Speed up HTML import parsing by ignoring Polymer core files (#4554)

Reduces the TTFB for the first time the Beverage Buddy edit dialog is opened from around 2200 ms to 550 ms. Related to #4532
vaadin · Aug 30, 2018 · 873c736 · 873c736
1 parent f47daba
commit 873c736
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Showing 3 changed files with 32 additions and 1 deletion.
diff --git a/flow-server/src/main/java/com/vaadin/flow/component/internal/HtmlDependencyParser.java b/flow-server/src/main/java/com/vaadin/flow/component/internal/HtmlDependencyParser.java
@@ -72,7 +72,7 @@ Collection<String> parseDependencies(VaadinService service) {
 
     private void parseDependencies(String path, Set<String> dependencies,
             VaadinService service) {
-        if (dependencies.contains(path)) {
+        if (dependencies.contains(path) || isBlacklisted(path)) {
             return;
         }
         dependencies.add(path);
@@ -97,6 +97,12 @@ private void parseDependencies(String path, Set<String> dependencies,
         }
     }
 
+    private static boolean isBlacklisted(String path) {
+        // Speed things up by not parsing files that are known to not use themes
+        return path.startsWith(ApplicationConstants.FRONTEND_PROTOCOL_PREFIX
+                + "bower_components/polymer/");
+    }
+
     private String resolveUri(String relative, String base) {
         if (relative.startsWith("/")) {
             return relative;

diff --git a/flow-server/src/test/java/com/vaadin/flow/component/internal/HtmlDependencyParserTest.java b/flow-server/src/test/java/com/vaadin/flow/component/internal/HtmlDependencyParserTest.java
@@ -19,6 +19,7 @@
 
 import java.net.URI;
 import java.util.Collection;
+import java.util.Collections;
 
 import org.junit.After;
 import org.junit.Assert;
@@ -176,6 +177,25 @@ public void dependenciesWithDifferentPathsIncludedOnlyOnce() {
                 dependencies.contains("frontend://relative.html"));
     }
 
+    @Test
+    public void polymerDependency_ignored() {
+        String root = "foo.html";
+        HtmlDependencyParser parser = new HtmlDependencyParser(root);
+
+        String importContent = "<link rel='import' href='bower_components/polymer/polymer-element.html'>";
+
+        servlet.addServletContextResource("/frontend/foo.html", importContent);
+
+        Collection<String> dependencies = parser.parseDependencies(service);
+
+        servlet.verifyServletContextResourceLoadedOnce("/frontend/" + root);
+        servlet.verifyServletContextResourceNotLoaded(
+                "/frontend/bower_components/polymer/polymer-element.html");
+
+        Assert.assertEquals(Collections.singleton("frontend://" + root),
+                dependencies);
+    }
+
     @Test
     public void normalizeURI() throws Exception {
         assertEquals("http://foo/bar", normalize("http://foo/bar"));

diff --git a/flow-server/src/test/java/com/vaadin/flow/server/MockServletServiceSessionSetup.java b/flow-server/src/test/java/com/vaadin/flow/server/MockServletServiceSessionSetup.java
@@ -164,6 +164,11 @@ public void verifyServletContextResourceLoadedOnce(String resource) {
                     .getResourceAsStream(resource);
 
         }
+
+        public void verifyServletContextResourceNotLoaded(String resource) {
+            Mockito.verify(servlet.getServletContext(), Mockito.never())
+                    .getResourceAsStream(resource);
+        }
     }
 
     public static class TestVaadinServletResponse