feat: optimize gateway by batching queries #667
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,177 @@ | ||
| 'use strict' | ||
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| const { preGatewayExecutionHandler } = require('../handlers') | ||
|
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| /** | ||
| * @typedef {Object.<string, { variables: Object, document: import('graphql').DocumentNode }>} GroupedQueries | ||
| */ | ||
|
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| /** | ||
| * Group GraphQL queries by their string and map them to their variables and document. | ||
| * @param {Array} queries | ||
| * @returns {GroupedQueries} | ||
| */ | ||
| function groupQueriesByDefinition (queries) { | ||
| const q = [...new Set(queries.map(q => q.query))] | ||
| const resultIndexes = [] | ||
| const mergedQueries = queries.reduce((acc, curr, queryIndex) => { | ||
| if (!acc[curr.query]) { | ||
| acc[curr.query] = { | ||
| document: curr.document, | ||
| variables: curr.variables | ||
| } | ||
| resultIndexes[q.indexOf(curr.query)] = [] | ||
| } else { | ||
| acc[curr.query].variables.representations = [ | ||
| ...acc[curr.query].variables.representations, | ||
| ...curr.variables.representations | ||
| ] | ||
| } | ||
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| for (let i = 0; i < curr.variables.representations.length; i++) { | ||
| resultIndexes[q.indexOf(curr.query)].push(queryIndex) | ||
| } | ||
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| return acc | ||
| }, {}) | ||
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| return { mergedQueries, resultIndexes } | ||
| } | ||
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| /** | ||
| * Fetches queries result from the service with batching (1 request for all the queries). | ||
| * @param {Object} params | ||
| * @param {Object} params.service The service that will receive one request with the batched queries | ||
| * @returns {Array} result | ||
| */ | ||
| async function fetchBactchedResult ({ mergeQueriesResult, context, serviceDefinition, service }) { | ||
| const { mergedQueries, resultIndexes } = mergeQueriesResult | ||
| const batchedQueries = [] | ||
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| for (const [query, { document, variables }] of Object.entries(mergedQueries)) { | ||
| let modifiedQuery | ||
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| if (context.preGatewayExecution !== null) { | ||
| ({ modifiedQuery } = await preGatewayExecutionHandler({ | ||
| schema: serviceDefinition.schema, | ||
| document, | ||
| context, | ||
| service: { name: service } | ||
| })) | ||
| } | ||
|
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| batchedQueries.push({ | ||
| operationName: document.definitions.find(d => d.kind === 'OperationDefinition').name.value, | ||
| query: modifiedQuery || query, | ||
| variables | ||
| }) | ||
| } | ||
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| const response = await serviceDefinition.sendRequest({ | ||
| originalRequestHeaders: context.reply.request.headers, | ||
| body: JSON.stringify(batchedQueries), | ||
| context | ||
| }) | ||
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| return buildResult({ resultIndexes, data: response.json }) | ||
| } | ||
|
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| /** | ||
| * | ||
| * @param {Object} params | ||
| * @param {Array<Number[]>} params.resultIndexes Array used to map results with queries | ||
| * @param {Array<Object>} params.data Array of data returned from GraphQL end point | ||
| * @returns {Array} result | ||
| */ | ||
| function buildResult ({ resultIndexes, data }) { | ||
| const result = [] | ||
|
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| for (const [queryIndex, queryResponse] of data.entries()) { | ||
| let entityIndex = 0 | ||
|
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| for (const entity of queryResponse.data._entities) { | ||
| if (!result[resultIndexes[queryIndex][entityIndex]]) { | ||
| result[resultIndexes[queryIndex][entityIndex]] = { | ||
| ...queryResponse, | ||
| json: { | ||
| data: { | ||
| _entities: [entity] | ||
| } | ||
| } | ||
| } | ||
| } else { | ||
| result[resultIndexes[queryIndex][entityIndex]].json.data._entities.push(entity) | ||
| } | ||
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| entityIndex++ | ||
| } | ||
| } | ||
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| return result | ||
| } | ||
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| /** | ||
| * Fetches queries result from the service without batching (1 request for each query) | ||
| * @param {Object} params | ||
| * @param {GroupedQueries} params.mergeQueriesResult | ||
| * @param {Object} params.service The service that will receive requests for the queries | ||
| * @returns {Array} result | ||
| */ | ||
| async function fetchResult ({ mergeQueriesResult, serviceDefinition, context, service }) { | ||
| const { mergedQueries, resultIndexes } = mergeQueriesResult | ||
| const queriesEntries = Object.entries(mergedQueries) | ||
| const data = await Promise.all( | ||
| queriesEntries.map(async ([query, { document, variables }]) => { | ||
| let modifiedQuery | ||
|
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| if (context.preGatewayExecution !== null) { | ||
| ({ modifiedQuery } = await preGatewayExecutionHandler({ | ||
| schema: serviceDefinition.schema, | ||
| document, | ||
| context, | ||
| service: { name: service } | ||
| })) | ||
| } | ||
|
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| const response = await serviceDefinition.sendRequest({ | ||
| originalRequestHeaders: context.reply.request.headers, | ||
| body: JSON.stringify({ | ||
| query: modifiedQuery || query, | ||
| variables | ||
| }), | ||
| context | ||
| }) | ||
|
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| return response.json | ||
| }) | ||
| ) | ||
|
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| return buildResult({ data, resultIndexes }) | ||
| } | ||
|
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| /** | ||
| * Fetches queries results from their shared service and returns array of data. | ||
| * It batches queries into one request if allowBatchedQueries is true for the service. | ||
| * @param {Object} params | ||
| * @param {Array} params.queries The list of queries to be executed | ||
| * @param {Object} params.service The service to send requests to | ||
| * @returns {Array} The array of results | ||
| */ | ||
| async function getQueryResult ({ context, queries, serviceDefinition, service }) { | ||
| const mergeQueriesResult = groupQueriesByDefinition(queries) | ||
| const params = { | ||
| mergeQueriesResult, | ||
| service, | ||
| serviceDefinition, | ||
| queries, | ||
| context | ||
| } | ||
|
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| if (serviceDefinition.allowBatchedQueries) { | ||
| return fetchBactchedResult({ ...params }) | ||
| } | ||
|
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| return fetchResult({ ...params }) | ||
| } | ||
|
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| module.exports = getQueryResult |
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This does not match the implementation anymore.