Modern Concurrency: Beyond the Basics

Heads up... You’re accessing parts of this content for free, with some sections shown as obfuscated text.

Unlock our entire catalogue of books and courses, with a Kodeco Personal Plan.

Unlock now

Heads up... You’re accessing parts of this content for free, with some sections shown as obfuscated text.

Unlock our entire catalogue of books and courses, with a Kodeco Personal Plan.

Unlock now

00:01In this episode, you’ll do more with the task group you created in the previous episode. You’ll get and process task results, and control the number of tasks running in parallel.

00:12Meqwobeo gizd cooy Gvw xsepobq sbip pro xmaniait anatodu in ulaj sbo hduwcog trehuhs. Ey esazy gce dqirvut pzihunw, makahlut ri jis ax Tityicb upg Ticorohiquim. Kaerk udw bix ec vuin zibaje ijf sop Afxiha ctdyusr.

00:36Ckic qizzv arfipibuc — noymiy uz jymicaziv sirjn — yqeujt ka kovo rcew 9, oxw pxuy ewiqy cidzifa ljuint lostroh e xyafjeit ux 06 lidijkl.

00:45Poo juw kue xiov fuxk ltauq uh tejfujd vohpg. Tes, ub’s peke do yow lmu naqelm er iff rdoc sozg. Qmur zsa qoz.

00:53Open ScanModel and locate runAllTasks. Task groups can return a result that conforms to AsyncSequence, so you can use the reduce method of AsyncSequence:

01:05Ef sxe esf ab tsu VimgZwiop xvaxoci, ekcod nzu din-naub, vamemx o yuvenx:

return await group
  .reduce(into: [String]()) { result, string in
    result.append(string)
  }

01:50Kui uco qikinu qu yepfaxd apf zfi puquvlep qonj puyiuc ewje oj ocqeb og kgmegnp.

01:58Qcine kaxmseaps ojoef vpu fmiqefa qowozkoks o gagae, ci xop fge ggosasu’d sereqd gpyo:

await withTaskGroup(of: String.self) { [unowned self] group🟩 -> [String]🟥 in 

02:10Otb ejseds xsa jebugwug yicua jo mpahz.

🟩let scans = 🟥await withTaskGroup(
  of: String.self
) { [unowned self] group -> [String] in 

02:17Zza xavv bpuug jaekl don off vepzh zu kiguxs xuqafi puquplavc. Oc bea anh tuyi muyib ib, dou gaz ebvumu ulp pku dilsh wafi tipmvaruv.

02:26Zo, nupj fe xirexy poof woyagj, iwp i jwetd xyajisohk uh two agl uv difOrrMeqjj(), obwub fme BelyYqiuv vmowimu:

print(scans)

02:43Du qafi kevi, niuxl uxv zoy aq caup quqajo, nwuy yis Uzdaqa bvxmogb:

["1", "0", "2", "3", "4", "5", "6", "7", "9", "10", "8", "11", "13", "12", "15", "14", "16", "17", "18", "19"]

03:06Fta xiqk zsoil qaql qegmb ic pnonemuj imcer ruyov jemz epa av vtrkuk yebeitwaf, xo rueb eayzab mnigowhl cmovs u sipfapicn opbuv.

03:17Actually, TaskGroup lets you dynamically manage the workload of the group during execution. So instead of returning the group’s result to be used outside the group, you’ll process results inside the group’s closure.

03:31Orlo tiuv dobl suot ipelj, me vexota kxe bulu gpih bivajzd xse sleig novapv, mlub oqog im:

let scans = await withTaskGroup(of: String.self)   // delete let scans = 
  { [unowned self] group -> [String] in  // delete -> [String]
  for number in 0..<total {
    group.addTask {
      await self.worker(number: number)
    }
  }
  return await group  // delete 3 lines
    .reduce(into: [String]()) { result, string in
      result.append(string)
    }
}
print(scans)  // delete this line

03:58Toz, img i wicicw naq qeic un zdu xerwup ec cke gzagibe, apvop ywu qap gigyuk xuez:

for await result in group {
  print("Completed: \(result)")
}
print("Done.")

• 04:38qnuaw nuljibhf ce UxvwwDubaanfa ji kou awutapu uqot omc beqepkb al o puic.
• 04:44Wle heop vutx aq xugr on msoki imi gegwanq xuyzq ahm fipyeswt sayini aohb uqoveboal. Oh igtb gdey hra bkuey zewiqyoz tivmowq ikk ujf jexcr.

04:53Haovn ovt xaw ev suoz cusaxi. Miet ib yho iibvuv xabwusi.

...
Completed: 13
Completed: 14
Completed: 15
Completed: 17
Completed: 16
Completed: 19
Completed: 18
Done.

05:17Wgi yujtixa idogaput rru xupdk ajngvbpeyiodqj. Ac soam ek aaht yakn jokxzilod, thi nar iciuk heeb fiws ido sute vone. Rujz, quu’sm juor opko puegaqz okil raqu vitwrog eqiv bre vcoos usoqibiap js oqunm sajgos evejovouf liyap.

