Use composite primary key for HostHistory and ContactHistory (#809)

* Use composite primary key for HostHistory and ContactHistory

* Update flyway file version

* Make getters private

* Add javadoc

* Rebase on HEAD

core/src/main/java/google/registry/model/contact/ContactHistory.java

@@ -17,8 +17,11 @@ package google.registry.model.contact;
 import com.googlecode.objectify.Key;
 import com.googlecode.objectify.annotation.EntitySubclass;
 import google.registry.model.EppResource;
+import google.registry.model.ImmutableObject;
+import google.registry.model.contact.ContactHistory.ContactHistoryId;
 import google.registry.model.reporting.HistoryEntry;
 import google.registry.persistence.VKey;
+import java.io.Serializable;
 import java.util.Optional;
 import javax.annotation.Nullable;
 import javax.persistence.Access;
@@ -28,6 +31,7 @@ import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
+import javax.persistence.IdClass;
 import javax.persistence.PostLoad;
 
 /**
@@ -47,13 +51,13 @@ import javax.persistence.PostLoad;
     })
 @EntitySubclass
 @Access(AccessType.FIELD)
+@IdClass(ContactHistoryId.class)
 public class ContactHistory extends HistoryEntry {
 
   // Store ContactBase instead of ContactResource so we don't pick up its @Id
   @Nullable ContactBase contactBase;
 
-  @Column(nullable = false)
-  VKey<ContactResource> contactRepoId;
+  @Id String contactRepoId;
 
   @Id
   @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "TempHistorySequenceGenerator")
@@ -76,7 +80,14 @@ public class ContactHistory extends HistoryEntry {
 
   /** The key to the {@link ContactResource} this is based off of. */
   public VKey<ContactResource> getContactRepoId() {
-    return contactRepoId;
+    return VKey.create(
+        ContactResource.class, contactRepoId, Key.create(ContactResource.class, contactRepoId));
+  }
+
+  /** Creates a {@link VKey} instance for this entity. */
+  public VKey<ContactHistory> createVKey() {
+    return VKey.create(
+        ContactHistory.class, new ContactHistoryId(contactRepoId, getId()), Key.create(this));
   }
 
   @PostLoad
@@ -87,10 +98,65 @@ public class ContactHistory extends HistoryEntry {
       contactBase = null;
     }
     // Fill in the full, symmetric, parent repo ID key
-    Key<ContactResource> parentKey =
-        Key.create(ContactResource.class, (String) contactRepoId.getSqlKey());
-    parent = parentKey;
-    contactRepoId = VKey.create(ContactResource.class, contactRepoId.getSqlKey(), parentKey);
+    parent = Key.create(ContactResource.class, contactRepoId);
+  }
+
+  /** Class to represent the composite primary key of {@link ContactHistory} entity. */
+  static class ContactHistoryId extends ImmutableObject implements Serializable {
+
+    private String contactRepoId;
+
+    private Long id;
+
+    /** Hibernate requires this default constructor. */
+    private ContactHistoryId() {}
+
+    ContactHistoryId(String contactRepoId, long id) {
+      this.contactRepoId = contactRepoId;
+      this.id = id;
+    }
+
+    /**
+     * Returns the contact repository id.
+     *
+     * <p>This method is private because it is only used by Hibernate.
+     */
+    @SuppressWarnings("unused")
+    private String getContactRepoId() {
+      return contactRepoId;
+    }
+
+    /**
+     * Returns the history revision id.
+     *
+     * <p>This method is private because it is only used by Hibernate.
+     */
+    @SuppressWarnings("unused")
+    private long getId() {
+      return id;
+    }
+
+    /**
+     * Sets the contact repository id.
+     *
+     * <p>This method is private because it is only used by Hibernate and should not be used
+     * externally to keep immutability.
+     */
+    @SuppressWarnings("unused")
+    private void setContactRepoId(String contactRepoId) {
+      this.contactRepoId = contactRepoId;
+    }
+
+    /**
+     * Sets the history revision id.
+     *
+     * <p>This method is private because it is only used by Hibernate and should not be used
+     * externally to keep immutability.
+     */
+    @SuppressWarnings("unused")
+    private void setId(long id) {
+      this.id = id;
+    }
   }
 
   @Override
@@ -111,9 +177,9 @@ public class ContactHistory extends HistoryEntry {
       return this;
     }
 
-    public Builder setContactRepoId(VKey<ContactResource> contactRepoId) {
+    public Builder setContactRepoId(String contactRepoId) {
       getInstance().contactRepoId = contactRepoId;
-      contactRepoId.maybeGetOfyKey().ifPresent(parent -> getInstance().parent = parent);
+      getInstance().parent = Key.create(ContactResource.class, contactRepoId);
       return this;
     }
 
