From 93e2a090d9b9130e7c3e4161bdc94974da376d0a Mon Sep 17 00:00:00 2001
From: Morten Kjetland <mbk@kjetland.com>
Date: Wed, 23 Mar 2011 08:24:02 +0100
Subject: [PATCH] [#674] improves speed when looking for new / removed classes
 in test-mode by caching the regexp-result for each file until the file has
 changed on disk.

---
 .../classloading/ApplicationClassloader.java  | 30 ++----
 .../hash/ClassStateHashCreator.java           | 99 +++++++++++++++++++
 2 files changed, 105 insertions(+), 24 deletions(-)
 create mode 100644 framework/src/play/classloading/hash/ClassStateHashCreator.java

diff --git a/framework/src/play/classloading/ApplicationClassloader.java b/framework/src/play/classloading/ApplicationClassloader.java
index c074c18f34..8360082d7e 100644
--- a/framework/src/play/classloading/ApplicationClassloader.java
+++ b/framework/src/play/classloading/ApplicationClassloader.java
@@ -26,6 +26,7 @@
 
 import play.Logger;
 import play.Play;
+import play.classloading.hash.ClassStateHashCreator;
 import play.vfs.VirtualFile;
 import play.cache.Cache;
 import play.classloading.ApplicationClasses.ApplicationClass;
@@ -38,6 +39,9 @@
  */
 public class ApplicationClassloader extends ClassLoader {
 
+
+    private final ClassStateHashCreator classStateHashCreator = new ClassStateHashCreator();
+
     /**
      * This protection domain applies to all loaded classes.
      */
@@ -319,6 +323,7 @@ public void detectChanges() {
         if (dirtySig) {
             throw new RuntimeException("Signature change !");
         }
+
         // Now check if there is new classes or removed classes
         int hash = computePathHash();
         if (hash != this.pathHash) {
@@ -347,30 +352,7 @@ public void detectChanges() {
     int pathHash = 0;
 
     int computePathHash() {
-        StringBuffer buf = new StringBuffer();
-        for (VirtualFile virtualFile : Play.javaPath) {
-            scan(buf, virtualFile);
-        }
-        return buf.toString().hashCode();
-    }
-
-    void scan(StringBuffer buf, VirtualFile current) {
-        if (!current.isDirectory()) {
-            if (current.getName().endsWith(".java")) {
-                Matcher matcher = Pattern.compile("\\s+class\\s([a-zA-Z0-9_]+)\\s+").matcher(current.contentAsString());
-                buf.append(current.getName());
-                buf.append("(");
-                while (matcher.find()) {
-                    buf.append(matcher.group(1));
-                    buf.append(",");
-                }
-                buf.append(")");
-            }
-        } else if (!current.getName().startsWith(".")) {
-            for (VirtualFile virtualFile : current.list()) {
-                scan(buf, virtualFile);
-            }
-        }
+        return classStateHashCreator.computePathHash(Play.javaPath);
     }
 
     /**
diff --git a/framework/src/play/classloading/hash/ClassStateHashCreator.java b/framework/src/play/classloading/hash/ClassStateHashCreator.java
new file mode 100644
index 0000000000..8c1eb1882c
--- /dev/null
+++ b/framework/src/play/classloading/hash/ClassStateHashCreator.java
@@ -0,0 +1,99 @@
+package play.classloading.hash;
+
+import play.vfs.VirtualFile;
+
+import java.io.File;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class ClassStateHashCreator {
+
+    private final Pattern classDefFinderPattern = Pattern.compile("\\s+class\\s([a-zA-Z0-9_]+)\\s+");
+
+    private static class FileWithClassDefs {
+        private final File file;
+        private final long size;
+        private final long lastModified;
+        private final String classDefs;
+
+        private FileWithClassDefs(File file, String classDefs) {
+            this.file = file;
+            this.classDefs = classDefs;
+
+            // store size and time for this file..
+            size = file.length();
+            lastModified = file.lastModified();
+        }
+
+        /**
+         * @return true if file has changed on disk
+         */
+        public boolean fileNotChanges( ) {
+            return size == file.length() && lastModified == file.lastModified();
+        }
+
+        public String getClassDefs() {
+            return classDefs;
+        }
+    }
+
+    private final Map<File, FileWithClassDefs> classDefsInFileCache = new HashMap<File, FileWithClassDefs>();
+
+    public synchronized int computePathHash(List<VirtualFile> paths) {
+        StringBuffer buf = new StringBuffer();
+        for (VirtualFile virtualFile : paths) {
+            scan(buf, virtualFile);
+        }
+        // TODO: should use better hashing-algorithm.. MD5? SHA1?
+        // I think hashCode() has too many collisions..
+        return buf.toString().hashCode();
+    }
+
+    private void scan(StringBuffer buf, VirtualFile current) {
+        if (!current.isDirectory()) {
+            if (current.getName().endsWith(".java")) {
+                buf.append( getClassDefsForFile(current));
+            }
+        } else if (!current.getName().startsWith(".")) {
+            // TODO: we could later optimizie it further if we check if the entire folder is unchanged
+            for (VirtualFile virtualFile : current.list()) {
+                scan(buf, virtualFile);
+            }
+        }
+    }
+
+    private String getClassDefsForFile( VirtualFile current ) {
+
+        File realFile = current.getRealFile();
+        // first we look in cache
+
+        FileWithClassDefs fileWithClassDefs = classDefsInFileCache.get( realFile );
+        if( fileWithClassDefs != null && fileWithClassDefs.fileNotChanges() ) {
+            // found the file in cache and it has not changed on disk
+            return fileWithClassDefs.getClassDefs();
+        }
+
+        // didn't find it or it has changed on disk
+        // we must re-parse it
+
+        StringBuilder buf = new StringBuilder();
+        Matcher matcher = classDefFinderPattern.matcher(current.contentAsString());
+        buf.append(current.getName());
+        buf.append("(");
+        while (matcher.find()) {
+            buf.append(matcher.group(1));
+            buf.append(",");
+        }
+        buf.append(")");
+        String classDefs = buf.toString();
+
+        // store it in cache
+        classDefsInFileCache.put( realFile, new FileWithClassDefs(realFile, classDefs));
+        return classDefs;
+    }
+
+
+}