Concurrency Coordination Reports

Atomic Claim Coordination Report

Record compare-and-set claims against a single slot and report the contention.

compare-and-set claim A coordination report can record a single-winner claim. An `java.util.concurrent.atomic.AtomicInteger` starts at zero for unclaimed, and `compareAndSet(0, id)` only succeeds for the first request, which writes its id into the slot; every later request reads a nonzero owner and is rejected. With no requests the slot is open, with one request it is claimed, and with competing requests it is contended. The status line summarizes the outcome and reports the winning owner id.

Atomic Claim Coordination Report

requests
AtomicClaimCoordinationReport.kt
Replay: real traced execution (multi-file project)
import java.util.concurrent.atomic.AtomicInteger

fun main() {
    val requests = 1
    val slot = AtomicInteger(0)
    var claimed = 0
    var rejected = 0

    for (i in 1..requests) {
        if (slot.compareAndSet(0, i)) {
            claimed++
        } else {
            rejected++
        }
    }

    val owner = slot.get()

    val status = if (claimed == 0) {
        "open"
    } else if (rejected > 0) {
        "contended"
    } else {
        "claimed"
    }

    println("requests=$requests claimed=$claimed rejected=$rejected owner=$owner $status")
}

import java.util.concurrent.atomic.AtomicInteger

fun main() {
    val requests = 0
    val slot = AtomicInteger(0)
    var claimed = 0
    var rejected = 0

    for (i in 1..requests) {
        if (slot.compareAndSet(0, i)) {
            claimed++
        } else {
            rejected++
        }
    }

    val owner = slot.get()

    val status = if (claimed == 0) {
        "open"
    } else if (rejected > 0) {
        "contended"
    } else {
        "claimed"
    }

    println("requests=$requests claimed=$claimed rejected=$rejected owner=$owner $status")
}

import java.util.concurrent.atomic.AtomicInteger

fun main() {
    val requests = 2
    val slot = AtomicInteger(0)
    var claimed = 0
    var rejected = 0

    for (i in 1..requests) {
        if (slot.compareAndSet(0, i)) {
            claimed++
        } else {
            rejected++
        }
    }

    val owner = slot.get()

    val status = if (claimed == 0) {
        "open"
    } else if (rejected > 0) {
        "contended"
    } else {
        "claimed"
    }

    println("requests=$requests claimed=$claimed rejected=$rejected owner=$owner $status")
}

  1. requests ← 1, slot ← 0, claimed ← 0, rejected ← 0

    3fun main() {4    val requests→ 1 = 1 //@requests=0, 25    val slot→ 0 = AtomicInteger(0)6    var claimed→ 0 = 07    var rejected→ 0 = 0

  2. for (i in 1..requests)

    9for (i1 in 1..requests1) {10    if (slot.compareAndSet(0, i)) {

  3. if (slot.compareAndSet(0, i))

    9for (i in 1..requests) {10    if (slot1.compareAndSet(0, i1)) {11        claimed0++12    } else {13        rejected++

  4. owner ← 1, status ← claimed

    17    val owner→ 1 = slot1.get()1819    val status→ claimed = if (claimed1 == 0) {20        "open"21    } else if (rejected0 > 0) {22        "contended"23    } else {24        "claimed"25    }2627    println("requests=$requests1 claimed=$claimed1 rejected=$rejected0 owner=$owner1 $statusclaimed")28}
    outputrequests=1 claimed=1 rejected=0 owner=1 claimed

  1. requests ← 0, slot ← 0, claimed ← 0, rejected ← 0, owner ← 0, status ← open

    3fun main() {4    val requests→ 0 = 05    val slot→ 0 = AtomicInteger(0)6    var claimed→ 0 = 07    var rejected→ 0 = 089    for (i in 1..requests) {10        if (slot.compareAndSet(0, i)) {11            claimed++12        } else {13            rejected++14        }15    }1617    val owner→ 0 = slot0.get()1819    val status→ open = if (claimed0 == 0) {20        "open"21    } else if (rejected0 > 0) {22        "contended"23    } else {24        "claimed"25    }2627    println("requests=$requests0 claimed=$claimed0 rejected=$rejected0 owner=$owner0 $statusopen")28}
    outputrequests=0 claimed=0 rejected=0 owner=0 open

  1. requests ← 2, slot ← 0, claimed ← 0, rejected ← 0

    3fun main() {4    val requests→ 2 = 25    val slot→ 0 = AtomicInteger(0)6    var claimed→ 0 = 07    var rejected→ 0 = 0

  2. for (i in 1..requests)

    pass 1 of 2
    9for (i1 in 1..requests2) {10    if (slot.compareAndSet(0, i)) {

  3. if (slot.compareAndSet(0, i))

    9for (i in 1..requests) {10    if (slot1.compareAndSet(0, i1)) {11        claimed0++12    } else {13        rejected++

  4. for (i in 1..requests)

    pass 2 of 2
    9for (i2 in 1..requests2) {10    if (slot.compareAndSet(0, i)) {

  5. else

    11        claimed++12    } else {13        rejected0++14    }15}

  6. owner ← 1, status ← contended

    17    val owner→ 1 = slot1.get()1819    val status→ contended = if (claimed1 == 0) {20        "open"21    } else if (rejected1 > 0) {22        "contended"23    } else {24        "claimed"25    }2627    println("requests=$requests2 claimed=$claimed1 rejected=$rejected1 owner=$owner1 $statuscontended")28}
    outputrequests=2 claimed=1 rejected=1 owner=1 contended