@@ -121,8 +187,7 @@ public class ContactHistory extends HistoryEntry {
     @Override
     public Builder setParent(Key<? extends EppResource> parent) {
       super.setParent(parent);
-      getInstance().contactRepoId =
-          VKey.create(ContactResource.class, parent.getName(), (Key<ContactResource>) parent);
+      getInstance().contactRepoId = parent.getName();
       return this;
     }
   }

core/src/main/java/google/registry/model/contact/ContactResource.java

@@ -51,7 +51,6 @@ public class ContactResource extends ContactBase
 
   @Override
   public VKey<ContactResource> createVKey() {
-    // TODO(mmuller): create symmetric keys if we can ever reload both sides.
     return VKey.create(ContactResource.class, getRepoId(), Key.create(this));
   }
 

core/src/main/java/google/registry/model/domain/DomainHistory.java

@@ -156,8 +156,10 @@ public class DomainHistory extends HistoryEntry {
     return VKey.create(DomainBase.class, domainRepoId, Key.create(DomainBase.class, domainRepoId));
   }
 
+  /** Creates a {@link VKey} instance for this entity. */
   public VKey<DomainHistory> createVKey() {
-    return VKey.createSql(DomainHistory.class, new DomainHistoryId(domainRepoId, getId()));
+    return VKey.create(
+        DomainHistory.class, new DomainHistoryId(domainRepoId, getId()), Key.create(this));
   }
 
   @PostLoad
@@ -188,19 +190,45 @@ public class DomainHistory extends HistoryEntry {
       this.id = id;
     }
 
-    String getDomainRepoId() {
+    /**
+     * Returns the domain repository id.
+     *
+     * <p>This method is private because it is only used by Hibernate.
+     */
+    @SuppressWarnings("unused")
+    private String getDomainRepoId() {
       return domainRepoId;
     }
 
-    void setDomainRepoId(String domainRepoId) {
-      this.domainRepoId = domainRepoId;
-    }
-
-    long getId() {
+    /**
+     * Returns the history revision id.
+     *
+     * <p>This method is private because it is only used by Hibernate.
+     */
+    @SuppressWarnings("unused")
+    private long getId() {
       return id;
     }
 
-    void setId(long id) {
+    /**
+     * Sets the domain repository id.
+     *
+     * <p>This method is private because it is only used by Hibernate and should not be used
+     * externally to keep immutability.
+     */
+    @SuppressWarnings("unused")
+    private void setDomainRepoId(String domainRepoId) {
+      this.domainRepoId = domainRepoId;
+    }
+
+    /**
+     * Sets the history revision id.
+     *
+     * <p>This method is private because it is only used by Hibernate and should not be used
+     * externally to keep immutability.
+     */
+    @SuppressWarnings("unused")
+    private void setId(long id) {
       this.id = id;
     }
   }

core/src/main/java/google/registry/model/host/HostHistory.java

@@ -14,11 +14,15 @@
 
 package google.registry.model.host;
 
+
 import com.googlecode.objectify.Key;
 import com.googlecode.objectify.annotation.EntitySubclass;
 import google.registry.model.EppResource;
+import google.registry.model.ImmutableObject;
+import google.registry.model.host.HostHistory.HostHistoryId;
 import google.registry.model.reporting.HistoryEntry;
 import google.registry.persistence.VKey;
+import java.io.Serializable;
 import java.util.Optional;
 import javax.annotation.Nullable;
 import javax.persistence.Access;
@@ -28,6 +32,7 @@ import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
+import javax.persistence.IdClass;
 import javax.persistence.PostLoad;
 
 /**
@@ -48,13 +53,13 @@ import javax.persistence.PostLoad;
     })
 @EntitySubclass
 @Access(AccessType.FIELD)
+@IdClass(HostHistoryId.class)
 public class HostHistory extends HistoryEntry {
 
   // Store HostBase instead of HostResource so we don't pick up its @Id
   @Nullable HostBase hostBase;
 
-  @Column(nullable = false)
-  VKey<HostResource> hostRepoId;
+  @Id String hostRepoId;
 
   @Id
   @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "TempHistorySequenceGenerator")
@@ -77,7 +82,12 @@ public class HostHistory extends HistoryEntry {
 
