From 755e319d6a656dc92bd4f2b486d8f5a44b0e7350 Mon Sep 17 00:00:00 2001
From: Lloyd Pique <lpique@google.com>
Date: Wed, 31 Jan 2018 16:46:15 -0800
Subject: SF: Cleanup EventControlThread

Primarily the goal was to eliminate the use of RefBase in various forms
from EventControlThread.

1) SurfaceFlinger only needs a std::unique_ptr<> and not an
android::sp<> to own the created instance.
2) Convert from android::Thread to std::thread, along with using
std::mutex and std::condition_variable to keep consistency.
3) The code only needs a reference to a function to call, rather than a
reference to all of SurfaceFlinger. This removes an unnecessary full
dependency.
4) Switch the header to #pragma once.
5) Added Clang thread annotations and enabled the corresponding warning.
6) Simplified the thread function to eliminate unnecessary locals and
indentation.
7) Added proper thread shutdown handling (invoked by dtor).

Bug: None
Test: Verified event control thread still works on Pixel XL

Change-Id: I2d5621b0cbbfb9e0f8c5831ccfc94704c95a4a55
---
 services/surfaceflinger/EventControlThread.cpp | 70 +++++++++++++++-----------
 1 file changed, 41 insertions(+), 29 deletions(-)

(limited to 'services/surfaceflinger/EventControlThread.cpp')

diff --git a/services/surfaceflinger/EventControlThread.cpp b/services/surfaceflinger/EventControlThread.cpp
index 6fd4cdf28e..ac54059360 100644
--- a/services/surfaceflinger/EventControlThread.cpp
+++ b/services/surfaceflinger/EventControlThread.cpp
@@ -14,45 +14,57 @@
  * limitations under the License.
  */
 
+#include <pthread.h>
+#include <sched.h>
+#include <sys/resource.h>
+
+#include <cutils/sched_policy.h>
+#include <log/log.h>
+#include <system/thread_defs.h>
+
 #include "EventControlThread.h"
-#include "SurfaceFlinger.h"
 
 namespace android {
 
-EventControlThread::EventControlThread(const sp<SurfaceFlinger>& flinger)
-      : mFlinger(flinger), mVsyncEnabled(false) {}
+EventControlThread::EventControlThread(EventControlThread::SetVSyncEnabledFunction function)
+      : mSetVSyncEnabled(function) {
+    pthread_setname_np(mThread.native_handle(), "EventControlThread");
+
+    pid_t tid = pthread_gettid_np(mThread.native_handle());
+    setpriority(PRIO_PROCESS, tid, ANDROID_PRIORITY_URGENT_DISPLAY);
+    set_sched_policy(tid, SP_FOREGROUND);
+}
+
+EventControlThread::~EventControlThread() {
+    {
+        std::lock_guard<std::mutex> lock(mMutex);
+        mKeepRunning = false;
+        mCondition.notify_all();
+    }
+    mThread.join();
+}
 
 void EventControlThread::setVsyncEnabled(bool enabled) {
-    Mutex::Autolock lock(mMutex);
+    std::lock_guard<std::mutex> lock(mMutex);
     mVsyncEnabled = enabled;
-    mCond.signal();
+    mCondition.notify_all();
 }
 
-bool EventControlThread::threadLoop() {
-    enum class VsyncState { Unset, On, Off };
-    auto currentVsyncState = VsyncState::Unset;
-
-    while (true) {
-        auto requestedVsyncState = VsyncState::On;
-        {
-            Mutex::Autolock lock(mMutex);
-            requestedVsyncState = mVsyncEnabled ? VsyncState::On : VsyncState::Off;
-            while (currentVsyncState == requestedVsyncState) {
-                status_t err = mCond.wait(mMutex);
-                if (err != NO_ERROR) {
-                    ALOGE("error waiting for new events: %s (%d)", strerror(-err), err);
-                    return false;
-                }
-                requestedVsyncState = mVsyncEnabled ? VsyncState::On : VsyncState::Off;
-            }
-        }
-
-        bool enable = requestedVsyncState == VsyncState::On;
-        mFlinger->setVsyncEnabled(HWC_DISPLAY_PRIMARY, enable);
-        currentVsyncState = requestedVsyncState;
-    }
+// Unfortunately std::unique_lock gives warnings with -Wthread-safety
+void EventControlThread::threadMain() NO_THREAD_SAFETY_ANALYSIS {
+    auto keepRunning = true;
+    auto currentVsyncEnabled = false;
 
-    return false;
+    while (keepRunning) {
+        mSetVSyncEnabled(currentVsyncEnabled);
+
+        std::unique_lock<std::mutex> lock(mMutex);
+        mCondition.wait(lock, [this, currentVsyncEnabled, keepRunning]() NO_THREAD_SAFETY_ANALYSIS {
+            return currentVsyncEnabled != mVsyncEnabled || keepRunning != mKeepRunning;
+        });
+        currentVsyncEnabled = mVsyncEnabled;
+        keepRunning = mKeepRunning;
+    }
 }
 
 } // namespace android
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