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Nat Goodspeed authored
The previous implementation went to some effort to crash if anyone attempted to create or destroy an LLInstanceTracker subclass instance during traversal. That restriction is manageable within a single thread, but becomes unworkable if it's possible that a given subclass might be used on more than one thread. Remove LLInstanceTracker::instance_iter, beginInstances(), endInstances(), also key_iter, beginKeys() and endKeys(). Instead, introduce key_snapshot() and instance_snapshot(), the only means of iterating over LLInstanceTracker instances. (These are intended to resemble functions, but in fact the current implementation simply presents the classes.) Iterating over a captured snapshot defends against container modifications during traversal. The term 'snapshot' reminds the coder that a new instance created during traversal will not be considered. To defend against instance deletion during traversal, a snapshot stores std::weak_ptrs which it lazily dereferences, skipping on the fly any that have expired. Dereferencing instance_snapshot::iterator gets you a reference rather than a pointer. Because some use cases want to delete all existing instances, add an instance_snapshot::deleteAll() method that extracts the pointer. Those cases used to require explicitly copying instance pointers into a separate container; instance_snapshot() now takes care of that. It remains the caller's responsibility to ensure that all instances of that LLInstanceTracker subclass were allocated on the heap. Replace unkeyed static LLInstanceTracker::getInstance(T*) -- which returned nullptr if that instance had been destroyed -- with new getWeak() method returning std::weak_ptr<T>. Caller must detect expiration of that weak_ptr. Adjust tests accordingly. Use of std::weak_ptr to detect expired instances requires engaging std::shared_ptr in the constructor. We now store shared_ptrs in the static containers (std::map for keyed, std::set for unkeyed). Make LLInstanceTrackerBase a template parameterized on the type of the static data it manages. For that reason, hoist static data class declarations out of the class definitions to an LLInstanceTrackerStuff namespace. Remove the static atomic sIterationNestDepth and its methods incrementDepth(), decrementDepth() and getDepth(), since they were used only to forbid creation and destruction during traversal. Add a std::mutex to static data. Introduce an internal LockStatic class that locks the mutex while providing a pointer to static data, making that the only way to access the static data. The LLINSTANCETRACKER_DTOR_NOEXCEPT macro goes away because we no longer expect ~LLInstanceTracker() to throw an exception in test programs. That affects LLTrace::StatBase as well as LLInstanceTracker itself. Adapt consumers to the new LLInstanceTracker API.
Nat Goodspeed authoredThe previous implementation went to some effort to crash if anyone attempted to create or destroy an LLInstanceTracker subclass instance during traversal. That restriction is manageable within a single thread, but becomes unworkable if it's possible that a given subclass might be used on more than one thread. Remove LLInstanceTracker::instance_iter, beginInstances(), endInstances(), also key_iter, beginKeys() and endKeys(). Instead, introduce key_snapshot() and instance_snapshot(), the only means of iterating over LLInstanceTracker instances. (These are intended to resemble functions, but in fact the current implementation simply presents the classes.) Iterating over a captured snapshot defends against container modifications during traversal. The term 'snapshot' reminds the coder that a new instance created during traversal will not be considered. To defend against instance deletion during traversal, a snapshot stores std::weak_ptrs which it lazily dereferences, skipping on the fly any that have expired. Dereferencing instance_snapshot::iterator gets you a reference rather than a pointer. Because some use cases want to delete all existing instances, add an instance_snapshot::deleteAll() method that extracts the pointer. Those cases used to require explicitly copying instance pointers into a separate container; instance_snapshot() now takes care of that. It remains the caller's responsibility to ensure that all instances of that LLInstanceTracker subclass were allocated on the heap. Replace unkeyed static LLInstanceTracker::getInstance(T*) -- which returned nullptr if that instance had been destroyed -- with new getWeak() method returning std::weak_ptr<T>. Caller must detect expiration of that weak_ptr. Adjust tests accordingly. Use of std::weak_ptr to detect expired instances requires engaging std::shared_ptr in the constructor. We now store shared_ptrs in the static containers (std::map for keyed, std::set for unkeyed). Make LLInstanceTrackerBase a template parameterized on the type of the static data it manages. For that reason, hoist static data class declarations out of the class definitions to an LLInstanceTrackerStuff namespace. Remove the static atomic sIterationNestDepth and its methods incrementDepth(), decrementDepth() and getDepth(), since they were used only to forbid creation and destruction during traversal. Add a std::mutex to static data. Introduce an internal LockStatic class that locks the mutex while providing a pointer to static data, making that the only way to access the static data. The LLINSTANCETRACKER_DTOR_NOEXCEPT macro goes away because we no longer expect ~LLInstanceTracker() to throw an exception in test programs. That affects LLTrace::StatBase as well as LLInstanceTracker itself. Adapt consumers to the new LLInstanceTracker API.
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llthreadlocalstorage.cpp 2.75 KiB
/**
* @file llthreadlocalstorage.cpp
* @author Richard
* @date 2013-1-11
* @brief implementation of thread local storage utility classes
*
* $LicenseInfo:firstyear=2013&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2010, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#include "linden_common.h"
#include "llthreadlocalstorage.h"
#include "llapr.h"
//
//LLThreadLocalPointerBase
//
bool LLThreadLocalPointerBase::sInitialized = false;
void LLThreadLocalPointerBase::set( void* value )
{
llassert(sInitialized && mThreadKey);
apr_status_t result = apr_threadkey_private_set((void*)value, mThreadKey);
if (result != APR_SUCCESS)
{
ll_apr_warn_status(result);
LL_ERRS() << "Failed to set thread local data" << LL_ENDL;
}
}
void* LLThreadLocalPointerBase::get() const
{
// llassert(sInitialized);
void* ptr;
apr_status_t result =
apr_threadkey_private_get(&ptr, mThreadKey);
if (result != APR_SUCCESS)
{
ll_apr_warn_status(result);
LL_ERRS() << "Failed to get thread local data" << LL_ENDL;
}
return ptr;
}
void LLThreadLocalPointerBase::initStorage( )
{
apr_status_t result = apr_threadkey_private_create(&mThreadKey, NULL, gAPRPoolp);
if (result != APR_SUCCESS)
{
ll_apr_warn_status(result); LL_ERRS() << "Failed to allocate thread local data" << LL_ENDL;
}
}
void LLThreadLocalPointerBase::destroyStorage()
{
if (sInitialized)
{
if (mThreadKey)
{
apr_status_t result = apr_threadkey_private_delete(mThreadKey);
if (result != APR_SUCCESS)
{
ll_apr_warn_status(result);
LL_ERRS() << "Failed to delete thread local data" << LL_ENDL;
}
}
}
}
//static
void LLThreadLocalPointerBase::initAllThreadLocalStorage()
{
if (!sInitialized)
{
for (auto& base : instance_snapshot())
{
base.initStorage();
}
sInitialized = true;
}
}
//static
void LLThreadLocalPointerBase::destroyAllThreadLocalStorage()
{
if (sInitialized)
{
//for (auto& base : instance_snapshot())
//{
// base.destroyStorage();
//}
sInitialized = false;
}
}