yegor256#173 Code review updates and some formatting changes

s3auth-hosts/src/main/java/com/s3auth/hosts/DomainStatsData.java

@@ -29,6 +29,7 @@
  */
 package com.s3auth.hosts;
 
+import com.jcabi.aspects.Immutable;
 import java.io.IOException;
 import java.util.Map;
 
@@ -38,6 +39,7 @@
  * @author Carlos Miranda ([email protected])
  * @version $Id$
  */
+@Immutable
 interface DomainStatsData {
 
     /**
@@ -46,15 +48,15 @@ interface DomainStatsData {
      * @param stats The stats to keep.
      * @throws IOException If something goes wrong.
      */
-    void put(final String domain, final Stats stats) throws IOException;
+    void put(String domain, Stats stats) throws IOException;
 
     /**
      * Get the stats for the given domain.
      * @param domain The domain whose stats we're interested in
      * @return The stats for this domain
      * @throws IOException If something goes wrong.
      */
-    Stats get(final String domain) throws IOException;
+    Stats get(String domain) throws IOException;
 
     /**
      * Get the stats for all domains.

s3auth-hosts/src/main/java/com/s3auth/hosts/H2DomainStatsData.java

@@ -148,22 +148,35 @@ public void put(final String domain, final Stats stats) throws IOException {
     @Override
     public Stats get(final String domain) throws IOException {
         try {
-            return new JdbcSession(this.connection())
-                .sql("SELECT SUM(BYTES) FROM DOMAIN_STATS WHERE DOMAIN = ?")
+            final JdbcSession session = new JdbcSession(this.connection())
+                .autocommit(false);
+            // @checkstyle LineLength (2 lines)
+            final Stats result = session
+                .sql("SELECT SUM(BYTES) FROM DOMAIN_STATS WHERE DOMAIN = ? FOR UPDATE")
                 .set(domain)
                 .select(STATS);
+            session.sql("DELETE FROM DOMAIN_STATS WHERE DOMAIN = ?")
+                .set(domain)
+                .execute()
+                .commit();
+            return result;
         } catch (final SQLException ex) {
             throw new IOException(ex);
         }
     }
 
     @Override
+    @SuppressWarnings("PMD.UseConcurrentHashMap")
     public Map<String, Stats> all() throws IOException {
         try {
+            final JdbcSession session = new JdbcSession(this.connection())
+                .autocommit(false);
             // @checkstyle LineLength (2 lines)
-            return new JdbcSession(this.connection())
-                .sql("SELECT DOMAIN, SUM(BYTES) FROM DOMAIN_STATS GROUP BY DOMAIN")
+            final Map<String, Stats> result = session
+                .sql("SELECT DOMAIN, SUM(BYTES) FROM DOMAIN_STATS GROUP BY DOMAIN FOR UPDATE")
                 .select(STATS_ALL);
+            session.sql("DELETE FROM DOMAIN_STATS").execute().commit();
+            return result;
         } catch (final SQLException ex) {
             throw new IOException(ex);
         }

s3auth-hosts/src/test/java/com/s3auth/hosts/H2DomainStatsDataTest.java

@@ -64,9 +64,13 @@ public long bytesTransferred() {
                 }
             }
         );
-        final long result = data.get(domain).bytesTransferred();
         MatcherAssert.assertThat(
-            result, Matchers.is(bytes)
+            data.get(domain).bytesTransferred(),
+            Matchers.is(bytes)
+        );
+        MatcherAssert.assertThat(
+            data.get(domain).bytesTransferred(),
+            Matchers.is(0L)
         );
     }
 
@@ -121,6 +125,10 @@ public long bytesTransferred() {
             stats.get(second).bytesTransferred(),
             Matchers.is((long) Tv.THOUSAND)
         );
+        MatcherAssert.assertThat(
+            data.all().size(),
+            Matchers.is(0)
+        );
     }
 
 }