| Qore Programming Language - C/C++ Library 1.0.8

StreamBase.h
1 /* -*- mode: c++; indent-tabs-mode: nil -*- */
2 /*
3 StreamBase.h
4
5 Qore Programming Language
6
7 Copyright (C) 2016 - 2020 Qore Technologies, s.r.o.
8
9 Permission is hereby granted, free of charge, to any person obtaining a
10 copy of this software and associated documentation files (the "Software"),
11 to deal in the Software without restriction, including without limitation
12 the rights to use, copy, modify, merge, publish, distribute, sublicense,
13 and/or sell copies of the Software, and to permit persons to whom the
14 Software is furnished to do so, subject to the following conditions:
15
16 The above copyright notice and this permission notice shall be included in
17 all copies or substantial portions of the Software.
18
19 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
22 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
23 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
24 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
25 DEALINGS IN THE SOFTWARE.
26
27 Note that the Qore library is released under a choice of three open-source
28 licenses: MIT (as above), LGPL 2+, or GPL 2+; see README-LICENSE for more
29 information.
30 */
31
32 #ifndef _QORE_STREAMBASE_H
33 #define _QORE_STREAMBASE_H
34
35 #include "qore/AbstractPrivateData.h"
36
37 #include <atomic>
38
39 DLLEXPORT extern QoreClass* QC_STREAMBASE;
40
44 class StreamBase : public AbstractPrivateData {
45 public:
53 DLLLOCAL bool check(ExceptionSink *xsink) {
54 if (tid.load(std::memory_order_relaxed) != q_gettid()) {
55 xsink->raiseException("STREAM-THREAD-ERROR", "this %s object was created in TID %d; it is an error " \
56 "to access it from any other thread (accessed from TID %d)", getName(),
57 tid.load(std::memory_order_relaxed), q_gettid());
58 return false;
59 }
60 return true;
61 }
62
68 DLLLOCAL void reassignThread(ExceptionSink *xsink) {
69 // use an atomic compare and exchange to ensure that we only update a stream where the thread is unassigned
70 int chktid = -1;
71 if (!tid.compare_exchange_strong(chktid, q_gettid(), std::memory_order_consume, std::memory_order_relaxed)) {
72 // do not raise an exception if reassigning to the same thread
73 if (chktid != q_gettid()) {
74 xsink->raiseException("STREAM-THREAD-ERROR", "this %s object is assigned to TID %d; it is an error " \
75 "to access it from any other thread (accessed from TID %d)", getName(), chktid, q_gettid());
76 }
77 }
78 }
79
85 DLLLOCAL void unassignThread(ExceptionSink *xsink) {
86 // use an atomic compare and exchange to ensure that we only update a stream where the thread is assigned to this thread
87 int chktid = q_gettid();
88 if (!tid.compare_exchange_strong(chktid, -1, std::memory_order_release, std::memory_order_relaxed)) {
89 // do not raise an exception if already unassigned
90 if (chktid != -1) {
91 xsink->raiseException("STREAM-THREAD-ERROR", "this %s object is assigned to TID %d; unassignment may " \
92 "be processed from that thread (accessed from TID %d)", getName(), chktid, q_gettid());
93 }
94 }
95 }
96
100 DLLLOCAL int getThreadId() {
101 return tid.load(std::memory_order_relaxed);
102 }
103
108 DLLLOCAL virtual const char *getName() = 0;
109
110 protected:
114 StreamBase() : tid(q_gettid()) {
115 }
116
117 private:
119
123 std::atomic<int> tid;
124 };
125
126 #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