leventov closed pull request #6662: Double-checked locking bugs
URL: https://github.com/apache/incubator-druid/pull/6662
This is a PR merged from a forked repository.
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diff --git a/aws-common/pom.xml b/aws-common/pom.xml
index 4b941c46c7d..941dc2847b0 100644
--- a/aws-common/pom.xml
+++ b/aws-common/pom.xml
@@ -45,6 +45,11 @@
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk-s3</artifactId>
</dependency>
+ <dependency>
+ <groupId>org.checkerframework</groupId>
+ <artifactId>checker</artifactId>
+ <version>${checkerframework.version}</version>
+ </dependency>
<!-- Tests -->
<dependency>
diff --git
a/aws-common/src/main/java/org/apache/druid/common/aws/LazyFileSessionCredentialsProvider.java
b/aws-common/src/main/java/org/apache/druid/common/aws/LazyFileSessionCredentialsProvider.java
index 7fc046b3165..483b32a777a 100644
---
a/aws-common/src/main/java/org/apache/druid/common/aws/LazyFileSessionCredentialsProvider.java
+++
b/aws-common/src/main/java/org/apache/druid/common/aws/LazyFileSessionCredentialsProvider.java
@@ -21,27 +21,43 @@
import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.AWSCredentialsProvider;
+import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
public class LazyFileSessionCredentialsProvider implements
AWSCredentialsProvider
{
- private AWSCredentialsConfig config;
- private FileSessionCredentialsProvider provider;
+ private final AWSCredentialsConfig config;
+
+ /**
+ * The field is declared volatile in order to ensure safe publication of the
object
+ * in {@link #getUnderlyingProvider()} without worrying about final modifiers
+ * on the fields of the created object
+ *
+ * @see <a
href="https://github.com/apache/incubator-druid/pull/6662#discussion_r237013157";>
+ *
https://github.com/apache/incubator-druid/pull/6662#discussion_r237013157</a>
+ */
+ @MonotonicNonNull
+ private volatile FileSessionCredentialsProvider provider;
public LazyFileSessionCredentialsProvider(AWSCredentialsConfig config)
{
this.config = config;
}
+ @EnsuresNonNull("provider")
private FileSessionCredentialsProvider getUnderlyingProvider()
{
- if (provider == null) {
+ FileSessionCredentialsProvider syncedProvider = provider;
+ if (syncedProvider == null) {
synchronized (config) {
- if (provider == null) {
- provider = new
FileSessionCredentialsProvider(config.getFileSessionCredentials());
+ syncedProvider = provider;
+ if (syncedProvider == null) {
+ syncedProvider = new
FileSessionCredentialsProvider(config.getFileSessionCredentials());
+ provider = syncedProvider;
}
}
}
- return provider;
+ return syncedProvider;
}
@Override
diff --git a/pom.xml b/pom.xml
index 4c2938ebad2..46a1355d728 100644
--- a/pom.xml
+++ b/pom.xml
@@ -100,6 +100,7 @@
<caffeine.version>2.5.5</caffeine.version>
<!-- When upgrading ZK, edit docs and integration tests as well
(integration-tests/docker-base/setup.sh) -->
<zookeeper.version>3.4.11</zookeeper.version>
+ <checkerframework.version>2.5.7</checkerframework.version>
<repoOrgId>apache.snapshots</repoOrgId>
<repoOrgName>Apache Snapshot Repository</repoOrgName>
<repoOrgUrl>https://repository.apache.org/snapshots</repoOrgUrl>
diff --git a/processing/pom.xml b/processing/pom.xml
index 4963e32acbe..c4d817ca926 100644
--- a/processing/pom.xml
+++ b/processing/pom.xml
@@ -111,6 +111,11 @@
<groupId>org.ow2.asm</groupId>
<artifactId>asm-commons</artifactId>
</dependency>
+ <dependency>
+ <groupId>org.checkerframework</groupId>
+ <artifactId>checker</artifactId>
+ <version>${checkerframework.version}</version>
+ </dependency>
<!-- Tests -->
<dependency>
diff --git
a/processing/src/main/java/org/apache/druid/query/aggregation/JavaScriptAggregatorFactory.java
b/processing/src/main/java/org/apache/druid/query/aggregation/JavaScriptAggregatorFactory.java
