Resolves #719: Support `.setReadVersion()` on `ReadTransaction`
This commit is contained in:
Alec Grieser
parent
735c45a3b0
commit
7ef189701e
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@ -40,11 +40,26 @@ class FDBTransaction extends NativeObjectWrapper implements Transaction, OptionC
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public final ReadTransaction snapshot;
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class ReadSnapshot implements ReadTransaction {
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@Override
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public boolean isSnapshot() {
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return true;
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}
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@Override
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public ReadTransaction snapshot() {
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return this;
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}
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@Override
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public CompletableFuture<Long> getReadVersion() {
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return FDBTransaction.this.getReadVersion();
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}
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@Override
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public void setReadVersion(long version) {
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FDBTransaction.this.setReadVersion(version);
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}
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@Override
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public CompletableFuture<byte[]> get(byte[] key) {
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return get_internal(key, true);
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@ -126,6 +141,16 @@ class FDBTransaction extends NativeObjectWrapper implements Transaction, OptionC
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return getRange(range, ReadTransaction.ROW_LIMIT_UNLIMITED);
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}
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@Override
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public void addReadConflictRangeIfNotSnapshot(byte[] keyBegin, byte[] keyEnd) {
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// Do nothing
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}
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@Override
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public void addReadConflictKeyIfNotSnapshot(byte[] key) {
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// Do nothing
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}
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@Override
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public TransactionOptions options() {
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return FDBTransaction.this.options();
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@ -157,6 +182,11 @@ class FDBTransaction extends NativeObjectWrapper implements Transaction, OptionC
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transactionOwner = true;
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}
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@Override
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public boolean isSnapshot() {
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return false;
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}
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@Override
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public ReadTransaction snapshot() {
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return snapshot;
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@ -321,11 +351,21 @@ class FDBTransaction extends NativeObjectWrapper implements Transaction, OptionC
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}
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}
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@Override
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public void addReadConflictRangeIfNotSnapshot(byte[] keyBegin, byte[] keyEnd) {
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addReadConflictRange(keyBegin, keyEnd);
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}
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@Override
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public void addReadConflictRange(byte[] keyBegin, byte[] keyEnd) {
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addConflictRange(keyBegin, keyEnd, ConflictRangeType.READ);
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}
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@Override
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public void addReadConflictKeyIfNotSnapshot(byte[] key) {
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addReadConflictKey(key);
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}
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@Override
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public void addReadConflictKey(byte[] key) {
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addConflictRange(key, ByteArrayUtil.join(key, new byte[]{(byte) 0}), ConflictRangeType.READ);
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@ -32,7 +32,7 @@ import com.apple.foundationdb.tuple.Tuple;
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* <br>
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* <b>Note:</b> Client must call {@link Transaction#commit()} and wait on the result on all transactions,
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* even ones that only read. This is done automatically when using the retry loops from
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* {@link Database#run(Function)}. This is explained more in the intro to {@link Transaction}.
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* {@link Database#run(java.util.function.Function)}. This is explained more in the intro to {@link Transaction}.
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*
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* @see Transaction
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*/
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@ -43,12 +43,71 @@ public interface ReadTransaction extends ReadTransactionContext {
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*/
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int ROW_LIMIT_UNLIMITED = 0;
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/**
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* Gets whether this transaction is a snapshot view of the database. In other words, this returns
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* whether read conflict ranges are omitted for any reads done through this {@code ReadTransaction}.
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* <br>
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* For more information about how to use snapshot reads correctly, see
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* <a href="/foundationdb/developer-guide.html#using-snapshot-reads" target="_blank">Using snapshot reads</a>.
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*
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* @return whether this is a snapshot view of the database with relaxed isolation properties
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* @see #snapshot()
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*/
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boolean isSnapshot();
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/**
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* Return a special-purpose, read-only view of the database. Reads done through this interface are known as "snapshot reads".
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* Snapshot reads selectively relax FoundationDB's isolation property, reducing
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* <a href="/foundationdb/developer-guide.html#transaction-conflicts" target="_blank">Transaction conflicts</a>
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* but making reasoning about concurrency harder.<br>
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* <br>
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* For more information about how to use snapshot reads correctly, see
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* <a href="/foundationdb/developer-guide.html#using-snapshot-reads" target="_blank">Using snapshot reads</a>.
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*
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* @return a read-only view of this {@code ReadTransaction} with relaxed isolation properties
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*/
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ReadTransaction snapshot();
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/**
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* Gets the version at which the reads for this {@code Transaction} will access the database.
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* @return the version for database reads
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*/
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CompletableFuture<Long> getReadVersion();
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/**
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* Directly sets the version of the database at which to execute reads. The
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* normal operation of a transaction is to determine an appropriately recent
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* version; this call overrides that behavior. If the version is set too
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* far in the past, {@code past_version} errors will be thrown from read operations.
