fix(WebDuplexStream): Improved read/write interface and error handling in WebDuplexStream

changelog.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## 2024-10-13 - 3.1.1 - fix(WebDuplexStream)
+Improved read/write interface and error handling in WebDuplexStream
+
+- Enhanced the IStreamToolsRead and IStreamToolsWrite interfaces for better Promise handling
+- Refined readFunction and writeFunction handling to accommodate asynchronous data processing and error propagation
+- Added internal _startReading method to facilitate initial data handling if readFunction is present
+- Maintained backward compatibility while ensuring data continuity when no writeFunction is specified
+
 ## 2024-10-13 - 3.1.0 - feat(core)
 Add support for creating Web ReadableStream from a file
 

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartstream',
-  version: '3.1.0',
+  version: '3.1.1',
   description: 'A library to simplify the creation and manipulation of Node.js streams, providing utilities for handling transform, duplex, and readable/writable streams effectively in TypeScript.'
 }

ts_web/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartstream',
-  version: '3.1.0',
+  version: '3.1.1',
   description: 'A library to simplify the creation and manipulation of Node.js streams, providing utilities for handling transform, duplex, and readable/writable streams effectively in TypeScript.'
 }

ts_web/classes.webduplexstream.ts

@@ -1,25 +1,22 @@
 import * as plugins from './plugins.js';
 
-
 // ========================================
-// READ
+// Interfaces for Read functionality
 // ========================================
 export interface IStreamToolsRead<TInput, TOutput> {
   done: () => void;
-  write: (writeArg: TInput) => void;
+  write: (writeArg: TInput) => Promise<void>;
 }
 
 /**
- * the read function is called anytime
- *   -> the WebDuplexStream is being read from
- *      and at the same time if nothing is enqueued
+ * The read function is called when data needs to be read into the stream.
  */
 export interface IStreamReadFunction<TInput, TOutput> {
   (toolsArg: IStreamToolsRead<TInput, TOutput>): Promise<void>;
 }
 
 // ========================================
-// WRITE
+// Interfaces for Write functionality
 // ========================================
 export interface IStreamToolsWrite<TInput, TOutput> {
   truncate: () => void;
@@ -27,15 +24,14 @@ export interface IStreamToolsWrite<TInput, TOutput> {
 }
 
 /**
- * the write function can return something.
- * It is called anytime a chunk is written to the stream.
+ * The write function is called whenever a chunk is written to the stream.
  */
 export interface IStreamWriteFunction<TInput, TOutput> {
   (chunkArg: TInput, toolsArg: IStreamToolsWrite<TInput, TOutput>): Promise<any>;
 }
 
 export interface IStreamFinalFunction<TInput, TOutput> {
-  (toolsArg: IStreamToolsWrite<TInput, TOutput>): Promise<TOutput>;
+  (toolsArg: IStreamToolsWrite<TInput, TOutput>): Promise<TOutput | void>;
 }
 
 export interface WebDuplexStreamOptions<TInput, TOutput> {
@@ -45,28 +41,15 @@ export interface WebDuplexStreamOptions<TInput, TOutput> {
 }
 
 export class WebDuplexStream<TInput = any, TOutput = any> extends TransformStream<TInput, TOutput> {
-  static fromUInt8Array(uint8Array: Uint8Array): WebDuplexStream<Uint8Array, Uint8Array> {
-    const stream = new WebDuplexStream<Uint8Array, Uint8Array>({
-      writeFunction: async (chunk, { push }) => {
-        push(chunk); // Directly push the chunk as is
-        return null;
-      }
-    });
-
-    const writer = stream.writable.getWriter();
-    writer.write(uint8Array).then(() => writer.close());
-
-    return stream;
-  }
-  
   // INSTANCE
   options: WebDuplexStreamOptions<TInput, TOutput>;
 
   constructor(optionsArg: WebDuplexStreamOptions<TInput, TOutput>) {
-    // here we call into the official web stream api
     super({
+      async start(controller) {
+        // Optionally initialize any state here
+      },
       async transform(chunk, controller) {
-        // Transformation logic remains unchanged
         if (optionsArg?.writeFunction) {
           const tools: IStreamToolsWrite<TInput, TOutput> = {
             truncate: () => controller.terminate(),
@@ -75,82 +58,78 @@ export class WebDuplexStream<TInput = any, TOutput = any> extends TransformStrea
 
