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Add support for asynchronous invocation entry (#146)
- Add several `asyncEntry` method in `Sph` interface and `SphU` class. - Add a new `AsyncEntry` class for asynchronous entry representation. Some refactor for `CtEntry`. - Refactored `CtSph` and implement `asyncEntryInternal` for asynchronous entry. - Add `runOnContext` and `replaceContext` method in `ContextUtil` for context switching.
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-109
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13 files changed

+982
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‎sentinel-core/src/main/java/com/alibaba/csp/sentinel/AsyncEntry.java

+84
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,84 @@
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/*
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* Copyright 1999-2018 Alibaba Group Holding Ltd.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.alibaba.csp.sentinel;
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import com.alibaba.csp.sentinel.context.Context;
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import com.alibaba.csp.sentinel.slotchain.ProcessorSlot;
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import com.alibaba.csp.sentinel.slotchain.ResourceWrapper;
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/**
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* The entry for asynchronous resources.
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*
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* @author Eric Zhao
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* @since 0.2.0
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*/
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public class AsyncEntry extends CtEntry {
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private Context asyncContext;
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AsyncEntry(ResourceWrapper resourceWrapper, ProcessorSlot<Object> chain, Context context) {
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super(resourceWrapper, chain, context);
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}
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/**
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* Remove current entry from local context, but does not exit.
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*/
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void cleanCurrentEntryInLocal() {
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Context originalContext = context;
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if (originalContext != null) {
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Entry curEntry = originalContext.getCurEntry();
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if (curEntry == this) {
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Entry parent = this.parent;
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originalContext.setCurEntry(parent);
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if (parent != null) {
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((CtEntry)parent).child = null;
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}
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} else {
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throw new IllegalStateException("Bad async context state");
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}
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}
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}
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public Context getAsyncContext() {
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return asyncContext;
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}
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/**
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* The async context should not be initialized until the node for current resource has been set to current entry.
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*/
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void initAsyncContext() {
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if (asyncContext == null) {
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this.asyncContext = Context.newAsyncContext(context.getEntranceNode(), context.getName())
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.setOrigin(context.getOrigin())
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.setCurEntry(this);
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} else {
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throw new IllegalStateException("Duplicate initialize of async context");
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}
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}
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@Override
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protected void clearEntryContext() {
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super.clearEntryContext();
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this.asyncContext = null;
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}
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@Override
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protected Entry trueExit(int count, Object... args) throws ErrorEntryFreeException {
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exitForContext(asyncContext, count, args);
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return parent;
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}
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}

