDRESSES}; const grpc_arg args_to_add[] = { grpc_lb_addresses_create_channel_arg(addresses), // A channel arg indicating if the target is a backend inferred from a // grpclb load balancer. grpc_channel_arg_integer_create( const_cast( GRPC_ARG_ADDRESS_IS_BACKEND_FROM_GRPCLB_LOAD_BALANCER), is_backend_from_grpclb_load_balancer), }; 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, GPR_ARRAY_SIZE(args_to_add)); grpc_lb_addresses_destroy(addresses); 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); } 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); if (grpc_lb_glb_trace.enabled()) { gpr_log(GPR_INFO, "[grpclb %p] Created new RR policy %p", this, rr_policy_.get()); } } grpc_channel_args_destroy(args); } void GrpcLb::OnRoundRobinRequestReresolutionLocked(void* arg, grpc_error* error) { GrpcLb* grpclb_policy = static_cast(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(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 CreateLoadBalancingPolicy( const LoadBalancingPolicy::Args& args) const override { /* Count the number of gRPC-LB addresses. There must be at least one. */ const grpc_arg* arg = grpc_channel_args_find(args.args, GRPC_ARG_LB_ADDRESSES); if (arg == nullptr || arg->type != GRPC_ARG_POINTER) { return nullptr; } grpc_lb_addresses* addresses = static_cast(arg->value.pointer.p); size_t num_grpclb_addrs = 0; for (size_t i = 0; i < addresses->num_addresses; ++i) { if (addresses->addresses[i].is_balancer) ++num_grpclb_addrs; } if (num_grpclb_addrs == 0) return nullptr; return OrphanablePtr(New(addresses, args)); } const char* name() const override { return "grpclb"; } }; } // 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::New())); grpc_channel_init_register_stage(GRPC_CLIENT_SUBCHANNEL, GRPC_CHANNEL_INIT_PRIORITY_LOW, maybe_add_client_load_reporting_filter, (void*)&grpc_client_load_reporting_filter); } void grpc_lb_policy_grpclb_shutdown() {}