alexshap created this revision.
1. Move everything into the namespace lldb_private
2. Add missing std::move in TaskPoolImpl::Worker
3. std::thread::hardware_concurrency may return 0, handle this case correctly
Repository:
rL LLVM
https://reviews.llvm.org/D40587
Files:
include/lldb/Host/TaskPool.h
source/Host/common/TaskPool.cpp
Index: source/Host/common/TaskPool.cpp
===================================================================
--- source/Host/common/TaskPool.cpp
+++ source/Host/common/TaskPool.cpp
@@ -14,6 +14,8 @@
#include <queue> // for queue
#include <thread> // for thread
+namespace lldb_private {
+
namespace {
class TaskPoolImpl {
public:
@@ -46,13 +48,20 @@
TaskPoolImpl::TaskPoolImpl() : m_thread_count(0) {}
+unsigned GetHardwareConcurrencyHint() {
+ // std::thread::hardware_concurrency may return 0
+ // if the value is not well defined or not computable.
+ static const unsigned g_hardware_concurrency =
+ std::max(1u, std::thread::hardware_concurrency());
+ return g_hardware_concurrency;
+}
+
void TaskPoolImpl::AddTask(std::function<void()> &&task_fn) {
- static const uint32_t max_threads = std::thread::hardware_concurrency();
const size_t min_stack_size = 8 * 1024 * 1024;
std::unique_lock<std::mutex> lock(m_tasks_mutex);
m_tasks.emplace(std::move(task_fn));
- if (m_thread_count < max_threads) {
+ if (m_thread_count < GetHardwareConcurrencyHint()) {
m_thread_count++;
// Note that this detach call needs to happen with the m_tasks_mutex held.
// This prevents the thread
@@ -77,7 +86,7 @@
break;
}
- std::function<void()> f = pool->m_tasks.front();
+ std::function<void()> f = std::move(pool->m_tasks.front());
pool->m_tasks.pop();
lock.unlock();
@@ -87,10 +96,9 @@
void TaskMapOverInt(size_t begin, size_t end,
const llvm::function_ref<void(size_t)> &func) {
+ const size_t num_workers = std::min<size_t>(end,
GetHardwareConcurrencyHint());
std::atomic<size_t> idx{begin};
- size_t num_workers =
- std::min<size_t>(end, std::thread::hardware_concurrency());
-
+
auto wrapper = [&idx, end, &func]() {
while (true) {
size_t i = idx.fetch_add(1);
@@ -107,3 +115,6 @@
for (size_t i = 0; i < num_workers; i++)
futures[i].wait();
}
+
+} // namespace lldb_private
+
Index: include/lldb/Host/TaskPool.h
===================================================================
--- include/lldb/Host/TaskPool.h
+++ include/lldb/Host/TaskPool.h
@@ -18,6 +18,8 @@
#include <mutex> // for mutex, unique_lock, condition_variable
#include <type_traits> // for forward, result_of, move
+namespace lldb_private {
+
// Global TaskPool class for running tasks in parallel on a set of worker
thread
// created the first
// time the task pool is used. The TaskPool provide no guarantee about the
order
@@ -89,4 +91,8 @@
void TaskMapOverInt(size_t begin, size_t end,
const llvm::function_ref<void(size_t)> &func);
+unsigned GetHardwareConcurrencyHint();
+
+} // namespace lldb_private
+
#endif // #ifndef utility_TaskPool_h_
Index: source/Host/common/TaskPool.cpp
===================================================================
--- source/Host/common/TaskPool.cpp
+++ source/Host/common/TaskPool.cpp
@@ -14,6 +14,8 @@
#include <queue> // for queue
#include <thread> // for thread
+namespace lldb_private {
+
namespace {
class TaskPoolImpl {
public:
@@ -46,13 +48,20 @@
TaskPoolImpl::TaskPoolImpl() : m_thread_count(0) {}
+unsigned GetHardwareConcurrencyHint() {
+ // std::thread::hardware_concurrency may return 0
+ // if the value is not well defined or not computable.
+ static const unsigned g_hardware_concurrency =
+ std::max(1u, std::thread::hardware_concurrency());
+ return g_hardware_concurrency;
+}
+
void TaskPoolImpl::AddTask(std::function<void()> &&task_fn) {
- static const uint32_t max_threads = std::thread::hardware_concurrency();
const size_t min_stack_size = 8 * 1024 * 1024;
std::unique_lock<std::mutex> lock(m_tasks_mutex);
m_tasks.emplace(std::move(task_fn));
- if (m_thread_count < max_threads) {
+ if (m_thread_count < GetHardwareConcurrencyHint()) {
m_thread_count++;
// Note that this detach call needs to happen with the m_tasks_mutex held.
// This prevents the thread
@@ -77,7 +86,7 @@
break;
}
- std::function<void()> f = pool->m_tasks.front();
+ std::function<void()> f = std::move(pool->m_tasks.front());
pool->m_tasks.pop();
lock.unlock();
@@ -87,10 +96,9 @@
void TaskMapOverInt(size_t begin, size_t end,
const llvm::function_ref<void(size_t)> &func) {
+ const size_t num_workers = std::min<size_t>(end, GetHardwareConcurrencyHint());
std::atomic<size_t> idx{begin};
- size_t num_workers =
- std::min<size_t>(end, std::thread::hardware_concurrency());
-
+
auto wrapper = [&idx, end, &func]() {
while (true) {
size_t i = idx.fetch_add(1);
@@ -107,3 +115,6 @@
for (size_t i = 0; i < num_workers; i++)
futures[i].wait();
}
+
+} // namespace lldb_private
+
Index: include/lldb/Host/TaskPool.h
===================================================================
--- include/lldb/Host/TaskPool.h
+++ include/lldb/Host/TaskPool.h
@@ -18,6 +18,8 @@
#include <mutex> // for mutex, unique_lock, condition_variable
#include <type_traits> // for forward, result_of, move
+namespace lldb_private {
+
// Global TaskPool class for running tasks in parallel on a set of worker thread
// created the first
// time the task pool is used. The TaskPool provide no guarantee about the order
@@ -89,4 +91,8 @@
void TaskMapOverInt(size_t begin, size_t end,
const llvm::function_ref<void(size_t)> &func);
+unsigned GetHardwareConcurrencyHint();
+
+} // namespace lldb_private
+
#endif // #ifndef utility_TaskPool_h_
_______________________________________________
lldb-commits mailing list
lldb-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
