/* * * Copyright 2016, Google Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following disclaimer * in the documentation and/or other materials provided with the * distribution. * * Neither the name of Google Inc. nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */ /** Implementation of the gRPC LB policy. * * This policy takes as input a set of resolved addresses {a1..an} for which the * LB set was set (it's the resolver's responsibility to ensure this). That is * to say, {a1..an} represent a collection of LB servers. * * An internal channel (\a glb_lb_policy.lb_channel) is created over {a1..an}. * This channel behaves just like a regular channel. In particular, the * constructed URI over the addresses a1..an will use the default pick first * policy to select from this list of LB server backends. * * The first time the policy gets a request for a pick, a ping, or to exit the * idle state, \a query_for_backends() is called. It creates an instance of \a * lb_client_data, an internal struct meant to contain the data associated with * the internal communication with the LB server. This instance is created via * \a lb_client_data_create(). There, the call over lb_channel to pick-first * from {a1..an} is created, the \a LoadBalancingRequest message is assembled * and all necessary callbacks for the progress of the internal call configured. * * Back in \a query_for_backends(), the internal *streaming* call to the LB * server (whichever address from {a1..an} pick-first chose) is kicked off. * It'll progress over the callbacks configured in \a lb_client_data_create() * (see the field docstrings of \a lb_client_data for more details). * * If the call fails with UNIMPLEMENTED, the original call will also fail. * There's a misconfiguration somewhere: at least one of {a1..an} isn't a LB * server, which contradicts the LB bit being set. If the internal call times * out, the usual behavior of pick-first applies, continuing to pick from the * list {a1..an}. * * Upon sucesss, a \a LoadBalancingResponse is expected in \a res_recv_cb. An * invalid one results in the termination of the streaming call. A new streaming * call should be created if possible, failing the original call otherwise. * For a valid \a LoadBalancingResponse, the server list of actual backends is * extracted. A Round Robin policy will be created from this list. There are two * possible scenarios: * * 1. This is the first server list received. There was no previous instance of * the Round Robin policy. \a rr_handover() will instantiate the RR policy * and perform all the pending operations over it. * 2. There's already a RR policy instance active. We need to introduce the new * one build from the new serverlist, but taking care not to disrupt the * operations in progress over the old RR instance. This is done by * decreasing the reference count on the old policy. The moment no more * references are held on the old RR policy, it'll be destroyed and \a * rr_connectivity_changed notified with a \a GRPC_CHANNEL_SHUTDOWN state. * At this point we can transition to a new RR instance safely, which is done * once again via \a rr_handover(). * * * Once a RR policy instance is in place (and getting updated as described), * calls to 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 * (ie, right after the creation of the gRPCLB policy, if an empty serverlist * is received, etc), pick/ping requests are added to a list of pending * picks/pings to be flushed and serviced as part of \a rr_handover() the moment * 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. */ /* TODO(dgq): * - Implement LB service forwarding (point 2c. in the doc's diagram). */ #include #include #include #include #include #include #include "src/core/ext/client_config/client_channel_factory.h" #include "src/core/ext/client_config/lb_policy_registry.h" #include "src/core/ext/client_config/parse_address.h" #include "src/core/ext/lb_policy/grpclb/grpclb.h" #include "src/core/ext/lb_policy/grpclb/load_balancer_api.h" #include "src/core/lib/iomgr/sockaddr_utils.h" #include "src/core/lib/support/string.h" #include "src/core/lib/surface/call.h" #include "src/core/lib/surface/channel.h" int grpc_lb_glb_trace = 0; typedef struct wrapped_rr_closure_arg { /* the original closure. Usually a on_complete/notify