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93 lines
2.6 KiB
Markdown
93 lines
2.6 KiB
Markdown
# go-throttle [](https://godoc.org/github.com/boz/go-throttle) [](https://travis-ci.org/boz/go-throttle)
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Package `throttle` provides functionality to limit the frequency with which code is called
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Throttling is of the `Trigger()` method and depends on the parameters passed (`period`, `trailing`).
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The `period` parameter defines how often the throttled code can run. A period of one second means
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that the throttled code will run at most once per second.
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The `trailing` parameter defines what hapens if `Trigger()` is called after the throttled code has been
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started, but before the period is finished. If `trailing` is false then these triggers are ignored.
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If `trailing` is true then the throttled code is executed one more time at the beginning of the next period.
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Example with `period = time.Second` and `trailing = false`:
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Whole seconds after first trigger...|0|0|0|0|1|1|1|1|
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Trigger() gets called...............|X| |X| | |X| | |
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Throttled code gets called..........|X| | | | |X| | |
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Note that the second `Trigger()` had no effect. The third `Trigger()` caused immediate execution of the
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throttled code.
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Example with `period = time.Second` and `trailing = true`:
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Whole seconds after first trigger...|0|0|0|0|1|1|1|1|
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Trigger() gets called...............|X| |X| | |X| | |
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Throttled code gets called..........|X| | | |X| | | |
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Note that the second `Trigger()` causes the throttled code to get called once the first period is over.
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The third `Trigger()` will do the same.
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## Usage
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Throttling execution of a function:
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```go
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throttle := throttle.ThrottleFunc(period, false, func() {
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fmt.Println("fun, throttled.")
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})
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go func() {
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for i := 0; i < 5; i++ {
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throttle.Trigger()
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time.Sleep(period / 6)
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}
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}()
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time.Sleep(2 * period)
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throttle.Stop()
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// Output: fun, throttled.
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```
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Throttling arbitrary code:
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```go
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package cache
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import (
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"time"
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"github.com/boz/go-throttle"
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)
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type CacheRebuilder struct {
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throttle throttle.Throttle
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}
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// Create a cache rebuilder which will rebuild the cache at most once every 5 minutes, regardless
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// of how often a rebuild is requested.
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func NewRebuilder() *CacheRebuilder {
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cr := &CacheRebuilder{NewThrottle(5*time.Minute, true)}
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go func() {
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for cr.throttle.Next() {
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cr.doRebuild()
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}
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}()
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return cr
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}
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func (cr *CacheRebuilder) Stop() {
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cr.throttle.Stop()
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}
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func (cr *CacheRebuilder) Rebuild() {
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cr.throttle.Trigger()
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}
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func (cr *CacheRebuilder) doRebuild() {
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// actually rebuild the cache.
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}
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```
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