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Reactive Relational Database Connectivity Driver Implementation for Postgresql
/*
* Copyright 2021 the original author or authors.
*
* 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
*
* https://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 io.r2dbc.postgresql;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.util.ReferenceCountUtil;
import io.netty.util.ReferenceCounted;
import io.r2dbc.postgresql.client.Binding;
import io.r2dbc.postgresql.client.ConnectionContext;
import io.r2dbc.postgresql.client.EncodedParameter;
import io.r2dbc.postgresql.client.SimpleQueryMessageFlow;
import io.r2dbc.postgresql.message.backend.BackendMessage;
import io.r2dbc.postgresql.message.backend.CommandComplete;
import io.r2dbc.postgresql.message.backend.EmptyQueryResponse;
import io.r2dbc.postgresql.message.backend.ErrorResponse;
import io.r2dbc.postgresql.message.frontend.Bind;
import io.r2dbc.postgresql.util.Assert;
import io.r2dbc.postgresql.util.GeneratedValuesUtils;
import io.r2dbc.postgresql.util.Operators;
import io.r2dbc.spi.Statement;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import reactor.core.publisher.Sinks;
import javax.annotation.Nonnull;
import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.function.Predicate;
import static io.r2dbc.postgresql.message.frontend.Execute.NO_LIMIT;
import static io.r2dbc.postgresql.util.PredicateUtils.or;
/**
* A generic {@link Statement}.
*
* @since 0.9
*/
final class PostgresqlStatement implements io.r2dbc.postgresql.api.PostgresqlStatement {
private static final Predicate WINDOW_UNTIL = or(CommandComplete.class::isInstance, EmptyQueryResponse.class::isInstance, ErrorResponse.class::isInstance);
private final ArrayDeque bindings;
private final ConnectionResources resources;
private final ConnectionContext connectionContext;
private final ParsedSql parsedSql;
private int fetchSize;
private String[] generatedColumns;
PostgresqlStatement(ConnectionResources resources, String sql) {
this.resources = Assert.requireNonNull(resources, "resources must not be null");
this.parsedSql = PostgresqlSqlParser.parse(Assert.requireNonNull(sql, "sql must not be null"));
this.connectionContext = resources.getClient().getContext();
this.bindings = new ArrayDeque<>(this.parsedSql.getParameterCount());
if (this.parsedSql.getStatementCount() > 1 && this.parsedSql.getParameterCount() > 0) {
throw new IllegalArgumentException(String.format("Statement '%s' cannot be created. This is often due to the presence of both multiple statements and parameters at the same time.", sql));
}
fetchSize(this.resources.getConfiguration().getFetchSize(sql));
}
@Override
public PostgresqlStatement add() {
Binding binding = this.bindings.peekLast();
if (binding != null) {
binding.validate();
}
this.bindings.add(new Binding(this.parsedSql.getParameterCount()));
return this;
}
@Override
public PostgresqlStatement bind(String identifier, Object value) {
return bind(getIdentifierIndex(identifier), value);
}
@Override
public PostgresqlStatement bind(int index, Object value) {
Assert.requireNonNull(value, "value must not be null");
BindingLogger.logBind(this.connectionContext, index, value);
getCurrentOrFirstBinding().add(index, this.resources.getCodecs().encode(value));
return this;
}
@Override
public PostgresqlStatement bindNull(String identifier, Class type) {
return bindNull(getIdentifierIndex(identifier), type);
}
@Override
public PostgresqlStatement bindNull(int index, Class type) {
Assert.requireNonNull(type, "type must not be null");
if (index >= this.parsedSql.getParameterCount()) {
throw new UnsupportedOperationException(String.format("Cannot bind parameter %d, statement has %d parameters", index, this.parsedSql.getParameterCount()));
}
BindingLogger.logBindNull(this.connectionContext, index, type);
getCurrentOrFirstBinding().add(index, this.resources.getCodecs().encodeNull(type));
return this;
}
@Nonnull
private Binding getCurrentOrFirstBinding() {
Binding binding = this.bindings.peekLast();
if (binding == null) {
Binding newBinding = new Binding(this.parsedSql.getParameterCount());
this.bindings.add(newBinding);
return newBinding;
} else {
return binding;
}
}
@Override
public Flux execute() {
if (this.generatedColumns == null) {
return execute(this.parsedSql.getSql());
}
return execute(GeneratedValuesUtils.augment(this.parsedSql.getSql(), this.generatedColumns));
}
@Override
public PostgresqlStatement returnGeneratedValues(String... columns) {
Assert.requireNonNull(columns, "columns must not be null");
if (this.parsedSql.hasDefaultTokenValue("RETURNING")) {
