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nicktorwaldnicktorwald
committedSep 18, 2019
Soft automatic schema reload
Now client keeps actual schema metadata and sends schemaId header to be checked against current Tarantool schema version. If client version mismatches DB version client does schema reloading in the background. Client operation interface was reworked in scope of support not only number identifiers for spaces and indexes but also their string names. Closes: #7, #137
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‎README.md

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@@ -130,6 +130,52 @@ all the results, you could override this:
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protected void complete(TarantoolPacket packet, TarantoolOp<?> future);
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```
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## String space/index resolution
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Each operation that requires space or index to be executed, can work with
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number ID as well as string name of a space or an index.
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Assume, we have `my_space` space with space ID `512` and its primary index
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`primary` with index ID `0`. Then, for instance, `select` operations can be
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performed using their names:
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```java
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client.syncOps().select(512, 0, Collections.singletonList(1), 0, 1, Iterator.EQ);
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// or using more convenient way
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client.syncOps().select("my_space", "primary", Collections.singletonList(1), 0, 1, Iterator.EQ);
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```
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Because _iproto_ has not yet supported string spaces and indexes, a client caches current server
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schema in memory. The client relies on protocol SCHEMA_ID and sends each request with respect to
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cached schema version. The schema is used primarily to resolve string names of spaces or indexes
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against its integer IDs.
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### Schema update
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1. Just after a (re-)connection to the Tarantool instance.
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The client cannot guarantee that new instance is the same and has same schema,
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thus, the client drops the cached schema and fetches new one.
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2. Receiving a schema version error as a response to our request.
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It's possible some request can be rejected by server because of schema
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mismatching between client and server. In this case the schema will be
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reloaded and the refused request will be resent using the updated schema
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version.
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3. Sending a DDL request and receiving a new version in a response.
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4. Sending a request against a non-existent space/index name.
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The client cannot exactly know whether name was not found because of
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it does not exist or it has not the latest schema version.
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### Schema support caveats
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1. Each schema reloading requires at least two extra requests to fetch spaces and
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indexes metadata respectively. There is also a ping request followed by reloading
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of the schema to check whether the client has outdated version (see point 4 in
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Schema update section).
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2. In some circumstance, requests can be rejected several times until both client's
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and server's versions matches. It may take significant amount of time or even be
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a cause of request timeout.
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3. The client guarantees an order of synchronous requests per thread. Other cases such
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as asynchronous or multi-threaded requests may be out of order before the execution.
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## Spring NamedParameterJdbcTemplate usage example
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The JDBC driver uses `TarantoolClient` implementation to provide a communication with server.