index e747ad68d73..b5e9ed173ee 100644
---
a/processing/src/main/java/org/apache/druid/query/aggregation/JavaScriptAggregatorFactory.java
+++
b/processing/src/main/java/org/apache/druid/query/aggregation/JavaScriptAggregatorFactory.java
@@ -33,6 +33,8 @@
import org.apache.druid.segment.BaseObjectColumnValueSelector;
import org.apache.druid.segment.ColumnSelectorFactory;
import org.apache.druid.segment.ColumnValueSelector;
+import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
import org.mozilla.javascript.Context;
import org.mozilla.javascript.ContextAction;
import org.mozilla.javascript.ContextFactory;
@@ -58,8 +60,15 @@
private final String fnCombine;
private final JavaScriptConfig config;
- // This variable is lazily initialized to avoid unnecessary JavaScript
compilation during JSON serde
- private JavaScriptAggregator.ScriptAggregator compiledScript;
+ /**
+ * The field is declared volatile in order to ensure safe publication of the
object
+ * in {@link #compileScript(String, String, String)} without worrying about
final modifiers
+ * on the fields of the created object
+ *
+ * @see <a
href="https://github.com/apache/incubator-druid/pull/6662#discussion_r237013157";>
+ *
https://github.com/apache/incubator-druid/pull/6662#discussion_r237013157</a>
+ */
+ private volatile JavaScriptAggregator.@MonotonicNonNull ScriptAggregator
compiledScript;
@JsonCreator
public JavaScriptAggregatorFactory(
@@ -89,7 +98,7 @@ public JavaScriptAggregatorFactory(
@Override
public Aggregator factorize(final ColumnSelectorFactory columnFactory)
{
- checkAndCompileScript();
+ JavaScriptAggregator.ScriptAggregator compiledScript = getCompiledScript();
return new JavaScriptAggregator(
fieldNames.stream().map(columnFactory::makeColumnValueSelector).collect(Collectors.toList()),
compiledScript
@@ -99,7 +108,7 @@ public Aggregator factorize(final ColumnSelectorFactory
columnFactory)
@Override
public BufferAggregator factorizeBuffered(final ColumnSelectorFactory
columnSelectorFactory)
{
- checkAndCompileScript();
+ JavaScriptAggregator.ScriptAggregator compiledScript = getCompiledScript();
return new JavaScriptBufferAggregator(
fieldNames.stream().map(columnSelectorFactory::makeColumnValueSelector).collect(Collectors.toList()),
compiledScript
@@ -115,7 +124,7 @@ public Comparator getComparator()
@Override
public Object combine(Object lhs, Object rhs)
{
- checkAndCompileScript();
+ JavaScriptAggregator.ScriptAggregator compiledScript = getCompiledScript();
return compiledScript.combine(((Number) lhs).doubleValue(), ((Number)
rhs).doubleValue());
}
@@ -135,7 +144,7 @@ public void reset(ColumnValueSelector selector)
@Override
public void fold(ColumnValueSelector selector)
{
- checkAndCompileScript();
+ JavaScriptAggregator.ScriptAggregator compiledScript =
getCompiledScript();
combined = compiledScript.combine(combined, selector.getDouble());
}
@@ -283,19 +292,24 @@ public String toString()
* This class can be used by multiple threads, so this function should be
thread-safe to avoid extra
* script compilation.
*/
- private void checkAndCompileScript()
+ @EnsuresNonNull("compiledScript")
+ private JavaScriptAggregator.ScriptAggregator getCompiledScript()
{
- if (compiledScript == null) {
- // JavaScript configuration should be checked when it's actually used
because someone might still want Druid
- // nodes to be able to deserialize JavaScript-based objects even though
JavaScript is disabled.
- Preconditions.checkState(config.isEnabled(), "JavaScript is disabled");
+ // JavaScript configuration should be checked when it's actually used
because someone might still want Druid
+ // nodes to be able to deserialize JavaScript-based objects even though
JavaScript is disabled.
