feat: support concurrency limit

README.md

@@ -36,7 +36,7 @@ online example: https://upload.react-component.vercel.app/
 
 ## Feature
 
-* support IE11+, Chrome, Firefox, Safari
+- support IE11+, Chrome, Firefox, Safari
 
 ## install
 
@@ -54,29 +54,30 @@ React.render(<Upload />, container);
 
 ### props
 
-|name|type|default| description|
-|-----|---|--------|----|
-|name | string | file| file param post to server |
-|style | object | {}| root component inline style |
-|className | string | - | root component className |
-|disabled | boolean | false | whether disabled |
-|component | "div"|"span" | "span"| wrap component name |
-|action| string &#124; function(file): string &#124; Promise&lt;string&gt; | | form action url |
-|method | string | post | request method |
-|directory| boolean | false | support upload whole directory |
-|data| object/function(file) | | other data object to post or a function which returns a data object(a promise object which resolve a data object) |
-|headers| object | {} | http headers to post, available in modern browsers |
-|accept | string | | input accept attribute |
-|capture | string | | input capture attribute |
-|multiple | boolean | false | only support ie10+|
-|onStart | function| | start upload file |
-|onError| function| | error callback |
-|onSuccess | function | | success callback |
-|onProgress | function || progress callback, only for modern browsers|
-|beforeUpload| function |null| before upload check, return false or a rejected Promise will stop upload, only for modern browsers|
-|customRequest | function | null | provide an override for the default xhr behavior for additional customization|
-|withCredentials | boolean | false | ajax upload with cookie send |
-|openFileDialogOnClick | boolean | true | useful for drag only upload as it does not trigger on enter key or click event |
+| name | type | default | description |
+| --- | --- | --- | --- |
+| name | string | file | file param post to server |
+| style | object | {} | root component inline style |
+| className | string | - | root component className |
+| disabled | boolean | false | whether disabled |
+| component | "div" &#124; "span" | "span" | wrap component name |
+| action | string &#124; function(file): string &#124; Promise&lt;string&gt; |  | form action url |
+| method | string | post | request method |
+| directory | boolean | false | support upload whole directory |
+| data | object/function(file) |  | other data object to post or a function which returns a data object(a promise object which resolve a data object) |
+| headers | object | {} | http headers to post, available in modern browsers |
+| accept | string |  | input accept attribute |
+| capture | string |  | input capture attribute |
+| multiple | boolean | false | only support ie10+ |
+| concurrencyLimit | number &#124; undefined | undefined | asynchronously posts files with the concurrency limit |
+| onStart | function |  | start upload file |
+| onError | function |  | error callback |
+| onSuccess | function |  | success callback |
+| onProgress | function |  | progress callback, only for modern browsers |
+| beforeUpload | function | null | before upload check, return false or a rejected Promise will stop upload, only for modern browsers |
+| customRequest | function | null | provide an override for the default xhr behavior for additional customization |
+| withCredentials | boolean | false | ajax upload with cookie send |
+| openFileDialogOnClick | boolean | true | useful for drag only upload as it does not trigger on enter key or click event |
 
 #### onError arguments
 
@@ -88,26 +89,23 @@ React.render(<Upload />, container);
 
 1. `result`: response body
 2. `file`: upload file
-3. `xhr`: xhr header, only for modern browsers which support AJAX upload. since
-   2.4.0
-
+3. `xhr`: xhr header, only for modern browsers which support AJAX upload. since 2.4.0
 
 ### customRequest
 
 Allows for advanced customization by overriding default behavior in AjaxUploader. Provide your own XMLHttpRequest calls to interface with custom backend processes or interact with AWS S3 service through the aws-sdk-js package.
 
 customRequest callback is passed an object with:
 
-* `onProgress: (event: { percent: number }): void`
-* `onError: (event: Error, body?: Object): void`
-* `onSuccess: (body: Object): void`
-* `data: Object`
-* `filename: String`
-* `file: File`
-* `withCredentials: Boolean`
-* `action: String`
-* `headers: Object`
-
+- `onProgress: (event: { percent: number }): void`
+- `onError: (event: Error, body?: Object): void`
+- `onSuccess: (body: Object): void`
+- `data: Object`
+- `filename: String`
+- `file: File`
+- `withCredentials: Boolean`
+- `action: String`
+- `headers: Object`
 
 ### methods
 

src/AjaxUploader.tsx

@@ -13,6 +13,7 @@
 import defaultRequest from './request';
 import traverseFileTree from './traverseFileTree';
 import getUid from './uid';
+import ConcurrencyRequester from './concurrencyRequest';
 
 interface ParsedFileInfo {
   origin: RcFile;
@@ -26,6 +27,8 @@
 
   reqs: any = {};
 
+  private concurrencyRequester?: ConcurrencyRequester<any>;
+
   private fileInput: HTMLInputElement;
 
   private _isMounted: boolean;
@@ -111,17 +114,26 @@
       return this.processFile(file, originFiles);
     });
 
+    const { onBatchStart, concurrencyLimit } = this.props;
+
+    if (concurrencyLimit) {
+      this.concurrencyRequester = new ConcurrencyRequester(concurrencyLimit);
+    }
+
     // Batch upload files
     Promise.all(postFiles).then(fileList => {
-      const { onBatchStart } = this.props;
-
       onBatchStart?.(fileList.map(({ origin, parsedFile }) => ({ file: origin, parsedFile })));
 
       fileList
         .filter(file => file.parsedFile !== null)
         .forEach(file => {
           this.post(file);
         });
+
+      // Asynchronously posts files with the concurrency limit.
+      if (this.concurrencyRequester) {
+        this.concurrencyRequester.send();
+      }
     });
   };
 
