#include "Queue.h"

#include "_CJavaScriptEventLoop.h"

using namespace swift;

/// Get the next-in-queue storage slot.

static Job *&nextInQueue(Job *cur) {

return reinterpret_cast<Job*&>(cur->SchedulerPrivate);

}

Job *Queue::claimNext() {

if (auto job = this->HeadJob) {

this->HeadJob = nextInQueue(job);

return job;

}

return nullptr;

}

Queue::Queue() : HeadJob(nullptr), isSpinning(false) {

this->Context = (EventLoopContext) {

.Queue = this,

.Promise = nullptr,

};

}

void runEnqueuedJobs(EventLoopContext *context) {

Queue *queue = (Queue *)(context->Queue);

assert(queue->isSpinning);

while (auto *job = queue->claimNext()) {

job->run(ExecutorRef::generic());

}

queue->isSpinning = false;

}

void Queue::insertJob(swift::Job *newJob) {

Job **position = &HeadJob;

while (auto cur = *position) {

// If we find a job with lower priority, insert here.

if (cur->getPriority() < newJob->getPriority()) {

nextInQueue(newJob) = cur;

*position = newJob;

return;

}

// Otherwise, keep advancing through the queue.

position = &nextInQueue(cur);

}

nextInQueue(newJob) = nullptr;

*position = newJob;

if (!isSpinning) {

isSpinning = true;

registerEventLoopHook(runEnqueuedJobs, &this->Context);

}

}