Replace autoflush with basic entity group transaction support
As an optional feature the database may implement entity group
transaction semantics, where a transaction can be started on a
single root entity (e.g. a Change object in Gerrit Code Review),
reads or updates applied, and later the transaction committed.
This feature better supports a database like Google AppEngine
where the entity group transactions are relatively slow.
Change-Id: I740dfbf6902e403347fd1838aee83271500e0c30
diff --git a/src/main/java/com/google/gwtorm/client/Access.java b/src/main/java/com/google/gwtorm/client/Access.java
index 27a26f7..b6872ff 100644
--- a/src/main/java/com/google/gwtorm/client/Access.java
+++ b/src/main/java/com/google/gwtorm/client/Access.java
@@ -155,6 +155,14 @@
void delete(Iterable<T> instances) throws OrmException;
/**
+ * Start a transaction on an object.
+ *
+ * @param key key describing the object (and its children).
+ * @throws OrmException a transaction cannot be started.
+ */
+ void beginTransaction(K key) throws OrmException;
+
+ /**
* Atomically update a single entity.
* <p>
* If the entity does not exist, the method returns {@code null} without
diff --git a/src/main/java/com/google/gwtorm/client/Schema.java b/src/main/java/com/google/gwtorm/client/Schema.java
index e18133a..1e8e2a0 100644
--- a/src/main/java/com/google/gwtorm/client/Schema.java
+++ b/src/main/java/com/google/gwtorm/client/Schema.java
@@ -55,30 +55,11 @@
* </pre>
*/
public interface Schema {
- /** @return true if auto flush is enabled (default). */
- boolean isAutoFlush();
+ /** Commit a pending transaction. */
+ public void commit() throws OrmException;
- /**
- * Set (or unset) the auto-flush flag for this connection.
- * <p>
- * If true writes are sent to the database by the time the method returns. If
- * false, writes will be sent at any time, or some later point in the future.
- * Callers should use {@link #flush()} to ensure the writes are visible, or
- * reset the auto flush flag to true.
- *
- * @param autoFlush the new setting.
- * @throws OrmException previously autoFlush was false, the new setting is
- * true, and flushed writes cannot be sent.
- */
- void setAutoFlush(boolean autoFlush) throws OrmException;
-
- /**
- * Ensures all modifications are now visible to others.
- *
- * @throws OrmException one or more modifications cannot be applied. The
- * writes are now inconsistent.
- */
- void flush() throws OrmException;
+ /** Abort a pending transaction, if one is already in progress, otherwise nop. */
+ public void rollback() throws OrmException;
/**
* Add any missing columns, create any missing tables or sequences.
diff --git a/src/main/java/com/google/gwtorm/client/impl/AbstractAccess.java b/src/main/java/com/google/gwtorm/client/impl/AbstractAccess.java
index 17ff862..287c816 100644
--- a/src/main/java/com/google/gwtorm/client/impl/AbstractAccess.java
+++ b/src/main/java/com/google/gwtorm/client/impl/AbstractAccess.java
@@ -30,6 +30,11 @@
implements Access<E, K> {
private static final int MAX_TRIES = 10;
+ @Override
+ public void beginTransaction(K key) throws OrmException {
+ // Do nothing by default.
+ }
+
public ResultSet<E> get(final Iterable<K> keys) throws OrmException {
final ArrayList<E> r = new ArrayList<E>();
for (final K key : keys) {
diff --git a/src/main/java/com/google/gwtorm/jdbc/JdbcSchema.java b/src/main/java/com/google/gwtorm/jdbc/JdbcSchema.java
index a4ecb8f..13ce9f9 100644
--- a/src/main/java/com/google/gwtorm/jdbc/JdbcSchema.java
+++ b/src/main/java/com/google/gwtorm/jdbc/JdbcSchema.java
@@ -40,20 +40,6 @@
conn = dbDef.newConnection();
}
- @Override
- public boolean isAutoFlush() {
- return true; // We are always flushing.
- }
-
- @Override
- public void setAutoFlush(boolean autoFlush) {
- }
-
- @Override
- public void flush() {
- // Do nothing, we flush by default during execution.
