Add span for static file handler

denoland · Dec 10, 2024 · 28c45de · 28c45de
1 parent 3054803
commit 28c45de
Show file tree

Hide file tree

Showing 2 changed files with 69 additions and 51 deletions.
diff --git a/src/middlewares/static_files.ts b/src/middlewares/static_files.ts
@@ -4,6 +4,8 @@ import type { MiddlewareFn } from "./mod.ts";
 import { ASSET_CACHE_BUST_KEY } from "../runtime/shared_internal.tsx";
 import { BUILD_ID } from "../runtime/build_id.ts";
 import { getBuildCache } from "../context.ts";
+import { tracer } from "../otel.ts";
+import { context, trace } from "@opentelemetry/api";
 
 /**
  * Fresh middleware to enable file-system based routing.
@@ -25,6 +27,7 @@ export function staticFiles<T>(): MiddlewareFn<T> {
     }
 
     // Fast path bail out
+    const startTime = performance.now() + performance.timeOrigin;
     const file = await buildCache.readFile(pathname);
     if (pathname === "/" || file === null) {
       // Optimization: Prevent long responses for favicon.ico requests
@@ -39,60 +42,74 @@ export function staticFiles<T>(): MiddlewareFn<T> {
       return new Response("Method Not Allowed", { status: 405 });
     }
 
-    const cacheKey = url.searchParams.get(ASSET_CACHE_BUST_KEY);
-    if (cacheKey !== null && BUILD_ID !== cacheKey) {
-      url.searchParams.delete(ASSET_CACHE_BUST_KEY);
-      const location = url.pathname + url.search;
-      file.close();
-      return new Response(null, {
-        status: 307,
-        headers: {
-          location,
-        },
-      });
-    }
+    const span = tracer.startSpan("static file", {
+      attributes: { "fresh.span_type": "static_file" },
+      startTime,
+    });
 
-    const ext = path.extname(pathname);
-    const etag = file.hash;
+    try {
+      const cacheKey = url.searchParams.get(ASSET_CACHE_BUST_KEY);
+      if (cacheKey !== null && BUILD_ID !== cacheKey) {
+        url.searchParams.delete(ASSET_CACHE_BUST_KEY);
+        const location = url.pathname + url.search;
+        file.close();
+        span.setAttribute("fresh.cache", "invalid_bust_key");
+        span.setAttribute("fresh.cache_key", cacheKey);
+        return new Response(null, {
+          status: 307,
+          headers: {
+            location,
+          },
+        });
+      }
 
-    const contentType = getContentType(ext);
-    const headers = new Headers({
-      "Content-Type": contentType ?? "text/plain",
-      vary: "If-None-Match",
-    });
+      const ext = path.extname(pathname);
+      const etag = file.hash;
 
-    const ifNoneMatch = req.headers.get("If-None-Match");
-    if (
-      ifNoneMatch !== null &&
-      (ifNoneMatch === etag || ifNoneMatch === `W/"${etag}"`)
-    ) {
-      file.close();
-      return new Response(null, { status: 304, headers });
-    } else if (etag !== null) {
-      headers.set("Etag", `W/"${etag}"`);
-    }
+      const contentType = getContentType(ext);
+      const headers = new Headers({
+        "Content-Type": contentType ?? "text/plain",
+        vary: "If-None-Match",
+      });
 
-    if (
-      ctx.config.mode !== "development" &&
-      (BUILD_ID === cacheKey ||
-        url.pathname.startsWith(
-          `${ctx.config.basePath}/_fresh/js/${BUILD_ID}/`,
-        ))
-    ) {
-      headers.append("Cache-Control", "public, max-age=31536000, immutable");
-    } else {
-      headers.append(
-        "Cache-Control",
-        "no-cache, no-store, max-age=0, must-revalidate",
-      );
-    }
+      const ifNoneMatch = req.headers.get("If-None-Match");
+      if (
+        ifNoneMatch !== null &&
+        (ifNoneMatch === etag || ifNoneMatch === `W/"${etag}"`)
+      ) {
+        file.close();
+        span.setAttribute("fresh.cache", "not_modified");
+        return new Response(null, { status: 304, headers });
+      } else if (etag !== null) {
+        headers.set("Etag", `W/"${etag}"`);
+      }
 
-    headers.set("Content-Length", String(file.size));
-    if (req.method === "HEAD") {
-      file.close();
-      return new Response(null, { status: 200, headers });
-    }
+      if (
+        ctx.config.mode !== "development" &&
+        (BUILD_ID === cacheKey ||
+          url.pathname.startsWith(
+            `${ctx.config.basePath}/_fresh/js/${BUILD_ID}/`,
+          ))
+      ) {
+        span.setAttribute("fresh.cache", "immutable");
+        headers.append("Cache-Control", "public, max-age=31536000, immutable");
+      } else {
+        span.setAttribute("fresh.cache", "no_cache");
+        headers.append(
+          "Cache-Control",
+          "no-cache, no-store, max-age=0, must-revalidate",
+        );
+      }
+
+      headers.set("Content-Length", String(file.size));
+      if (req.method === "HEAD") {
+        file.close();
+        return new Response(null, { status: 200, headers });
+      }
 
-    return new Response(file.readable, { headers });
+      return new Response(file.readable, { headers });
+    } finally {
+      span.end();
+    }
   };
 }
diff --git a/src/plugins/fs_routes/render_middleware.ts b/src/plugins/fs_routes/render_middleware.ts
@@ -33,8 +33,9 @@ export function renderMiddleware<State>(
   return async (ctx) => {
     let result: PageResponse<unknown> | undefined;
     if (handler !== undefined) {
-      const res = await tracer.startActiveSpan("handler", async (span) => {
-        span.setAttribute("fresh.span_type", "fs_routes/handler");
+      const res = await tracer.startActiveSpan("handler", {
+        attributes: { "fresh.span_type": "fs_routes/handler" },
+      }, async (span) => {
         try {
           const res = await handler(ctx);
           span.setAttribute(