Java tutorial
// Copyright (C) 2017 The Android Open Source Project // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. package com.google.gerrit.server.schema; import static com.google.common.base.Preconditions.checkState; import com.google.common.collect.ImmutableList; import com.google.common.util.concurrent.CheckedFuture; import com.google.common.util.concurrent.Futures; import com.google.gerrit.reviewdb.client.Account; import com.google.gerrit.reviewdb.client.Change; import com.google.gerrit.reviewdb.client.ChangeMessage; import com.google.gerrit.reviewdb.client.PatchLineComment; import com.google.gerrit.reviewdb.client.PatchSet; import com.google.gerrit.reviewdb.client.PatchSetApproval; import com.google.gerrit.reviewdb.server.ChangeAccess; import com.google.gerrit.reviewdb.server.ChangeMessageAccess; import com.google.gerrit.reviewdb.server.PatchLineCommentAccess; import com.google.gerrit.reviewdb.server.PatchSetAccess; import com.google.gerrit.reviewdb.server.PatchSetApprovalAccess; import com.google.gerrit.reviewdb.server.ReviewDb; import com.google.gerrit.reviewdb.server.ReviewDbWrapper; import com.google.gwtorm.client.Key; import com.google.gwtorm.server.Access; import com.google.gwtorm.server.AtomicUpdate; import com.google.gwtorm.server.ListResultSet; import com.google.gwtorm.server.OrmException; import com.google.gwtorm.server.ResultSet; import java.util.Map; import java.util.function.Function; /** * Wrapper for ReviewDb that never calls the underlying change tables. * * <p>See {@link NotesMigrationSchemaFactory} for discussion. */ class NoChangesReviewDbWrapper extends ReviewDbWrapper { private static <T> ResultSet<T> empty() { return new ListResultSet<>(ImmutableList.of()); } private static <T, K extends Key<?>> CheckedFuture<T, OrmException> emptyFuture() { return Futures.immediateCheckedFuture(null); } private final ChangeAccess changes; private final PatchSetApprovalAccess patchSetApprovals; private final ChangeMessageAccess changeMessages; private final PatchSetAccess patchSets; private final PatchLineCommentAccess patchComments; private boolean inTransaction; NoChangesReviewDbWrapper(ReviewDb db) { super(db); changes = new Changes(this, delegate); patchSetApprovals = new PatchSetApprovals(this, delegate); changeMessages = new ChangeMessages(this, delegate); patchSets = new PatchSets(this, delegate); patchComments = new PatchLineComments(this, delegate); } @Override public boolean changesTablesEnabled() { return false; } @Override public ChangeAccess changes() { return changes; } @Override public PatchSetApprovalAccess patchSetApprovals() { return patchSetApprovals; } @Override public ChangeMessageAccess changeMessages() { return changeMessages; } @Override public PatchSetAccess patchSets() { return patchSets; } @Override public PatchLineCommentAccess patchComments() { return patchComments; } @Override public void commit() throws OrmException { if (!inTransaction) { // This reads a little weird, we're not in a transaction, so why are we calling commit? // Because we want to let the underlying ReviewDb do its normal thing in this case (which may // be throwing an exception, or not, depending on implementation). delegate.commit(); } } @Override public void rollback() throws OrmException { if (inTransaction) { inTransaction = false; } else { // See comment in commit(): we want to let the underlying ReviewDb do its thing. delegate.rollback(); } } private abstract static class AbstractDisabledAccess<T, K extends Key<?>> implements Access<T, K> { // Don't even hold a reference to delegate, so it's not possible to use it accidentally. private final NoChangesReviewDbWrapper wrapper; private final String relationName; private final int relationId; private final Function<T, K> primaryKey; private final Function<Iterable<T>, Map<K, T>> toMap; private AbstractDisabledAccess(NoChangesReviewDbWrapper wrapper, Access<T, K> delegate) { this.wrapper = wrapper; this.relationName = delegate.getRelationName(); this.relationId = delegate.getRelationID(); this.primaryKey = delegate::primaryKey; this.toMap = delegate::toMap; } @Override public final int getRelationID() { return relationId; } @Override public final String getRelationName() { return relationName; } @Override public final K primaryKey(T entity) { return primaryKey.apply(entity); } @Override public final