fix bug of dead lock in compression ratio (#641)

server/src/main/java/org/apache/iotdb/db/conf/adapter/CompressionRatio.java

@@ -18,6 +18,7 @@
  */
 package org.apache.iotdb.db.conf.adapter;
 
+import com.google.common.util.concurrent.AtomicDouble;
 import java.io.File;
 import java.io.IOException;
 import java.util.Locale;
@@ -55,6 +56,8 @@ public class CompressionRatio {
 
   private static final double DEFAULT_COMPRESSION_RATIO = 2.0;
 
+  private AtomicDouble compressionRatio = new AtomicDouble(DEFAULT_COMPRESSION_RATIO);
+
   /**
    * The total sum of all compression ratios.
    */
@@ -87,8 +90,9 @@ public class CompressionRatio {
     File newFile = SystemFileFactory.INSTANCE.getFile(directory,
         String.format(Locale.ENGLISH, RATIO_FILE_PATH_FORMAT, compressionRatioSum, calcTimes));
     persist(oldFile, newFile);
+    compressionRatio.set(compressionRatioSum / calcTimes);
     if (LOGGER.isInfoEnabled()) {
-      LOGGER.info("Compression ratio is {}", getRatio());
+      LOGGER.info("Compression ratio is {}", compressionRatio.get());
     }
     if (CONFIG.isEnableParameterAdapter()) {
       if (LOGGER.isInfoEnabled()) {
@@ -112,8 +116,8 @@ public class CompressionRatio {
   /**
    * Get the average compression ratio for all closed files
    */
-  public synchronized double getRatio() {
-    return calcTimes == 0 ? DEFAULT_COMPRESSION_RATIO : compressionRatioSum / calcTimes;
+  public double getRatio() {
+    return compressionRatio.get();
   }
 
   private void persist(File oldFile, File newFile) throws IOException {
@@ -158,6 +162,7 @@ public class CompressionRatio {
       }
       calcTimes = maxTimes;
       compressionRatioSum = maxCompressionRatioSum;
+      compressionRatio.set(compressionRatioSum / calcTimes);
       LOGGER.debug(
           "After restoring from compression ratio file, compressionRatioSum = {}, calcTimes = {}",
           compressionRatioSum, calcTimes);
@@ -199,3 +204,4 @@ public class CompressionRatio {
 
   }
 }
+