- }
-
public final Connection getConnection() {
return conn;
}
diff --git a/src/main/java/com/google/gwtorm/nosql/NoSqlSchema.java b/src/main/java/com/google/gwtorm/nosql/NoSqlSchema.java
index f130ca7..697a6c3 100644
--- a/src/main/java/com/google/gwtorm/nosql/NoSqlSchema.java
+++ b/src/main/java/com/google/gwtorm/nosql/NoSqlSchema.java
@@ -21,26 +21,10 @@
/** Internal base class for implementations of {@link Schema}. */
public abstract class NoSqlSchema extends AbstractSchema {
- private boolean autoFlush = true;
-
protected NoSqlSchema(final NoSqlDatabase<?, ?, ?> d) {
}
@Override
- public boolean isAutoFlush() {
- return autoFlush;
- }
-
- @Override
- public void setAutoFlush(boolean autoFlush) throws OrmException {
- if (!this.autoFlush && autoFlush) {
- flush();
- }
-
- this.autoFlush = autoFlush;
- }
-
- @Override
public void pruneSchema(StatementExecutor e) throws OrmException {
// Assume no action is required in a default NoSQL environment.
}
diff --git a/src/main/java/com/google/gwtorm/nosql/generic/GenericAccess.java b/src/main/java/com/google/gwtorm/nosql/generic/GenericAccess.java
index 8c4df87..7bad7da 100644
--- a/src/main/java/com/google/gwtorm/nosql/generic/GenericAccess.java
+++ b/src/main/java/com/google/gwtorm/nosql/generic/GenericAccess.java
@@ -331,18 +331,12 @@
return new ListResultSet<T>(res);
}
- private void maybeFlush() throws OrmException {
- if (db.isAutoFlush()) {
- db.flush();
- }
- }
-
@Override
public void insert(Iterable<T> instances) throws OrmException {
for (T obj : instances) {
insertOne(obj);
}
- maybeFlush();
+ db.flush();
}
private void insertOne(T nObj) throws OrmException {
@@ -357,7 +351,7 @@
for (T obj : instances) {
upsertOne(obj, true);
}
- maybeFlush();
+ db.flush();
}
@Override
@@ -365,7 +359,7 @@
for (T obj : instances) {
upsertOne(obj, false);
}
- maybeFlush();
+ db.flush();
}
private void upsertOne(T newObj, boolean mustExist) throws OrmException {
@@ -447,7 +441,7 @@
pruneOldIndexes(oldObj, null);
cache().remove(primaryKey(oldObj));
}
- maybeFlush();
+ db.flush();
}
@Override
diff --git a/src/main/java/com/google/gwtorm/nosql/generic/GenericSchema.java b/src/main/java/com/google/gwtorm/nosql/generic/GenericSchema.java
index 81b62aa..9d7837c 100644
--- a/src/main/java/com/google/gwtorm/nosql/generic/GenericSchema.java
+++ b/src/main/java/com/google/gwtorm/nosql/generic/GenericSchema.java
@@ -46,6 +46,9 @@
db = d;
}
+ public void flush() throws OrmException {
+ }
+
/** @return the database that created this schema instance. */
public GenericDatabase<?, ?, ?> getDatabase() {
return db;
diff --git a/src/main/java/com/google/gwtorm/server/AbstractSchema.java b/src/main/java/com/google/gwtorm/server/AbstractSchema.java
index 11a934c..1164a22 100644
--- a/src/main/java/com/google/gwtorm/server/AbstractSchema.java
+++ b/src/main/java/com/google/gwtorm/server/AbstractSchema.java
@@ -19,6 +19,16 @@
/** Base implementation any generated schema must implement. */
public abstract class AbstractSchema implements Schema {
+ @Override
+ public void commit() throws OrmException {
+ // Do nothign by default.
+ }
+
+ @Override
+ public void rollback() throws OrmException {
+ // Do nothign by default.
+ }
+
/**
* Obtain the next unique value from a pool of available numbers.
* <p>
