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//===------------ TaskDispatch.cpp - ORC task dispatch utils --------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/ExecutionEngine/Orc/TaskDispatch.h"
#include "llvm/Config/llvm-config.h" // for LLVM_ENABLE_THREADS
#include "llvm/ExecutionEngine/Orc/Core.h"
namespace llvm {
namespace orc {
char Task::ID = 0;
char GenericNamedTask::ID = 0;
char IdleTask::ID = 0;
const char *GenericNamedTask::DefaultDescription = "Generic Task";
void Task::anchor() {}
void IdleTask::anchor() {}
TaskDispatcher::~TaskDispatcher() = default;
void InPlaceTaskDispatcher::dispatch(std::unique_ptr<Task> T) { T->run(); }
void InPlaceTaskDispatcher::shutdown() {}
#if LLVM_ENABLE_THREADS
void DynamicThreadPoolTaskDispatcher::dispatch(std::unique_ptr<Task> T) {
enum { Normal, Materialization, Idle } TaskKind;
if (isa<MaterializationTask>(*T))
TaskKind = Materialization;
else if (isa<IdleTask>(*T))
TaskKind = Idle;
else
TaskKind = Normal;
{
std::lock_guard<std::mutex> Lock(DispatchMutex);
// Reject new tasks if they're dispatched after a call to shutdown.
if (Shutdown)
return;
if (TaskKind == Materialization) {
// If this is a materialization task and there are too many running
// already then queue this one up and return early.
if (!canRunMaterializationTaskNow())
return MaterializationTaskQueue.push_back(std::move(T));
// Otherwise record that we have a materialization task running.
++NumMaterializationThreads;
} else if (TaskKind == Idle) {
if (!canRunIdleTaskNow())
return IdleTaskQueue.push_back(std::move(T));
}
++Outstanding;
}
std::thread([this, T = std::move(T), TaskKind]() mutable {
while (true) {
// Run the task.
T->run();
// Reset the task to free any resources. We need this to happen *before*
// we notify anyone (via Outstanding) that this thread is done to ensure
// that we don't proceed with JIT shutdown while still holding resources.
// (E.g. this was causing "Dangling SymbolStringPtr" assertions).
T.reset();
// Check the work queue state and either proceed with the next task or
// end this thread.
std::lock_guard<std::mutex> Lock(DispatchMutex);
if (TaskKind == Materialization)
--NumMaterializationThreads;
--Outstanding;
if (!MaterializationTaskQueue.empty() && canRunMaterializationTaskNow()) {
// If there are any materialization tasks running then steal that work.
T = std::move(MaterializationTaskQueue.front());
MaterializationTaskQueue.pop_front();
TaskKind = Materialization;
++NumMaterializationThreads;
++Outstanding;
} else if (!IdleTaskQueue.empty() && canRunIdleTaskNow()) {
T = std::move(IdleTaskQueue.front());
IdleTaskQueue.pop_front();
TaskKind = Idle;
++Outstanding;
} else {
if (Outstanding == 0)
OutstandingCV.notify_all();
return;
}
}
}).detach();
}
void DynamicThreadPoolTaskDispatcher::shutdown() {
std::unique_lock<std::mutex> Lock(DispatchMutex);
Shutdown = true;
OutstandingCV.wait(Lock, [this]() { return Outstanding == 0; });
}
bool DynamicThreadPoolTaskDispatcher::canRunMaterializationTaskNow() {
return !MaxMaterializationThreads ||
(NumMaterializationThreads < *MaxMaterializationThreads);
}
bool DynamicThreadPoolTaskDispatcher::canRunIdleTaskNow() {
return !MaxMaterializationThreads ||
(Outstanding < *MaxMaterializationThreads);
}
#endif
} // namespace orc
} // namespace llvm
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