Class TaskGroup

src/bthread/task_group.h:84–382

Thread-local group of tasks. Notice that most methods involving context switching are static otherwise pointer `this' may change after wakeup. The **pg parameters in following function are updated before returning.

// pointer `this' may change after wakeup. The **pg parameters in following
// function are updated before returning.
class TaskGroup {
public:
    // Create task `fn(arg)' with attributes `attr' in TaskGroup *pg and put
    // the identifier into `tid'. Switch to the new task and schedule old task
    // to run.
    // Return 0 on success, errno otherwise.
    static int start_foreground(TaskGroup** pg,
                                bthread_t* __restrict tid,
                                const bthread_attr_t* __restrict attr,
                                void * (*fn)(void*),
                                void* __restrict arg);

    // Create task `fn(arg)' with attributes `attr' in this TaskGroup, put the
    // identifier into `tid'. Schedule the new thread to run.
    //   Called from worker: start_background<false>
    //   Called from non-worker: start_background<true>
    // Return 0 on success, errno otherwise.
    template <bool REMOTE>
    int start_background(bthread_t* __restrict tid,
                         const bthread_attr_t* __restrict attr,
                         void * (*fn)(void*),
                         void* __restrict arg);

    // Suspend caller and run next bthread in TaskGroup *pg.
    static void sched(TaskGroup** pg);
    static void ending_sched(TaskGroup** pg);

    // Suspend caller and run bthread `next_tid' in TaskGroup *pg.
    // Purpose of this function is to avoid pushing `next_tid' to _rq and
    // then being popped by sched(pg), which is not necessary.
    static void sched_to(TaskGroup** pg, TaskMeta* next_meta);
    static void sched_to(TaskGroup** pg, bthread_t next_tid);
    static void exchange(TaskGroup** pg, TaskMeta* next_meta);

    // The callback will be run in the beginning of next-run bthread.
    // Can't be called by current bthread directly because it often needs
    // the target to be suspended already.
    typedef void (*RemainedFn)(void*);
    void set_remained(RemainedFn cb, void* arg) {
        _last_context_remained = cb;
        _last_context_remained_arg = arg;
    }
    
    // Suspend caller for at least |timeout_us| microseconds.
    // If |timeout_us| is 0, this function does nothing.
    // If |group| is NULL or current thread is non-bthread, call usleep(3)
    // instead. This function does not create thread-local TaskGroup.
    // Returns: 0 on success, -1 otherwise and errno is set.
    static int usleep(TaskGroup** pg, uint64_t timeout_us);

    // Suspend caller and run another bthread. When the caller will resume
    // is undefined.
    static void yield(TaskGroup** pg);

    // Suspend caller until bthread `tid' terminates.
    static int join(bthread_t tid, void** return_value);

    // Returns true iff the bthread `tid' still exists. Notice that it is