‎sentinel-core/src/main/java/com/alibaba/csp/sentinel/CtEntry.java

+103
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,103 @@
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/*
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* Copyright 1999-2018 Alibaba Group Holding Ltd.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.alibaba.csp.sentinel;
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import com.alibaba.csp.sentinel.context.Context;
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import com.alibaba.csp.sentinel.context.ContextUtil;
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import com.alibaba.csp.sentinel.node.Node;
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import com.alibaba.csp.sentinel.slotchain.ProcessorSlot;
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import com.alibaba.csp.sentinel.slotchain.ResourceWrapper;
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/**
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* Linked entry within current context.
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*
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* @author jialiang.linjl
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* @author Eric Zhao
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*/
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class CtEntry extends Entry {
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protected Entry parent = null;
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protected Entry child = null;
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protected ProcessorSlot<Object> chain;
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protected Context context;
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CtEntry(ResourceWrapper resourceWrapper, ProcessorSlot<Object> chain, Context context) {
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super(resourceWrapper);
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this.chain = chain;
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this.context = context;
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setUpEntryFor(context);
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}
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private void setUpEntryFor(Context context) {
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this.parent = context.getCurEntry();
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if (parent != null) {
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((CtEntry)parent).child = this;
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}
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context.setCurEntry(this);
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}
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@Override
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public void exit(int count, Object... args) throws ErrorEntryFreeException {
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trueExit(count, args);
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}
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protected void exitForContext(Context context, int count, Object... args) throws ErrorEntryFreeException {
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if (context != null) {
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if (context.getCurEntry() != this) {
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// Clean previous call stack.
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CtEntry e = (CtEntry)context.getCurEntry();
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while (e != null) {
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e.exit(count, args);
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e = (CtEntry)e.parent;
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}
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throw new ErrorEntryFreeException("The order of entry free is can't be paired with the order of entry");
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} else {
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if (chain != null) {
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chain.exit(context, resourceWrapper, count, args);
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}
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// Restore the call stack.
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context.setCurEntry(parent);
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if (parent != null) {
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((CtEntry)parent).child = null;
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}
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if (parent == null) {
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// Auto-created entry indicates immediate exit.
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ContextUtil.exit();
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}
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// Clean the reference of context in current entry to avoid duplicate exit.
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clearEntryContext();
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}
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}
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}
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protected void clearEntryContext() {
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this.context = null;
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}
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@Override
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protected Entry trueExit(int count, Object... args) throws ErrorEntryFreeException {
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exitForContext(context, count, args);
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return parent;
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}
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@Override
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public Node getLastNode() {
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return parent == null ? null : parent.getCurNode();
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}
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}

‎sentinel-core/src/main/java/com/alibaba/csp/sentinel/CtSph.java

+46-63
Original file line numberDiff line numberDiff line change
@@ -23,7 +23,6 @@
2323
import com.alibaba.csp.sentinel.context.Context;
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import com.alibaba.csp.sentinel.context.ContextUtil;
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import com.alibaba.csp.sentinel.context.NullContext;
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import com.alibaba.csp.sentinel.node.Node;
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import com.alibaba.csp.sentinel.slotchain.MethodResourceWrapper;
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import com.alibaba.csp.sentinel.slotchain.ProcessorSlot;
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import com.alibaba.csp.sentinel.slotchain.ProcessorSlotChain;
@@ -54,6 +53,46 @@ public class CtSph implements Sph {
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private static final Object LOCK = new Object();
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private AsyncEntry asyncEntryInternal(ResourceWrapper resourceWrapper, int count, Object... args) throws BlockException {
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Context context = ContextUtil.getContext();
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if (context instanceof NullContext) {
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// Init the entry only. No rule checking will occur.
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return new AsyncEntry(resourceWrapper, null, context);
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}
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if (context == null) {
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context = MyContextUtil.myEnter(Constants.CONTEXT_DEFAULT_NAME, "", resourceWrapper.getType());
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}
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// Global switch is turned off, so no rule checking will be done.
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if (!Constants.ON) {
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return new AsyncEntry(resourceWrapper, null, context);
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}
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ProcessorSlot<Object> chain = lookProcessChain(resourceWrapper);
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// Means processor cache size exceeds {@link Constants.MAX_SLOT_CHAIN_SIZE}, so no rule checking will be done.
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if (chain == null) {
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return new AsyncEntry(resourceWrapper, null, context);
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}
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AsyncEntry asyncEntry = new AsyncEntry(resourceWrapper, chain, context);
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try {
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chain.entry(context, resourceWrapper, null, count, args);
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// Initiate the async context.
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asyncEntry.initAsyncContext();
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} catch (BlockException e1) {
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asyncEntry.exit(count, args);
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throw e1;
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} catch (Throwable e1) {
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RecordLog.info("Sentinel unexpected exception", e1);
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} finally {
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// The asynchronous call may take time in background, and current context should not be hanged on it.
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// So we need to remove current async entry from current context.
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asyncEntry.cleanCurrentEntryInLocal();
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}
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return asyncEntry;
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}
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/**
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* Do all {@link Rule}s checking about the resource.
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*
@@ -146,68 +185,6 @@ private ProcessorSlot<Object> lookProcessChain(ResourceWrapper resourceWrapper)
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return chain;
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}
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private static class CtEntry extends Entry {
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protected Entry parent = null;
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protected Entry child = null;
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private ProcessorSlot<Object> chain;
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private Context context;
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CtEntry(ResourceWrapper resourceWrapper, ProcessorSlot<Object> chain, Context context) {
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super(resourceWrapper);
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this.chain = chain;
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this.context = context;
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parent = context.getCurEntry();
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if (parent != null) {
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((CtEntry)parent).child = this;
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}
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context.setCurEntry(this);
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}
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@Override
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public void exit(int count, Object... args) throws ErrorEntryFreeException {
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trueExit(count, args);
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}
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@Override
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protected Entry trueExit(int count, Object... args) throws ErrorEntryFreeException {
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if (context != null) {
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if (context.getCurEntry() != this) {
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// Clean previous call stack.
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CtEntry e = (CtEntry)context.getCurEntry();
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while (e != null) {
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e.exit(count, args);
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e = (CtEntry)e.parent;
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}
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throw new ErrorEntryFreeException(
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"The order of entry free is can't be paired with the order of entry");
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} else {
185-
if (chain != null) {
186-
chain.exit(context, resourceWrapper, count, args);
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}
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// Modify the call stack.
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context.setCurEntry(parent);
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if (parent != null) {
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((CtEntry)parent).child = null;
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}
193-
if (parent == null) {
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// Auto-created entry indicates immediate exit.
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ContextUtil.exit();
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}
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// Clean the reference of context in current entry to avoid duplicate exit.
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context = null;
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}
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}
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return parent;
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}
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@Override
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public Node getLastNode() {
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return parent == null ? null : parent.getCurNode();
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}
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}
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/**
212189
* This class is used for skip context name checking.
213190
*/
@@ -276,4 +253,10 @@ public Entry entry(String name, EntryType type, int count, Object... args) throw
276253
StringResourceWrapper resource = new StringResourceWrapper(name, type);
277254
return entry(resource, count, args);
278255
}
256+
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@Override
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public AsyncEntry asyncEntry(String name, EntryType type, int count, Object... args) throws BlockException {
259+
StringResourceWrapper resource = new StringResourceWrapper(name, type);
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return asyncEntryInternal(resource, count, args);
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}
279262
}

