diff options
author | 2024-01-17 14:54:30 +0000 | |
---|---|---|
committer | 2024-01-17 14:54:30 +0000 | |
commit | 906639ad7eb92e9d631599f78979908930e59c84 (patch) | |
tree | dfef6d0a5ba47c49c214e4537a89dee6ad528df8 /vendor/github.com/sourcegraph/conc/iter/iter.go | |
parent | [bugfix] Better Postgres search case insensitivity (#2526) (diff) | |
download | gotosocial-906639ad7eb92e9d631599f78979908930e59c84.tar.xz |
[chore] update viper version (#2539)
* update viper version
* removes our last uses of the slice package
* fix tests
Diffstat (limited to 'vendor/github.com/sourcegraph/conc/iter/iter.go')
-rw-r--r-- | vendor/github.com/sourcegraph/conc/iter/iter.go | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/vendor/github.com/sourcegraph/conc/iter/iter.go b/vendor/github.com/sourcegraph/conc/iter/iter.go new file mode 100644 index 000000000..124b4f940 --- /dev/null +++ b/vendor/github.com/sourcegraph/conc/iter/iter.go @@ -0,0 +1,85 @@ +package iter + +import ( + "runtime" + "sync/atomic" + + "github.com/sourcegraph/conc" +) + +// defaultMaxGoroutines returns the default maximum number of +// goroutines to use within this package. +func defaultMaxGoroutines() int { return runtime.GOMAXPROCS(0) } + +// Iterator can be used to configure the behaviour of ForEach +// and ForEachIdx. The zero value is safe to use with reasonable +// defaults. +// +// Iterator is also safe for reuse and concurrent use. +type Iterator[T any] struct { + // MaxGoroutines controls the maximum number of goroutines + // to use on this Iterator's methods. + // + // If unset, MaxGoroutines defaults to runtime.GOMAXPROCS(0). + MaxGoroutines int +} + +// ForEach executes f in parallel over each element in input. +// +// It is safe to mutate the input parameter, which makes it +// possible to map in place. +// +// ForEach always uses at most runtime.GOMAXPROCS goroutines. +// It takes roughly 2µs to start up the goroutines and adds +// an overhead of roughly 50ns per element of input. For +// a configurable goroutine limit, use a custom Iterator. +func ForEach[T any](input []T, f func(*T)) { Iterator[T]{}.ForEach(input, f) } + +// ForEach executes f in parallel over each element in input, +// using up to the Iterator's configured maximum number of +// goroutines. +// +// It is safe to mutate the input parameter, which makes it +// possible to map in place. +// +// It takes roughly 2µs to start up the goroutines and adds +// an overhead of roughly 50ns per element of input. +func (iter Iterator[T]) ForEach(input []T, f func(*T)) { + iter.ForEachIdx(input, func(_ int, t *T) { + f(t) + }) +} + +// ForEachIdx is the same as ForEach except it also provides the +// index of the element to the callback. +func ForEachIdx[T any](input []T, f func(int, *T)) { Iterator[T]{}.ForEachIdx(input, f) } + +// ForEachIdx is the same as ForEach except it also provides the +// index of the element to the callback. +func (iter Iterator[T]) ForEachIdx(input []T, f func(int, *T)) { + if iter.MaxGoroutines == 0 { + // iter is a value receiver and is hence safe to mutate + iter.MaxGoroutines = defaultMaxGoroutines() + } + + numInput := len(input) + if iter.MaxGoroutines > numInput { + // No more concurrent tasks than the number of input items. + iter.MaxGoroutines = numInput + } + + var idx atomic.Int64 + // Create the task outside the loop to avoid extra closure allocations. + task := func() { + i := int(idx.Add(1) - 1) + for ; i < numInput; i = int(idx.Add(1) - 1) { + f(i, &input[i]) + } + } + + var wg conc.WaitGroup + for i := 0; i < iter.MaxGoroutines; i++ { + wg.Go(task) + } + wg.Wait() +} |