Map<K, T> toMap(Iterable<T> iterable) { return toMap.apply(iterable); } @Override public final ResultSet<T> iterateAllEntities() { return empty(); } @Override public final CheckedFuture<T, OrmException> getAsync(K key) { return emptyFuture(); } @Override public final ResultSet<T> get(Iterable<K> keys) { return empty(); } @Override public final void insert(Iterable<T> instances) { // Do nothing. } @Override public final void update(Iterable<T> instances) { // Do nothing. } @Override public final void upsert(Iterable<T> instances) { // Do nothing. } @Override public final void deleteKeys(Iterable<K> keys) { // Do nothing. } @Override public final void delete(Iterable<T> instances) { // Do nothing. } @Override public final void beginTransaction(K key) { // Keep track of when we've started a transaction so that we can avoid calling commit/rollback // on the underlying ReviewDb. This is just a simple arm's-length approach, and may produce // slightly different results from a native ReviewDb in corner cases like: // * beginning transactions on different tables simultaneously // * doing work between commit and rollback // These kinds of things are already misuses of ReviewDb, and shouldn't be happening in // current code anyway. checkState(!wrapper.inTransaction, "already in transaction"); wrapper.inTransaction = true; } @Override public final T atomicUpdate(K key, AtomicUpdate<T> update) { return null; } @Override public final T get(K id) { return null; } } private static class Changes extends AbstractDisabledAccess<Change, Change.Id> implements ChangeAccess { private Changes(NoChangesReviewDbWrapper wrapper, ReviewDb db) { super(wrapper, db.changes()); } @Override public ResultSet<Change> all() { return empty(); } } private static class ChangeMessages extends AbstractDisabledAccess<ChangeMessage, ChangeMessage.Key> implements ChangeMessageAccess { private ChangeMessages(NoChangesReviewDbWrapper wrapper, ReviewDb db) { super(wrapper, db.changeMessages()); } @Override public ResultSet<ChangeMessage> byChange(Change.Id id) throws OrmException { return empty(); } @Override public ResultSet<ChangeMessage> byPatchSet(PatchSet.Id id) throws OrmException { return empty(); } @Override public ResultSet<ChangeMessage> all() throws OrmException { return empty(); } } private static class PatchSets extends AbstractDisabledAccess<PatchSet, PatchSet.Id> implements PatchSetAccess { private PatchSets(NoChangesReviewDbWrapper wrapper, ReviewDb db) { super(wrapper, db.patchSets()); } @Override public ResultSet<PatchSet> byChange(Change.Id id) { return empty(); } @Override public ResultSet<PatchSet> all() { return empty(); } } private static class PatchSetApprovals extends AbstractDisabledAccess<PatchSetApproval, PatchSetApproval.Key> implements PatchSetApprovalAccess { private PatchSetApprovals(NoChangesReviewDbWrapper wrapper, ReviewDb db) { super(wrapper, db.patchSetApprovals()); } @Override public ResultSet<PatchSetApproval> byChange(Change.Id id) { return empty(); } @Override public ResultSet<PatchSetApproval> byPatchSet(PatchSet.Id id) { return empty(); } @Override public ResultSet<PatchSetApproval> byPatchSetUser(PatchSet.Id patchSet, Account.Id account) { return empty(); } @Override public ResultSet<PatchSetApproval> all() { return empty(); } } private static class PatchLineComments extends AbstractDisabledAccess<PatchLineComment, PatchLineComment.Key> implements PatchLineCommentAccess { private PatchLineComments(NoChangesReviewDbWrapper wrapper, ReviewDb db) { super(wrapper, db.patchComments()); } @Override public ResultSet<PatchLineComment> byChange(Change.Id id) { return empty(); } @Override public ResultSet<PatchLineComment> byPatchSet(PatchSet.Id id) { return empty(); } @Override public ResultSet<PatchLineComment> publishedByChangeFile(Change.Id id, String file) { return empty(); } @Override public ResultSet<PatchLineComment> publishedByPatchSet(PatchSet.Id patchset) { return empty(); } @Override public ResultSet<PatchLineComment> draftByPatchSetAuthor(PatchSet.Id patchset, Account.Id author) { return empty(); } @Override public ResultSet<PatchLineComment> draftByChangeFileAuthor(Change.Id id, String file, Account.Id author) { return empty(); } @Override public ResultSet<PatchLineComment> draftByAuthor(Account.Id author) { return empty(); } @Override public ResultSet<PatchLineComment> all() { return empty(); } } }