@@ -230,7 +242,11 @@
     };
 
     onStart(origin);
-    this.reqs[uid] = request(requestOption);
+    if (this.concurrencyRequester) {
+      this.reqs[uid] = this.concurrencyRequester.append(requestOption);
+    } else {
+      this.reqs[uid] = request(requestOption);
+    }
   }
 
   reset() {

src/concurrencyRequest.ts

@@ -0,0 +1,155 @@
+import type { ConcurrencyRequestTask, UploadRequestOption } from './interface';
+import { onXHRLoad, prepareData, prepareXHR } from './request';
+
+/**
+ * Asynchronously processes an array of items with a concurrency limit.
+ *
+ * @template T - Type of the input items.
+ * @template U - Type of the result of the asynchronous task.
+ *
+ * @param {number} concurrencyLimit - The maximum number of asynchronous tasks to execute concurrently.
+ * @param {T[]} items - The array of items to process asynchronously.
+ * @param {(item: T) => Promise<U>} asyncTask - The asynchronous task to be performed on each item.
+ *
+ * @returns {Promise<U[]>} - A promise that resolves to an array of results from the asynchronous tasks.
+ */
+async function asyncPool<T, U>(
+  concurrencyLimit: number,
+  items: T[],
+  asyncTask: (item: T) => Promise<U>,
+): Promise<U[]> {
+  const tasks: Promise<U>[] = [];
+  const pendings: Promise<U>[] = [];
+
+  for (const item of items) {
+    const task = asyncTask(item);
+    tasks.push(task);
+
+    if (concurrencyLimit <= items.length) {
+      task.then(() => {
+        pendings.splice(pendings.indexOf(task), 1);
+      });
+      pendings.push(task);
+
+      if (pendings.length >= concurrencyLimit) {
+        await Promise.race(pendings);
+      }
+    }
+  }
+
+  return Promise.all(tasks);
+}
+
+type DataType = 'form' | 'blob' | 'string';
+
+/**
+ * Represents a class for handling concurrent requests with a specified concurrency limit.
+ *
+ * @template T - The type of data to be uploaded.
+ */
+export default class ConcurrencyRequester<T> {
+  /**
+   * The concurrency limit for handling requests simultaneously.
+   */
+  private concurrencyLimit: number;
+
+  /**
+   * An array to store the tasks for concurrent requests.
+   */
+  private tasks: ConcurrencyRequestTask[] = [];
+
+  /**
+   * The type of data to be sent in the request ('form', 'blob', or 'string').
+   */
+  private dataType: DataType;
+
+  /**
+   * Creates an instance of ConcurrencyRequester.
+   *
+   * @param {number} concurrencyLimit - The concurrency limit for handling requests simultaneously.
+   * @param {DataType} [dataType='form'] - The type of data to be sent in the request ('form', 'blob', or 'string').
+   */
+  constructor(concurrencyLimit: number, dataType: DataType = 'form') {
+    this.concurrencyLimit = concurrencyLimit;
+    this.dataType = dataType;
+  }
+
+  /**
+   * Prepares data based on the specified data type.
+   *
+   * @param {UploadRequestOption<T>} option - The upload request option.
+   * @returns {string | Blob | FormData} - The prepared data based on the specified data type.
+   * @private
+   */
+  private prepareData = (option: UploadRequestOption<T>): string | Blob | FormData => {
+    if (this.dataType === 'form') {
+      return prepareData(option);
+    }
+
+    return option.file;
+  };
+
+  /**
+   * Prepares a task for a concurrent request.
+   *
+   * @param {UploadRequestOption<T>} option - The upload request option.
+   * @returns {ConcurrencyRequestTask} - The prepared task for the concurrent request.
+   * @private
+   */
+  private prepare = (option: UploadRequestOption<T>): ConcurrencyRequestTask => {
+    const xhr = prepareXHR(option);
+
+    const data = this.prepareData(option);
+
+    const task: ConcurrencyRequestTask = { xhr, data };
+
+    xhr.onerror = function error(e) {
+      task.done?.();
+      option.onError(e);
+    };
+
+    xhr.onload = function onload() {
+      task.done?.();
+
+      onXHRLoad(this, option);
+    };
+
+    return task;
+  };
+
+  /**
+   * Appends a new upload request to the tasks array.
+   *
+   * @param {UploadRequestOption<T>} option - The upload request option.
+   * @returns {{ abort: () => void }} - An object with an `abort` function to cancel the request.
+   */
+  append = (option: UploadRequestOption<T>): { abort: () => void } => {
+    const task = this.prepare(option);
+
+    this.tasks.push(task);
+
+    return {
+      abort() {
+        task.xhr.abort();
+      },
+    };
+  };
+
+  /**
+   * Sends all the appended requests concurrently.
+   */
+  send = (): void => {
+    asyncPool(
+      this.concurrencyLimit,
+      this.tasks,
+      item =>
+        new Promise<void>(resolve => {
+          const xhr = item.xhr;
+
+          item.done = resolve;
+
+          xhr.send(item.data);
+        }),
+    );
+  };
+}

src/interface.tsx

@@ -44,6 +44,7 @@ export interface UploadProps
     input?: React.CSSProperties;
   };
   hasControlInside?: boolean;
+  concurrencyLimit?: number;
 }
 
 export interface UploadProgressEvent extends Partial<ProgressEvent> {
@@ -76,3 +77,9 @@ export interface UploadRequestOption<T = any> {
 export interface RcFile extends File {
   uid: string;
 }
+
+export interface ConcurrencyRequestTask {
+  xhr: XMLHttpRequest;
+  data: File | FormData | string | Blob;
+  done?: () => void;
+}