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package terraform
import (
"sort"
"strings"
)
// Semaphore is a wrapper around a channel to provide
// utility methods to clarify that we are treating the
// channel as a semaphore
type Semaphore chan struct{}
// NewSemaphore creates a semaphore that allows up
// to a given limit of simultaneous acquisitions
func NewSemaphore(n int) Semaphore {
if n == 0 {
panic("semaphore with limit 0")
}
ch := make(chan struct{}, n)
return Semaphore(ch)
}
// Acquire is used to acquire an available slot.
// Blocks until available.
func (s Semaphore) Acquire() {
s <- struct{}{}
}
// TryAcquire is used to do a non-blocking acquire.
// Returns a bool indicating success
func (s Semaphore) TryAcquire() bool {
select {
case s <- struct{}{}:
return true
default:
return false
}
}
// Release is used to return a slot. Acquire must
// be called as a pre-condition.
func (s Semaphore) Release() {
select {
case <-s:
default:
panic("release without an acquire")
}
}
// resourceProvider returns the provider name for the given type.
func resourceProvider(t, alias string) string {
if alias != "" {
return alias
}
idx := strings.IndexRune(t, '_')
if idx == -1 {
// If no underscores, the resource name is assumed to be
// also the provider name, e.g. if the provider exposes
// only a single resource of each type.
return t
}
return t[:idx]
}
// strSliceContains checks if a given string is contained in a slice
// When anybody asks why Go needs generics, here you go.
func strSliceContains(haystack []string, needle string) bool {
for _, s := range haystack {
if s == needle {
return true
}
}
return false
}
// deduplicate a slice of strings
func uniqueStrings(s []string) []string {
if len(s) < 2 {
return s
}
sort.Strings(s)
result := make([]string, 1, len(s))
result[0] = s[0]
for i := 1; i < len(s); i++ {
if s[i] != result[len(result)-1] {
result = append(result, s[i])
}
}
return result
}
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