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<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>ratelimiter: Go Coverage Report</title>
<style>
body {
background: black;
color: rgb(80, 80, 80);
}
body, pre, #legend span {
font-family: Menlo, monospace;
font-weight: bold;
}
#topbar {
background: black;
position: fixed;
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}
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margin-top: 50px;
}
#nav, #legend {
float: left;
margin-left: 10px;
}
#legend {
margin-top: 12px;
}
#nav {
margin-top: 10px;
}
#legend span {
margin: 0 5px;
}
.cov0 { color: rgb(192, 0, 0) }
.cov1 { color: rgb(128, 128, 128) }
.cov2 { color: rgb(116, 140, 131) }
.cov3 { color: rgb(104, 152, 134) }
.cov4 { color: rgb(92, 164, 137) }
.cov5 { color: rgb(80, 176, 140) }
.cov6 { color: rgb(68, 188, 143) }
.cov7 { color: rgb(56, 200, 146) }
.cov8 { color: rgb(44, 212, 149) }
.cov9 { color: rgb(32, 224, 152) }
.cov10 { color: rgb(20, 236, 155) }
</style>
</head>
<body>
<div id="topbar">
<div id="nav">
<select id="files">
<option value="file0">github.com/Narasimha1997/ratelimiter/attribute_limiter.go (93.6%)</option>
<option value="file1">github.com/Narasimha1997/ratelimiter/limiter.go (100.0%)</option>
<option value="file2">github.com/Narasimha1997/ratelimiter/window.go (100.0%)</option>
</select>
</div>
<div id="legend">
<span>not tracked</span>
<span class="cov0">not covered</span>
<span class="cov8">covered</span>
</div>
</div>
<div id="content">
<pre class="file" id="file0" style="display: none">package ratelimiter
import (
"fmt"
"sync"
"time"
)
// AttributeMap is a custom map type of string key and Limiter instance as value
type AttributeMap map[string]Limiter
// AttributeBasedLimiter is an instance that can manage multiple rate limiter instances
// with different configutations.
type AttributeBasedLimiter struct {
attributeMap AttributeMap
m sync.Mutex
syncMode bool
}
// HasKey check if AttributeBasedLimiter has a limiter for the key.
//
// Parameters:
//
// 1. key: a unique key string, example: IP address, token, uuid etc
//
// Returns a boolean flag, if true, the key is already present, false otherwise.
func (a *AttributeBasedLimiter) HasKey(key string) bool <span class="cov8" title="1">{
a.m.Lock()
_, ok := a.attributeMap[key]
a.m.Unlock()
return ok
}</span>
// CreateNewKey create a new key-limiter assiociation.
//
// Parameters:
//
// 1. key: a unique key string, example: IP address, token, uuid etc
//
// 2. limit: The number of tasks to be allowd
//
// 3. size: duration
//
// Returns error if the key already exists.
func (a *AttributeBasedLimiter) CreateNewKey(key string, limit uint64, size time.Duration) error <span class="cov8" title="1">{
a.m.Lock()
defer a.m.Unlock()
return a.createNewKey(key, limit, size)
}</span>
func (a *AttributeBasedLimiter) createNewKey(key string, limit uint64, size time.Duration) error <span class="cov8" title="1">{
if _, ok := a.attributeMap[key]; ok </span><span class="cov8" title="1">{
return fmt.Errorf(
"key %s is already defined", key,
)
}</span>
// create a new entry:
<span class="cov8" title="1">if !a.syncMode </span><span class="cov8" title="1">{
a.attributeMap[key] = NewDefaultLimiter(limit, size)
}</span> else<span class="cov8" title="1"> {
a.attributeMap[key] = NewSyncLimiter(limit, size)
}</span>
<span class="cov8" title="1">return nil</span>
}
// HasOrCreateKey check if AttributeBasedLimiter has a limiter for the key.
// Create a new key-limiter assiociation if the key not exists.
