mirror of https://github.com/facebook/rocksdb.git
122 lines
3.8 KiB
C++
122 lines
3.8 KiB
C++
/*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. 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,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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#ifndef THRIFT_ASYNC_TEVENTBASEMANAGER_H
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#define THRIFT_ASYNC_TEVENTBASEMANAGER_H 1
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#include "thrift/lib/cpp/concurrency/ThreadLocal.h"
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namespace apache { namespace thrift { namespace async {
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class TEventBase;
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/**
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* Manager for per-thread TEventBase objects.
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* This class will find or create a TEventBase for the current
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* thread, associated with thread-specific storage for that thread.
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* Although a typical application will generally only have one
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* TEventBaseManager, there is no restriction on multiple instances;
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* the TEventBases belong to one instance are isolated from those of
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* another.
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*/
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class TEventBaseManager {
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public:
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TEventBaseManager() {}
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~TEventBaseManager() {}
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/**
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* Get the TEventBase for this thread, or create one if none exists yet.
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*
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* If no TEventBase exists for this thread yet, a new one will be created and
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* returned. May throw std::bad_alloc if allocation fails.
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*/
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TEventBase* getEventBase() const {
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// localStore_.get() will never return NULL.
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// InfoManager::allocate() will throw an exception instead if it cannot
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// allocate a new EventBaseInfo or TEventBase.
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return localStore_.get()->eventBase;
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}
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/**
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* Get the TEventBase for this thread.
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*
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* Returns NULL if no TEventBase has been created for this thread yet.
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*/
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TEventBase* getExistingEventBase() const {
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EventBaseInfo* info = localStore_.getNoAlloc();
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if (info == NULL) {
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return NULL;
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}
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return info->eventBase;
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}
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/**
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* Set the TEventBase to be used by this thread.
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*
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* This may only be called if no TEventBase has been defined for this thread
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* yet. If a TEventBase is already defined for this thread, a
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* TLibraryException is thrown. std::bad_alloc may also be thrown if
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* allocation fails while setting the TEventBase.
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*
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* This should typically be invoked by the code that will call loop() on the
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* TEventBase, to make sure the TEventBaseManager points to the correct
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* TEventBase that is actually running in this thread.
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*/
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void setEventBase(TEventBase *eventBase, bool takeOwnership);
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/**
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* Clear the TEventBase for this thread.
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*
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* This can be used if the code driving the TEventBase loop() has finished
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* the loop and new events should no longer be added to the TEventBase.
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*/
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void clearEventBase();
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private:
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struct EventBaseInfo {
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EventBaseInfo(TEventBase *evb, bool owned)
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: eventBase(evb),
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owned(owned) {}
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TEventBase *eventBase;
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bool owned;
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};
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class InfoManager {
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public:
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EventBaseInfo* allocate();
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void destroy(EventBaseInfo* info);
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void replace(EventBaseInfo* oldInfo, EventBaseInfo* newInfo) {
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if (oldInfo != newInfo) {
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destroy(oldInfo);
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}
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}
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};
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// Forbidden copy constructor and assignment opererator
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TEventBaseManager(TEventBaseManager const &);
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TEventBaseManager& operator=(TEventBaseManager const &);
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concurrency::ThreadLocal<EventBaseInfo, InfoManager> localStore_;
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};
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}}} // apache::thrift::async
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#endif // THRIFT_ASYNC_TEVENTBASEMANAGER_H
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