improve detection of jdk8 G1 logs

Author: chewiebug

src/main/java/com/tagtraum/perf/gcviewer/imp/DataReaderFactory.java

@@ -57,7 +57,7 @@ public DataReader getDataReader(GCResource gcResource, InputStream inStream) thr
                     break;
                 }
             }
-            byte[] buf = new byte[ONE_KB * 3];
+            byte[] buf = new byte[FOUR_KB];
             int length = in.read(buf);
             in.reset();
 
@@ -161,7 +161,7 @@ else if (s.contains(" (young)") || s.contains("G1Ergonomics") || s.contains(" (m
             // G1 logger usually starts with "<timestamp>: [GC pause (young)...]"
             // but can start with  <timestamp>: [G1Ergonomics (Heap Sizing) expand the heap...
             // with certain logging flaggs.
-            if (getLogger().isLoggable(Level.INFO)) getLogger().info("File format: Sun 1.6.x G1 collector");
+            if (getLogger().isLoggable(Level.INFO)) getLogger().info("File format: Sun 1.6.x .. 1.8.x G1 collector");
             return new DataReaderSun1_6_0G1(gcResource, in, GcLogType.SUN1_6G1);
         }
         else if (s.contains("[Times:") || s.contains("[Pause Init Mark") /* Shenandoah, -XX:-PrintGCDetails */) {

src/test/java/com/tagtraum/perf/gcviewer/imp/TestDataReaderFactory.java

@@ -323,6 +323,14 @@ public void testOracleG1J8() throws Exception {
         assertDataReader(DataReaderSun1_6_0G1.class, dr.getClass());
     }
 
+    @Test
+    public void testOracleG1J8_StringDeduplication() throws Exception {
+        DataReaderFactory factory = new DataReaderFactory();
+        DataReader dr = factory.getDataReader(new GcResourceFile("byteArray"),
+                getInputStreamOpenJdk("SampleSun1_8_0G1StringDeduplication.txt"));
+        assertDataReader(DataReaderSun1_6_0G1.class, dr.getClass());
+    }
+
     @Test
     public void testOracleShenandoahJ8Simple() throws Exception {
         DataReaderFactory factory = new DataReaderFactory();