Smoothen event source parser by feeding in smaller chunks (#151)

It seems like several things, including the event parser (straight up
CPU performance), and node's ability to interleave stream segments when
running lots of concurrent streams, are worsened by having streams with
enormous chunks.

This change splits the stream into newlines, which seems to produce much
better results.

packages/proxy/src/proxy.ts

@@ -328,12 +328,24 @@ export async function proxyV1({
       stream = new ReadableStream<Uint8Array>({
         start(controller) {
           if ("body" in cachedData && cachedData.body) {
-            controller.enqueue(new TextEncoder().encode(cachedData.body));
+            for (const line of cachedData.body.split("\n")) {
+              controller.enqueue(new TextEncoder().encode(line));
+            }
           } else if ("data" in cachedData && cachedData.data) {
             const data = Buffer.from(cachedData.data, "base64");
-            const uint8Array = new Uint8Array(data);
-            controller.enqueue(uint8Array);
+            let start = 0;
+            for (let i = 0; i < data.length; i++) {
+              if (data[i] === 10) {
+                // 10 is ASCII/UTF-8 code for \n
+                controller.enqueue(data.subarray(start, i + 1));
+                start = i + 1;
+              }
+            }
+            if (start < data.length) {
+              controller.enqueue(data.subarray(start));
+            }
           }
+
           controller.close();
         },
       });
@@ -485,7 +497,6 @@ export async function proxyV1({
             cacheKey,
             JSON.stringify({ headers: proxyResponseHeaders, data: dataB64 }),
           );
-          controller.terminate();
         },
       });
 
@@ -590,7 +601,11 @@ export async function proxyV1({
           });
         }
         if (isStreaming) {
-          eventSourceParser?.feed(new TextDecoder().decode(chunk));
+          const start = Date.now();
+          let textChunks = new TextDecoder().decode(chunk);
+          eventSourceParser?.feed(textChunks);
+          const end = Date.now();
+          console.log(`time to feed ${chunk.length} bytes: ${end - start}ms`);
         } else {
           allChunks.push(chunk);
         }