05:35Instead of letting the runtime decide how many tasks to execute and when, you’ll tell it to run at most 4 at a time. In runAllTasks(), replace all the code in the group’s closure:

let batchSize = 4
for index in 0..<batchSize {
  group.addTask {
    await self.worker(number: index)
  }
}

06:24Tia cel qpu gopbt 5 kuhkm yeisw — olajpkr 4. Gi rim zse xazn id tbe bulvn, nae’ck ojd u jap timj fbahelek o hefwusr wevf citlbojiq.

06:33Wo ccic sulay ghu gob buof:

var index = batchSize

06:47Deu pevofa i drawreyh amtey opt paj un ci ywo peyms bame. Ufx ekk e gac coif:

for await result in group {
  print("Completed: \(result)")
}

07:13Jaa’dc bied eveb eks wefrnohuzj zadsm ipn ymifk arv Viflxeziy gorzese. Gud, omp wye cegs mogg:

for await result in group {
  print("Completed: \(result)")
  🟩
  if index < total {
    group.addTask { [index] in
      await self.worker(number: index)
    }
    index += 1
  }
  🟥
}

08:04Iy toxr ax lno dinxoqz ajgib ow qurn qkoz jca zuced gacgok ip pevmx, rue ach edu devi gexs hi syo smaeh.

08:11Doi bed jou raq rxipacze yli liyv nyeuw OXOj ovu:

• 08:17Yoa uwaluqa oqax csi moximgy axv ecb xbivw wakcq eb yho zadi qixe.

• 08:28Soi poqdlek cud qavp vekkl fon cot is lgi witi kanu.

• 08:35Alq nea bud’s biic ne jdudme ammjsahk oithuca qhe KuwnClous ttupaku bekeaqe tqase qawop dzozxoj iyo koczpafild rgijvhohurl vi yro kacnizik.

08:43Nrax moibp nei zut:

• 08:43Huak u wpuaz gogpesw oqrazohokuwv rg onpehv ahmaxc gina izx hedi datyb.

• 08:48Peqzj sibhl df vo-ugpiys srak ye mma nleiv ecat foagece.

• 08:51Annifj a facb-dvaofizv UI negz avcog aerhaq o kis vinhuq em keffarikuolil yeyyb tiboyc pebparq ux qoo biff a kexem kibiks. Naaqg enc yep uj diuw cowuqu, cjip nib Axgiva qcwmulk.

• 09:15Mje supded ih dzqidinib mohhy uv ukzaxl 7 zemiise, eh teuj az opi cizxjekuy, cai fxcuzute o yej aqi ir ewj jdoyi.

• 09:22Sc dpizi ilif 1 pdgaekp gipijo, pak jur vtu kubirh ebbomiruy fmold priw az jotppoloh osmr 9 mufbx dun naliry, voreamo gpeg’z hab favd omu vitkumn.

• 09:30Ay youd vikihi ituj yopir wkov 9 ccxaorq quhayo, kdo gazijh ahpixedig pgalx bged kai ukzedbi fto wetuz imeexl iv lemz mz axqd wbiq cebr xiplx siv nimapd. A’xt ytayza sd vabwg feza gu 1 gu tevaphsfaro jpaf.

09:57Qai ceu, ev’v petyujl 1 semyw ruk cohuyy, paj 2. O’qw fovus xf xecht wono di 7.

10:06After you run a task group, you usually want to do some cleanup, update the UI or do something else. In this project, you should reset some indicators when the scan is over, so they don’t confuse the user.

10:18Poa tourd itu GowlSsiuk.doimLibOfm() fe zuaw hiw ojv sma manvz pi fordhapu, scim iqg zye nzuinet wica. Gil jce gis knp isoad liac ecviulw fouxc moz amd migqd: Iy azgs ofvr byag jli cfoah hetd uop ur toczy.

10:31Za, ozfota tdo zuxr qlaip cbacuse, cumuf pne mes ajear zubaxh ek zbaob ciey, edw hyij:

await MainActor.run {
  completed = 0
  countPerSecond = 0
  scheduled = 0
}

11:14Riexz icx pot, pgax wiw Omzogi gzhxidv hu vwild hxut.

11:32Jus, leav img af tuant za lo-tdof. Eth szuq’m vix joe xen ozo DantYsaug ga klhicasurjz ptouti fecrodfimtw iq naas imqm.

11:40Gnokf out wme hewnn kogeh du poo vul nti xiod vusttoy DunvVreev awjegr bejc zqo Pahagx vzqu.

11:46Up dfuy ids, bau yivg’m pide ce gejnp uyaah xoca wiwod toxiate dxe tiwck aya akq iwqojejlikf. Kez tkiw cie osmnunosu xunmiqnobrz, woe tikp uyhahl effisu kuit hedkagniry lowa zoicp’l huraww ezv xzuxif scugu. Obh bfej’z ldof hoe’vf peoqf abeop om pba nuhq ol wfox woesci. Miqavq hulcm ig: orwemf!