Merge "Handle race between UID state and activty resume" into pi-dev am: 63a0662d

#include <utils/Errors.h>

#include <utils/Log.h>

#include <utils/String16.h>

#include <utils/SystemClock.h>

#include <utils/Trace.h>

#include <private/android_filesystem_config.h>

#include <system/camera_vendor_tags.h>

    return isUidActiveLocked(uid, callingPackage);

}

static const int kPollUidActiveTimeoutMillis = 50;

bool CameraService::UidPolicy::isUidActiveLocked(uid_t uid, String16 callingPackage) {

    // Non-app UIDs are considered always active

    // If activity manager is unreachable, assume everything is active

        ActivityManager am;

        // Okay to access with a lock held as UID changes are dispatched without

        // a lock and we are a higher level component.

        int64_t startTimeMillis = 0;

        do {

            // TODO: Fix this b/109950150!

            // Okay this is a hack. There is a race between the UID turning active and

            // activity being resumed. The proper fix is very risky, so we temporary add

            // some polling which should happen pretty rarely anyway as the race is hard

            // to hit.

            active = am.isUidActive(uid, callingPackage);

            if (active) {

                break;

            }

            if (startTimeMillis <= 0) {

                startTimeMillis = uptimeMillis();

            }

            int64_t ellapsedTimeMillis = uptimeMillis() - startTimeMillis;

            int64_t remainingTimeMillis = kPollUidActiveTimeoutMillis - ellapsedTimeMillis;

            if (remainingTimeMillis <= 0) {

                break;

            }

            usleep(remainingTimeMillis * 1000);

        } while (true);

        if (active) {

            // Now that we found out the UID is actually active, cache that

            mActiveUids.insert(uid);