resolving-load-balancer.js
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"use strict";
/*
* Copyright 2019 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.
*
*/
Object.defineProperty(exports, "__esModule", { value: true });
exports.ResolvingLoadBalancer = void 0;
const load_balancer_1 = require("./load-balancer");
const service_config_1 = require("./service-config");
const channel_1 = require("./channel");
const resolver_1 = require("./resolver");
const picker_1 = require("./picker");
const backoff_timeout_1 = require("./backoff-timeout");
const constants_1 = require("./constants");
const metadata_1 = require("./metadata");
const logging = require("./logging");
const constants_2 = require("./constants");
const uri_parser_1 = require("./uri-parser");
const load_balancer_child_handler_1 = require("./load-balancer-child-handler");
const TRACER_NAME = 'resolving_load_balancer';
function trace(text) {
logging.trace(constants_2.LogVerbosity.DEBUG, TRACER_NAME, text);
}
const DEFAULT_LOAD_BALANCER_NAME = 'pick_first';
function getDefaultConfigSelector(serviceConfig) {
return function defaultConfigSelector(methodName, metadata) {
var _a, _b;
const splitName = methodName.split('/').filter(x => x.length > 0);
const service = (_a = splitName[0]) !== null && _a !== void 0 ? _a : '';
const method = (_b = splitName[1]) !== null && _b !== void 0 ? _b : '';
if (serviceConfig && serviceConfig.methodConfig) {
for (const methodConfig of serviceConfig.methodConfig) {
for (const name of methodConfig.name) {
if (name.service === service && (name.method === undefined || name.method === method)) {
return {
methodConfig: methodConfig,
pickInformation: {},
status: constants_1.Status.OK
};
}
}
}
}
return {
methodConfig: { name: [] },
pickInformation: {},
status: constants_1.Status.OK
};
};
}
class ResolvingLoadBalancer {
/**
* Wrapper class that behaves like a `LoadBalancer` and also handles name
* resolution internally.
* @param target The address of the backend to connect to.
* @param channelControlHelper `ChannelControlHelper` instance provided by
* this load balancer's owner.
* @param defaultServiceConfig The default service configuration to be used
* if none is provided by the name resolver. A `null` value indicates
* that the default behavior should be the default unconfigured behavior.
* In practice, that means using the "pick first" load balancer
* implmentation
*/
constructor(target, channelControlHelper, channelOptions, onSuccessfulResolution, onFailedResolution) {
this.target = target;
this.channelControlHelper = channelControlHelper;
this.channelOptions = channelOptions;
this.onSuccessfulResolution = onSuccessfulResolution;
this.onFailedResolution = onFailedResolution;
this.latestChildState = channel_1.ConnectivityState.IDLE;
this.latestChildPicker = new picker_1.QueuePicker(this);
/**
* This resolving load balancer's current connectivity state.
*/
this.currentState = channel_1.ConnectivityState.IDLE;
/**
* The service config object from the last successful resolution, if
* available. A value of null indicates that we have not yet received a valid
* service config from the resolver.
*/
this.previousServiceConfig = null;
/**
* Indicates whether we should attempt to resolve again after the backoff
* timer runs out.
*/
this.continueResolving = false;
if (channelOptions['grpc.service_config']) {
this.defaultServiceConfig = service_config_1.validateServiceConfig(JSON.parse(channelOptions['grpc.service_config']));
}
else {
this.defaultServiceConfig = {
loadBalancingConfig: [],
methodConfig: [],
};
}
this.updateState(channel_1.ConnectivityState.IDLE, new picker_1.QueuePicker(this));
this.childLoadBalancer = new load_balancer_child_handler_1.ChildLoadBalancerHandler({
createSubchannel: channelControlHelper.createSubchannel.bind(channelControlHelper),
requestReresolution: () => {
/* If the backoffTimeout is running, we're still backing off from
* making resolve requests, so we shouldn't make another one here.
* In that case, the backoff timer callback will call
* updateResolution */
if (this.backoffTimeout.isRunning()) {
this.continueResolving = true;
}
else {
this.updateResolution();
}
},
updateState: (newState, picker) => {
this.latestChildState = newState;
this.latestChildPicker = picker;
this.updateState(newState, picker);
},
});
this.innerResolver = resolver_1.createResolver(target, {
onSuccessfulResolution: (addressList, serviceConfig, serviceConfigError, configSelector, attributes) => {
var _a;
let workingServiceConfig = null;
/* This first group of conditionals implements the algorithm described
* in https://github.com/grpc/proposal/blob/master/A21-service-config-error-handling.md
* in the section called "Behavior on receiving a new gRPC Config".