//
// Parameters:
//
// 1. key: a unique key string, example: IP address, token, uuid etc
//
// 2. limit: The number of tasks to be allowd
//
// 3. size: duration
//
// Return true if the key exists or is created successfully.
func (a *AttributeBasedLimiter) HasOrCreateKey(key string, limit uint64, size time.Duration) bool <span class="cov8" title="1">{
a.m.Lock()
defer a.m.Unlock()
if _, ok := a.attributeMap[key]; ok </span><span class="cov8" title="1">{
return true
}</span>
<span class="cov8" title="1">if err := a.createNewKey(key, limit, size); err == nil </span><span class="cov8" title="1">{
return true
}</span>
<span class="cov0" title="0">return false</span>
}
// ShouldAllow makes decison whether n tasks can be allowed or not.
//
// Parameters:
//
// key: a unique key string, example: IP address, token, uuid etc
//
// n: number of tasks to be processed, set this as 1 for a single task.
// (Example: An HTTP request)
//
// Returns (bool, error).
// (false, error) when limiter is inactive (or it is killed) or key is not present.
// (true/false, nil) if key exists and n tasks can be allowed or not.
func (a *AttributeBasedLimiter) ShouldAllow(key string, n uint64) (bool, error) <span class="cov8" title="1">{
a.m.Lock()
defer a.m.Unlock()
limiter, ok := a.attributeMap[key]
if ok </span><span class="cov8" title="1">{
return limiter.ShouldAllow(n)
}</span>
<span class="cov8" title="1">return false, fmt.Errorf("key %s not found", key)</span>
}
// MustShouldAllow makes decison whether n tasks can be allowed or not.
//
// Parameters:
//
// key: a unique key string, example: IP address, token, uuid etc
//
// n: number of tasks to be processed, set this as 1 for a single task.
// (Example: An HTTP request)
//
// Returns bool.
// (false) when limiter is inactive (or it is killed) or n tasks can be not allowed.
// (true) when n tasks can be allowed or new key-limiter.
func (a *AttributeBasedLimiter) MustShouldAllow(key string, n uint64, limit uint64, size time.Duration) bool <span class="cov8" title="1">{
a.m.Lock()
defer a.m.Unlock()
if limiter, ok := a.attributeMap[key]; ok </span><span class="cov8" title="1">{
allowed, err := limiter.ShouldAllow(n)
return allowed && err == nil
}</span>
<span class="cov8" title="1">err := a.createNewKey(key, limit, size)
if err != nil </span><span class="cov0" title="0">{
return err == nil
}</span>
// check ratelimiter on newly created key:
<span class="cov8" title="1">limiter := a.attributeMap[key]
allowed, err := limiter.ShouldAllow(n)
return allowed && err == nil</span>
}
// DeleteKey remove the key and kill its underlying limiter.
//
// Parameters:
//
// 1.key: a unique key string, example: IP address, token, uuid etc
//
// Returns an error if the key is not present.
func (a *AttributeBasedLimiter) DeleteKey(key string) error <span class="cov8" title="1">{
a.m.Lock()
defer a.m.Unlock()
if limiter, ok := a.attributeMap[key]; ok </span><span class="cov8" title="1">{
err := limiter.Kill()
if err != nil </span><span class="cov0" title="0">{
return err
}</span>
<span class="cov8" title="1">delete(a.attributeMap, key)
return nil</span>
}
<span class="cov8" title="1">return fmt.Errorf("key %s not found", key)</span>
}
// NewAttributeBasedLimiter creates an instance of AttributeBasedLimiter and returns it's pointer.
//
// Parameters:
//
// 1. backgroundSliding: if set to true, DefaultLimiter will be used as an underlying limiter,
// else, SyncLimiter will be used.
func NewAttributeBasedLimiter(backgroundSliding bool) *AttributeBasedLimiter <span class="cov8" title="1">{
return &AttributeBasedLimiter{
attributeMap: make(AttributeMap),
syncMode: !backgroundSliding,
}
}</span>
</pre>
<pre class="file" id="file1" style="display: none">package ratelimiter
import (
"context"
"fmt"
"sync"
"time"
)
// Limiter is an interface that is implemented by DefaultLimiter and SyncLimiter
type Limiter interface {
Kill() error
ShouldAllow(n uint64) (bool, error)
}
// DefaultLimiter maintains all the structures used for rate limting using a background goroutine.
type DefaultLimiter struct {
previous *Window
current *Window
lock sync.Mutex
size time.Duration
limit uint64
killed bool
windowContext context.Context
cancelFn func()
}
// ShouldAllow makes decison whether n tasks can be allowed or not.
