[GitHub] [ozone] elek commented on a change in pull request #2331: HDDS-5247. EC: Create ECReplicationConfig on client side based on input string

[GitBox <gi...@apache.org>]

elek commented on a change in pull request #2331:
URL: https://github.com/apache/ozone/pull/2331#discussion_r652453883



##########
File path: hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/client/ECReplicationConfig.java
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@@ -36,6 +43,29 @@ public ECReplicationConfig(int data, int parity) {
     this.parity = parity;
   }
 
+  public ECReplicationConfig(String string) {
+    final Pattern pattern = Pattern.compile("(\\d+)-(\\d+)");
+    final Matcher matcher = pattern.matcher(string);

Review comment:
       Good point. Let me move it to a static final constant.
   
   Answering the question is slightly harder. Compilation time I couldn't see any optimization:
   
   
   ```
   javap -v org.apache.hadoop.hdds.client.ECReplicationConfig
   
   ...
   
     public org.apache.hadoop.hdds.client.ECReplicationConfig(java.lang.String);
       descriptor: (Ljava/lang/String;)V
       flags: ACC_PUBLIC
       Code:
         stack=3, locals=4, args_size=2
            0: aload_0
            1: invokespecial #1                  // Method java/lang/Object."<init>":()V
            4: ldc           #4                  // String (\d+)-(\d+)
            6: invokestatic  #5                  // Method java/util/regex/Pattern.compile:(Ljava/lang/String;)Ljava/util/regex/Pattern;
            9: astore_2
   ```
   
   The call is really compiled as is to the method.
   
   Runtime optimization it's another question, but I don't think that it's possible easily as hostpost JVM would require understanding about the idempotency of `Pattern.compile` (second call on `Pattern.compile` returns with a value which is equivalent to the first one.)
   
   --> looks better to move the compile to a static field...
   




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