Faster bugreports (3/n)

Post 'DumpHals', 'DumpBoard' and 'DumpIncidentReport' to the
thread pool. 30% is improved compared with single thread run.

Bug: 136262402
Test: atest dumpstate_test
Test: atest dumpstate_smoke_test
Test: atest BugreportManagerTestCases
Test: atest CtsBugreportTestCases
Test: Manual enable and disable parallel run
Test: Manual trigger report using hardware key and shortcut
Change-Id: Iea3a6e676f05149a3f2cfc1fcd475c70ea253d08
diff --git a/cmds/dumpstate/TaskQueue.cpp b/cmds/dumpstate/TaskQueue.cpp
new file mode 100644
index 0000000..8550aec
--- /dev/null
+++ b/cmds/dumpstate/TaskQueue.cpp
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+#include "TaskQueue.h"
+
+namespace android {
+namespace os {
+namespace dumpstate {
+
+TaskQueue::~TaskQueue() {
+    run(/* do_cancel = */true);
+}
+
+void TaskQueue::run(bool do_cancel) {
+    std::unique_lock lock(lock_);
+    while (!tasks_.empty()) {
+        auto task = tasks_.front();
+        tasks_.pop();
+        lock.unlock();
+        std::invoke(task, do_cancel);
+        lock.lock();
+    }
+}
+
+}  // namespace dumpstate
+}  // namespace os
+}  // namespace android