‎src/main/java/org/tarantool/AbstractTarantoolOps.java

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package org.tarantool;
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import static org.tarantool.RequestArguments.cacheLookupValue;
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import static org.tarantool.RequestArguments.value;
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4-
public abstract class AbstractTarantoolOps<Space, Tuple, Operation, Result>
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implements TarantoolClientOps<Space, Tuple, Operation, Result> {
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import org.tarantool.schema.TarantoolSchemaMeta;
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import java.util.List;
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public abstract class AbstractTarantoolOps<Result>
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implements TarantoolClientOps<List<?>, Object, Result> {
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private Code callCode = Code.CALL;
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9-
protected abstract Result exec(Code code, Object... args);
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protected abstract Result exec(TarantoolRequest request);
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protected abstract TarantoolSchemaMeta getSchemaMeta();
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public Result select(Integer space, Integer index, List<?> key, int offset, int limit, Iterator iterator) {
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return select(space, index, key, offset, limit, iterator.getValue());
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}
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public Result select(Space space, Space index, Tuple key, int offset, int limit, Iterator iterator) {
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@Override
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public Result select(String space, String index, List<?> key, int offset, int limit, Iterator iterator) {
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return select(space, index, key, offset, limit, iterator.getValue());
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}
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public Result select(Space space, Space index, Tuple key, int offset, int limit, int iterator) {
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@Override
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public Result select(Integer space, Integer index, List<?> key, int offset, int limit, int iterator) {
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return exec(
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new TarantoolRequest(
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Code.SELECT,
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value(Key.SPACE), value(space),
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value(Key.INDEX), value(index),
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value(Key.KEY), value(key),
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value(Key.ITERATOR), value(iterator),
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value(Key.LIMIT), value(limit),
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value(Key.OFFSET), value(offset)
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)
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);
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}
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@Override
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public Result select(String space, String index, List<?> key, int offset, int limit, int iterator) {
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return exec(
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new TarantoolRequest(
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Code.SELECT,
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value(Key.SPACE), cacheLookupValue(() -> getSchemaMeta().getSpace(space).getId()),
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value(Key.INDEX), cacheLookupValue(() -> getSchemaMeta().getSpaceIndex(space, index).getId()),
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value(Key.KEY), value(key),
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value(Key.ITERATOR), value(iterator),
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value(Key.LIMIT), value(limit),
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value(Key.OFFSET), value(offset)
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)
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);
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}
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@Override
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public Result insert(Integer space, List<?> tuple) {
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return exec(new TarantoolRequest(
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Code.INSERT,
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value(Key.SPACE), value(space),
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value(Key.TUPLE), value(tuple)
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)
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);
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}
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@Override
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public Result insert(String space, List<?> tuple) {
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return exec(
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new TarantoolRequest(
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Code.INSERT,
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value(Key.SPACE), cacheLookupValue(() -> getSchemaMeta().getSpace(space).getId()),
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value(Key.TUPLE), value(tuple)
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)
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);
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}
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@Override
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public Result replace(Integer space, List<?> tuple) {
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return exec(
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new TarantoolRequest(
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Code.REPLACE,
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value(Key.SPACE), value(space),
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value(Key.TUPLE), value(tuple)
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)
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);
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}
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@Override
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public Result replace(String space, List<?> tuple) {
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return exec(
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Code.SELECT,
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Key.SPACE, space,
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Key.INDEX, index,
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Key.KEY, key,
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Key.ITERATOR, iterator,
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Key.LIMIT, limit,
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Key.OFFSET, offset
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new TarantoolRequest(
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Code.REPLACE,
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value(Key.SPACE), cacheLookupValue(() -> getSchemaMeta().getSpace(space).getId()),
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value(Key.TUPLE), value(tuple)
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)
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);
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}
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27-
public Result insert(Space space, Tuple tuple) {
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return exec(Code.INSERT, Key.SPACE, space, Key.TUPLE, tuple);
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@Override
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public Result update(Integer space, List<?> key, Object... operations) {
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return exec(
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new TarantoolRequest(
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Code.UPDATE,
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value(Key.SPACE), value(space),
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value(Key.KEY), value(key),
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value(Key.TUPLE), value(operations)
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)
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);
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}
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31-
public Result replace(Space space, Tuple tuple) {
32-
return exec(Code.REPLACE, Key.SPACE, space, Key.TUPLE, tuple);
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@Override
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public Result update(String space, List<?> key, Object... operations) {
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return exec(
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new TarantoolRequest(
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Code.UPDATE,
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value(Key.SPACE), cacheLookupValue(() -> getSchemaMeta().getSpace(space).getId()),
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value(Key.KEY), value(key),
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value(Key.TUPLE), value(operations)
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)
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);
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}
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@Override
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public Result upsert(Integer space, List<?> key, List<?> defTuple, Object... operations) {
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return exec(
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new TarantoolRequest(
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Code.UPSERT,
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value(Key.SPACE), value(space),
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value(Key.KEY), value(key),
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value(Key.TUPLE), value(defTuple),
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value(Key.UPSERT_OPS), value(operations)
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)
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);
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}
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35-
public Result update(Space space, Tuple key, Operation... args) {
36-
return exec(Code.UPDATE, Key.SPACE, space, Key.KEY, key, Key.TUPLE, args);
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@Override
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public Result upsert(String space, List<?> key, List<?> defTuple, Object... operations) {
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return exec(
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new TarantoolRequest(
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Code.UPSERT,
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value(Key.SPACE), cacheLookupValue(() -> getSchemaMeta().getSpace(space).getId()),
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value(Key.KEY), value(key),
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value(Key.TUPLE), value(defTuple),
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value(Key.UPSERT_OPS), value(operations)
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)
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);
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}
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39-
public Result upsert(Space space, Tuple key, Tuple def, Operation... args) {
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return exec(Code.UPSERT, Key.SPACE, space, Key.KEY, key, Key.TUPLE, def, Key.UPSERT_OPS, args);
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@Override
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public Result delete(Integer space, List<?> key) {
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return exec(
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new TarantoolRequest(
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Code.DELETE,
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value(Key.SPACE), value(space),
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value(Key.KEY), value(key)
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)
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);
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}
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public Result delete(Space space, Tuple key) {
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return exec(Code.DELETE, Key.SPACE, space, Key.KEY, key);
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@Override
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public Result delete(String space, List<?> key) {
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return exec(
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new TarantoolRequest(
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Code.DELETE,
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value(Key.SPACE), cacheLookupValue(() -> getSchemaMeta().getSpace(space).getId()),
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value(Key.KEY), value(key)
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)
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);
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}
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@Override
47174
public Result call(String function, Object... args) {
48-
return exec(callCode, Key.FUNCTION, function, Key.TUPLE, args);
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return exec(
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new TarantoolRequest(
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callCode,
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value(Key.FUNCTION), value(function),
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value(Key.TUPLE), value(args)
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)
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);
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}
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@Override
51185
public Result eval(String expression, Object... args) {
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return exec(Code.EVAL, Key.EXPRESSION, expression, Key.TUPLE, args);
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return exec(
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new TarantoolRequest(
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Code.EVAL,
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value(Key.EXPRESSION), value(expression),
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value(Key.TUPLE), value(args)
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)
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);
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}
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@Override
55196
public void ping() {
56-
exec(Code.PING);
197+
exec(new TarantoolRequest(Code.PING));
57198
}
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59200
public void setCallCode(Code callCode) {
60201
this.callCode = callCode;
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}
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62204
}

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