‎sentinel-core/src/main/java/com/alibaba/csp/sentinel/Sph.java

+16-3
Original file line numberDiff line numberDiff line change
@@ -27,6 +27,7 @@
2727
* @author qinan.qn
2828
* @author jialiang.linjl
2929
* @author leyou
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* @author Eric Zhao
3031
*/
3132
public interface Sph {
3233

@@ -135,11 +136,23 @@ public interface Sph {
135136
* @param type the resource is an inbound or an outbound method. This is used
136137
* to mark whether it can be blocked when the system is unstable
137138
* @param count the count that the resource requires
138-
* @param args the parameters of the method. It can also be counted by setting
139-
* hot parameter rule
140-
* @return entry get.
139+
* @param args the parameters of the method. It can also be counted by setting hot parameter rule
140+
* @return entry get
141141
* @throws BlockException if the block criteria is met
142142
*/
143143
Entry entry(String name, EntryType type, int count, Object... args) throws BlockException;
144144

145+
/**
146+
* Create a protected asynchronous resource.
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*
148+
* @param name the unique name for the protected resource
149+
* @param type the resource is an inbound or an outbound method. This is used
150+
* to mark whether it can be blocked when the system is unstable
151+
* @param count the count that the resource requires
152+
* @param args the parameters of the method. It can also be counted by setting hot parameter rule
153+
* @return created asynchronous entry
154+
* @throws BlockException if the block criteria is met
155+
* @since 0.2.0
156+
*/
157+
AsyncEntry asyncEntry(String name, EntryType type, int count, Object... args) throws BlockException;
145158
}

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