Schema versions: Pass arguments into upgrade method, not to the constructor

Schema migrations do all their work in the upgrade method. This is the
place where they need to access the arguments. If the arguments are
passed into the constructor, each schema migration must save the
arguments in a local member veriable to make them accessible from the
upgrade method. To save this boilerplate code we now directly pass the
arguments into the upgrade method. This means schema versions don't
need to define any constructor since the default constructor is all that
is needed.

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: Ie35d088bde76c0d11440b073034ecdae8df59a2c

java/com/google/gerrit/server/schema/NoteDbSchemaUpdater.java

@@ -91,7 +91,7 @@ public class NoteDbSchemaUpdater {
     for (int nextVersion : requiredUpgrades(currentVersion, schemaVersions.keySet())) {
       try {
         ui.message(String.format("Migrating data to schema %d ...", nextVersion));
-        NoteDbSchemaVersions.get(schemaVersions, nextVersion, args).upgrade(ui);
+        NoteDbSchemaVersions.get(schemaVersions, nextVersion).upgrade(args, ui);
         versionManager.increment(nextVersion - 1);
       } catch (Exception e) {
         throw new OrmException(

java/com/google/gerrit/server/schema/NoteDbSchemaVersion.java

@@ -22,9 +22,8 @@ import com.google.inject.Singleton;
 /**
  * Schema upgrade implementation.
  *
- * <p>Implementations must define a single public constructor that takes an {@link Arguments}. The
- * recommended idiom is to pull out whichever individual fields from the {@code Arguments} are
- * required by this implementation.
+ * <p>Implementations must have a single non-private constructor with no arguments (e.g. the default
+ * constructor).
  */
 interface NoteDbSchemaVersion {
   @Singleton
@@ -39,5 +38,5 @@ interface NoteDbSchemaVersion {
     }
   }
 
-  void upgrade(UpdateUI ui) throws Exception;
+  void upgrade(Arguments args, UpdateUI ui) throws Exception;
 }

java/com/google/gerrit/server/schema/NoteDbSchemaVersions.java

@@ -45,13 +45,11 @@ public class NoteDbSchemaVersions {
   }
 
   public static NoteDbSchemaVersion get(
-      ImmutableSortedMap<Integer, Class<? extends NoteDbSchemaVersion>> schemaVersions,
-      int i,
-      NoteDbSchemaVersion.Arguments args) {
+      ImmutableSortedMap<Integer, Class<? extends NoteDbSchemaVersion>> schemaVersions, int i) {
     Class<? extends NoteDbSchemaVersion> clazz = schemaVersions.get(i);
     checkArgument(clazz != null, "Schema version not found: %s", i);
     try {
-      return clazz.getDeclaredConstructor(NoteDbSchemaVersion.Arguments.class).newInstance(args);
+      return clazz.getDeclaredConstructor().newInstance();
     } catch (InstantiationException
         | IllegalAccessException
         | NoSuchMethodException

java/com/google/gerrit/server/schema/Schema_180.java

@@ -15,13 +15,8 @@
 package com.google.gerrit.server.schema;
 
 public class Schema_180 implements NoteDbSchemaVersion {
-  @SuppressWarnings("unused")
-  Schema_180(Arguments args) {
-    // Do nothing.
-  }
-
   @Override
-  public void upgrade(UpdateUI ui) {
+  public void upgrade(Arguments args, UpdateUI ui) {
     // Do nothing; only used to populate the version ref, which is done by the caller.
   }
 }