           try {
             const writeReturnChunk = await optionsArg.writeFunction(chunk, tools);
-            if (writeReturnChunk) { // return chunk is optional
+            if (writeReturnChunk !== undefined && writeReturnChunk !== null) {
               controller.enqueue(writeReturnChunk);
             }
           } catch (err) {
             controller.error(err);
           }
         } else {
-          controller.error(new Error('No write function provided'));
+          // If no writeFunction is provided, pass the chunk through
+          controller.enqueue(chunk as unknown as TOutput);
         }
       },
       async flush(controller) {
-        // Flush logic remains unchanged
         if (optionsArg?.finalFunction) {
           const tools: IStreamToolsWrite<TInput, TOutput> = {
             truncate: () => controller.terminate(),
-            push: (pipeObject) => controller.enqueue(pipeObject),
+            push: (pushArg) => controller.enqueue(pushArg),
           };
 
-          optionsArg.finalFunction(tools)
-            .then(finalChunk => {
-              if (finalChunk) {
-                controller.enqueue(finalChunk);
-              }
-            })  
-            .catch(err => controller.error(err))
-            .finally(() => controller.terminate());
+          try {
+            const finalChunk = await optionsArg.finalFunction(tools);
+            if (finalChunk) {
+              controller.enqueue(finalChunk);
+            }
+          } catch (err) {
+            controller.error(err);
+          } finally {
+            controller.terminate();
+          }
         } else {
           controller.terminate();
         }
-      }
+      },
     });
 
     this.options = optionsArg;
+
+    // Start producing data if readFunction is provided
+    if (this.options.readFunction) {
+      this._startReading();
+    }
   }
 
-  // Method to create a custom readable stream that integrates the readFunction
-  // readFunction is executed whenever the stream is being read from and nothing is enqueued
-  getCustomReadableStream() {
-    const readableStream = this.readable;
-    const options = this.options;
-    const customReadable = new ReadableStream({
-      async pull(controller) {
-        const reader = readableStream.getReader();
+  private async _startReading() {
+    const writable = this.writable;
+    const writer = writable.getWriter();
 
-        // Check the current state of the original stream
-        const { value, done } = await reader.read();
-        reader.releaseLock();
+    const tools: IStreamToolsRead<TInput, TOutput> = {
+      done: () => writer.close(),
+      write: async (writeArg) => await writer.write(writeArg),
+    };
 
-        if (done) {
-          // If the original stream is done, close the custom readable stream
-          controller.close();
-        } else {
-          if (value) {
-            // If there is data in the original stream, enqueue it and do not execute the readFunction
-            controller.enqueue(value);
-          } else if (options.readFunction) {
-            // If the original stream is empty, execute the readFunction and read again
-            await options.readFunction({
-              done: () => controller.close(),
-              write: (writeArg) => controller.enqueue(writeArg),
-            });
+    try {
+      await this.options.readFunction(tools);
+    } catch (err) {
+      writer.abort(err);
+    } finally {
+      writer.releaseLock();
+    }
+  }
 
-            const newReader = readableStream.getReader();
-            const { value: newValue, done: newDone } = await newReader.read();
-            newReader.releaseLock();
-
-            if (newDone) {
-              controller.close();
-            } else {
-              controller.enqueue(newValue);
-            }
-          }
-        }
-      }
+  // Static method example (adjust as needed)
+  static fromUInt8Array(uint8Array: Uint8Array): WebDuplexStream<Uint8Array, Uint8Array> {
+    const stream = new WebDuplexStream<Uint8Array, Uint8Array>({
+      writeFunction: async (chunk, { push }) => {
+        push(chunk); // Directly push the chunk as is
+        return null;
+      },
     });
 
-    return customReadable;
+    const writer = stream.writable.getWriter();
+    writer.write(uint8Array).then(() => writer.close());
+
+    return stream;
   }
 }