Ichthyostega
806db414dd
* Lumiera source code always was copyrighted by individual contributors * there is no entity "Lumiera.org" which holds any copyrights * Lumiera source code is provided under the GPL Version 2+ == Explanations == Lumiera as a whole is distributed under Copyleft, GNU General Public License Version 2 or above. For this to become legally effective, the ''File COPYING in the root directory is sufficient.'' The licensing header in each file is not strictly necessary, yet considered good practice; attaching a licence notice increases the likeliness that this information is retained in case someone extracts individual code files. However, it is not by the presence of some text, that legally binding licensing terms become effective; rather the fact matters that a given piece of code was provably copyrighted and published under a license. Even reformatting the code, renaming some variables or deleting parts of the code will not alter this legal situation, but rather creates a derivative work, which is likewise covered by the GPL! The most relevant information in the file header is the notice regarding the time of the first individual copyright claim. By virtue of this initial copyright, the first author is entitled to choose the terms of licensing. All further modifications are permitted and covered by the License. The specific wording or format of the copyright header is not legally relevant, as long as the intention to publish under the GPL remains clear. The extended wording was based on a recommendation by the FSF. It can be shortened, because the full terms of the license are provided alongside the distribution, in the file COPYING.
128 lines
4.1 KiB
C++
128 lines
4.1 KiB
C++
/*
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DIAGNOSTIC-CONTEXT.hpp - thread local stack for explicitly collecting diagnostic context info
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Copyright (C)
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2010, Hermann Vosseler <Ichthyostega@web.de>
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**Lumiera** is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2 of the License, or (at your
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option) any later version. See the file COPYING for further details.
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*/
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/** @file diagnostic-context.hpp
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** Facility for collecting diagnostic context information explicitly.
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** Unlike a trace logging run, this facility is intended to be fed explicitly with
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** diagnostic information describing the currently ongoing operation in a semantic
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** high-level manner. The rationale is to pinpoint \em those pieces of information,
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** which aren't obvious when just looking at a callstack with the debugger.
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** Instances of the class DiagnosticContext should be placed explicitly as automatic
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** (stack) variable into selected relevant scopes; these "information frames" could
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** be accessed from an enclosed scope as a per-thread stack. DiagnosticContext
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** provides an controlled environment for adding diagnostic code on demand; typically
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** to be configured such as to resolve into an empty class for release builds.
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**/
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#ifndef LIB_DIAGNOSTIC_CONTEXT_H
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#define LIB_DIAGNOSTIC_CONTEXT_H
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#include "lib/error.hpp"
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#include "lib/nocopy.hpp"
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namespace lib {
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/**
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* Diagnostic data frame to collect specific information concerning a scope.
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* To be placed explicitly as an automatic (stack) variable. Provides a controlled
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* environment for hooking up diagnostic code. Within each thread, a stack of
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* such information frames concerning nested scopes is maintained automatically.
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* It can be accessed via static API.
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* @warning relies on thread-local access; never use this within global data structures.
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*/
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template<typename VAL>
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class DiagnosticContext
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: util::NonCopyable
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{
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using ValSequence = std::vector<VAL>;
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const VAL value_;
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DiagnosticContext * const prev_;
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/** embedded thread local pointer
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* to the innermost context encountered */
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static DiagnosticContext* &
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current()
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{
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thread_local DiagnosticContext* accessPoint;
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return accessPoint;
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}
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public:
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DiagnosticContext(VAL const& value_to_log = VAL())
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: value_{value_to_log}
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, prev_{current()}
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{
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current() = this;
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}
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~DiagnosticContext()
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{
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ASSERT (this == current());
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current() = prev_;
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}
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operator VAL const&() ///< access the payload by conversion
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{
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return value_;
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}
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/** accessing the innermost diagnostic context created */
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static DiagnosticContext&
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access ()
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{
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DiagnosticContext* innermost = current();
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if (!innermost)
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throw lumiera::error::Logic ("Accessing Diagnostic context out of order; "
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"an instance should have been created within "
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"an enclosing scope");
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return *innermost;
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}
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/** snapshot of the current stack of diagnostic frames
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* @return vector with all the payload values currently on the thread-local diagnostic stack.
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* Might be empty. Values start with frame next to the current scope and end with outermost.
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* @warning can be inefficient on very large stacks
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* @todo benchmark and improve the data structure used for the snapshot.
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* Vector is not an optimal choice here.
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*/
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static ValSequence
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extractStack()
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{
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ValSequence loggedValues;
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DiagnosticContext* next = current();
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while (next)
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{
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loggedValues.push_back (*next);
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next = next->prev_;
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}
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return loggedValues;
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}
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};
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} // namespace lib
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#endif
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