   /** The key to the {@link google.registry.model.host.HostResource} this is based off of. */
   public VKey<HostResource> getHostRepoId() {
-    return hostRepoId;
+    return VKey.create(HostResource.class, hostRepoId, Key.create(HostResource.class, hostRepoId));
+  }
+
+  /** Creates a {@link VKey} instance for this entity. */
+  public VKey<HostHistory> createVKey() {
+    return VKey.create(HostHistory.class, new HostHistoryId(hostRepoId, getId()), Key.create(this));
   }
 
   @PostLoad
@@ -88,9 +98,65 @@ public class HostHistory extends HistoryEntry {
       hostBase = null;
     }
     // Fill in the full, symmetric, parent repo ID key
-    Key<HostResource> parentKey = Key.create(HostResource.class, (String) hostRepoId.getSqlKey());
-    parent = parentKey;
-    hostRepoId = VKey.create(HostResource.class, hostRepoId.getSqlKey(), parentKey);
+    parent = Key.create(HostResource.class, hostRepoId);
+  }
+
+  /** Class to represent the composite primary key of {@link HostHistory} entity. */
+  static class HostHistoryId extends ImmutableObject implements Serializable {
+
+    private String hostRepoId;
+
+    private Long id;
+
+    /** Hibernate requires this default constructor. */
+    private HostHistoryId() {}
+
+    HostHistoryId(String hostRepoId, long id) {
+      this.hostRepoId = hostRepoId;
+      this.id = id;
+    }
+
+    /**
+     * Returns the host repository id.
+     *
+     * <p>This method is private because it is only used by Hibernate.
+     */
+    @SuppressWarnings("unused")
+    private String getHostRepoId() {
+      return hostRepoId;
+    }
+
+    /**
+     * Returns the history revision id.
+     *
+     * <p>This method is private because it is only used by Hibernate.
+     */
+    @SuppressWarnings("unused")
+    private long getId() {
+      return id;
+    }
+
+    /**
+     * Sets the host repository id.
+     *
+     * <p>This method is private because it is only used by Hibernate and should not be used
+     * externally to keep immutability.
+     */
+    @SuppressWarnings("unused")
+    private void setHostRepoId(String hostRepoId) {
+      this.hostRepoId = hostRepoId;
+    }
+
+    /**
+     * Sets the history revision id.
+     *
+     * <p>This method is private because it is only used by Hibernate and should not be used
+     * externally to keep immutability.
+     */
+    @SuppressWarnings("unused")
+    private void setId(long id) {
+      this.id = id;
+    }
   }
 
   @Override
@@ -111,9 +177,9 @@ public class HostHistory extends HistoryEntry {
       return this;
     }
 
-    public Builder setHostRepoId(VKey<HostResource> hostRepoId) {
+    public Builder setHostRepoId(String hostRepoId) {
       getInstance().hostRepoId = hostRepoId;
-      hostRepoId.maybeGetOfyKey().ifPresent(parent -> getInstance().parent = parent);
+      getInstance().parent = Key.create(HostResource.class, hostRepoId);
       return this;
     }
 
@@ -121,8 +187,7 @@ public class HostHistory extends HistoryEntry {
     @Override
     public Builder setParent(Key<? extends EppResource> parent) {
       super.setParent(parent);
-      getInstance().hostRepoId =
-          VKey.create(HostResource.class, parent.getName(), (Key<HostResource>) parent);
+      getInstance().hostRepoId = parent.getName();
       return this;
     }
   }

core/src/main/java/google/registry/model/reporting/HistoryEntry.java

@@ -308,19 +308,10 @@ public class HistoryEntry extends ImmutableObject implements Buildable, Datastor
           new DomainHistory.Builder().copyFrom(this).setDomainRepoId(parent.getName()).build();
     } else if (parentKind.equals(getKind(HostResource.class))) {
       resultEntity =
-          new HostHistory.Builder()
-              .copyFrom(this)
-              .setHostRepoId(
-                  VKey.create(HostResource.class, parent.getName(), (Key<HostResource>) parent))
-              .build();
+          new HostHistory.Builder().copyFrom(this).setHostRepoId(parent.getName()).build();
     } else if (parentKind.equals(getKind(ContactResource.class))) {
       resultEntity =
-          new ContactHistory.Builder()
-              .copyFrom(this)
-              .setContactRepoId(
-                  VKey.create(
-                      ContactResource.class, parent.getName(), (Key<ContactResource>) parent))
-              .build();
+          new ContactHistory.Builder().copyFrom(this).setContactRepoId(parent.getName()).build();
     } else {
       throw new IllegalStateException(
           String.format("Unknown kind of HistoryEntry parent %s", parentKind));