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Fix internal bug when amount of context exceeds the threshold (#152) 

- When amount of context exceeds the threshold, the `NullContext` will be set to current thread local. Thus, when checking context in `CtSph#entry`, once `NullContext` detected, the entry will not do rule checking on the slot chain.
- Cache the default context during initialization. Then when amount of context exceeds the threshold, entries under default context can do rule checking under default context.
- Enhance the error message

Signed-off-by: Eric Zhao <sczyh16@gmail.com>
This commit is contained in:
Eric Zhao 2018-09-19 14:01:07 +08:00 committed by GitHub
parent 91f27977e9
commit be43a31dc4
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GPG Key ID: 4AEE18F83AFDEB23
7 changed files with 110 additions and 9 deletions
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2
sentinel-core/src/main/java/com/alibaba/csp/sentinel/Constants.java
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@ -31,7 +31,7 @@ public class Constants {
public final static int MAX_CONTEXT_NAME_SIZE = 2000;
public final static int MAX_SLOT_CHAIN_SIZE = 6000;
public final static String ROOT_ID = "machine-root";
public final static String CONTEXT_DEFAULT_NAME = "default_context_name";
public final static String CONTEXT_DEFAULT_NAME = "sentinel_default_context";
public final static DefaultNode ROOT = new EntranceNode(new StringResourceWrapper(ROOT_ID, EntryType.IN),
Env.nodeBuilder.buildClusterNode());

17
sentinel-core/src/main/java/com/alibaba/csp/sentinel/CtEntry.java
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@ -17,6 +17,7 @@ package com.alibaba.csp.sentinel;
import com.alibaba.csp.sentinel.context.Context;
import com.alibaba.csp.sentinel.context.ContextUtil;
import com.alibaba.csp.sentinel.context.NullContext;
import com.alibaba.csp.sentinel.node.Node;
import com.alibaba.csp.sentinel.slotchain.ProcessorSlot;
import com.alibaba.csp.sentinel.slotchain.ResourceWrapper;
@ -44,6 +45,10 @@ class CtEntry extends Entry {
}
private void setUpEntryFor(Context context) {
// The entry should not be associated to NullContext.
if (context instanceof NullContext) {
return;
}
this.parent = context.getCurEntry();
if (parent != null) {
((CtEntry)parent).child = this;
@ -58,14 +63,21 @@ class CtEntry extends Entry {
protected void exitForContext(Context context, int count, Object... args) throws ErrorEntryFreeException {
if (context != null) {
// Null context should exit without clean-up.
if (context instanceof NullContext) {
return;
}
if (context.getCurEntry() != this) {
String curEntryNameInContext = context.getCurEntry() == null ? null : context.getCurEntry().getResourceWrapper().getName();
// Clean previous call stack.
CtEntry e = (CtEntry)context.getCurEntry();
while (e != null) {
e.exit(count, args);
e = (CtEntry)e.parent;
}
throw new ErrorEntryFreeException("The order of entry free is can't be paired with the order of entry");
String errorMessage = String.format("The order of entry exit can't be paired with the order of entry"
+ ", current entry in context: <%s>, but expected: <%s>", curEntryNameInContext, resourceWrapper.getName());
throw new ErrorEntryFreeException(errorMessage);
} else {
if (chain != null) {
chain.exit(context, resourceWrapper, count, args);
@ -76,7 +88,8 @@ class CtEntry extends Entry {
((CtEntry)parent).child = null;
}
if (parent == null) {
// Auto-created entry indicates immediate exit.
// Default context (auto entered) will be exited automatically.
// Note: NullContext won't be exited automatically.
ContextUtil.exit();
}
// Clean the reference of context in current entry to avoid duplicate exit.

7
sentinel-core/src/main/java/com/alibaba/csp/sentinel/CtSph.java
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@ -56,7 +56,8 @@ public class CtSph implements Sph {
private AsyncEntry asyncEntryInternal(ResourceWrapper resourceWrapper, int count, Object... args) throws BlockException {
Context context = ContextUtil.getContext();
if (context instanceof NullContext) {
// Init the entry only. No rule checking will occur.
// The {@link NullContext} indicates that the amount of context has exceeded the threshold,
// so here init the entry only. No rule checking will be done.
return new AsyncEntry(resourceWrapper, null, context);
}
if (context == null) {
@ -112,7 +113,8 @@ public class CtSph implements Sph {
public Entry entry(ResourceWrapper resourceWrapper, int count, Object... args) throws BlockException {
Context context = ContextUtil.getContext();
if (context instanceof NullContext) {
// Init the entry only. No rule checking will occur.
// The {@link NullContext} indicates that the amount of context has exceeded the threshold,
// so here init the entry only. No rule checking will be done.
return new CtEntry(resourceWrapper, null, context);
}
@ -142,6 +144,7 @@ public class CtSph implements Sph {
e.exit(count, args);
throw e1;
} catch (Throwable e1) {
// This should not happen, unless there are errors existing in Sentinel internal.
RecordLog.info("Sentinel unexpected exception", e1);
}
return e;

