pw_thread: adds thread creation

Adds a std::thread like API through a new pw_thread facade based
on the STL's std::thread API, however with more restricted function
entry routine format support and backend specific option support
to permit non-portable configuration of thread settings/parameters
including static context allocations.

In addition this provides an initial set of backends based on using
the STL's std::thread directly.

Change-Id: Ib8c3cbdc434044e204e67e58d861a40e4acec9b4
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/30920
Reviewed-by: Wyatt Hepler <hepler@google.com>
Reviewed-by: Keir Mierle <keir@google.com>
Commit-Queue: Ewout van Bekkum <ewout@google.com>

3 files changed, 98 insertions, 0 deletions

diff --git a/pw_thread_stl/public/pw_thread_stl/options.h b/pw_thread_stl/public/pw_thread_stl/options.h
new file mode 100644
index 000000000..26f5bf578
--- /dev/null
+++ b/pw_thread_stl/public/pw_thread_stl/options.h
@@ -0,0 +1,26 @@
+// Copyright 2020 The Pigweed Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+#pragma once
+
+#include "pw_thread/thread.h"
+
+namespace pw::thread::stl {
+
+// Unfortunately std::thread:attributes was not accepted into the C++ standard.
+// Instead, users are expected to start the thread and after dynamically adjust
+// the thread's attributes using std::thread::native_handle based on the native
+// threading APIs.
+class Options : public thread::Options {};
+
+}  // namespace pw::thread::stl
diff --git a/pw_thread_stl/public/pw_thread_stl/thread_inline.h b/pw_thread_stl/public/pw_thread_stl/thread_inline.h
new file mode 100644
index 000000000..018e80755
--- /dev/null
+++ b/pw_thread_stl/public/pw_thread_stl/thread_inline.h
@@ -0,0 +1,47 @@
+// Copyright 2020 The Pigweed Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+#pragma once
+
+#include <thread>
+
+namespace pw::thread {
+
+inline Thread::Thread() : native_type_() {}
+
+inline Thread::Thread(const Options&, ThreadRoutine entry, void* arg) {
+  native_type_ = std::thread(entry, arg);
+}
+
+inline Thread& Thread::operator=(Thread&& other) {
+  native_type_ = std::move(other.native_type_);
+  return *this;
+}
+
+inline Thread::~Thread() = default;
+
+inline Id Thread::get_id() const { return native_type_.get_id(); }
+
+inline void Thread::join() { native_type_.join(); }
+
+inline void Thread::detach() { native_type_.detach(); }
+
+inline void Thread::swap(Thread& other) {
+  native_type_.swap(other.native_handle());
+}
+
+inline Thread::native_handle_type Thread::native_handle() {
+  return native_type_;
+}
+
+}  // namespace pw::thread
diff --git a/pw_thread_stl/public/pw_thread_stl/thread_native.h b/pw_thread_stl/public/pw_thread_stl/thread_native.h
new file mode 100644
index 000000000..d3592de1b
--- /dev/null
+++ b/pw_thread_stl/public/pw_thread_stl/thread_native.h
@@ -0,0 +1,25 @@
+// Copyright 2020 The Pigweed Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+#pragma once
+
+#include <thread>
+
+#define PW_THREAD_JOINING_ENABLED 1
+
+namespace pw::thread::backend {
+
+using NativeThread = std::thread;
+using NativeThreadHandle = std::thread&;
+
+}  // namespace pw::thread::backend