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* <i>Infrequently used.</i>
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*
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* @param version the version at which to read from the database
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*/
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void setReadVersion(long version);
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/**
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* Adds the read conflict range that this {@code ReadTransaction} would have added as if it had read
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* the given key range. If this is a {@linkplain #snapshot() snapshot} view of the database, this will
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* not add the conflict range. This mirrors how reading a range through a snapshot view
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* of the database does not add a conflict range for the read keys.
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*
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* @param keyBegin the first key in the range (inclusive)
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* @param keyEnd the last key in the range (exclusive)
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* @see Transaction#addReadConflictRange(byte[], byte[])
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*/
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void addReadConflictRangeIfNotSnapshot(byte[] keyBegin, byte[] keyEnd);
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/**
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* Adds the read conflict range that this {@code ReadTransaction} would have added as if it had read
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* the given key. If this is a {@linkplain #snapshot() snapshot} view of the database, this will
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* not add the conflict range. This mirrors how reading a key through a snapshot view
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* of the database does not add a conflict range for the read key.
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*
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* @param key the key to add to the read conflict range set (it this is not a snapshot view of the database)
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* @see Transaction#addReadConflictKey(byte[])
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*/
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void addReadConflictKeyIfNotSnapshot(byte[] key);
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/**
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* Gets a value from the database. The call will return {@code null} if the key is not
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* present in the database.
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@ -76,31 +76,6 @@ import com.apple.foundationdb.tuple.Tuple;
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*/
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public interface Transaction extends AutoCloseable, ReadTransaction, TransactionContext {
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/**
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* Return special-purpose, read-only view of the database. Reads done through this interface are known as "snapshot reads".
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* Snapshot reads selectively relax FoundationDB's isolation property, reducing
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* <a href="/foundationdb/developer-guide.html#transaction-conflicts" target="_blank">Transaction conflicts</a>
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* but making reasoning about concurrency harder.<br>
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* <br>
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* For more information about how to use snapshot reads correctly, see
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* <a href="/foundationdb/developer-guide.html#using-snapshot-reads" target="_blank">Using snapshot reads</a>.
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*
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* @return a read-only view of this {@code Transaction} with relaxed isolation properties
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*/
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ReadTransaction snapshot();
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/**
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* Directly sets the version of the database at which to execute reads. The
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* normal operation of a transaction is to determine an appropriately recent
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* version; this call overrides that behavior. If the version is set too
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* far in the past, {@code past_version} errors will be thrown from read operations.
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* <i>Infrequently used.</i>
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*
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* @param version the version at which to read from the database
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*/
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void setReadVersion(long version);
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/**
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* Adds a range of keys to the transaction's read conflict ranges as if you
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* had read the range. As a result, other transactions that write a key in
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@ -116,7 +91,7 @@ public interface Transaction extends AutoCloseable, ReadTransaction, Transaction
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* the key. As a result, other transactions that concurrently write this key
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* could cause the transaction to fail with a conflict.
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*
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* @param key the key to be added to the range
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* @param key the key to be added to the read conflict range set
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*/
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void addReadConflictKey(byte[] key);
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@ -35,6 +35,7 @@ Bindings
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* Python: Removed ``fdb.init``, ``fdb.create_cluster``, and ``fdb.Cluster``. ``fdb.open`` no longer accepts a ``database_name`` parameter. `(PR #942) <https://github.com/apple/foundationdb/pull/942>`_
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* Java: Deprecated ``FDB.createCluster`` and ``Cluster``. The preferred way to get a ``Database`` is by using ``FDB.open``, which should work in both new and old API versions. `(PR #942) <https://github.com/apple/foundationdb/pull/942>`_
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* Java: Removed ``Cluster(long cPtr, Executor executor)`` constructor. This is API breaking for any code that has subclassed the ``Cluster`` class and is not protected by API versioning. `(PR #942) <https://github.com/apple/foundationdb/pull/942>`_
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* Java: Several methods relevant to read-only transactions have been moved into the ``ReadTransaction`` interface.
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* Ruby: Removed ``FDB.init``, ``FDB.create_cluster``, and ``FDB.Cluster``. ``FDB.open`` no longer accepts a ``database_name`` parameter. `(PR #942) <https://github.com/apple/foundationdb/pull/942>`_
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* Golang: Deprecated ``fdb.StartNetwork``, ``fdb.Open``, ``fdb.MustOpen``, and ``fdb.CreateCluster`` and added ``fdb.OpenDatabase`` and ``fdb.MustOpenDatabase``. The preferred way to start the network and get a ``Database`` is by using ``FDB.OpenDatabase`` or ``FDB.OpenDefault``. `(PR #942) <https://github.com/apple/foundationdb/pull/942>`_
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* Flow: Deprecated ``API::createCluster`` and ``Cluster`` and added ``API::createDatabase``. The preferred way to get a ``Database`` is by using ``API::createDatabase``. `(PR #942) <https://github.com/apple/foundationdb/pull/942>`_
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