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1'use strict'2 3const diagnosticsChannel = require('node:diagnostics_channel')4const util = require('../core/util')5const DeduplicationHandler = require('../handler/deduplication-handler')6const { normalizeHeaders, makeCacheKey, makeDeduplicationKey } = require('../util/cache.js')7 8const pendingRequestsChannel = diagnosticsChannel.channel('undici:request:pending-requests')9 10/**11 * @param {import('../../types/interceptors.d.ts').default.DeduplicateInterceptorOpts} [opts]12 * @returns {import('../../types/dispatcher.d.ts').default.DispatcherComposeInterceptor}13 */14module.exports = (opts = {}) => {15  const {16    methods = ['GET'],17    skipHeaderNames = [],18    excludeHeaderNames = [],19    maxBufferSize = 5 * 1024 * 102420  } = opts21 22  if (typeof opts !== 'object' || opts === null) {23    throw new TypeError(`expected type of opts to be an Object, got ${opts === null ? 'null' : typeof opts}`)24  }25 26  if (!Array.isArray(methods)) {27    throw new TypeError(`expected opts.methods to be an array, got ${typeof methods}`)28  }29 30  for (const method of methods) {31    if (!util.safeHTTPMethods.includes(method)) {32      throw new TypeError(`expected opts.methods to only contain safe HTTP methods, got ${method}`)33    }34  }35 36  if (!Array.isArray(skipHeaderNames)) {37    throw new TypeError(`expected opts.skipHeaderNames to be an array, got ${typeof skipHeaderNames}`)38  }39 40  if (!Array.isArray(excludeHeaderNames)) {41    throw new TypeError(`expected opts.excludeHeaderNames to be an array, got ${typeof excludeHeaderNames}`)42  }43 44  if (!Number.isFinite(maxBufferSize) || maxBufferSize <= 0) {45    throw new TypeError(`expected opts.maxBufferSize to be a positive finite number, got ${maxBufferSize}`)46  }47 48  // Convert to lowercase Set for case-insensitive header matching49  const skipHeaderNamesSet = new Set(skipHeaderNames.map(name => name.toLowerCase()))50 51  // Convert to lowercase Set for case-insensitive header exclusion from deduplication key52  const excludeHeaderNamesSet = new Set(excludeHeaderNames.map(name => name.toLowerCase()))53 54  /**55   * Map of pending requests for deduplication56   * @type {Map<string, DeduplicationHandler>}57   */58  const pendingRequests = new Map()59 60  return dispatch => {61    return (opts, handler) => {62      if (!opts.origin || methods.includes(opts.method) === false) {63        return dispatch(opts, handler)64      }65 66      opts = {67        ...opts,68        headers: normalizeHeaders(opts)69      }70 71      // Skip deduplication if request contains any of the specified headers72      if (skipHeaderNamesSet.size > 0) {73        for (const headerName of Object.keys(opts.headers)) {74          if (skipHeaderNamesSet.has(headerName.toLowerCase())) {75            return dispatch(opts, handler)76          }77        }78      }79 80      const cacheKey = makeCacheKey(opts)81      const dedupeKey = makeDeduplicationKey(cacheKey, excludeHeaderNamesSet)82 83      // Check if there's already a pending request for this key84      const pendingHandler = pendingRequests.get(dedupeKey)85      if (pendingHandler) {86        // Add this handler to the waiting list when safe.87        // If body streaming has already started, this request must be sent independently.88        if (pendingHandler.addWaitingHandler(handler)) {89          return true90        }91 92        return dispatch(opts, handler)93      }94 95      // Create a new deduplication handler96      const deduplicationHandler = new DeduplicationHandler(97        handler,98        () => {99          // Clean up when request completes100          pendingRequests.delete(dedupeKey)101          if (pendingRequestsChannel.hasSubscribers) {102            pendingRequestsChannel.publish({ size: pendingRequests.size, key: dedupeKey, type: 'removed' })103          }104        },105        maxBufferSize106      )107 108      // Register the pending request109      pendingRequests.set(dedupeKey, deduplicationHandler)110      if (pendingRequestsChannel.hasSubscribers) {111        pendingRequestsChannel.publish({ size: pendingRequests.size, key: dedupeKey, type: 'added' })112      }113 114      return dispatch(opts, deduplicationHandler)115    }116  }117}118