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Diffstat (limited to 'src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c')
| -rw-r--r-- | src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c | 1417 |
1 files changed, 1417 insertions, 0 deletions
diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c new file mode 100644 index 0000000000..71c7bd958e --- /dev/null +++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c @@ -0,0 +1,1417 @@ +/* + * + * 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_locked() is called. This function sets up + * and initiates the internal communication with the LB server. In particular, + * it's responsible for instantiating the internal *streaming* call to the LB + * server (whichever address from {a1..an} pick-first chose). This call is + * serviced by two callbacks, \a lb_on_server_status_received and \a + * lb_on_response_received. The former will be called when the call to the LB + * server completes. This can happen if the LB server closes the connection or + * if this policy itself cancels the call (for example because it's shutting + * down). If the internal call times out, the usual behavior of pick-first + * applies, continuing to pick from the list {a1..an}. + * + * Upon sucesss, the incoming \a LoadBalancingResponse is processed by \a + * res_recv. 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_locked() 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 + * glb_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_locked(). + * + * + * 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_locked() 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). + */ + +/* 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 "src/core/lib/iomgr/sockaddr.h" + +#include <errno.h> + +#include <string.h> + +#include <grpc/byte_buffer_reader.h> +#include <grpc/grpc.h> +#include <grpc/support/alloc.h> +#include <grpc/support/host_port.h> +#include <grpc/support/string_util.h> +#include <grpc/support/time.h> + +#include "src/core/ext/filters/client_channel/client_channel.h" +#include "src/core/ext/filters/client_channel/client_channel_factory.h" +#include "src/core/ext/filters/client_channel/lb_policy_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/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/load_balancer_api.h" +#include "src/core/lib/channel/channel_args.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/support/backoff.h" +#include "src/core/lib/support/string.h" +#include "src/core/lib/surface/call.h" +#include "src/core/lib/surface/channel.h" +#include "src/core/lib/transport/static_metadata.h" + +#define GRPC_GRPCLB_MIN_CONNECT_TIMEOUT_SECONDS 20 +#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 + +int grpc_lb_glb_trace = 0; + +/* add lb_token of selected subchannel (address) to the call's initial + * metadata */ +static grpc_error *initial_metadata_add_lb_token( + grpc_exec_ctx *exec_ctx, grpc_metadata_batch *initial_metadata, + grpc_linked_mdelem *lb_token_mdelem_storage, grpc_mdelem lb_token) { + GPR_ASSERT(lb_token_mdelem_storage != NULL); + GPR_ASSERT(!GRPC_MDISNULL(lb_token)); + return grpc_metadata_batch_add_tail(exec_ctx, initial_metadata, + lb_token_mdelem_storage, lb_token); +} + +typedef struct wrapped_rr_closure_arg { + /* the closure instance using this struct as argument */ + grpc_closure wrapper_closure; + + /* 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 pick's initial metadata, kept in order to append the LB token for the + * pick */ + grpc_metadata_batch *initial_metadata; + + /* the picked target, used to determine which LB token to add to the pick's + * initial metadata */ + grpc_connected_subchannel **target; + + /* the LB token associated with the pick */ + grpc_mdelem lb_token; + + /* storage for the lb token initial metadata mdelem */ + grpc_linked_mdelem *lb_token_mdelem_storage; + + /* The RR instance related to the closure */ + grpc_lb_policy *rr_policy; + + /* heap memory to be freed upon closure execution. */ + void *free_when_done; +} 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; + + GPR_ASSERT(wc_arg->wrapped_closure != NULL); + grpc_closure_sched(exec_ctx, wc_arg->wrapped_closure, GRPC_ERROR_REF(error)); + + if (wc_arg->rr_policy != NULL) { + /* if *target is NULL, no pick has been made by the RR policy (eg, all + * addresses failed to connect). There won't be any user_data/token + * available */ + if (*wc_arg->target != NULL) { + if (!GRPC_MDISNULL(wc_arg->lb_token)) { + initial_metadata_add_lb_token(exec_ctx, wc_arg->initial_metadata, + wc_arg->lb_token_mdelem_storage, + GRPC_MDELEM_REF(wc_arg->lb_token)); + } else { + gpr_log(GPR_ERROR, + "No LB token for connected subchannel pick %p (from RR " + "instance %p).", + (void *)*wc_arg->target, (void *)wc_arg->rr_policy); + abort(); + } + } + if (grpc_lb_glb_trace) { + gpr_log(GPR_INFO, "Unreffing RR %p", (void *)wc_arg->rr_policy); + } + GRPC_LB_POLICY_UNREF(exec_ctx, wc_arg->rr_policy, "wrapped_rr_closure"); + } + GPR_ASSERT(wc_arg->free_when_done != NULL); + gpr_free(wc_arg->free_when_done); +} + +/* 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; + + /* original pick()'s arguments */ + grpc_lb_policy_pick_args pick_args; + + /* output