throw new IllegalStateException("Statement already includes RETURNING clause");
}
if (!this.parsedSql.hasDefaultTokenValue("DELETE", "INSERT", "UPDATE")) {
throw new IllegalStateException("Statement is not a DELETE, INSERT, or UPDATE command");
}
this.generatedColumns = columns;
return this;
}
@Override
public PostgresqlStatement fetchSize(int rows) {
Assert.isTrue(rows >= 0, "fetch size must be greater or equal zero");
this.fetchSize = rows;
return this;
}
@Override
public String toString() {
return "PostgresqlStatement{" +
"bindings=" + this.bindings +
", context=" + this.resources +
", sql='" + this.parsedSql.getSql() + '\'' +
", generatedColumns=" + Arrays.toString(this.generatedColumns) +
'}';
}
Binding getCurrentBinding() {
return getCurrentOrFirstBinding();
}
private int getIdentifierIndex(String identifier) {
Assert.requireNonNull(identifier, "identifier must not be null");
Assert.requireType(identifier, String.class, "identifier must be a String");
if (!identifier.startsWith("$")) {
throw new NoSuchElementException(String.format("\"%s\" is not a valid identifier", identifier));
}
try {
return Integer.parseInt(identifier.substring(1)) - 1;
} catch (NumberFormatException e) {
throw new NoSuchElementException(String.format("\"%s\" is not a valid identifier", identifier));
}
}
private Flux execute(String sql) {
ExceptionFactory factory = ExceptionFactory.withSql(sql);
CompletableFuture onCancel = new CompletableFuture<>();
AtomicBoolean canceled = new AtomicBoolean();
if (this.parsedSql.getParameterCount() != 0) {
// Extended query protocol
if (this.bindings.size() == 0) {
throw new IllegalStateException("No parameters have been bound");
}
this.bindings.forEach(Binding::validate);
int fetchSize = this.fetchSize;
return Flux.defer(() -> {
// possible optimization: fetch all when statement is already prepared or first statement to be prepared
if (this.bindings.size() == 1) {
Binding binding = this.bindings.peekFirst();
Flux messages = collectBindingParameters(binding).flatMapMany(values -> ExtendedFlowDelegate.runQuery(this.resources, factory, sql, binding, values, fetchSize,
new AtomicBoolean()));
return Flux.just(PostgresqlResult.toResult(this.resources, messages, factory));
}
Iterator iterator = this.bindings.iterator();
Sinks.Many bindings = Sinks.many().unicast().onBackpressureBuffer();
onCancel.whenComplete((unused, throwable) -> {
clearBindings(iterator, canceled);
});
return bindings.asFlux()
.map(it -> {
Flux messages =
collectBindingParameters(it).flatMapMany(values -> ExtendedFlowDelegate.runQuery(this.resources, factory, sql, it, values, this.fetchSize, canceled)).doOnComplete(() -> tryNextBinding(iterator, bindings, canceled));
return PostgresqlResult.toResult(this.resources, messages, factory);
})
.doOnCancel(() -> clearBindings(iterator, canceled))
.doOnError(e -> clearBindings(iterator, canceled))
.doOnSubscribe(it -> bindings.emitNext(iterator.next(), Sinks.EmitFailureHandler.FAIL_FAST));
}).cast(io.r2dbc.postgresql.api.PostgresqlResult.class);
}
Flux exchange;
// Simple Query protocol
if (this.fetchSize != NO_LIMIT) {
exchange = ExtendedFlowDelegate.runQuery(this.resources, factory, sql, Binding.EMPTY, Collections.emptyList(), this.fetchSize, canceled);
} else {
exchange = SimpleQueryMessageFlow.exchange(this.resources.getClient(), sql);
}
return exchange.windowUntil(WINDOW_UNTIL)
.doOnDiscard(ReferenceCounted.class, ReferenceCountUtil::release) // ensure release of rows within WindowPredicate
.map(messages -> PostgresqlResult.toResult(this.resources, messages, factory))
.as(source -> Operators.discardOnCancel(source, () -> {
canceled.set(true);
onCancel.complete(null);
}));
}
private static void tryNextBinding(Iterator iterator, Sinks.Many bindingSink, AtomicBoolean canceled) {
if (canceled.get()) {
return;
}
try {
if (iterator.hasNext()) {
bindingSink.emitNext(iterator.next(), Sinks.EmitFailureHandler.FAIL_FAST);
} else {
bindingSink.emitComplete(Sinks.EmitFailureHandler.FAIL_FAST);
}
} catch (Exception e) {
bindingSink.emitError(e, Sinks.EmitFailureHandler.FAIL_FAST);
}
}
private static Mono> collectBindingParameters(Binding binding) {
return Flux.fromIterable(binding.getParameterValues())
.concatMap(f -> {
if (f == EncodedParameter.NULL_VALUE) {
return Flux.just(Bind.NULL_VALUE);
} else {
return Flux.from(f)
.reduce(Unpooled.compositeBuffer(), (c, b) -> c.addComponent(true, b));
}
})
.collectList();
}
private void clearBindings(Iterator iterator, AtomicBoolean canceled) {
canceled.set(true);
while (iterator.hasNext()) {
// exhaust iterator, ignore returned elements
iterator.next();
}
this.bindings.forEach(Binding::clear);
}
}
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