+ Preconditions.checkState(config.isEnabled(), "JavaScript is disabled");
+ JavaScriptAggregator.ScriptAggregator syncedCompiledScript =
compiledScript;
+ if (syncedCompiledScript == null) {
synchronized (config) {
- if (compiledScript == null) {
- compiledScript = compileScript(fnAggregate, fnReset, fnCombine);
+ syncedCompiledScript = compiledScript;
+ if (syncedCompiledScript == null) {
+ syncedCompiledScript = compileScript(fnAggregate, fnReset,
fnCombine);
+ compiledScript = syncedCompiledScript;
}
}
}
+ return syncedCompiledScript;
}
@VisibleForTesting
diff --git
a/processing/src/main/java/org/apache/druid/query/aggregation/post/JavaScriptPostAggregator.java
b/processing/src/main/java/org/apache/druid/query/aggregation/post/JavaScriptPostAggregator.java
index 9bd6dc66a45..1ed1318fd88 100644
---
a/processing/src/main/java/org/apache/druid/query/aggregation/post/JavaScriptPostAggregator.java
+++
b/processing/src/main/java/org/apache/druid/query/aggregation/post/JavaScriptPostAggregator.java
@@ -28,6 +28,8 @@
import org.apache.druid.query.aggregation.AggregatorFactory;
import org.apache.druid.query.aggregation.PostAggregator;
import org.apache.druid.query.cache.CacheKeyBuilder;
+import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
import org.mozilla.javascript.Context;
import org.mozilla.javascript.ContextFactory;
import org.mozilla.javascript.ScriptableObject;
@@ -87,8 +89,16 @@ public double apply(Object[] args)
private final String function;
private final JavaScriptConfig config;
- // This variable is lazily initialized to avoid unnecessary JavaScript
compilation during JSON serde
- private Function fn;
+ /**
+ * The field is declared volatile in order to ensure safe publication of the
object
+ * in {@link #compile(String)} without worrying about final modifiers
+ * on the fields of the created object
+ *
+ * @see <a
href="https://github.com/apache/incubator-druid/pull/6662#discussion_r237013157";>
+ *
https://github.com/apache/incubator-druid/pull/6662#discussion_r237013157</a>
+ */
+ @MonotonicNonNull
+ private volatile Function fn;
@JsonCreator
public JavaScriptPostAggregator(
@@ -123,7 +133,7 @@ public Comparator getComparator()
@Override
public Object compute(Map<String, Object> combinedAggregators)
{
- checkAndCompileScript();
+ Function fn = getCompiledScript();
final Object[] args = new Object[fieldNames.size()];
int i = 0;
for (String field : fieldNames) {
@@ -136,22 +146,24 @@ public Object compute(Map<String, Object>
combinedAggregators)
* {@link #compute} can be called by multiple threads, so this function
should be thread-safe to avoid extra
* script compilation.
*/
- private void checkAndCompileScript()
+ @EnsuresNonNull("fn")
+ private Function getCompiledScript()
{
- if (fn == null) {
- // JavaScript configuration should be checked when it's actually used
because someone might still want Druid
- // nodes to be able to deserialize JavaScript-based objects even though
JavaScript is disabled.
- Preconditions.checkState(config.isEnabled(), "JavaScript is disabled");
-
- // Synchronizing here can degrade the performance significantly because
this method is called per input row.
- // However, early compilation of JavaScript functions can occur some
memory issues due to unnecessary compilation
- // involving Java class generation each time, and thus this will be
better.
+ // JavaScript configuration should be checked when it's actually used
because someone might still want Druid
+ // nodes to be able to deserialize JavaScript-based objects even though
JavaScript is disabled.
+ Preconditions.checkState(config.isEnabled(), "JavaScript is disabled");
+
+ Function syncedFn = fn;
+ if (syncedFn == null) {
synchronized (config) {
- if (fn == null) {
- fn = compile(function);
+ syncedFn = fn;
+ if (syncedFn == null) {
+ syncedFn = compile(function);
+ fn = syncedFn;
}
}
}
+ return syncedFn;
}
@Override
diff --git
a/processing/src/main/java/org/apache/druid/query/extraction/JavaScriptExtractionFn.java
b/processing/src/main/java/org/apache/druid/query/extraction/JavaScriptExtractionFn.java
index 06892ecd772..3b95b7507b1 100644
---
a/processing/src/main/java/org/apache/druid/query/extraction/JavaScriptExtractionFn.java
+++
b/processing/src/main/java/org/apache/druid/query/extraction/JavaScriptExtractionFn.java
@@ -27,6 +27,8 @@
import org.apache.druid.common.config.NullHandling;
import org.apache.druid.java.util.common.StringUtils;
import org.apache.druid.js.JavaScriptConfig;
+import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
import org.mozilla.javascript.Context;
import org.mozilla.javascript.ContextFactory;
import org.mozilla.javascript.ScriptableObject;
@@ -69,8 +71,16 @@ public String apply(Object input)
private final boolean injective;
private final JavaScriptConfig config;
- // This variable is lazily initialized to avoid unnecessary JavaScript
compilation during JSON serde
- private Function<Object, String> fn;
+ /**
+ * The field is declared volatile in order to ensure safe publication of the
object
+ * in {@link #compile(String)} without worrying about final modifiers
+ * on the fields of the created object
+ *
+ * @see <a
href="https://github.com/apache/incubator-druid/pull/6662#discussion_r237013157";>
+ *
https://github.com/apache/incubator-druid/pull/6662#discussion_r237013157</a>
+ */
+ @MonotonicNonNull
+ private volatile Function<Object, String> fn;
@JsonCreator
public JavaScriptExtractionFn(
@@ -112,7 +122,7 @@ public boolean isInjective()
@Nullable
public String apply(@Nullable Object value)
{
- checkAndCompileScript();
+ Function<Object, String> fn = getCompiledScript();
return NullHandling.emptyToNullIfNeeded(fn.apply(value));
}
@@ -120,19 +130,24 @@ public String apply(@Nullable Object value)
* {@link #apply(Object)} can be called by multiple threads, so this
function should be thread-safe to avoid extra
* script compilation.