11
sentinel-core/src/main/java/com/alibaba/csp/sentinel/context/Context.java
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@ -187,4 +187,15 @@ public class Context {
public Node getOriginNode() {
return curEntry == null ? null : curEntry.getOriginNode();
}
@Override
public String toString() {
return "Context{" +
"name='" + name + '\'' +
", entranceNode=" + entranceNode +
", curEntry=" + curEntry +
", origin='" + origin + '\'' +
", async=" + async +
'}';
}
}

26
sentinel-core/src/main/java/com/alibaba/csp/sentinel/context/ContextUtil.java
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@ -49,13 +49,35 @@ public class ContextUtil {
private static ThreadLocal<Context> contextHolder = new ThreadLocal<Context>();
/**
* Holds all {@link EntranceNode}
* Holds all {@link EntranceNode}.
*/
private static volatile Map<String, DefaultNode> contextNameNodeMap = new HashMap<String, DefaultNode>();
private static final ReentrantLock LOCK = new ReentrantLock();
private static final Context NULL_CONTEXT = new NullContext();
static {
// Cache the entrance node for default context.
initDefaultContext();
}
private static void initDefaultContext() {
String defaultContextName = Constants.CONTEXT_DEFAULT_NAME;
EntranceNode node = new EntranceNode(new StringResourceWrapper(defaultContextName, EntryType.IN), null);
Constants.ROOT.addChild(node);
contextNameNodeMap.put(defaultContextName, node);
}
/**
* Not thread-safe, only for test.
*/
static void resetContextMap() {
if (contextNameNodeMap != null) {
contextNameNodeMap.clear();
initDefaultContext();
}
}
/**
* <p>
* Enter the invocation context. The context is ThreadLocal, meaning that
@ -99,6 +121,7 @@ public class ContextUtil {
DefaultNode node = localCacheNameMap.get(name);
if (node == null) {
if (localCacheNameMap.size() > Constants.MAX_CONTEXT_NAME_SIZE) {
contextHolder.set(NULL_CONTEXT);
return NULL_CONTEXT;
} else {
try {
@ -106,6 +129,7 @@ public class ContextUtil {
node = contextNameNodeMap.get(name);
if (node == null) {
if (contextNameNodeMap.size() > Constants.MAX_CONTEXT_NAME_SIZE) {
contextHolder.set(NULL_CONTEXT);
return NULL_CONTEXT;
} else {
node = new EntranceNode(new StringResourceWrapper(name, EntryType.IN), null);

3
sentinel-core/src/main/java/com/alibaba/csp/sentinel/context/NullContext.java
View File

@ -27,7 +27,6 @@ import com.alibaba.csp.sentinel.Constants;
public class NullContext extends Context {
public NullContext() {
super(null, null);
super(null, "null_context_internal");
}
}

53
sentinel-core/src/test/java/com/alibaba/csp/sentinel/context/ContextTest.java
View File

@ -15,7 +15,11 @@
*/
package com.alibaba.csp.sentinel.context;
import com.alibaba.csp.sentinel.Constants;
import com.alibaba.csp.sentinel.TestUtil;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import static org.junit.Assert.*;
@ -28,9 +32,56 @@ import static org.junit.Assert.*;
*/
public class ContextTest {
@Before
public void setUp() {
resetContextMap();
}
@After
public void cleanUp() {
ContextUtil.exit();
TestUtil.cleanUpContext();
}
@Test
public void testEnterCustomContextWhenExceedsThreshold() {
fillContext();
try {
String contextName = "abc";
ContextUtil.enter(contextName, "bcd");
Context curContext = ContextUtil.getContext();
assertNotEquals(contextName, curContext.getName());
assertTrue(curContext instanceof NullContext);
assertEquals("", curContext.getOrigin());
} finally {
ContextUtil.exit();
resetContextMap();
}
}
@Test
public void testDefaultContextWhenExceedsThreshold() {
fillContext();
try {
ContextUtil.trueEnter(Constants.CONTEXT_DEFAULT_NAME, "");
Context curContext = ContextUtil.getContext();
assertEquals(Constants.CONTEXT_DEFAULT_NAME, curContext.getName());
assertNotNull(curContext.getEntranceNode());
} finally {
ContextUtil.exit();
resetContextMap();
}
}
private void fillContext() {
for (int i = 0; i < Constants.MAX_CONTEXT_NAME_SIZE; i++) {
ContextUtil.enter("test-context-" + i);
ContextUtil.exit();
}
}
private void resetContextMap() {
ContextUtil.resetContextMap();
Constants.ROOT.removeChildList();
}
@Test