//
// Parameters:
//
// 1. n: number of tasks to be processed, set this as 1 for a single task. (Example: An HTTP request)
//
// Returns (bool, error). (false, error) if limiter is inactive (or it is killed). Otherwise,
// (true/false, nil) depending on whether n tasks can be allowed or not.
func (l *DefaultLimiter) ShouldAllow(n uint64) (bool, error) <span class="cov8" title="1">{
l.lock.Lock()
defer l.lock.Unlock()
if l.killed </span><span class="cov8" title="1">{
return false, fmt.Errorf("function ShouldAllow called on an inactive instance")
}</span>
<span class="cov8" title="1">if l.limit == 0 || l.size < time.Millisecond </span><span class="cov8" title="1">{
return false, fmt.Errorf("invalid limiter configuration")
}</span>
<span class="cov8" title="1">currentTime := time.Now()
currentWindowBoundary := currentTime.Sub(l.current.getStartTime())
w := float64(l.size-currentWindowBoundary) / float64(l.size)
currentSlidingRequests := uint64(w*float64(l.previous.count)) + l.current.count
if currentSlidingRequests+n > l.limit </span><span class="cov8" title="1">{
return false, nil
}</span>
// add current request count to window of current count
<span class="cov8" title="1">l.current.updateCount(n)
return true, nil</span>
}
func (l *DefaultLimiter) progressiveWindowSlider() <span class="cov8" title="1">{
for </span><span class="cov8" title="1">{
select </span>{
case <-l.windowContext.Done():<span class="cov8" title="1">
return</span>
default:<span class="cov8" title="1">
toSleepDuration := l.size - time.Since(l.current.getStartTime())
time.Sleep(toSleepDuration)
l.lock.Lock()
// make current as previous and create a new current window
l.previous.setStateFrom(l.current)
l.current.resetToTime(time.Now())
l.lock.Unlock()</span>
}
}
}
// Kill the limiter, returns error if the limiter has been killed already.
func (l *DefaultLimiter) Kill() error <span class="cov8" title="1">{
l.lock.Lock()
defer l.lock.Unlock()
if l.killed </span><span class="cov8" title="1">{
return fmt.Errorf("called Kill on already killed limiter")
}</span>
<span class="cov8" title="1">defer l.cancelFn()
l.killed = true
return nil</span>
}
// NewDefaultLimiter creates an instance of DefaultLimiter and returns it's pointer.
//
// Parameters:
//
// 1. limit: The number of tasks to be allowd
//
// 2. size: duration
func NewDefaultLimiter(limit uint64, size time.Duration) *DefaultLimiter <span class="cov8" title="1">{
previous := NewWindow(0, time.Unix(0, 0))
current := NewWindow(0, time.Unix(0, 0))
childCtx, cancelFn := context.WithCancel(context.Background())
limiter := &DefaultLimiter{
previous: previous,
current: current,
lock: sync.Mutex{},
size: size,
limit: limit,
killed: false,
windowContext: childCtx,
cancelFn: cancelFn,
}
go limiter.progressiveWindowSlider()
return limiter
}</span>
// SyncLimiter maintains all the structures used for rate limting on demand.
type SyncLimiter struct {
previous *Window
current *Window
lock sync.Mutex
size time.Duration
limit uint64
killed bool
}
func (s *SyncLimiter) getNSlidesSince(now time.Time) (time.Duration, time.Time) <span class="cov8" title="1">{
sizeAlignedTime := now.Truncate(s.size)
timeSinceStart := sizeAlignedTime.Sub(s.current.getStartTime())
return timeSinceStart / s.size, sizeAlignedTime
}</span>
// ShouldAllow makes decison whether n tasks can be allowed or not.
