StreamBase.h
/* -*- mode: c++; indent-tabs-mode: nil -*- */
/*
StreamBase.h
Qore Programming Language
Copyright (C) 2016 - 2020 Qore Technologies, s.r.o.
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
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and/or sell copies of the Software, and to permit persons to whom the
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The above copyright notice and this permission notice shall be included in
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DEALINGS IN THE SOFTWARE.
Note that the Qore library is released under a choice of three open-source
licenses: MIT (as above), LGPL 2+, or GPL 2+; see README-LICENSE for more
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*/
#ifndef _QORE_STREAMBASE_H
#define _QORE_STREAMBASE_H
#include "qore/AbstractPrivateData.h"
#include <atomic>
DLLEXPORT extern QoreClass* QC_STREAMBASE;
class StreamBase : public AbstractPrivateData {
public:
DLLLOCAL bool check(ExceptionSink *xsink) {
if (tid.load(std::memory_order_relaxed) != q_gettid()) {
xsink->raiseException("STREAM-THREAD-ERROR", "this %s object was created in TID %d; it is an error " \
"to access it from any other thread (accessed from TID %d)", getName(),
tid.load(std::memory_order_relaxed), q_gettid());
return false;
}
return true;
}
DLLLOCAL void reassignThread(ExceptionSink *xsink) {
// use an atomic compare and exchange to ensure that we only update a stream where the thread is unassigned
int chktid = -1;
if (!tid.compare_exchange_strong(chktid, q_gettid(), std::memory_order_consume, std::memory_order_relaxed)) {
// do not raise an exception if reassigning to the same thread
if (chktid != q_gettid()) {
xsink->raiseException("STREAM-THREAD-ERROR", "this %s object is assigned to TID %d; it is an error " \
"to access it from any other thread (accessed from TID %d)", getName(), chktid, q_gettid());
}
}
}
DLLLOCAL void unassignThread(ExceptionSink *xsink) {
// use an atomic compare and exchange to ensure that we only update a stream where the thread is assigned to this thread
int chktid = q_gettid();
if (!tid.compare_exchange_strong(chktid, -1, std::memory_order_release, std::memory_order_relaxed)) {
// do not raise an exception if already unassigned
if (chktid != -1) {
xsink->raiseException("STREAM-THREAD-ERROR", "this %s object is assigned to TID %d; unassignment may " \
"be processed from that thread (accessed from TID %d)", getName(), chktid, q_gettid());
}
}
}
DLLLOCAL int getThreadId() {
return tid.load(std::memory_order_relaxed);
}
DLLLOCAL virtual const char *getName() = 0;
protected:
StreamBase() : tid(q_gettid()) {
}
private:
std::atomic<int> tid;
};
#endif // _QORE_STREAMBASE_H
StreamBase::getThreadId
DLLLOCAL int getThreadId()
Get currently assigned thread id.
Definition: StreamBase.h:100
AbstractPrivateData
the base class for all data to be used as private data of Qore objects
Definition: AbstractPrivateData.h:44
StreamBase::reassignThread
DLLLOCAL void reassignThread(ExceptionSink *xsink)
Reassigns current thread as thread used for stream manipulation, see check()
Definition: StreamBase.h:68
ExceptionSink::raiseException
DLLEXPORT AbstractQoreNode * raiseException(const char *err, const char *fmt,...)
appends a Qore-language exception to the list
StreamBase::getName
virtual DLLLOCAL const char * getName()=0
Returns the name of the class.
QoreClass
defines a Qore-language class
Definition: QoreClass.h:239
ExceptionSink
container for holding Qore-language exception information and also for registering a "thread_exit" ca...
Definition: ExceptionSink.h:48
StreamBase::check
DLLLOCAL bool check(ExceptionSink *xsink)
Checks that the current thread is the same as when the instance was created or assigned via unassignT...
Definition: StreamBase.h:53
StreamBase::unassignThread
DLLLOCAL void unassignThread(ExceptionSink *xsink)
Unassigns current thread as thread used for stream manipulation, see check()
Definition: StreamBase.h:85
StreamBase
Base class for private data of stream implementations in C++.
Definition: StreamBase.h:44
StreamBase::StreamBase
StreamBase()
Constructor.
Definition: StreamBase.h:114
q_gettid
DLLEXPORT int q_gettid() noexcept
returns the current TID number