*/
- private void checkAndCompileScript()
+ @EnsuresNonNull("fn")
+ private Function<Object, String> getCompiledScript()
{
- if (fn == null) {
- // JavaScript configuration should be checked when it's actually used
because someone might still want Druid
- // nodes to be able to deserialize JavaScript-based objects even though
JavaScript is disabled.
- Preconditions.checkState(config.isEnabled(), "JavaScript is disabled");
+ // JavaScript configuration should be checked when it's actually used
because someone might still want Druid
+ // nodes to be able to deserialize JavaScript-based objects even though
JavaScript is disabled.
+ Preconditions.checkState(config.isEnabled(), "JavaScript is disabled");
+ Function<Object, String> syncedFn = fn;
+ if (syncedFn == null) {
synchronized (config) {
- if (fn == null) {
- fn = compile(function);
+ syncedFn = fn;
+ if (syncedFn == null) {
+ syncedFn = compile(function);
+ fn = syncedFn;
}
}
}
+ return syncedFn;
}
@Override
diff --git
a/processing/src/main/java/org/apache/druid/query/filter/JavaScriptDimFilter.java
b/processing/src/main/java/org/apache/druid/query/filter/JavaScriptDimFilter.java
index 0569aa481d6..b211e38ad78 100644
---
a/processing/src/main/java/org/apache/druid/query/filter/JavaScriptDimFilter.java
+++
b/processing/src/main/java/org/apache/druid/query/filter/JavaScriptDimFilter.java
@@ -30,6 +30,8 @@
import org.apache.druid.js.JavaScriptConfig;
import org.apache.druid.query.extraction.ExtractionFn;
import org.apache.druid.segment.filter.JavaScriptFilter;
+import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
import org.mozilla.javascript.Context;
import org.mozilla.javascript.Function;
import org.mozilla.javascript.ScriptableObject;
@@ -44,8 +46,16 @@
private final ExtractionFn extractionFn;
private final JavaScriptConfig config;
- // This variable is lazily initialized to avoid unnecessary JavaScript
compilation during JSON serde
- private JavaScriptPredicateFactory predicateFactory;
+ /**
+ * The field is declared volatile in order to ensure safe publication of the
object
+ * in {@link JavaScriptPredicateFactory(String, ExtractionFn)} without
worrying about final modifiers
+ * on the fields of the created object
+ *
+ * @see <a
href="https://github.com/apache/incubator-druid/pull/6662#discussion_r237013157";>
+ *
https://github.com/apache/incubator-druid/pull/6662#discussion_r237013157</a>
+ */
+ @MonotonicNonNull
+ private volatile JavaScriptPredicateFactory predicateFactory;
@JsonCreator
public JavaScriptDimFilter(
@@ -107,7 +117,7 @@ public DimFilter optimize()
@Override
public Filter toFilter()
{
- checkAndCreatePredicateFactory();
+ JavaScriptPredicateFactory predicateFactory = getPredicateFactory();
return new JavaScriptFilter(dimension, predicateFactory);
}
@@ -115,19 +125,24 @@ public Filter toFilter()
* This class can be used by multiple threads, so this function should be
thread-safe to avoid extra
* script compilation.
*/
- private void checkAndCreatePredicateFactory()
+ @EnsuresNonNull("predicateFactory")
+ private JavaScriptPredicateFactory getPredicateFactory()
{
- if (predicateFactory == null) {
- // JavaScript configuration should be checked when it's actually used
because someone might still want Druid
- // nodes to be able to deserialize JavaScript-based objects even though
JavaScript is disabled.
- Preconditions.checkState(config.isEnabled(), "JavaScript is disabled");
+ // JavaScript configuration should be checked when it's actually used
because someone might still want Druid
+ // nodes to be able to deserialize JavaScript-based objects even though
JavaScript is disabled.
+ Preconditions.checkState(config.isEnabled(), "JavaScript is disabled");
+ JavaScriptPredicateFactory syncedFnPredicateFactory = predicateFactory;
+ if (syncedFnPredicateFactory == null) {
synchronized (config) {
- if (predicateFactory == null) {
- predicateFactory = new JavaScriptPredicateFactory(function,
extractionFn);
+ syncedFnPredicateFactory = predicateFactory;
+ if (syncedFnPredicateFactory == null) {
+ syncedFnPredicateFactory = new JavaScriptPredicateFactory(function,
extractionFn);
+ predicateFactory = syncedFnPredicateFactory;
}
}
}
+ return syncedFnPredicateFactory;
}
@Override
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