syncthing/vendor/github.com/onsi/ginkgo/internal/spec/index_computer.go

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package spec
func ParallelizedIndexRange(length int, parallelTotal int, parallelNode int) (startIndex int, count int) {
if length == 0 {
return 0, 0
}
// We have more nodes than tests. Trivial case.
if parallelTotal >= length {
if parallelNode > length {
return 0, 0
} else {
return parallelNode - 1, 1
}
}
// This is the minimum amount of tests that a node will be required to run
minTestsPerNode := length / parallelTotal
// This is the maximum amount of tests that a node will be required to run
// The algorithm guarantees that this would be equal to at least the minimum amount
// and at most one more
maxTestsPerNode := minTestsPerNode
if length%parallelTotal != 0 {
maxTestsPerNode++
}
// Number of nodes that will have to run the maximum amount of tests per node
numMaxLoadNodes := length % parallelTotal
// Number of nodes that precede the current node and will have to run the maximum amount of tests per node
var numPrecedingMaxLoadNodes int
if parallelNode > numMaxLoadNodes {
numPrecedingMaxLoadNodes = numMaxLoadNodes
} else {
numPrecedingMaxLoadNodes = parallelNode - 1
}
// Number of nodes that precede the current node and will have to run the minimum amount of tests per node
var numPrecedingMinLoadNodes int
if parallelNode <= numMaxLoadNodes {
numPrecedingMinLoadNodes = 0
} else {
numPrecedingMinLoadNodes = parallelNode - numMaxLoadNodes - 1
}
// Evaluate the test start index and number of tests to run
startIndex = numPrecedingMaxLoadNodes*maxTestsPerNode + numPrecedingMinLoadNodes*minTestsPerNode
if parallelNode > numMaxLoadNodes {
count = minTestsPerNode
} else {
count = maxTestsPerNode
}
return
}