238 lines
8.1 KiB
C++
Executable File
238 lines
8.1 KiB
C++
Executable File
/**
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* @file llcoros.cpp
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* @author Nat Goodspeed
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* @date 2009-06-03
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* @brief Implementation for llcoros.
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*
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* $LicenseInfo:firstyear=2009&license=viewerlgpl$
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* Second Life Viewer Source Code
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* Copyright (C) 2010, Linden Research, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation;
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* version 2.1 of the License only.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
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* $/LicenseInfo$
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*/
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// Precompiled header
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#include "linden_common.h"
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// associated header
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#include "llcoros.h"
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// STL headers
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// std headers
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// external library headers
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#include <boost/bind.hpp>
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#include <boost/thread/tss.hpp>
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// other Linden headers
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#include "llevents.h"
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#include "llerror.h"
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#include "stringize.h"
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namespace {
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// do nothing, when we need nothing done
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void no_cleanup(LLCoros::coro::self*) {}
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// When the dcoroutine library calls a top-level callable, it implicitly
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// passes coro::self& as the first parameter. All our consumer code used to
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// explicitly pass coro::self& down through all levels of call stack, because
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// at the leaf level we need it for context-switching. But since coroutines
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// are based on cooperative switching, we can cause the top-level entry point
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// to stash a static pointer to the currently-running coroutine, and manage it
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// appropriately as we switch out and back in. That eliminates the need to
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// pass it as an explicit parameter down through every level, which is
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// unfortunately viral in nature. Finding it implicitly rather than explicitly
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// allows minor maintenance in which a leaf-level function adds a new async
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// I/O call that suspends the calling coroutine, WITHOUT having to propagate
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// coro::self& through every function signature down to that point -- and of
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// course through every other caller of every such function.
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// We use a boost::thread_specific_ptr because each thread potentially has its
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// own distinct pool of coroutines.
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// This thread_specific_ptr does NOT own the 'self' object! It merely
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// identifies it. For this reason we instantiate it with a no-op cleanup
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// function.
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static boost::thread_specific_ptr<LLCoros::coro::self>
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sCurrentSelf(no_cleanup);
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} // anonymous
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//static
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LLCoros::coro::self& llcoro::get_self()
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{
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LLCoros::coro::self* current_self = sCurrentSelf.get();
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if (! current_self)
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{
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LL_ERRS("LLCoros") << "Calling get_self() from non-coroutine context!" << LL_ENDL;
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}
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return *current_self;
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}
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llcoro::Suspending::Suspending():
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mSuspended(sCurrentSelf.get())
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{
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// For the duration of our time away from this coroutine, sCurrentSelf
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// must NOT refer to this coroutine.
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sCurrentSelf.reset();
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}
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llcoro::Suspending::~Suspending()
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{
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// Okay, we're back, reinstate previous value of sCurrentSelf.
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sCurrentSelf.reset(mSuspended);
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}
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LLCoros::LLCoros():
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// MAINT-2724: default coroutine stack size too small on Windows.
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// Previously we used
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// boost::context::guarded_stack_allocator::default_stacksize();
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// empirically this is 64KB on Windows and Linux. Try quadrupling.
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mStackSize(256*1024)
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{
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// Register our cleanup() method for "mainloop" ticks
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LLEventPumps::instance().obtain("mainloop").listen(
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"LLCoros", boost::bind(&LLCoros::cleanup, this, _1));
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}
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bool LLCoros::cleanup(const LLSD&)
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{
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// Walk the mCoros map, checking and removing completed coroutines.
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for (CoroMap::iterator mi(mCoros.begin()), mend(mCoros.end()); mi != mend; )
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{
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// Has this coroutine exited (normal return, exception, exit() call)
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// since last tick?
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if (mi->second->exited())
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{
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LL_INFOS("LLCoros") << "LLCoros: cleaning up coroutine " << mi->first << LL_ENDL;
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// The erase() call will invalidate its passed iterator value --
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// so increment mi FIRST -- but pass its original value to
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// erase(). This is what postincrement is all about.
