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node_modules/next/dist/esm/server/lib/dedupe-fetch.js

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+/**
+ * Based on https://github.com/facebook/react/blob/d4e78c42a94be027b4dc7ed2659a5fddfbf9bd4e/packages/react/src/ReactFetch.js
+ */ import * as React from 'react';
+import { cloneResponse } from './clone-response';
+import { InvariantError } from '../../shared/lib/invariant-error';
+const simpleCacheKey = '["GET",[],null,"follow",null,null,null,null]' // generateCacheKey(new Request('https://blank'));
+;
+// Headers that should not affect deduplication
+// traceparent and tracestate are used for distributed tracing and should not affect cache keys
+const headersToExcludeInCacheKey = new Set([
+    'traceparent',
+    'tracestate'
+]);
+function generateCacheKey(request) {
+    // We pick the fields that goes into the key used to dedupe requests.
+    // We don't include the `cache` field, because we end up using whatever
+    // caching resulted from the first request.
+    // Notably we currently don't consider non-standard (or future) options.
+    // This might not be safe. TODO: warn for non-standard extensions differing.
+    // IF YOU CHANGE THIS UPDATE THE simpleCacheKey ABOVE.
+    const filteredHeaders = Array.from(request.headers.entries()).filter(([key])=>!headersToExcludeInCacheKey.has(key.toLowerCase()));
+    return JSON.stringify([
+        request.method,
+        filteredHeaders,
+        request.mode,
+        request.redirect,
+        request.credentials,
+        request.referrer,
+        request.referrerPolicy,
+        request.integrity
+    ]);
+}
+export function createDedupeFetch(originalFetch) {
+    const getCacheEntries = React.cache(// eslint-disable-next-line @typescript-eslint/no-unused-vars -- url is the cache key
+    (url)=>[]);
+    return function dedupeFetch(resource, options) {
+        if (options && options.signal) {
+            // If we're passed a signal, then we assume that
+            // someone else controls the lifetime of this object and opts out of
+            // caching. It's effectively the opt-out mechanism.
+            // Ideally we should be able to check this on the Request but
+            // it always gets initialized with its own signal so we don't
+            // know if it's supposed to override - unless we also override the
+            // Request constructor.
+            return originalFetch(resource, options);
+        }
+        // Normalize the Request
+        let url;
+        let cacheKey;
+        if (typeof resource === 'string' && !options) {
+            // Fast path.
+            cacheKey = simpleCacheKey;
+            url = resource;
+        } else {
+            // Normalize the request.
+            // if resource is not a string or a URL (its an instance of Request)
+            // then do not instantiate a new Request but instead
+            // reuse the request as to not disturb the body in the event it's a ReadableStream.
+            const request = typeof resource === 'string' || resource instanceof URL ? new Request(resource, options) : resource;
+            if (request.method !== 'GET' && request.method !== 'HEAD' || request.keepalive) {
+                // We currently don't dedupe requests that might have side-effects. Those
+                // have to be explicitly cached. We assume that the request doesn't have a
+                // body if it's GET or HEAD.
+                // keepalive gets treated the same as if you passed a custom cache signal.
+                return originalFetch(resource, options);
+            }
+            cacheKey = generateCacheKey(request);
+            url = request.url;
+        }
+        const cacheEntries = getCacheEntries(url);
+        for(let i = 0, j = cacheEntries.length; i < j; i += 1){
+            const [key, promise] = cacheEntries[i];
+            if (key === cacheKey) {
+                return promise.then(()=>{
+                    const response = cacheEntries[i][2];
+                    if (!response) throw Object.defineProperty(new InvariantError('No cached response'), "__NEXT_ERROR_CODE", {
+                        value: "E579",
+                        enumerable: false,
+                        configurable: true
+                    });
+                    // We're cloning the response using this utility because there exists
+                    // a bug in the undici library around response cloning. See the
+                    // following pull request for more details:
+                    // https://github.com/vercel/next.js/pull/73274
+                    const [cloned1, cloned2] = cloneResponse(response);
+                    cacheEntries[i][2] = cloned2;
+                    return cloned1;
+                });
+            }
+        }
+        // We pass the original arguments here in case normalizing the Request
+        // doesn't include all the options in this environment.
+        const promise = originalFetch(resource, options);
+        const entry = [
+            cacheKey,
+            promise,
+            null
+        ];
+        cacheEntries.push(entry);
+        return promise.then((response)=>{
+            // We're cloning the response using this utility because there exists
+            // a bug in the undici library around response cloning. See the
+            // following pull request for more details:
+            // https://github.com/vercel/next.js/pull/73274
+            const [cloned1, cloned2] = cloneResponse(response);
+            entry[2] = cloned2;
+            return cloned1;
+        });
+    };
+}
+
+//# sourceMappingURL=dedupe-fetch.js.map