RATIS-1890. SegmentedRaftLogCache#shouldEvict should only iterate ove…

…r closed segments once (apache#921)
szetszwo · Sep 19, 2023 · be28b39 · be28b39
1 parent 05f3922
commit be28b39
Showing 1 changed file with 42 additions and 8 deletions.
diff --git a/...server/src/main/java/org/apache/ratis/server/raftlog/segmented/SegmentedRaftLogCache.java b/...server/src/main/java/org/apache/ratis/server/raftlog/segmented/SegmentedRaftLogCache.java
@@ -157,6 +157,38 @@ public String toString() {
     }
   }
 
+  private static class CacheInfo {
+    static CacheInfo get(List<LogSegment> list) {
+      long size = 0L;
+      long count = 0L;
+      for (LogSegment segment: list) {
+        if (segment.hasCache()) {
+          count++;
+          size += segment.getTotalCacheSize();
+        }
+      }
+      return new CacheInfo(size, count);
+    }
+
+    /** Total cache size in bytes. */
+    private final long size;
+    /** The number of cached segments. */
+    private final long count;
+
+    CacheInfo(long size, long count) {
+      this.size = size;
+      this.count = count;
+    }
+
+    public long getSize() {
+      return size;
+    }
+
+    public long getCount() {
+      return count;
+    }
+  }
+
   static class LogSegmentList {
     private final Object name;
     private final List<LogSegment> segments = new CopyOnWriteArrayList<>();
@@ -191,8 +223,8 @@ long getTotalFileSize() {
       return sizeInBytes;
     }
 
-    long getTotalCacheSize() {
-      return segments.stream().mapToLong(LogSegment::getTotalCacheSize).sum();
+    CacheInfo getCacheInfo() {
+      return CacheInfo.get(segments);
     }
 
     long countCached() {
@@ -410,13 +442,15 @@ long getOpenSegmentSizeInBytes() {
     return openSegment == null ? 0 : openSegment.getTotalFileSize();
   }
 
-  private long getTotalCacheSize() {
-    return closedSegments.getTotalCacheSize() +
-            Optional.ofNullable(openSegment).map(LogSegment::getTotalCacheSize).orElse(0L);
-  }
-
   boolean shouldEvict() {
-    return closedSegments.countCached() > maxCachedSegments || getTotalCacheSize() > maxSegmentCacheSize;
+    final CacheInfo closedSegmentsCacheInfo = closedSegments.getCacheInfo();
+    if (closedSegmentsCacheInfo.getCount() > maxCachedSegments) {
+      return true;
+    }
+
+    final long size = closedSegmentsCacheInfo.getSize()
+        + Optional.ofNullable(openSegment).map(LogSegment::getTotalCacheSize).orElse(0L);
+    return size > maxSegmentCacheSize;
   }
 
   void evictCache(long[] followerIndices, long safeEvictIndex, long lastAppliedIndex) {