Add embedding worker

Signed-off-by: Jay Wang <jay@zijie.wang>

Author: xiaohk

examples/rag-playground/src/components/prompt-panel/prompt-panel.ts

@@ -1,7 +1,9 @@
 import { LitElement, css, unsafeCSS, html, PropertyValues } from 'lit';
 import { customElement, property, state, query } from 'lit/decorators.js';
 import { unsafeHTML } from 'lit/directives/unsafe-html.js';
-import { pipeline } from '@xenova/transformers';
+import { EmbeddingModel } from '../../workers/embedding';
+
+import type { EmbeddingWorkerMessage } from '../../workers/embedding';
 
 import componentCSS from './prompt-panel.css?inline';
 import EmbeddingWorkerInline from '../../workers/embedding?worker&inline';
@@ -17,12 +19,25 @@ export class MememoPromptPanel extends LitElement {
   //==========================================================================||
   embeddingWorker: Worker;
 
+  embeddingWorkerRequestCount = 0;
+
+  get embeddingWorkerRequestID() {
+    this.embeddingWorkerRequestCount++;
+    return `prompt-panel-${this.embeddingWorkerRequestCount}`;
+  }
+
   //==========================================================================||
   //                             Lifecycle Methods                            ||
   //==========================================================================||
   constructor() {
     super();
     this.embeddingWorker = new EmbeddingWorkerInline();
+    this.embeddingWorker.addEventListener(
+      'message',
+      (e: MessageEvent<EmbeddingWorkerMessage>) => {
+        this.embeddingWorkerMessageHandler(e);
+      }
+    );
   }
 
   firstUpdated() {
@@ -40,12 +55,43 @@ export class MememoPromptPanel extends LitElement {
   //==========================================================================||
   async initData() {}
 
-  async getEmbedding() {}
+  getEmbedding() {
+    const message: EmbeddingWorkerMessage = {
+      command: 'startExtractEmbedding',
+      payload: {
+        detail: '',
+        requestID: this.embeddingWorkerRequestID,
+        model: EmbeddingModel.gteSmall,
+        sentences: ['Hello, how are you', 'yo']
+      }
+    };
+    this.embeddingWorker.postMessage(message);
+  }
 
   //==========================================================================||
   //                              Event Handlers                              ||
   //==========================================================================||
 
+  embeddingWorkerMessageHandler(e: MessageEvent<EmbeddingWorkerMessage>) {
+    switch (e.data.command) {
+      case 'finishExtractEmbedding': {
+        const embeddings = e.data.payload.embeddings;
+        console.log(embeddings);
+        break;
+      }
+
+      case 'error': {
+        console.error('Worker error: ', e.data.payload.message);
+        break;
+      }
+
+      default: {
+        console.error('Worker: unknown message', e.data.command);
+        break;
+      }
+    }
+  }
+
   //==========================================================================||
   //                             Private Helpers                              ||
   //==========================================================================||

examples/rag-playground/src/workers/embedding.ts

@@ -10,7 +10,7 @@ export type EmbeddingWorkerMessage =
       command: 'startExtractEmbedding';
       payload: {
         requestID: string;
-        text: string;
+        sentences: string[];
         model: EmbeddingModel;
         detail: string;
       };
@@ -19,10 +19,10 @@ export type EmbeddingWorkerMessage =
       command: 'finishExtractEmbedding';
       payload: {
         requestID: string;
-        text: string;
+        sentences: string[];
         model: EmbeddingModel;
         detail: string;
-        embedding: number[];
+        embeddings: number[][];
       };
     }
   | {
@@ -39,26 +39,56 @@ const extractors: Record<EmbeddingModel, Promise<FeatureExtractionPipeline>> = {
   'gte-small': pipeline('feature-extraction', 'gte-small')
 };
 
+/**
+ * Helper function to handle calls from the main thread
+ * @param e Message event
+ */
+self.onmessage = (e: MessageEvent<EmbeddingWorkerMessage>) => {
+  switch (e.data.command) {
+    case 'startExtractEmbedding': {
+      const { model, sentences, requestID, detail } = e.data.payload;
+      startExtractEmbedding(model, sentences, requestID, detail);
+      break;
+    }
+
+    default: {
+      console.error('Worker: unknown message', e.data.command);
+      break;
+    }
+  }
+};
+
 /**
  * Extract embedding from the input text
  * @param model Embedding model
  * @param text Input text
  */
-export const getEmbedding = async (
+export const startExtractEmbedding = async (
   model: EmbeddingModel,
-  text: string,
+  sentences: string[],
   requestID: string,
   detail: string
 ) => {
   try {
     const extractor = await extractors[model];
-    const sentences = [text];
     const output = await extractor(sentences, {
       pooling: 'mean',
       normalize: true
     });
 
-    const embedding = Array.from<number>(output.data as Float32Array);
+    const embeddings: number[][] = [];
+    const flattenEmbedding: number[] = Array.from<number>(
+      output.data as Float32Array
+    );
+
+    // Un-flatten the embedding output
+    for (let i = 0; i < output.dims[0]; i++) {
+      const curRow = flattenEmbedding.slice(
+        i * output.dims[1],
+        (i + 1) * output.dims[1]
+      );
+      embeddings.push(curRow);
+    }
 
     // Send result to the main thread
     const message: EmbeddingWorkerMessage = {
@@ -67,8 +97,8 @@ export const getEmbedding = async (
         model,
         requestID,
         detail,
-        text,
-        embedding
+        sentences,
+        embeddings
       }
     };
     postMessage(message);