argument where to store the pick()ed connected subchannel, or NULL + * upon error. */ + grpc_connected_subchannel **target; + + /* args for wrapped_on_complete */ + wrapped_rr_closure_arg wrapped_on_complete_arg; +} pending_pick; + +static void add_pending_pick(pending_pick **root, + const grpc_lb_policy_pick_args *pick_args, + grpc_connected_subchannel **target, + grpc_closure *on_complete) { + pending_pick *pp = gpr_zalloc(sizeof(*pp)); + pp->next = *root; + pp->pick_args = *pick_args; + pp->target = target; + pp->wrapped_on_complete_arg.wrapped_closure = on_complete; + pp->wrapped_on_complete_arg.target = target; + pp->wrapped_on_complete_arg.initial_metadata = pick_args->initial_metadata; + pp->wrapped_on_complete_arg.lb_token_mdelem_storage = + pick_args->lb_token_mdelem_storage; + pp->wrapped_on_complete_arg.free_when_done = pp; + grpc_closure_init(&pp->wrapped_on_complete_arg.wrapper_closure, + wrapped_rr_closure, &pp->wrapped_on_complete_arg, + grpc_schedule_on_exec_ctx); + *root = pp; +} + +/* Same as the \a pending_pick struct but for ping operations */ +typedef struct pending_ping { + struct pending_ping *next; + + /* 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_zalloc(sizeof(*pping)); + pping->wrapped_notify_arg.wrapped_closure = notify; + pping->wrapped_notify_arg.free_when_done = pping; + pping->next = *root; + grpc_closure_init(&pping->wrapped_notify_arg.wrapper_closure, + wrapped_rr_closure, &pping->wrapped_notify_arg, + grpc_schedule_on_exec_ctx); + *root = pping; +} + +/* + * glb_lb_policy + */ +typedef struct rr_connectivity_data rr_connectivity_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; + + /** who the client is trying to communicate with */ + const char *server_name; + grpc_client_channel_factory *cc_factory; + grpc_channel_args *args; + + /** deadline for the LB's call */ + gpr_timespec deadline; + + /** 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; + + bool shutting_down; + + /************************************************************/ + /* client data associated with the LB server communication */ + /************************************************************/ + /* Status from the LB server has been received. This signals the end of the LB + * call. */ + grpc_closure lb_on_server_status_received; + + /* A response from the LB server has been received. Process it */ + grpc_closure lb_on_response_received; + + /* LB call retry timer callback. */ + grpc_closure lb_on_call_retry; + + grpc_call *lb_call; /* streaming call to the LB server, */ + + grpc_metadata_array lb_initial_metadata_recv; /* initial MD from LB server */ + grpc_metadata_array + lb_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 *lb_request_payload; + + /* response the LB server, if any. Processed in lb_on_response_received() */ + grpc_byte_buffer *lb_response_payload; + + /* call status code and details, set in lb_on_server_status_received() */ + grpc_status_code lb_call_status; + grpc_slice lb_call_status_details; + + /** LB call retry backoff state */ + gpr_backoff lb_call_backoff_state; + + /** LB call retry timer */ + grpc_timer lb_call_retry_timer; +} 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 bool is_server_valid(const grpc_grpclb_server *server, size_t idx, + bool log) { + const grpc_grpclb_ip_address *ip = &server->ip_address; + if (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 (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; +} + +/* vtable for LB tokens in grpc_lb_addresses. */ +static void *lb_token_copy(void *token) { + return token == NULL + ? NULL + : (void *)GRPC_MDELEM_REF((grpc_mdelem){(uintptr_t)token}).payload; +} +static void lb_token_destroy(grpc_exec_ctx *exec_ctx, void *token) { + if (token != NULL) { + GRPC_MDELEM_UNREF(exec_ctx, (grpc_mdelem){(uintptr_t)token}); + } +} +static int lb_token_cmp(void *token1, void *token2) { + if (token1 > token2) return 1; + if (token1 < token2) return -1; + return 0; +} +static const grpc_lb_user_data_vtable lb_token_vtable = { + lb_token_copy, lb_token_destroy, lb_token_cmp}; + +static void parse_server(const grpc_grpclb_server *server, + grpc_resolved_address *addr) { + const uint16_t netorder_port = 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; + memset(addr, 0, sizeof(*addr)); + if (ip->size == 4) { + addr->len = sizeof(struct sockaddr_in); + struct sockaddr_in *addr4 = (struct sockaddr_in *)&addr->addr; + addr4->sin_family = AF_INET; + memcpy(&addr4->sin_addr, ip->bytes, ip->size); + addr4->sin_port = netorder_port; + } else if (ip->size == 16) { + addr->len = sizeof(struct sockaddr_in6); + struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)&addr->addr; + addr6->sin6_family = AF_INET6; + memcpy(&addr6->sin6_addr, ip->bytes, ip->size); + addr6->sin6_port = netorder_port; + } +} + +/* Returns addresses extracted from \a serverlist. */ +static grpc_lb_addresses *process_serverlist_locked( + grpc_exec_ctx *exec_ctx, 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 (is_server_valid(serverlist->servers[i], i, true)) ++num_valid; + } + if (num_valid == 0) return NULL; + + 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) { + GPR_ASSERT(addr_idx < num_valid); + const grpc_grpclb_server *server = serverlist->servers[sl_idx]; + if (!is_server_valid(serverlist->servers[sl_idx], sl_idx, false)) continue; + + /* address processing */ + grpc_resolved_address addr; + parse_server(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(exec_ctx, 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 */, + NULL /* balancer_name */, user_data); + ++addr_idx; + } + GPR_ASSERT(addr_idx == num_valid); + return lb_addresses; +} + +/* returns true if the new RR policy should replace the current one, if any */ +static bool update_lb_connectivity_status_locked( + grpc_exec_ctx *exec_ctx, glb_lb_policy *glb_policy, + grpc_connectivity_state new_rr_state, grpc_error *new_rr_state_error) { + const grpc_connectivity_state curr_glb_state = + grpc_connectivity_state_check(&glb_policy->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 (new_rr_state) { + case GRPC_CHANNEL_TRANSIENT_FAILURE: + case GRPC_CHANNEL_SHUTDOWN: + GPR_ASSERT(new_rr_state_error != GRPC_ERROR_NONE); + return false; /* don't replace the RR policy */ + case GRPC_CHANNEL_INIT: + case GRPC_CHANNEL_IDLE: + case GRPC_CHANNEL_CONNECTING: + case GRPC_CHANNEL_READY: + GPR_ASSERT(new_rr_state_error == GRPC_ERROR_NONE); + } + + if (grpc_lb_glb_trace) { + gpr_log(GPR_INFO, + "Setting grpclb's state to %s from new RR policy %p state.", + grpc_connectivity_state_name(new_rr_state), + (void *)glb_policy->rr_policy); + } + grpc_connectivity_state_set(exec_ctx, &glb_policy->state_tracker, + new_rr_state, GRPC_ERROR_REF(new_rr_state_error), + "update_lb_connectivity_status_locked"); + return true; +} + +/* perform 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 be otherwise resposible for */ +static bool pick_from_internal_rr_locked( + grpc_exec_ctx *exec_ctx, grpc_lb_policy *rr_policy, + const grpc_lb_policy_pick_args *pick_args, + grpc_connected_subchannel **target, wrapped_rr_closure_arg *wc_arg) { + GPR_ASSERT(rr_policy != NULL); + const bool pick_done = grpc_lb_policy_pick_locked( + exec_ctx, rr_policy, pick_args, target, (void **)&wc_arg->lb_token, + &wc_arg->wrapper_closure); + if (pick_done) { + /* synchronous grpc_lb_policy_pick call. Unref the RR policy. */ + 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, "glb_pick_sync"); + + /* add the load reporting initial metadata */ + initial_metadata_add_lb_token(exec_ctx, pick_args->initial_metadata, + pick_args->lb_token_mdelem_storage, + GRPC_MDELEM_REF(wc_arg->lb_token)); + + gpr_free(wc_arg); + } + /* else, the pending pick will be registered and taken care of by the + * pending pick list inside the RR policy (glb_policy->rr_policy). + * Eventually, wrapped_on_complete will be called, which will -among other + * things- add the LB token to the call's initial metadata */ + return pick_done; +} + +static grpc_lb_policy *create_rr_locked( + grpc_exec_ctx *exec_ctx, const grpc_grpclb_serverlist *serverlist, + glb_lb_policy *glb_policy) { + GPR_ASSERT(serverlist != NULL && serverlist->num_servers > 0); + + grpc_lb_policy_args args; + memset(&args, 0, sizeof(args)); + args.client_channel_factory = glb_policy->cc_factory; + args.combiner = glb_policy->base.combiner; + grpc_lb_addresses *addresses = + process_serverlist_locked(exec_ctx, serverlist); + + // 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 arg = grpc_lb_addresses_create_channel_arg(addresses); + args.args = grpc_channel_args_copy_and_add_and_remove( + glb_policy->args, keys_to_remove, GPR_ARRAY_SIZE(keys_to_remove), &arg, + 1); + + grpc_lb_policy *rr = grpc_lb_policy_create(exec_ctx, "round_robin", &args); + GPR_ASSERT(rr != NULL); + grpc_lb_addresses_destroy(exec_ctx, addresses); + grpc_channel_args_destroy(exec_ctx, args.args); + return rr; +} + +static void glb_rr_connectivity_changed_locked(grpc_exec_ctx *exec_ctx, + void *arg, grpc_error *error); +/* glb_policy->rr_policy may be NULL (initial handover) */ +static void rr_handover_locked(grpc_exec_ctx *exec_ctx, + glb_lb_policy *glb_policy) { + GPR_ASSERT(glb_policy->serverlist != NULL && + glb_policy->serverlist->num_servers > 0); + + if (glb_policy->shutting_down) return; + + grpc_lb_policy *new_rr_policy = + create_rr_locked(exec_ctx, glb_policy->serverlist, glb_policy); + if (new_rr_policy == NULL) { + gpr_log(GPR_ERROR, + "Failure creating a RoundRobin policy for serverlist update with " + "%lu entries. The previous RR instance (%p), if any, will continue " + "to be used. Future updates from the LB will attempt to create new " + "instances.", + (unsigned long)glb_policy->serverlist->num_servers, + (void *)glb_policy->rr_policy); + return; + } + + grpc_error *new_rr_state_error = NULL; + const grpc_connectivity_state new_rr_state = + grpc_lb_policy_check_connectivity_locked(exec_ctx, new_rr_policy, + &new_rr_state_error); + /* Connectivity state is a function of the new RR policy just created */ + const bool replace_old_rr = update_lb_connectivity_status_locked( + exec_ctx, glb_policy, new_rr_state, new_rr_state_error); + + if (!replace_old_rr) { + /* dispose of the new RR policy that won't be used after all */ + GRPC_LB_POLICY_UNREF(exec_ctx, new_rr_policy, "rr_handover_no_replace"); + if (grpc_lb_glb_trace) { + gpr_log(GPR_INFO, + "Keeping old RR policy (%p) despite new serverlist: new RR " + "policy was in %s connectivity state.", + (void *)glb_policy->rr_policy, + grpc_connectivity_state_name(new_rr_state)); + } + return; + } + + if (grpc_lb_glb_trace) { + gpr_log(GPR_INFO, "Created RR policy (%p) to replace old RR (%p)", + (void *)new_rr_policy, (void *)glb_policy->rr_policy); + } + + if (glb_policy->rr_policy != NULL) { + /* if we are phasing out an existing RR instance, unref it. */ + GRPC_LB_POLICY_UNREF(exec_ctx, glb_policy->rr_policy, "rr_handover"); + } + + /* Finally update the RR policy to the newly created one */ + glb_policy->rr_policy = new_rr_policy; + + /* 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(exec_ctx, + glb_policy->rr_policy->interested_parties, + glb_policy->base.interested_parties); + + /* Allocate the data for the tracking of the new RR policy's connectivity. + * It'll be deallocated in glb_rr_connectivity_changed() */ + rr_connectivity_data *rr_connectivity = + gpr_zalloc(sizeof(rr_connectivity_data)); + grpc_closure_init(&rr_connectivity->on_change, + glb_rr_connectivity_changed_locked, rr_connectivity, + grpc_combiner_scheduler(glb_policy->base.combiner, false)); + rr_connectivity->glb_policy = glb_policy; + rr_connectivity->state = new_rr_state; + + /* Subscribe to changes to the connectivity of the new RR */ + GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "rr_connectivity_cb"); + grpc_lb_policy_notify_on_state_change_locked(exec_ctx, glb_policy->rr_policy, + &rr_connectivity->state, + &rr_connectivity->on_change); + grpc_lb_policy_exit_idle_locked(exec_ctx, glb_policy->rr_policy); + + /* Update picks and pings in wait */ + 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); + } + pick_from_internal_rr_locked(exec_ctx, glb_policy->rr_policy, + &pp->pick_args, pp->target, + &pp->wrapped_on_complete_arg); + } + + 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_locked(exec_ctx, glb_policy->rr_policy, + &pping->wrapped_notify_arg.wrapper_closure); + } +} + +static void glb_rr_connectivity_changed_locked(grpc_exec_ctx *exec_ctx, + void *arg, grpc_error *error) { + rr_connectivity_data *rr_connectivity = arg; + glb_lb_policy *glb_policy = rr_connectivity->glb_policy; + + const bool shutting_down = glb_policy->shutting_down; + bool unref_needed = false; + GRPC_ERROR_REF(error); + + if (rr_connectivity->state == GRPC_CHANNEL_SHUTDOWN || shutting_down) { + /* RR policy shutting down. Don't renew subscription and free the arg of + * this callback. In addition we need to stash away the current policy to + * be UNREF'd after releasing the lock. Otherwise, if the UNREF is the last + * one, the policy would be destroyed, alongside the lock, which would + * result in a use-after-free */ + unref_needed = true; + gpr_free(rr_connectivity); + } else { /* rr state != SHUTDOWN && !shutting down: biz as usual */ + update_lb_connectivity_status_locked(exec_ctx, glb_policy, + rr_connectivity->state, error); + /* Resubscribe. Reuse the "rr_connectivity_cb" weak ref. */ + grpc_lb_policy_notify_on_state_change_locked( + exec_ctx, glb_policy->rr_policy, &rr_connectivity->state, + &rr_connectivity->on_change); + } + if (unref_needed) { + GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base, + "rr_connectivity_cb"); + } + GRPC_ERROR_UNREF(error); +} + +static void destroy_balancer_name(grpc_exec_ctx *exec_ctx, + void *balancer_name) { + gpr_free(balancer_name); +} + +static void *copy_balancer_name(void *balancer_name) { + return gpr_strdup(balancer_name); +} + +static grpc_slice_hash_table_entry targets_info_entry_create( + const char *address, const char *balancer_name) { + static const grpc_slice_hash_table_vtable vtable = {destroy_balancer_name, + copy_balancer_name}; + grpc_slice_hash_table_entry entry; + entry.key = grpc_slice_from_copied_string(address); + entry.value = (void *)balancer_name; + entry.vtable = &vtable; + return entry; +} + +/* Returns the target URI for the LB service whose addresses are in \a + * addresses. Using this URI, a bidirectional streaming channel will be created + * for the reception of load balancing updates. + * + * The output argument \a targets_info will be updated to contain a mapping of + * "LB server address" to "balancer name", as reported by the naming system. + * This mapping will be propagated via the channel arguments of the + * aforementioned LB streaming channel, to be used by the security connector for + * secure naming checks. The user is responsible for freeing \a targets_info. */ +static char *get_lb_uri_target_addresses(grpc_exec_ctx *exec_ctx, + const grpc_lb_addresses *addresses, + grpc_slice_hash_table **targets_info) { + 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; + } + /* All input 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. Otherwise, something has gone wrong. */ + GPR_ASSERT(num_grpclb_addrs > 0); + + grpc_slice_hash_table_entry *targets_info_entries = + gpr_malloc(sizeof(*targets_info_entries) * num_grpclb_addrs); + + /* construct a target ipvX://ip1:port1,ip2:port2,... from the addresses in \a + * addresses */ + /* TODO(dgq): support mixed ip version */ + char **addr_strs = gpr_malloc(sizeof(char *) * num_grpclb_addrs); + size_t addr_index = 0; + + for (size_t i = 0; i < addresses->num_addresses; i++) { + if (addresses->addresses[i].user_data != NULL) { + gpr_log(GPR_ERROR, + "This LB policy doesn't support user data. It will be ignored"); + } + if (addresses->addresses[i].is_balancer) { + char *addr_str; + GPR_ASSERT(grpc_sockaddr_to_string( + &addr_str, &addresses->addresses[i].address, true) > 0); + targets_info_entries[addr_index] = targets_info_entry_create( + addr_str, addresses->addresses[i].balancer_name); + addr_strs[addr_index++] = addr_str; + } + } + GPR_ASSERT(addr_index == num_grpclb_addrs); + + size_t uri_path_len; + char *uri_path = gpr_strjoin_sep((const char **)addr_strs, num_grpclb_addrs, + ",", &uri_path_len); + for (size_t i = 0; i < num_grpclb_addrs; i++) gpr_free(addr_strs[i]); + gpr_free(addr_strs); + + char *target_uri_str = NULL; + /* TODO(dgq): Don't assume all addresses will share the scheme of the first + * one */ + gpr_asprintf(&target_uri_str, "%s:%s", + grpc_sockaddr_get_uri_scheme(&addresses->addresses[0].address), + uri_path); + gpr_free(uri_path); + + *targets_info = + grpc_slice_hash_table_create(num_grpclb_addrs, targets_info_entries); + for (size_t i = 0; i < num_grpclb_addrs; i++) { + grpc_slice_unref_internal(exec_ctx, targets_info_entries[i].key); + } + gpr_free(targets_info_entries); + + return target_uri_str; +} + +static grpc_lb_policy *glb_create(grpc_exec_ctx *exec_ctx, + grpc_lb_policy_factory *factory, + grpc_lb_policy_args *args) { + /* Count the number of gRPC-LB addresses. There must be at least one. + * TODO(roth): For now, we ignore non-balancer addresses, but in the + * future, we may change the behavior such that we fall back to using + * the non-balancer addresses if we cannot reach any balancers. At that + * time, this should be changed to allow a list with no balancer addresses, + * since the resolver might fail to return a balancer address even when + * this is the right LB policy to use. */ + const grpc_arg *arg = + grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES); + GPR_ASSERT(arg != NULL && arg->type == GRPC_ARG_POINTER); + grpc_lb_addresses *addresses = 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 NULL; + + glb_lb_policy *glb_policy = gpr_zalloc(sizeof(*glb_policy)); + + /* Get server name. */ + arg = grpc_channel_args_find(args->args, GRPC_ARG_SERVER_URI); + GPR_ASSERT(arg != NULL); + GPR_ASSERT(arg->type == GRPC_ARG_STRING); + grpc_uri *uri = grpc_uri_parse(exec_ctx, arg->value.string, true); + GPR_ASSERT(uri->path[0] != '\0'); + glb_policy->server_name = + gpr_strdup(uri->path[0] == '/' ? uri->path + 1 : uri->path); + if (grpc_lb_glb_trace) { + gpr_log(GPR_INFO, "Will use '%s' as the server name for LB request.", + glb_policy->server_name); + } + grpc_uri_destroy(uri); + + glb_policy->cc_factory = args->client_channel_factory; + glb_policy->args = grpc_channel_args_copy(args->args); + GPR_ASSERT(glb_policy->cc_factory != NULL); + + grpc_slice_hash_table *targets_info = NULL; + /* Create a client channel over them to communicate with a LB service */ + char *lb_service_target_addresses = + get_lb_uri_target_addresses(exec_ctx, addresses, &targets_info); + grpc_channel_args *lb_channel_args = + get_lb_channel_args(exec_ctx, targets_info, args->args); + glb_policy->lb_channel = grpc_lb_policy_grpclb_create_lb_channel( + exec_ctx, lb_service_target_addresses, args->client_channel_factory, + lb_channel_args); + grpc_slice_hash_table_unref(exec_ctx, targets_info); + grpc_channel_args_destroy(exec_ctx, lb_channel_args); + gpr_free(lb_service_target_addresses); + if (glb_policy->lb_channel == NULL) { + gpr_free(glb_policy); + return NULL; + } + grpc_lb_policy_init(&glb_policy->base, &glb_lb_policy_vtable, args->combiner); + 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); + gpr_free((void *)glb_policy->server_name); + grpc_channel_args_destroy(exec_ctx, glb_policy->args); + 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_free(glb_policy); +} + +static void glb_shutdown_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { + glb_lb_policy *glb_policy = (glb_lb_policy *)pol; + glb_policy->shutting_down = true; + + pending_pick *pp = glb_policy->pending_picks; + glb_policy->pending_picks = NULL; + pending_ping *pping = glb_policy->pending_pings; + glb_policy->pending_pings = NULL; + if (glb_policy->rr_policy) { + 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_FROM_STATIC_STRING("Channel Shutdown"), "glb_shutdown"); + /* We need a copy of the lb_call pointer because we can't cancell the call + * while holding glb_policy->mu: lb_on_server_status_received, invoked due to + * the cancel, needs to acquire that same lock */ + grpc_call *lb_call = glb_policy->lb_call; + + /* glb_policy->lb_call and this local lb_call must be consistent at this point + * because glb_policy->lb_call is only assigned in lb_call_init_locked as part + * of query_for_backends_locked, which can only be invoked while + * glb_policy->shutting_down is false. */ + if (lb_call != NULL) { + grpc_call_cancel(lb_call, NULL); + /* lb_on_server_status_received will pick up the cancel and clean up */ + } + while (pp != NULL) { + pending_pick *next = pp->next; + *pp->target = NULL; + grpc_closure_sched(exec_ctx, &pp->wrapped_on_complete_arg.wrapper_closure, + GRPC_ERROR_NONE); + pp = next; + } + + while (pping != NULL) { + pending_ping *next = pping->next; + grpc_closure_sched(exec_ctx, &pping->wrapped_notify_arg.wrapper_closure, + GRPC_ERROR_NONE); + pping = next; + } +} + +static void glb_cancel_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, + grpc_connected_subchannel **target, + grpc_error *error) { + glb_lb_policy *glb_policy = (glb_lb_policy *)pol; + pending_pick *pp = glb_policy->pending_picks; + glb_policy->pending_picks = NULL; + while (pp != NULL) { + pending_pick *next = pp->next; + if (pp->target == target) { + *target = NULL; + grpc_closure_sched(exec_ctx, &pp->wrapped_on_complete_arg.wrapper_closure, + GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING( + "Pick Cancelled", &error, 1)); + } else { + pp->next = glb_policy->pending_picks; + glb_policy->pending_picks = pp; + } + pp = next; + } + GRPC_ERROR_UNREF(error); +} + +static void glb_cancel_picks_locked(grpc_exec_ctx *exec_ctx, + grpc_lb_policy *pol, + uint32_t initial_metadata_flags_mask, + uint32_t initial_metadata_flags_eq, + grpc_error *error) { + glb_lb_policy *glb_policy = (glb_lb_policy *)pol; + pending_pick *pp = glb_policy->pending_picks; + glb_policy->pending_picks = NULL; + while (pp != NULL) { + pending_pick *next = pp->next; + if ((pp->pick_args.initial_metadata_flags & initial_metadata_flags_mask) == + initial_metadata_flags_eq) { + grpc_closure_sched(exec_ctx, &pp->wrapped_on_complete_arg.wrapper_closure, + GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING( + "Pick Cancelled", &error, 1)); + } else { + pp->next = glb_policy->pending_picks; + glb_policy->pending_picks = pp; + } + pp = next; + } + GRPC_ERROR_UNREF(error); +} + +static void query_for_backends_locked(grpc_exec_ctx *exec_ctx, + glb_lb_policy *glb_policy); +static void start_picking_locked(grpc_exec_ctx *exec_ctx, + glb_lb_policy *glb_policy) { + glb_policy->started_picking = true; + gpr_backoff_reset(&glb_policy->lb_call_backoff_state); + query_for_backends_locked(exec_ctx, glb_policy); +} + +static void glb_exit_idle_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { + glb_lb_policy *glb_policy = (glb_lb_policy *)pol; + if (!glb_policy->started_picking) { + start_picking_locked(exec_ctx, glb_policy); + } +} + +static int glb_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, + const grpc_lb_policy_pick_args *pick_args, + grpc_connected_subchannel **target, void **user_data, + grpc_closure *on_complete) { + if (pick_args->lb_token_mdelem_storage == NULL) { + *target = NULL; + grpc_closure_sched(exec_ctx, on_complete, + GRPC_ERROR_CREATE_FROM_STATIC_STRING( + "No mdelem storage for the LB token. Load reporting " + "won't work without it. Failing")); + return 0; + } + + glb_lb_policy *glb_policy = (glb_lb_policy *)pol; + glb_policy->deadline = pick_args->deadline; + bool pick_done; + + if (glb_policy->rr_policy != NULL) { + if (grpc_lb_glb_trace) { + gpr_log(GPR_INFO, "grpclb %p about to PICK from RR %p", + (void *)glb_policy, (void *)glb_policy->rr_policy); + } + GRPC_LB_POLICY_REF(glb_policy->rr_policy, "glb_pick"); + + wrapped_rr_closure_arg *wc_arg = gpr_zalloc(sizeof(wrapped_rr_closure_arg)); + + grpc_closure_init(&wc_arg->wrapper_closure, wrapped_rr_closure, wc_arg, + grpc_schedule_on_exec_ctx); + wc_arg->rr_policy = glb_policy->rr_policy; + wc_arg->target = target; + wc_arg->wrapped_closure = on_complete; + wc_arg->lb_token_mdelem_storage = pick_args->lb_token_mdelem_storage; + wc_arg->initial_metadata = pick_args->initial_metadata; + wc_arg->free_when_done = wc_arg; + pick_done = pick_from_internal_rr_locked(exec_ctx, glb_policy->rr_policy, + pick_args, target, wc_arg); + } else { + if (grpc_lb_glb_trace) { + gpr_log(GPR_DEBUG, + "No RR policy in grpclb instance %p. Adding to grpclb's pending " + "picks", + (void *)(glb_policy)); + } + add_pending_pick(&glb_policy->pending_picks, pick_args, target, + on_complete); + + if (!glb_policy->started_picking) { + start_picking_locked(exec_ctx, glb_policy); + } + pick_done = false; + } + return pick_done; +} + +static grpc_connectivity_state glb_check_connectivity_locked( + grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, + grpc_error **connectivity_error) { + glb_lb_policy *glb_policy = (glb_lb_policy *)pol; + return grpc_connectivity_state_get(&glb_policy->state_tracker, + connectivity_error); +} + +static void glb_ping_one_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, + grpc_closure *closure) { + glb_lb_policy *glb_policy = (glb_lb_policy *)pol; + if (glb_policy->rr_policy) { + grpc_lb_policy_ping_one_locked(exec_ctx, glb_policy->rr_policy, closure); + } else { + add_pending_ping(&glb_policy->pending_pings, closure); + if (!glb_policy->started_picking) { + start_picking_locked(exec_ctx, glb_policy); + } + } +} + +static void glb_notify_on_state_change_locked(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; + grpc_connectivity_state_notify_on_state_change( + exec_ctx, &glb_policy->state_tracker, current, notify); +} + +static void lb_on_server_status_received_locked(grpc_exec_ctx *exec_ctx, + void *arg, grpc_error *error); +static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg, + grpc_error *error); +static void lb_call_init_locked(grpc_exec_ctx *exec_ctx, + glb_lb_policy *glb_policy) { + GPR_ASSERT(glb_policy->server_name != NULL); + GPR_ASSERT(glb_policy->server_name[0] != '\0'); + GPR_ASSERT(!glb_policy->shutting_down); + + /* Note the following LB call progresses every time there's activity in \a + * glb_policy->base.interested_parties, which is comprised of the polling + * entities from \a client_channel. */ + grpc_slice host = grpc_slice_from_copied_string(glb_policy->server_name); + glb_policy->lb_call = grpc_channel_create_pollset_set_call( + exec_ctx, glb_policy->lb_channel, NULL, GRPC_PROPAGATE_DEFAULTS, + glb_policy->base.interested_parties, + GRPC_MDSTR_SLASH_GRPC_DOT_LB_DOT_V1_DOT_LOADBALANCER_SLASH_BALANCELOAD, + &host, glb_policy->deadline, NULL); + + grpc_metadata_array_init(&glb_policy->lb_initial_metadata_recv); + grpc_metadata_array_init(&glb_policy->lb_trailing_metadata_recv); + + grpc_grpclb_request *request = + grpc_grpclb_request_create(glb_policy->server_name); + grpc_slice request_payload_slice = grpc_grpclb_request_encode(request); + glb_policy->lb_request_payload = + grpc_raw_byte_buffer_create(&request_payload_slice, 1); + grpc_slice_unref_internal(exec_ctx, request_payload_slice); + grpc_grpclb_request_destroy(request); + + grpc_closure_init(&glb_policy->lb_on_server_status_received, + lb_on_server_status_received_locked, glb_policy, + grpc_combiner_scheduler(glb_policy->base.combiner, false)); + grpc_closure_init(&glb_policy->lb_on_response_received, + lb_on_response_received_locked, glb_policy, + grpc_combiner_scheduler(glb_policy->base.combiner, false)); + + gpr_backoff_init(&glb_policy->lb_call_backoff_state, + GRPC_GRPCLB_INITIAL_CONNECT_BACKOFF_SECONDS, + GRPC_GRPCLB_RECONNECT_BACKOFF_MULTIPLIER, + GRPC_GRPCLB_RECONNECT_JITTER, + GRPC_GRPCLB_MIN_CONNECT_TIMEOUT_SECONDS * 1000, + GRPC_GRPCLB_RECONNECT_MAX_BACKOFF_SECONDS * 1000); +} + +static void lb_call_destroy_locked(grpc_exec_ctx *exec_ctx, + glb_lb_policy *glb_policy) { + GPR_ASSERT(glb_policy->lb_call != NULL); + grpc_call_destroy(glb_policy->lb_call); + glb_policy->lb_call = NULL; + + grpc_metadata_array_destroy(&glb_policy->lb_initial_metadata_recv); + grpc_metadata_array_destroy(&glb_policy->lb_trailing_metadata_recv); + + grpc_byte_buffer_destroy(glb_policy->lb_request_payload); + grpc_slice_unref_internal(exec_ctx, glb_policy->lb_call_status_details); +} + +/* + * Auxiliary functions and LB client callbacks. + */ +static void query_for_backends_locked(grpc_exec_ctx *exec_ctx, + glb_lb_policy *glb_policy) { + GPR_ASSERT(glb_policy->lb_channel != NULL); + if (glb_policy->shutting_down) return; + + lb_call_init_locked(exec_ctx, glb_policy); + + if (grpc_lb_glb_trace) { + gpr_log(GPR_INFO, "Query for backends (grpclb: %p, lb_call: %p)", + (void *)glb_policy, (void *)glb_policy->lb_call); + } + GPR_ASSERT(glb_policy->lb_call != NULL); + + grpc_call_error call_error; + grpc_op ops[4]; + 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++; + + op->op = GRPC_OP_RECV_INITIAL_METADATA; + op->data.recv_initial_metadata.recv_initial_metadata = + &glb_policy->lb_initial_metadata_recv; + op->flags = 0; + op->reserved = NULL; + op++; + + GPR_ASSERT(glb_policy->lb_request_payload != NULL); + op->op = GRPC_OP_SEND_MESSAGE; + op->data.send_message.send_message = glb_policy->lb_request_payload; + op->flags = 0; + op->reserved = NULL; + op++; + + op->op = GRPC_OP_RECV_STATUS_ON_CLIENT; + op->data.recv_status_on_client.trailing_metadata = + &glb_policy->lb_trailing_metadata_recv; + op->data.recv_status_on_client.status = &glb_policy->lb_call_status; + op->data.recv_status_on_client.status_details = + &glb_policy->lb_call_status_details; + op->flags = 0; + op->reserved = NULL; + op++; + /* take a weak ref (won't prevent calling of \a glb_shutdown if the strong ref + * count goes to zero) to be unref'd in lb_on_server_status_received */ + GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "lb_on_server_status_received"); + call_error = grpc_call_start_batch_and_execute( + exec_ctx, glb_policy->lb_call, ops, (size_t)(op - ops), + &glb_policy->lb_on_server_status_received); + GPR_ASSERT(GRPC_CALL_OK == call_error); + + op = ops; + op->op = GRPC_OP_RECV_MESSAGE; + op->data.recv_message.recv_message = &glb_policy->lb_response_payload; + op->flags = 0; + op->reserved = NULL; + op++; + /* take another weak ref to be unref'd in lb_on_response_received */ + GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "lb_on_response_received"); + call_error = grpc_call_start_batch_and_execute( + exec_ctx, glb_policy->lb_call, ops, (size_t)(op - ops), + &glb_policy->lb_on_response_received); + GPR_ASSERT(GRPC_CALL_OK == call_error); +} + +static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg, + grpc_error *error) { + glb_lb_policy *glb_policy = arg; + + grpc_op ops[2]; + memset(ops, 0, sizeof(ops)); + grpc_op *op = ops; + if (glb_policy->lb_response_payload != NULL) { + gpr_backoff_reset(&glb_policy->lb_call_backoff_state); + /* Received data from the LB server. Look inside + * glb_policy->lb_response_payload, for a serverlist. */ + grpc_byte_buffer_reader bbr; + grpc_byte_buffer_reader_init(&bbr, glb_policy->lb_response_payload); + grpc_slice response_slice = grpc_byte_buffer_reader_readall(&bbr); + grpc_byte_buffer_destroy(glb_policy->lb_response_payload); + grpc_grpclb_serverlist *serverlist = + grpc_grpclb_response_parse_serverlist(response_slice); + if (serverlist != NULL) { + GPR_ASSERT(glb_policy->lb_call != NULL); + grpc_slice_unref_internal(exec_ctx, response_slice); + if (grpc_lb_glb_trace) { + gpr_log(GPR_INFO, "Serverlist with %lu servers received", + (unsigned long)serverlist->num_servers); + for (size_t i = 0; i < serverlist->num_servers; ++i) { + grpc_resolved_address addr; + parse_server(serverlist->servers[i], &addr); + char *ipport; + grpc_sockaddr_to_string(&ipport, &addr, false); + gpr_log(GPR_INFO, "Serverlist[%lu]: %s", (unsigned long)i, ipport); + gpr_free(ipport); + } + } + + /* update serverlist */ + if (serverlist->num_servers > 0) { + if (grpc_grpclb_serverlist_equals(glb_policy->serverlist, serverlist)) { + if (grpc_lb_glb_trace) { + gpr_log(GPR_INFO, + "Incoming server list identical to current, ignoring."); + } + grpc_grpclb_destroy_serverlist(serverlist); + } else { /* new serverlist */ + if (glb_policy->serverlist != NULL) { + /* dispose of the old serverlist */ + grpc_grpclb_destroy_serverlist(glb_policy->serverlist); + } + /* and update the copy in the glb_lb_policy instance. This serverlist + * instance will be destroyed either upon the next update or in + * glb_destroy() */ + glb_policy->serverlist = serverlist; + + rr_handover_locked(exec_ctx, glb_policy); + } + } 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"); + } + } + } else { /* serverlist == NULL */ + gpr_log(GPR_ERROR, "Invalid LB response received: '%s'. Ignoring.", + grpc_dump_slice(response_slice, GPR_DUMP_ASCII | GPR_DUMP_HEX)); + grpc_slice_unref_internal(exec_ctx, response_slice); + } + + if (!glb_policy->shutting_down) { + /* keep listening for serverlist updates */ + op->op = GRPC_OP_RECV_MESSAGE; + op->data.recv_message.recv_message = &glb_policy->lb_response_payload; + op->flags = 0; + op->reserved = NULL; + op++; + /* reuse the "lb_on_response_received" weak ref taken in + * query_for_backends_locked() */ + const grpc_call_error call_error = grpc_call_start_batch_and_execute( + exec_ctx, glb_policy->lb_call, ops, (size_t)(op - ops), + &glb_policy->lb_on_response_received); /* loop */ + GPR_ASSERT(GRPC_CALL_OK == call_error); + } + } else { /* empty payload: call cancelled. */ + /* dispose of the "lb_on_response_received" weak ref taken in + * query_for_backends_locked() and reused in every reception loop */ + GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base, + "lb_on_response_received_empty_payload"); + } +} + +static void lb_call_on_retry_timer_locked(grpc_exec_ctx *exec_ctx, void *arg, + grpc_error *error) { + glb_lb_policy *glb_policy = arg; + + if (!glb_policy->shutting_down) { + if (grpc_lb_glb_trace) { + gpr_log(GPR_INFO, "Restaring call to LB server (grpclb %p)", + (void *)glb_policy); + } + GPR_ASSERT(glb_policy->lb_call == NULL); + query_for_backends_locked(exec_ctx, glb_policy); + } + GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base, + "grpclb_on_retry_timer"); +} + +static void lb_on_server_status_received_locked(grpc_exec_ctx *exec_ctx, + void *arg, grpc_error *error) { + glb_lb_policy *glb_policy = arg; + + GPR_ASSERT(glb_policy->lb_call != NULL); + + if (grpc_lb_glb_trace) { + char *status_details = + grpc_slice_to_c_string(glb_policy->lb_call_status_details); + gpr_log(GPR_DEBUG, + "Status from LB server received. Status = %d, Details = '%s', " + "(call: %p)", + glb_policy->lb_call_status, status_details, + (void *)glb_policy->lb_call); + gpr_free(status_details); + } + + /* We need to perform cleanups no matter what. */ + lb_call_destroy_locked(exec_ctx, glb_policy); + + if (!glb_policy->shutting_down) { + /* if we aren't shutting down, restart the LB client call after some time */ + gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC); + gpr_timespec next_try = + gpr_backoff_step(&glb_policy->lb_call_backoff_state, now); + if (grpc_lb_glb_trace) { + gpr_log(GPR_DEBUG, "Connection to LB server lost (grpclb: %p)...", + (void *)glb_policy); + gpr_timespec timeout = gpr_time_sub(next_try, now); + if (gpr_time_cmp(timeout, gpr_time_0(timeout.clock_type)) > 0) { + gpr_log(GPR_DEBUG, "... retrying in %" PRId64 ".%09d seconds.", + timeout.tv_sec, timeout.tv_nsec); + } else { + gpr_log(GPR_DEBUG, "... retrying immediately."); + } + } + GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "grpclb_retry_timer"); + grpc_closure_init( + &glb_policy->lb_on_call_retry, lb_call_on_retry_timer_locked, + glb_policy, grpc_combiner_scheduler(glb_policy->base.combiner, false)); + grpc_timer_init(exec_ctx, &glb_policy->lb_call_retry_timer, next_try, + &glb_policy->lb_on_call_retry, now); + } + GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base, + "lb_on_server_status_received"); +} + +/* Code wiring the policy with the rest of the core */ +static const grpc_lb_policy_vtable glb_lb_policy_vtable = { + glb_destroy, + glb_shutdown_locked, + glb_pick_locked, + glb_cancel_pick_locked, + glb_cancel_picks_locked, + glb_ping_one_locked, + glb_exit_idle_locked, + glb_check_connectivity_locked, + glb_notify_on_state_change_locked}; + +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() {} |