cb for pick() and ping() * calls against the internal RR instance, respectively. */ grpc_closure *wrapped_closure; /* The RR instance related to the closure */ grpc_lb_policy *rr_policy; /* when not NULL, represents a pending_{pick,ping} node to be freed upon * closure execution */ void *owning_pending_node; /* to be freed if not NULL */ } wrapped_rr_closure_arg; /* 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 */ static void wrapped_rr_closure(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) { wrapped_rr_closure_arg *wc_arg = arg; if (wc_arg->rr_policy != NULL) { if (grpc_lb_glb_trace) { gpr_log(GPR_INFO, "Unreffing RR (0x%" PRIxPTR ")", (intptr_t)wc_arg->rr_policy); } GRPC_LB_POLICY_UNREF(exec_ctx, wc_arg->rr_policy, "wrapped_rr_closure"); } GPR_ASSERT(wc_arg->wrapped_closure != NULL); grpc_exec_ctx_sched(exec_ctx, wc_arg->wrapped_closure, error, NULL); gpr_free(wc_arg->owning_pending_node); } /* 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/updated. * * One particularity is the wrapping of the user-provided \a on_complete closure * (in \a wrapped_on_complete and \a wrapped_on_complete_arg). This is needed in * order to correctly unref the RR policy instance upon completion of the pick. * See \a wrapped_rr_closure for details. */ typedef struct pending_pick { struct pending_pick *next; /* polling entity for the pick()'s async notification */ grpc_polling_entity *pollent; /* the initial metadata for the pick. See grpc_lb_policy_pick() */ grpc_metadata_batch *initial_metadata; /* bitmask passed to pick() and used for selective cancelling. See * grpc_lb_policy_cancel_picks() */ uint32_t initial_metadata_flags; /* output argument where to store the pick()ed connected subchannel, or NULL * upon error. */ grpc_connected_subchannel **target; /* a closure wrapping the original on_complete one to be invoked once the * pick() has completed (regardless of success) */ grpc_closure wrapped_on_complete; /* args for wrapped_on_complete */ wrapped_rr_closure_arg wrapped_on_complete_arg; } pending_pick; static void add_pending_pick(pending_pick **root, grpc_polling_entity *pollent, grpc_metadata_batch *initial_metadata, uint32_t initial_metadata_flags, grpc_connected_subchannel **target, grpc_closure *on_complete) { pending_pick *pp = gpr_malloc(sizeof(*pp)); memset(pp, 0, sizeof(pending_pick)); memset(&pp->wrapped_on_complete_arg, 0, sizeof(wrapped_rr_closure_arg)); pp->next = *root; pp->pollent = pollent; pp->target = target; pp->initial_metadata = initial_metadata; pp->initial_metadata_flags = initial_metadata_flags; pp->wrapped_on_complete_arg.wrapped_closure = on_complete; grpc_closure_init(&pp->wrapped_on_complete, wrapped_rr_closure, &pp->wrapped_on_complete_arg); *root = pp; } /* Same as the \a pending_pick struct but for ping operations */ typedef struct pending_ping { struct pending_ping *next; /* a closure wrapping the original on_complete one to be invoked once the * ping() has completed (regardless of success) */ grpc_closure wrapped_notify; /* args for wrapped_notify */ wrapped_rr_closure_arg wrapped_notify_arg; } pending_ping; static void add_pending_ping(pending_ping **root, grpc_closure *notify) { pending_ping *pping = gpr_malloc(sizeof(*pping)); memset(pping, 0, sizeof(pending_ping)); memset(&pping->wrapped_notify_arg, 0, sizeof(wrapped_rr_closure_arg)); pping->next = *root; grpc_closure_init(&pping->wrapped_notify, wrapped_rr_closure, &pping->wrapped_notify_arg); pping->wrapped_notify_arg.wrapped_closure = notify; *root = pping; } /* * glb_lb_policy */ typedef struct rr_connectivity_data rr_connectivity_data; typedef struct lb_client_data lb_client_data; static const grpc_lb_policy_vtable glb_lb_policy_vtable; typedef struct glb_lb_policy { /** base policy: must be first */ grpc_lb_policy base; /** mutex protecting remaining members */ gpr_mu mu; grpc_client_channel_factory *cc_factory; /** for communicating with the LB server */ grpc_channel *lb_channel; /** the RR policy to use of the backend servers returned by the LB server */ grpc_lb_policy *rr_policy; bool started_picking; /** our connectivity state tracker */ grpc_connectivity_state_tracker state_tracker; /** stores the deserialized response from the LB. May be NULL until one such * response has arrived. */ grpc_grpclb_serverlist *serverlist; /** list of picks that are waiting on RR's policy connectivity */ pending_pick *pending_picks; /** list of pings that are waiting on RR's policy connectivity */ pending_ping *pending_pings; /** client data associated with the LB server communication */ lb_client_data *lb_client; /** for tracking of the RR connectivity */ rr_connectivity_data *rr_connectivity; /* a wrapped (see \a wrapped_rr_closure) on-complete closure for readily * available RR picks */ grpc_closure wrapped_on_complete; /* arguments for the wrapped_on_complete closure */ wrapped_rr_closure_arg wc_arg; } glb_lb_policy; /* Keeps track and reacts to changes in connectivity of the RR instance */ struct rr_connectivity_data { grpc_closure on_change; grpc_connectivity_state state; glb_lb_policy *glb_policy; }; static grpc_lb_policy *create_rr(grpc_exec_ctx *exec_ctx, const grpc_grpclb_serverlist *serverlist, glb_lb_policy *glb_policy) { /* TODO(dgq): support mixed ip version */ GPR_ASSERT(serverlist != NULL && serverlist->num_servers > 0); char **host_ports = gpr_malloc(sizeof(char *) * serverlist->num_servers); for (size_t i = 0; i < serverlist->num_servers; ++i) { gpr_join_host_port(&host_ports[i], serverlist->servers[i]->ip_address, serverlist->servers[i]->port); } size_t uri_path_len; char *concat_ipports = gpr_strjoin_sep( (const char **)host_ports, serverlist->num_servers, ",", &uri_path_len); grpc_lb_policy_args args; args.client_channel_factory = glb_policy->cc_factory; args.addresses = gpr_malloc(sizeof(grpc_resolved_addresses)); args.addresses->naddrs = serverlist->num_servers; args.addresses->addrs = gpr_malloc(sizeof(grpc_resolved_address) * args.addresses->naddrs); size_t out_addrs_idx = 0; for (size_t i = 0; i < serverlist->num_servers; ++i) { grpc_uri uri; struct sockaddr_storage sa; size_t sa_len; uri.path = host_ports[i]; if (parse_ipv4(&uri, &sa, &sa_len)) { /* TODO(dgq): add support for ipv6 */ memcpy(args.addresses->addrs[out_addrs_idx].addr, &sa, sa_len); args.addresses->addrs[out_addrs_idx].len = sa_len; ++out_addrs_idx; } else { gpr_log(GPR_ERROR, "Invalid LB service address '%s', ignoring.", host_ports[i]); } } grpc_lb_policy *rr = grpc_lb_policy_create(exec_ctx, "round_robin", &args); gpr_free(concat_ipports); for (size_t i = 0; i < serverlist->num_servers; i++) { gpr_free(host_ports[i]); } gpr_free(host_ports); gpr_free(args.addresses->addrs); gpr_free(args.addresses); return rr; } static void rr_handover(grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy, grpc_error *error) { GRPC_ERROR_REF(error); glb_policy->rr_policy = create_rr(exec_ctx, glb_policy->serverlist, glb_policy); if (grpc_lb_glb_trace) { gpr_log(GPR_INFO, "Created RR policy (0x%" PRIxPTR ")", (intptr_t)glb_policy->rr_policy); } GPR_ASSERT(glb_policy->rr_policy != NULL); glb_policy->rr_connectivity->state = grpc_lb_policy_check_connectivity( exec_ctx, glb_policy->rr_policy, &error); grpc_lb_policy_notify_on_state_change( exec_ctx, glb_policy->rr_policy, &glb_policy->rr_connectivity->state, &glb_policy->rr_connectivity->on_change); grpc_connectivity_state_set(exec_ctx, &glb_policy->state_tracker, glb_policy->rr_connectivity->state, error, "rr_handover"); grpc_lb_policy_exit_idle(exec_ctx, glb_policy->rr_policy); /* flush pending ops */ pending_pick *pp; while ((pp = glb_policy->pending_picks)) { glb_policy->pending_picks = pp->next; GRPC_LB_POLICY_REF(glb_policy->rr_policy, "rr_handover_pending_pick"); pp->wrapped_on_complete_arg.rr_policy = glb_policy->rr_policy; if (grpc_lb_glb_trace) { gpr_log(GPR_INFO, "Pending pick about to PICK from 0x%" PRIxPTR "", (intptr_t)glb_policy->rr_policy); } grpc_lb_policy_pick(exec_ctx, glb_policy->rr_policy, pp->pollent, pp->initial_metadata, pp->initial_metadata_flags, pp->target, &pp->wrapped_on_complete); pp->wrapped_on_complete_arg.owning_pending_node = pp; } pending_ping *pping; while ((pping = glb_policy->pending_pings)) { glb_policy->pending_pings = pping->next; GRPC_LB_POLICY_REF(glb_policy->rr_policy, "rr_handover_pending_ping"); pping->wrapped_notify_arg.rr_policy = glb_policy->rr_policy; if (grpc_lb_glb_trace) { gpr_log(GPR_INFO, "Pending ping about to PING from 0x%" PRIxPTR "", (intptr_t)glb_policy->rr_policy); } grpc_lb_policy_ping_one(exec_ctx, glb_policy->rr_policy, &pping->wrapped_notify); pping->wrapped_notify_arg.owning_pending_node = pping; } GRPC_ERROR_UNREF(error); } static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) { rr_connectivity_data *rr_conn_data = arg; glb_lb_policy *glb_policy = rr_conn_data->glb_policy; if (rr_conn_data->state == GRPC_CHANNEL_SHUTDOWN) { if (glb_policy->serverlist != NULL) { /* a RR policy is shutting down but there's a serverlist available -> * perform a handover */ rr_handover(exec_ctx, glb_policy, error); } else { /* shutting down and no new serverlist available. Bail out. */ gpr_free(rr_conn_data); } } else { if (error == GRPC_ERROR_NONE) { /* RR not shutting down. Mimic the RR's policy state */ grpc_connectivity_state_set(exec_ctx, &glb_policy->state_tracker, rr_conn_data->state, error, "rr_connectivity_changed"); /* resubscribe */ grpc_lb_policy_notify_on_state_change(exec_ctx, glb_policy->rr_policy, &rr_conn_data->state, &rr_conn_data->on_change); } else { /* error */ gpr_free(rr_conn_data); } } GRPC_ERROR_UNREF(error); } static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx, grpc_lb_policy_factory *factory, grpc_lb_policy_args *args) { glb_lb_policy *glb_policy = gpr_malloc(sizeof(*glb_policy)); memset(glb_policy, 0, sizeof(*glb_policy)); /* All input addresses in args->addresses come from a resolver that claims * they are LB services. It's the resolver's responsibility to make sure this * policy is only instantiated and used in that case. * * Create a client channel over them to communicate with a LB service */ glb_policy->cc_factory = args->client_channel_factory; GPR_ASSERT(glb_policy->cc_factory != NULL); if (args->addresses->naddrs == 0) { return NULL; } /* construct a target from the args->addresses, in the form * ipvX://ip1:port1,ip2:port2,... * TODO(dgq): support mixed ip version */ char **addr_strs = gpr_malloc(sizeof(char *) * args->addresses->naddrs); addr_strs[0] = grpc_sockaddr_to_uri((const struct sockaddr *)&args->addresses->addrs[0]); for (size_t i = 1; i < args->addresses->naddrs; i++) { GPR_ASSERT(grpc_sockaddr_to_string( &addr_strs[i], (const struct sockaddr *)&args->addresses->addrs[i], true) == 0); } size_t uri_path_len; char *target_uri_str = gpr_strjoin_sep( (const char **)addr_strs, args->addresses->naddrs, ",", &uri_path_len); /* will pick using pick_first */ glb_policy->lb_channel = grpc_client_channel_factory_create_channel( exec_ctx, glb_policy->cc_factory, target_uri_str, GRPC_CLIENT_CHANNEL_TYPE_LOAD_BALANCING, NULL); gpr_free(target_uri_str); for (size_t i = 0; i < args->addresses->naddrs; i++) { gpr_free(addr_strs[i]); } gpr_free(addr_strs); if (glb_policy->lb_channel == NULL) { gpr_free(glb_policy); return NULL; } rr_connectivity_data *rr_connectivity = gpr_malloc(sizeof(rr_connectivity_data)); memset(rr_connectivity, 0, sizeof(rr_connectivity_data)); grpc_closure_init(&rr_connectivity->on_change, rr_connectivity_changed, rr_connectivity); rr_connectivity->glb_policy = glb_policy; glb_policy->rr_connectivity = rr_connectivity; grpc_lb_policy_init(&glb_policy->base, &glb_lb_policy_vtable); gpr_mu_init(&glb_policy->mu); grpc_connectivity_state_init(&glb_policy->state_tracker, GRPC_CHANNEL_IDLE, "grpclb"); return &glb_policy->base; } static void glb_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { glb_lb_policy *glb_policy = (glb_lb_policy *)pol; GPR_ASSERT(glb_policy->pending_picks == NULL); GPR_ASSERT(glb_policy->pending_pings == NULL); grpc_channel_destroy(glb_policy->lb_channel); glb_policy->lb_channel = NULL; grpc_connectivity_state_destroy(exec_ctx, &glb_policy->state_tracker); if (glb_policy->serverlist != NULL) { grpc_grpclb_destroy_serverlist(glb_policy->serverlist); } gpr_mu_destroy(&glb_policy->mu); gpr_free(glb_policy); } static void glb_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { glb_lb_policy *glb_policy = (glb_lb_policy *)pol; gpr_mu_lock(&glb_policy->mu); pending_pick *pp = glb_policy->pending_picks; glb_policy->pending_picks = NULL; pending_ping *pping = glb_policy->pending_pings; glb_policy->pending_pings = NULL; gpr_mu_unlock(&glb_policy->mu); while (pp != NULL) { pending_pick *next = pp->next; *pp->target = NULL; grpc_exec_ctx_sched(exec_ctx, &pp->wrapped_on_complete, GRPC_ERROR_NONE, NULL); gpr_free(pp); pp = next; } while (pping != NULL) { pending_ping *next = pping->next; grpc_exec_ctx_sched(exec_ctx, &pping->wrapped_notify, GRPC_ERROR_NONE, NULL); pping = next; } if (glb_policy->rr_policy) { /* unsubscribe */ grpc_lb_policy_notify_on_state_change( exec_ctx, glb_policy->rr_policy, NULL, &glb_policy->rr_connectivity->on_change); GRPC_LB_POLICY_UNREF(exec_ctx, glb_policy->rr_policy, "glb_shutdown"); } grpc_connectivity_state_set( exec_ctx, &glb_policy->state_tracker, GRPC_CHANNEL_SHUTDOWN, GRPC_ERROR_CREATE("Channel Shutdown"), "glb_shutdown"); } static void glb_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_connected_subchannel **target) { glb_lb_policy *glb_policy = (glb_lb_policy *)pol; gpr_mu_lock(&glb_policy->mu); pending_pick *pp = glb_policy->pending_picks; glb_policy->pending_picks = NULL; while (pp != NULL) { pending_pick *next = pp->next; if (pp->target == target) { grpc_polling_entity_del_from_pollset_set( exec_ctx, pp->pollent, glb_policy->base.interested_parties); *target = NULL; grpc_exec_ctx_sched(exec_ctx, &pp->wrapped_on_complete, GRPC_ERROR_CANCELLED, NULL); gpr_free(pp); } else { pp->next = glb_policy->pending_picks; glb_policy->pending_picks = pp; } pp = next; } gpr_mu_unlock(&glb_policy->mu); } static grpc_call *lb_client_data_get_call(lb_client_data *lb_client); static void glb_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, uint32_t initial_metadata_flags_mask, uint32_t initial_metadata_flags_eq) { glb_lb_policy *glb_policy = (glb_lb_policy *)pol; gpr_mu_lock(&glb_policy->mu); if (glb_policy->lb_client != NULL) { /* cancel the call to the load balancer service, if any */ grpc_call_cancel(lb_client_data_get_call(glb_policy->lb_client), NULL); } pending_pick *pp = glb_policy->pending_picks; glb_policy->pending_picks = NULL; while (pp != NULL) { pending_pick *next = pp->next; if ((pp->initial_metadata_flags & initial_metadata_flags_mask) == initial_metadata_flags_eq) { grpc_polling_entity_del_from_pollset_set( exec_ctx, pp->pollent, glb_policy->base.interested_parties); grpc_exec_ctx_sched(exec_ctx, &pp->wrapped_on_complete, GRPC_ERROR_CANCELLED, NULL); gpr_free(pp); } else { pp->next = glb_policy->pending_picks; glb_policy->pending_picks = pp; } pp = next; } gpr_mu_unlock(&glb_policy->mu); } static void query_for_backends(grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy); static void start_picking(grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy) { glb_policy->started_picking = true; query_for_backends(exec_ctx, glb_policy); } static void glb_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { glb_lb_policy *glb_policy = (glb_lb_policy *)pol; gpr_mu_lock(&glb_policy->mu); if (!glb_policy->started_picking) { start_picking(exec_ctx, glb_policy); } gpr_mu_unlock(&glb_policy->mu); } static int glb_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_polling_entity *pollent, grpc_metadata_batch *initial_metadata, uint32_t initial_metadata_flags, grpc_connected_subchannel **target, grpc_closure *on_complete) { glb_lb_policy *glb_policy = (glb_lb_policy *)pol; gpr_mu_lock(&glb_policy->mu); int r; if (glb_policy->rr_policy != NULL) { if (grpc_lb_glb_trace) { gpr_log(GPR_INFO, "about to PICK from 0x%" PRIxPTR "", (intptr_t)glb_policy->rr_policy); } GRPC_LB_POLICY_REF(glb_policy->rr_policy, "glb_pick"); memset(&glb_policy->wc_arg, 0, sizeof(wrapped_rr_closure_arg)); glb_policy->wc_arg.rr_policy = glb_policy->rr_policy; glb_policy->wc_arg.wrapped_closure = on_complete; grpc_closure_init(&glb_policy->wrapped_on_complete, wrapped_rr_closure, &glb_policy->wc_arg); r = grpc_lb_policy_pick(exec_ctx, glb_policy->rr_policy, pollent, initial_metadata, initial_metadata_flags, target, &glb_policy->wrapped_on_complete); if (r != 0) { /* the call to grpc_lb_policy_pick has been sychronous. Unreffing the RR * policy and notify the original callback */ glb_policy->wc_arg.wrapped_closure = NULL; if (grpc_lb_glb_trace) { gpr_log(GPR_INFO, "Unreffing RR (0x%" PRIxPTR ")", (intptr_t)glb_policy->wc_arg.rr_policy); } GRPC_LB_POLICY_UNREF(exec_ctx, glb_policy->wc_arg.rr_policy, "glb_pick"); grpc_exec_ctx_sched(exec_ctx, glb_policy->wc_arg.wrapped_closure, GRPC_ERROR_NONE, NULL); } } else { grpc_polling_entity_add_to_pollset_set(exec_ctx, pollent, glb_policy->base.interested_parties); add_pending_pick(&glb_policy->pending_picks, pollent, initial_metadata, initial_metadata_flags, target, on_complete); if (!glb_policy->started_picking) { start_picking(exec_ctx, glb_policy); } r = 0; } gpr_mu_unlock(&glb_policy->mu); return r; } static grpc_connectivity_state glb_check_connectivity( grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_error **connectivity_error) { glb_lb_policy *glb_policy = (glb_lb_policy *)pol; grpc_connectivity_state st; gpr_mu_lock(&glb_policy->mu); st = grpc_connectivity_state_check(&glb_policy->state_tracker, connectivity_error); gpr_mu_unlock(&glb_policy->mu); return st; } static void glb_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_closure *closure) { glb_lb_policy *glb_policy = (glb_lb_policy *)pol; gpr_mu_lock(&glb_policy->mu); if (glb_policy->rr_policy) { grpc_lb_policy_ping_one(exec_ctx, glb_policy->rr_policy, closure); } else { add_pending_ping(&glb_policy->pending_pings, closure); if (!glb_policy->started_picking) { start_picking(exec_ctx, glb_policy); } } gpr_mu_unlock(&glb_policy->mu); } static void glb_notify_on_state_change(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_connectivity_state *current, grpc_closure *notify) { glb_lb_policy *glb_policy = (glb_lb_policy *)pol; gpr_mu_lock(&glb_policy->mu); grpc_connectivity_state_notify_on_state_change( exec_ctx, &glb_policy->state_tracker, current, notify); gpr_mu_unlock(&glb_policy->mu); } /* * lb_client_data * * Used internally for the client call to the LB */ typedef struct lb_client_data { gpr_mu mu; /* called once initial metadata's been sent */ grpc_closure md_sent; /* called once initial metadata's been received */ grpc_closure md_rcvd; /* called once the LoadBalanceRequest has been sent to the LB server. See * src/proto/grpc/.../load_balancer.proto */ grpc_closure req_sent; /* A response from the LB server has been received (or error). Process it */ grpc_closure res_rcvd; /* After the client has sent a close to the LB server */ grpc_closure close_sent; /* ... and the status from the LB server has been received */ grpc_closure srv_status_rcvd; grpc_call *lb_call; /* streaming call to the LB server, */ gpr_timespec deadline; /* for the streaming call to the LB server */ grpc_metadata_array initial_metadata_recv; /* initial MD from LB server */ grpc_metadata_array trailing_metadata_recv; /* trailing MD from LB server */ /* what's being sent to the LB server. Note that its value may vary if the LB * server indicates a redirect. */ grpc_byte_buffer *request_payload; /* response from the LB server, if any. Processed in res_recv_cb() */ grpc_byte_buffer *response_payload; /* the call's status and status detailset in srv_status_rcvd_cb() */ grpc_status_code status; char *status_details; size_t status_details_capacity; /* pointer back to the enclosing policy */ glb_lb_policy *glb_policy; } lb_client_data; static void md_sent_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error); static void md_recv_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error); static void req_sent_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error); static void res_recv_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error); static void close_sent_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error); static void srv_status_rcvd_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error); static lb_client_data *lb_client_data_create(glb_lb_policy *glb_policy) { lb_client_data *lb_client = gpr_malloc(sizeof(lb_client_data)); memset(lb_client, 0, sizeof(lb_client_data)); gpr_mu_init(&lb_client->mu); grpc_closure_init(&lb_client->md_sent, md_sent_cb, lb_client); grpc_closure_init(&lb_client->md_rcvd, md_recv_cb, lb_client); grpc_closure_init(&lb_client->req_sent, req_sent_cb, lb_client); grpc_closure_init(&lb_client->res_rcvd, res_recv_cb, lb_client); grpc_closure_init(&lb_client->close_sent, close_sent_cb, lb_client); grpc_closure_init(&lb_client->srv_status_rcvd, srv_status_rcvd_cb, lb_client); /* TODO(dgq): get the deadline from the client config instead of fabricating * one here. */ lb_client->deadline = gpr_time_add(gpr_now(GPR_CLOCK_MONOTONIC), gpr_time_from_seconds(3, GPR_TIMESPAN)); lb_client->lb_call = grpc_channel_create_pollset_set_call( glb_policy->lb_channel, NULL, GRPC_PROPAGATE_DEFAULTS, glb_policy->base.interested_parties, "/BalanceLoad", NULL, /* FIXME(dgq): which "host" value to use? */ lb_client->deadline, NULL); grpc_metadata_array_init(&lb_client->initial_metadata_recv); grpc_metadata_array_init(&lb_client->trailing_metadata_recv); grpc_grpclb_request *request = grpc_grpclb_request_create( "load.balanced.service.name"); /* FIXME(dgq): get the name of the load balanced service from the resolver */ gpr_slice request_payload_slice = grpc_grpclb_request_encode(request); lb_client->request_payload = grpc_raw_byte_buffer_create(&request_payload_slice, 1); gpr_slice_unref(request_payload_slice); grpc_grpclb_request_destroy(request); lb_client->status_details = NULL; lb_client->status_details_capacity = 0; lb_client->glb_policy = glb_policy; return lb_client; } static void lb_client_data_destroy(lb_client_data *lb_client) { grpc_metadata_array_destroy(&lb_client->initial_metadata_recv); grpc_metadata_array_destroy(&lb_client->trailing_metadata_recv); grpc_byte_buffer_destroy(lb_client->request_payload); gpr_free(lb_client->status_details); gpr_mu_destroy(&lb_client->mu); gpr_free(lb_client); } static grpc_call *lb_client_data_get_call(lb_client_data *lb_client) { return lb_client->lb_call; } /* * Auxiliary functions and LB client callbacks. */ static void query_for_backends(grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy) { GPR_ASSERT(glb_policy->lb_channel != NULL); glb_policy->lb_client = lb_client_data_create(glb_policy); grpc_call_error call_error; grpc_op ops[1]; memset(ops, 0, sizeof(ops)); grpc_op *op = ops; op->op = GRPC_OP_SEND_INITIAL_METADATA; op->data.send_initial_metadata.count = 0; op->flags = 0; op->reserved = NULL; op++; call_error = grpc_call_start_batch_and_execute( exec_ctx, glb_policy->lb_client->lb_call, ops, (size_t)(op - ops), &glb_policy->lb_client->md_sent); GPR_ASSERT(GRPC_CALL_OK == call_error); op = ops; op->op = GRPC_OP_RECV_STATUS_ON_CLIENT; op->data.recv_status_on_client.trailing_metadata = &glb_policy->lb_client->trailing_metadata_recv; op->data.recv_status_on_client.status = &glb_policy->lb_client->status; op->data.recv_status_on_client.status_details = &glb_policy->lb_client->status_details; op->data.recv_status_on_client.status_details_capacity = &glb_policy->lb_client->status_details_capacity; op->flags = 0; op->reserved = NULL; op++; call_error = grpc_call_start_batch_and_execute( exec_ctx, glb_policy->lb_client->lb_call, ops, (size_t)(op - ops), &glb_policy->lb_client->srv_status_rcvd); GPR_ASSERT(GRPC_CALL_OK == call_error); } static void md_sent_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) { lb_client_data *lb_client = arg; GPR_ASSERT(lb_client->lb_call); grpc_op ops[1]; memset(ops, 0, sizeof(ops)); grpc_op *op = ops; op->op = GRPC_OP_RECV_INITIAL_METADATA; op->data.recv_initial_metadata = &lb_client->initial_metadata_recv; op->flags = 0; op->reserved = NULL; op++; grpc_call_error call_error = grpc_call_start_batch_and_execute( exec_ctx, lb_client->lb_call, ops, (size_t)(op - ops), &lb_client->md_rcvd); GPR_ASSERT(GRPC_CALL_OK == call_error); } static void md_recv_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) { lb_client_data *lb_client = arg; GPR_ASSERT(lb_client->lb_call); grpc_op ops[1]; memset(ops, 0, sizeof(ops)); grpc_op *op = ops; op->op = GRPC_OP_SEND_MESSAGE; op->data.send_message = lb_client->request_payload; op->flags = 0; op->reserved = NULL; op++; grpc_call_error call_error = grpc_call_start_batch_and_execute( exec_ctx, lb_client->lb_call, ops, (size_t)(op - ops), &lb_client->req_sent); GPR_ASSERT(GRPC_CALL_OK == call_error); } static void req_sent_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) { lb_client_data *lb_client = arg; grpc_op ops[1]; memset(ops, 0, sizeof(ops)); grpc_op *op = ops; op->op = GRPC_OP_RECV_MESSAGE; op->data.recv_message = &lb_client->response_payload; op->flags = 0; op->reserved = NULL; op++; grpc_call_error call_error = grpc_call_start_batch_and_execute( exec_ctx, lb_client->lb_call, ops, (size_t)(op - ops), &lb_client->res_rcvd); GPR_ASSERT(GRPC_CALL_OK == call_error); } static void res_recv_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) { lb_client_data *lb_client = arg; grpc_op ops[2]; memset(ops, 0, sizeof(ops)); grpc_op *op = ops; if (lb_client->response_payload != NULL) { /* Received data from the LB server. Look inside * lb_client->response_payload, for * a serverlist. */ grpc_byte_buffer_reader