[Java] Simplify term gap scanning logic by removing `ALIGNED_HEADER_L…

…ENGTH` and streamlining non-zero frame lookup.
aeron-io · Jan 24, 2025 · d22a389 · d22a389
1 parent f2933f8
commit d22a389
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Showing 2 changed files with 42 additions and 10 deletions.
diff --git a/aeron-client/src/main/java/io/aeron/logbuffer/TermGapScanner.java b/aeron-client/src/main/java/io/aeron/logbuffer/TermGapScanner.java
@@ -15,7 +15,6 @@
  */
 package io.aeron.logbuffer;
 
-import org.agrona.BitUtil;
 import org.agrona.concurrent.UnsafeBuffer;
 
 import static io.aeron.logbuffer.FrameDescriptor.FRAME_ALIGNMENT;
@@ -31,8 +30,6 @@
  */
 public class TermGapScanner
 {
-    private static final int ALIGNED_HEADER_LENGTH = BitUtil.align(HEADER_LENGTH, FRAME_ALIGNMENT);
-
     /**
      * Handler for notifying of gaps in the log.
      */
@@ -82,19 +79,17 @@ public static int scanForGap(
         final int gapBeginOffset = offset;
         if (offset < limitOffset)
         {
-            final int limit = limitOffset - ALIGNED_HEADER_LENGTH;
-            while (offset < limit)
+            offset += HEADER_LENGTH;
+            while (offset < limitOffset)
             {
-                offset += FRAME_ALIGNMENT;
-
-                if (0 != termBuffer.getIntVolatile(offset))
+                if (0 != frameLengthVolatile(termBuffer, offset))
                 {
-                    offset -= ALIGNED_HEADER_LENGTH;
                     break;
                 }
+                offset += HEADER_LENGTH;
             }
 
-            final int gapLength = (offset - gapBeginOffset) + ALIGNED_HEADER_LENGTH;
+            final int gapLength = offset - gapBeginOffset;
             handler.onGap(termId, gapBeginOffset, gapLength);
         }
 

diff --git a/aeron-client/src/test/java/io/aeron/logbuffer/TermGapScannerTest.java b/aeron-client/src/test/java/io/aeron/logbuffer/TermGapScannerTest.java
@@ -24,6 +24,7 @@
 import static org.agrona.BitUtil.align;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 class TermGapScannerTest
 {
@@ -51,6 +52,7 @@ void shouldReportGapAtBeginningOfBuffer()
         assertEquals(0, TermGapScanner.scanForGap(termBuffer, TERM_ID, 0, highWaterMark, gapHandler));
 
         verify(gapHandler).onGap(TERM_ID, 0, frameOffset);
+        verifyNoMoreInteractions(gapHandler);
     }
 
     @Test
@@ -67,6 +69,7 @@ void shouldReportSingleGapWhenBufferNotFull()
         assertEquals(tail, TermGapScanner.scanForGap(termBuffer, TERM_ID, tail, highWaterMark, gapHandler));
 
         verify(gapHandler).onGap(TERM_ID, tail, align(HEADER_LENGTH, FRAME_ALIGNMENT));
+        verifyNoMoreInteractions(gapHandler);
     }
 
     @Test
@@ -83,6 +86,7 @@ void shouldReportSingleGapWhenBufferIsFull()
         assertEquals(tail, TermGapScanner.scanForGap(termBuffer, TERM_ID, tail, highWaterMark, gapHandler));
 
         verify(gapHandler).onGap(TERM_ID, tail, align(HEADER_LENGTH, FRAME_ALIGNMENT));
+        verifyNoMoreInteractions(gapHandler);
     }
 
     @Test
@@ -100,4 +104,37 @@ void shouldReportNoGapWhenHwmIsInPadding()
 
         verifyNoInteractions(gapHandler);
     }
+
+    @Test
+    void shouldReportSingleHeaderGap()
+    {
+        final int offset = 8192 + 384;
+        when(termBuffer.getIntVolatile(offset)).thenReturn(0);
+        when(termBuffer.getIntVolatile(offset + HEADER_LENGTH)).thenReturn(128);
+
+        assertEquals(
+            offset, TermGapScanner.scanForGap(termBuffer, TERM_ID, offset, LOG_BUFFER_CAPACITY, gapHandler));
+
+        verify(termBuffer).getIntVolatile(offset);
+        verify(termBuffer).getIntVolatile(offset + HEADER_LENGTH);
+        verify(gapHandler).onGap(TERM_ID, offset, HEADER_LENGTH);
+        verifyNoMoreInteractions(gapHandler, termBuffer);
+    }
+
+    @Test
+    void shouldReportGapAtTheEndOfTheBuffer()
+    {
+        final int offset = LOG_BUFFER_CAPACITY - 128;
+        when(termBuffer.getIntVolatile(offset)).thenReturn(0);
+
+        assertEquals(
+            offset, TermGapScanner.scanForGap(termBuffer, TERM_ID, offset, LOG_BUFFER_CAPACITY, gapHandler));
+
+        verify(termBuffer).getIntVolatile(offset);
+        verify(termBuffer).getIntVolatile(offset + HEADER_LENGTH);
+        verify(termBuffer).getIntVolatile(offset + 2 * HEADER_LENGTH);
+        verify(termBuffer).getIntVolatile(offset + 3 * HEADER_LENGTH);
+        verify(gapHandler).onGap(TERM_ID, offset, 128);
+        verifyNoMoreInteractions(gapHandler, termBuffer);
+    }
 }