//
// Parameters:
//
// 1. n: number of tasks to be processed, set this as 1 for a single task. (Example: An HTTP request)
//
// Returns (bool, error). (false, error) if limiter is inactive (or it is killed). Otherwise,
// (true/false, error) depending on whether n tasks can be allowed or not.
func (s *SyncLimiter) ShouldAllow(n uint64) (bool, error) <span class="cov8" title="1">{
s.lock.Lock()
defer s.lock.Unlock()
if s.killed </span><span class="cov8" title="1">{
return false, fmt.Errorf("function ShouldAllow called on an inactive instance")
}</span>
<span class="cov8" title="1">if s.limit == 0 || s.size < time.Millisecond </span><span class="cov8" title="1">{
return false, fmt.Errorf("invalid limiter configuration")
}</span>
<span class="cov8" title="1">currentTime := time.Now()
// advance the window on demand, as this doesn't make use of goroutine.
nSlides, alignedCurrentTime := s.getNSlidesSince(currentTime)
// window slide shares both current and previous windows.
if nSlides == 1 </span><span class="cov8" title="1">{
s.previous.setToState(
alignedCurrentTime.Add(-s.size),
s.current.count,
)
s.current.resetToTime(
alignedCurrentTime,
)
}</span> else<span class="cov8" title="1"> if nSlides > 1 </span><span class="cov8" title="1">{
s.previous.resetToTime(
alignedCurrentTime.Add(-s.size),
)
s.current.resetToTime(
alignedCurrentTime,
)
}</span>
<span class="cov8" title="1">currentWindowBoundary := currentTime.Sub(s.current.getStartTime())
w := float64(s.size-currentWindowBoundary) / float64(s.size)
currentSlidingRequests := uint64(w*float64(s.previous.count)) + s.current.count
if currentSlidingRequests+n > s.limit </span><span class="cov8" title="1">{
return false, nil
}</span>
// add current request count to window of current count
<span class="cov8" title="1">s.current.updateCount(n)
return true, nil</span>
}
// Kill the limiter, returns error if the limiter has been killed already.
func (s *SyncLimiter) Kill() error <span class="cov8" title="1">{
s.lock.Lock()
defer s.lock.Unlock()
if s.killed </span><span class="cov8" title="1">{
return fmt.Errorf("called Kill on already killed limiter")
}</span>
// kill is a dummy implementation for SyncLimiter,
// because there is no need of stopping a go-routine.
<span class="cov8" title="1">s.killed = true
return nil</span>
}
// NewSyncLimiter creates an instance of SyncLimiter and returns it's pointer.
//
// Parameters:
//
// 1. limit: The number of tasks to be allowd
//
// 2. size: duration
func NewSyncLimiter(limit uint64, size time.Duration) *SyncLimiter <span class="cov8" title="1">{
current := NewWindow(0, time.Unix(0, 0))
previous := NewWindow(0, time.Unix(0, 0))
return &SyncLimiter{
previous: previous,
current: current,
lock: sync.Mutex{},
killed: false,
size: size,
limit: limit,
}
}</span>
</pre>
<pre class="file" id="file2" style="display: none">package ratelimiter
import (
"time"
)
// Window represents the structure of timing-window at given point of time.
type Window struct {
count uint64
startTime time.Time
}
func (w *Window) updateCount(n uint64) <span class="cov8" title="1">{
w.count += n
}</span>
func (w *Window) getStartTime() time.Time <span class="cov8" title="1">{
return w.startTime
}</span>
func (w *Window) setStateFrom(other *Window) <span class="cov8" title="1">{
w.count = other.count
w.startTime = other.startTime
}</span>
func (w *Window) resetToTime(startTime time.Time) <span class="cov8" title="1">{
w.count = 0
w.startTime = startTime
}</span>
func (w *Window) setToState(startTime time.Time, count uint64) <span class="cov8" title="1">{
w.startTime = startTime
w.count = count
}</span>
// Creates and returns a pointer to the new Window instance.
//
// Parameters:
//
// 1. count: The initial count of the window.
//
// 2. startTime: The initial starting time of the window.
func NewWindow(count uint64, startTime time.Time) *Window <span class="cov8" title="1">{
return &Window{
count: count,
startTime: startTime,
}
}</span>
</pre>
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