fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph
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100 lines
3.4 KiB
100 lines
3.4 KiB
/*
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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_TASYNCSIGNALHANDLER_H_
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#define THRIFT_ASYNC_TASYNCSIGNALHANDLER_H_ 1
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#include "thrift/lib/cpp/thrift_config.h"
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#include <event.h>
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#include <map>
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namespace apache { namespace thrift { namespace async {
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class TEventBase;
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/**
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* A handler to receive notification about POSIX signals.
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*
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* TAsyncSignalHandler allows code to process signals from within a TEventBase
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* loop. Standard signal handlers interrupt execution of the main thread, and
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* are run while the main thread is paused. As a result, great care must be
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* taken to avoid race conditions if the signal handler has to access or modify
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* any data used by the main thread.
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*
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* TAsyncSignalHandler solves this problem by running the TAsyncSignalHandler
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* callback in normal thread of execution, as a TEventBase callback.
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*
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* TAsyncSignalHandler may only be used in a single thread. It will only
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* process signals received by the thread where the TAsyncSignalHandler is
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* registered. It is the user's responsibility to ensure that signals are
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* delivered to the desired thread in multi-threaded programs.
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*/
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class TAsyncSignalHandler {
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public:
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/**
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* Create a new TAsyncSignalHandler.
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*/
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TAsyncSignalHandler(TEventBase* eventBase);
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virtual ~TAsyncSignalHandler();
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/**
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* Register to receive callbacks about the specified signal.
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*
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* Once the handler has been registered for a particular signal,
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* signalReceived() will be called each time this thread receives this
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* signal.
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*
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* Throws a TException if an error occurs, or if this handler is already
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* registered for this signal.
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*/
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void registerSignalHandler(int signum);
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/**
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* Unregister for callbacks about the specified signal.
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*
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* Throws a TException if an error occurs, or if this signal was not
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* registered.
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*/
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void unregisterSignalHandler(int signum);
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/**
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* signalReceived() will called to indicate that the specified signal has
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* been received.
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*
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* signalReceived() will always be invoked from the TEventBase loop (i.e.,
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* after the main POSIX signal handler has returned control to the TEventBase
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* thread).
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*/
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virtual void signalReceived(int signum) THRIFT_NOEXCEPT = 0;
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private:
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typedef std::map<int, struct event> SignalEventMap;
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// Forbidden copy constructor and assignment operator
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TAsyncSignalHandler(TAsyncSignalHandler const &);
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TAsyncSignalHandler& operator=(TAsyncSignalHandler const &);
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static void libeventCallback(int signum, short events, void* arg);
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TEventBase* eventBase_;
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SignalEventMap signalEvents_;
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};
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}}} // apache::thrift::async
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#endif // THRIFT_ASYNC_TASYNCSIGNALHANDLER_H_
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