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Commit d0afeb7c authored by Pascal Mütschard's avatar Pascal Mütschard
Browse files

Improvements to SF's BackgroundExcecutor. 

- stop using utils/Singleton.h (it's marked as DO NOT USE)
- add a low priority instance
- explicitly set the thread priorities for both the HP and LP instances.

Test: manual, libsurfaceflinger_unittest
Bug: http://b/336461947
Change-Id: Ie10f663ed43aad21ba2a5235cd86a1101dec0cd7
parent 3e48aa43

services/surfaceflinger/BackgroundExecutor.cpp

+21 −3
Original line number Diff line number Diff line
@@ -19,6 +19,9 @@ 
#define LOG_TAG "BackgroundExecutor"

#define ATRACE_TAG ATRACE_TAG_GRAPHICS



#include <processgroup/sched_policy.h>

#include <pthread.h>

#include <sched.h>

#include <utils/Log.h>

#include <mutex>
@@ -26,14 +29,24 @@ 


namespace android {



ANDROID_SINGLETON_STATIC_INSTANCE(BackgroundExecutor);

namespace {



BackgroundExecutor::BackgroundExecutor() : Singleton<BackgroundExecutor>() {

void set_thread_priority(bool highPriority) {

    set_sched_policy(0, highPriority ? SP_FOREGROUND : SP_BACKGROUND);

    struct sched_param param = {0};

    param.sched_priority = highPriority ? 2 : 0 /* must be 0 for non-RT */;

    sched_setscheduler(gettid(), highPriority ? SCHED_FIFO : SCHED_NORMAL, &param);

}



} // anonymous namespace



BackgroundExecutor::BackgroundExecutor(bool highPriority) {

    // mSemaphore must be initialized before any calls to

    // BackgroundExecutor::sendCallbacks. For this reason, we initialize it

    // within the constructor instead of within mThread.

    LOG_ALWAYS_FATAL_IF(sem_init(&mSemaphore, 0, 0), "sem_init failed");

    mThread = std::thread([&]() {

    mThread = std::thread([&, highPriority]() {

        set_thread_priority(highPriority);

        while (!mDone) {

            LOG_ALWAYS_FATAL_IF(sem_wait(&mSemaphore), "sem_wait failed (%d)", errno);

            auto callbacks = mCallbacksQueue.pop();
@@ -45,6 +58,11 @@ BackgroundExecutor::BackgroundExecutor() : Singleton<BackgroundExecutor>() { 
            }

        }

    });

    if (highPriority) {

        pthread_setname_np(mThread.native_handle(), "BckgrndExec HP");

    } else {

        pthread_setname_np(mThread.native_handle(), "BckgrndExec LP");

    }

}



BackgroundExecutor::~BackgroundExecutor() {

services/surfaceflinger/BackgroundExecutor.h

+14 −3
Original line number Diff line number Diff line
@@ -18,7 +18,6 @@ 


#include <ftl/small_vector.h>

#include <semaphore.h>

#include <utils/Singleton.h>

#include <thread>



#include "LocklessQueue.h"
@@ -26,10 +25,20 @@ 
namespace android {



// Executes tasks off the main thread.

class BackgroundExecutor : public Singleton<BackgroundExecutor> {

class BackgroundExecutor {

public:

    BackgroundExecutor();

    ~BackgroundExecutor();



    static BackgroundExecutor& getInstance() {

        static BackgroundExecutor instance(true);

        return instance;

    }



    static BackgroundExecutor& getLowPriorityInstance() {

        static BackgroundExecutor instance(false);

        return instance;

    }



    using Callbacks = ftl::SmallVector<std::function<void()>, 10>;

    // Queues callbacks onto a work queue to be executed by a background thread.

    // This is safe to call from multiple threads.
@@ -37,6 +46,8 @@ public: 
    void flushQueue();



private:

    BackgroundExecutor(bool highPriority);



    sem_t mSemaphore;

    std::atomic_bool mDone = false;