*/
if (serviceConfig === null) {
// Step 4 and 5
if (serviceConfigError === null) {
// Step 5
this.previousServiceConfig = null;
workingServiceConfig = this.defaultServiceConfig;
}
else {
// Step 4
if (this.previousServiceConfig === null) {
// Step 4.ii
this.handleResolutionFailure(serviceConfigError);
}
else {
// Step 4.i
workingServiceConfig = this.previousServiceConfig;
}
}
}
else {
// Step 3
workingServiceConfig = serviceConfig;
this.previousServiceConfig = serviceConfig;
}
const workingConfigList = (_a = workingServiceConfig === null || workingServiceConfig === void 0 ? void 0 : workingServiceConfig.loadBalancingConfig) !== null && _a !== void 0 ? _a : [];
const loadBalancingConfig = load_balancer_1.getFirstUsableConfig(workingConfigList, true);
if (loadBalancingConfig === null) {
// There were load balancing configs but none are supported. This counts as a resolution failure
this.handleResolutionFailure({
code: constants_1.Status.UNAVAILABLE,
details: 'All load balancer options in service config are not compatible',
metadata: new metadata_1.Metadata(),
});
return;
}
this.childLoadBalancer.updateAddressList(addressList, loadBalancingConfig, attributes);
const finalServiceConfig = workingServiceConfig !== null && workingServiceConfig !== void 0 ? workingServiceConfig : this.defaultServiceConfig;
this.onSuccessfulResolution(configSelector !== null && configSelector !== void 0 ? configSelector : getDefaultConfigSelector(finalServiceConfig));
},
onError: (error) => {
this.handleResolutionFailure(error);
},
}, channelOptions);
this.backoffTimeout = new backoff_timeout_1.BackoffTimeout(() => {
if (this.continueResolving) {
this.updateResolution();
this.continueResolving = false;
}
else {
this.updateState(this.latestChildState, this.latestChildPicker);
}
});
this.backoffTimeout.unref();
}
updateResolution() {
this.innerResolver.updateResolution();
if (this.currentState === channel_1.ConnectivityState.IDLE) {
this.updateState(channel_1.ConnectivityState.CONNECTING, new picker_1.QueuePicker(this));
}
}
updateState(connectivityState, picker) {
trace(uri_parser_1.uriToString(this.target) +
' ' +
channel_1.ConnectivityState[this.currentState] +
' -> ' +
channel_1.ConnectivityState[connectivityState]);
// Ensure that this.exitIdle() is called by the picker
if (connectivityState === channel_1.ConnectivityState.IDLE) {
picker = new picker_1.QueuePicker(this);
}
this.currentState = connectivityState;
this.channelControlHelper.updateState(connectivityState, picker);
}
handleResolutionFailure(error) {
if (this.latestChildState === channel_1.ConnectivityState.IDLE) {
this.updateState(channel_1.ConnectivityState.TRANSIENT_FAILURE, new picker_1.UnavailablePicker(error));
this.onFailedResolution(error);
}
this.backoffTimeout.runOnce();
}
exitIdle() {
this.childLoadBalancer.exitIdle();
if (this.currentState === channel_1.ConnectivityState.IDLE) {
if (this.backoffTimeout.isRunning()) {
this.continueResolving = true;
}
else {
this.updateResolution();
}
this.updateState(channel_1.ConnectivityState.CONNECTING, new picker_1.QueuePicker(this));
}
}
updateAddressList(addressList, lbConfig) {
throw new Error('updateAddressList not supported on ResolvingLoadBalancer');
}
resetBackoff() {
this.backoffTimeout.reset();
this.childLoadBalancer.resetBackoff();
}
destroy() {
this.childLoadBalancer.destroy();
this.innerResolver.destroy();
this.updateState(channel_1.ConnectivityState.SHUTDOWN, new picker_1.UnavailablePicker());
}
getTypeName() {
return 'resolving_load_balancer';
}
}
exports.ResolvingLoadBalancer = ResolvingLoadBalancer;
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