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mCoros.erase(mi++);
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}
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else
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{
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// Still live, just skip this entry as if incrementing at the top
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// of the loop as usual.
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++mi;
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}
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}
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return false;
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}
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std::string LLCoros::generateDistinctName(const std::string& prefix) const
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{
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// Allowing empty name would make getName()'s not-found return ambiguous.
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if (prefix.empty())
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{
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LL_ERRS("LLCoros") << "LLCoros::launch(): pass non-empty name string" << LL_ENDL;
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}
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// If the specified name isn't already in the map, just use that.
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std::string name(prefix);
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// Find the lowest numeric suffix that doesn't collide with an existing
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// entry. Start with 2 just to make it more intuitive for any interested
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// parties: e.g. "joe", "joe2", "joe3"...
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for (int i = 2; ; name = STRINGIZE(prefix << i++))
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{
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if (mCoros.find(name) == mCoros.end())
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{
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LL_INFOS("LLCoros") << "LLCoros: launching coroutine " << name << LL_ENDL;
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return name;
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}
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}
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}
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bool LLCoros::kill(const std::string& name)
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{
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CoroMap::iterator found = mCoros.find(name);
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if (found == mCoros.end())
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{
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return false;
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}
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// Because this is a boost::ptr_map, erasing the map entry also destroys
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// the referenced heap object, in this case the boost::coroutine object,
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// which will terminate the coroutine.
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mCoros.erase(found);
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return true;
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}
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std::string LLCoros::getName() const
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{
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// Walk the existing coroutines, looking for the current one.
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void* self_id = llcoro::get_self().get_id();
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for (CoroMap::const_iterator mi(mCoros.begin()), mend(mCoros.end()); mi != mend; ++mi)
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{
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namespace coro_private = boost::dcoroutines::detail;
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if (static_cast<void*>(coro_private::coroutine_accessor::get_impl(const_cast<coro&>(*mi->second)).get())
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== self_id)
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{
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return mi->first;
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}
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}
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return "";
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}
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void LLCoros::setStackSize(S32 stacksize)
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{
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LL_INFOS("LLCoros") << "Setting coroutine stack size to " << stacksize << LL_ENDL;
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mStackSize = stacksize;
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}
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namespace {
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// Top-level wrapper around caller's coroutine callable. This function accepts
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// the coroutine library's implicit coro::self& parameter and sets sCurrentSelf
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// but does not pass it down to the caller's callable.
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void toplevel(LLCoros::coro::self& self, const LLCoros::callable_t& callable)
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{
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sCurrentSelf.reset(&self);
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callable();
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sCurrentSelf.reset();
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}
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} // anonymous
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/*****************************************************************************
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* MUST BE LAST
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*****************************************************************************/
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// Turn off MSVC optimizations for just LLCoros::launch() -- see
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// DEV-32777. But MSVC doesn't support push/pop for optimization flags as it
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// does for warning suppression, and we really don't want to force
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// optimization ON for other code even in Debug or RelWithDebInfo builds.
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#if LL_MSVC
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// work around broken optimizations
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#pragma warning(disable: 4748)
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#pragma optimize("", off)
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#endif // LL_MSVC
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std::string LLCoros::launch(const std::string& prefix, const callable_t& callable)
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{
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std::string name(generateDistinctName(prefix));
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// Wrap the caller's callable in our toplevel() function so we can manage
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// sCurrentSelf appropriately at startup and shutdown of each coroutine.
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coro* newCoro = new coro(boost::bind(toplevel, _1, callable), mStackSize);
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// Store it in our pointer map
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mCoros.insert(name, newCoro);
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/* Run the coroutine until its first wait, then return here */
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(*newCoro)(std::nothrow);
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return name;
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}
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#if LL_MSVC
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// reenable optimizations
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#pragma optimize("", on)
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#endif // LL_MSVC
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