Remove old TaskManager system

Replace it with a newer, fancier, WorkQueue-inspired
one that's just a global common thread pool.

Test: hwuiunit passes
Change-Id: Ib5d03104a08bbac9a4ec67a1bfc0db2b35d6700f
diff --git a/libs/hwui/thread/CommonPool.cpp b/libs/hwui/thread/CommonPool.cpp
new file mode 100644
index 0000000..7f94a15
--- /dev/null
+++ b/libs/hwui/thread/CommonPool.cpp
@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2019 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 "CommonPool.h"
+
+#include <sys/resource.h>
+#include <utils/Trace.h>
+#include "renderthread/RenderThread.h"
+
+#include <array>
+
+namespace android {
+namespace uirenderer {
+
+CommonPool::CommonPool() {
+    ATRACE_CALL();
+
+    CommonPool* pool = this;
+    // Create 2 workers
+    for (int i = 0; i < THREAD_COUNT; i++) {
+        std::thread worker([pool, i] {
+            {
+                std::array<char, 20> name{"hwuiTask"};
+                snprintf(name.data(), name.size(), "hwuiTask%d", i);
+                auto self = pthread_self();
+                pthread_setname_np(self, name.data());
+                setpriority(PRIO_PROCESS, 0, PRIORITY_FOREGROUND);
+                auto startHook = renderthread::RenderThread::getOnStartHook();
+                if (startHook) {
+                    startHook(name.data());
+                }
+            }
+            pool->workerLoop();
+        });
+        worker.detach();
+    }
+}
+
+void CommonPool::post(Task&& task) {
+    static CommonPool pool;
+    pool.enqueue(std::move(task));
+}
+
+void CommonPool::enqueue(Task&& task) {
+    std::unique_lock lock(mLock);
+    while (!mWorkQueue.hasSpace()) {
+        lock.unlock();
+        usleep(100);
+        lock.lock();
+    }
+    mWorkQueue.push(std::move(task));
+    if (mWaitingThreads == THREAD_COUNT || (mWaitingThreads > 0 && mWorkQueue.size() > 1)) {
+        mCondition.notify_one();
+    }
+}
+
+void CommonPool::workerLoop() {
+    std::unique_lock lock(mLock);
+    while (true) {
+        if (!mWorkQueue.hasWork()) {
+            mWaitingThreads++;
+            mCondition.wait(lock);
+            mWaitingThreads--;
+        }
+        // Need to double-check that work is still available now that we have the lock
+        // It may have already been grabbed by a different thread
+        while (mWorkQueue.hasWork()) {
+            auto work = mWorkQueue.pop();
+            lock.unlock();
+            work();
+            lock.lock();
+        }
+    }
+}
+
+}  // namespace uirenderer
+}  // namespace android
\ No newline at end of file