bbr; grpc_byte_buffer_reader_init(&bbr, lb_client->response_payload); gpr_slice response_slice = grpc_byte_buffer_reader_readall(&bbr); grpc_byte_buffer_destroy(lb_client->response_payload); grpc_grpclb_serverlist *serverlist = grpc_grpclb_response_parse_serverlist(response_slice); if (serverlist != NULL) { gpr_slice_unref(response_slice); if (grpc_lb_glb_trace) { gpr_log(GPR_INFO, "Serverlist with %zu servers received", serverlist->num_servers); } /* update serverlist */ if (serverlist->num_servers > 0) { if (grpc_grpclb_serverlist_equals(lb_client->glb_policy->serverlist, serverlist)) { if (grpc_lb_glb_trace) { gpr_log(GPR_INFO, "Incoming server list identical to current, ignoring."); } } else { /* new serverlist */ if (lb_client->glb_policy->serverlist != NULL) { /* dispose of the old serverlist */ grpc_grpclb_destroy_serverlist(lb_client->glb_policy->serverlist); } /* and update the copy in the glb_lb_policy instance */ lb_client->glb_policy->serverlist = serverlist; } if (lb_client->glb_policy->rr_policy == NULL) { /* initial "handover", in this case from a null RR policy, meaning * it'll just create the first RR policy instance */ rr_handover(exec_ctx, lb_client->glb_policy, error); } else { /* unref the RR policy, eventually leading to its substitution with a * new one constructed from the received serverlist (see * rr_connectivity_changed) */ GRPC_LB_POLICY_UNREF(exec_ctx, lb_client->glb_policy->rr_policy, "serverlist_received"); } } else { if (grpc_lb_glb_trace) { gpr_log(GPR_INFO, "Received empty server list. Picks will stay pending until a " "response with > 0 servers is received"); } } /* keep listening for serverlist updates */ op->op = GRPC_OP_RECV_MESSAGE; op->data.recv_message = &lb_client->response_payload; op->flags = 0; op->reserved = NULL; op++; const grpc_call_error call_error = grpc_call_start_batch_and_execute( exec_ctx, lb_client->lb_call, ops, (size_t)(op - ops), &lb_client->res_rcvd); /* loop */ GPR_ASSERT(GRPC_CALL_OK == call_error); return; } GPR_ASSERT(serverlist == NULL); gpr_log(GPR_ERROR, "Invalid LB response received: '%s'", gpr_dump_slice(response_slice, GPR_DUMP_ASCII)); gpr_slice_unref(response_slice); /* Disconnect from server returning invalid response. */ op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT; op->flags = 0; op->reserved = NULL; op++; grpc_call_error call_error = grpc_call_start_batch_and_execute( exec_ctx, lb_client->lb_call, ops, (size_t)(op - ops), &lb_client->close_sent); GPR_ASSERT(GRPC_CALL_OK == call_error); } /* empty payload: call cancelled by server. Cleanups happening in * srv_status_rcvd_cb */ } static void close_sent_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) { if (grpc_lb_glb_trace) { gpr_log(GPR_INFO, "Close from LB client sent. Waiting from server status now"); } } static void srv_status_rcvd_cb(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) { lb_client_data *lb_client = arg; glb_lb_policy *glb_policy = lb_client->glb_policy; if (grpc_lb_glb_trace) { gpr_log(GPR_INFO, "status from lb server received. Status = %d, Details = '%s', " "Capaticy " "= %zu", lb_client->status, lb_client->status_details, lb_client->status_details_capacity); } grpc_call_destroy(lb_client->lb_call); lb_client_data_destroy(lb_client); glb_policy->lb_client = NULL; /* TODO(dgq): deal with stream termination properly (fire up another one? fail * the original call?) */ } /* Code wiring the policy with the rest of the core */ static const grpc_lb_policy_vtable glb_lb_policy_vtable = { glb_destroy, glb_shutdown, glb_pick, glb_cancel_pick, glb_cancel_picks, glb_ping_one, glb_exit_idle, glb_check_connectivity, glb_notify_on_state_change}; static void glb_factory_ref(grpc_lb_policy_factory *factory) {} static void glb_factory_unref(grpc_lb_policy_factory *factory) {} static const grpc_lb_policy_factory_vtable glb_factory_vtable = { glb_factory_ref, glb_factory_unref, glb_create, "grpclb"}; static grpc_lb_policy_factory glb_lb_policy_factory = {&glb_factory_vtable}; grpc_lb_policy_factory *grpc_glb_lb_factory_create() { return &glb_lb_policy_factory; } /* Plugin registration */ void grpc_lb_policy_grpclb_init() { grpc_register_lb_policy(grpc_glb_lb_factory_create()); grpc_register_tracer("glb", &grpc_lb_glb_trace); } void grpc_lb_policy_grpclb_shutdown() {}