bayfrontmedia/leaky-bucket

Framework-agnostic throttling using the leaky bucket algorithm.

Leaky Bucket

Framework-agnostic throttling using the leaky bucket algorithm.

A bucket has a defined capacity and leak rate per minute. Buckets can also store additional arbitrary data.

• License
• Author
• Requirements
• Installation
• Usage

License

This project is open source and available under the MIT License.

Author

• Bayfront Media homepage
• Bayfront Media GitHub

Requirements

• PHP ^8.0
• PDO PHP extension
• JSON PHP extension

Installation

composer require bayfrontmedia/leaky-bucket

Usage

Storage adapter

A Bayfront\LeakyBucket\ApadpterInterface must be passed to the Bayfront\LeakyBucket\Bucket constructor. There are a variety of storage adapters available, each with their own required configuration.

Flysystem

The Flysystem adapter allows you to use a Flysystem League\Flysystem\Filesystem v3 instance for bucket storage.

use Bayfront\LeakyBucket\Adapters\Flysystem;

$adapter = new Flysystem($filesystem, '/root_path');

Local

The Local adapter allows you to store buckets locally using native PHP.

use Bayfront\LeakyBucket\Adapters\Local;

$adapter = new Local('/root_path');

PDO

The PDO adapter allows you to use a \PDO instance for bucket storage into a database.

The PDO adapter will create/use a table named "buckets" unless otherwise specified in the constructor.

use Bayfront\LeakyBucket\Adapters\PDO;

$adapter = new PDO($dbh, 'table_to_use');

Use the up method to create the necessary database table to be used by this adapter. Use the down method to remove the database table.

These methods throw a Bayfront\LeakyBucket\AdapterException exception.

try {

    $adapter->up();

} catch (AdapterException $e) {
    die($e->getMessage());
}

Start using Leaky Bucket

Once your adapter has been created, it can be used with Leaky Bucket. In addition, an optional settings array can be passed to the constructor. The default settings are shown below.

use Bayfront\LeakyBucket\AdapterException;
use Bayfront\LeakyBucket\BucketException;
use Bayfront\LeakyBucket\Bucket;

// Create/retrieve a bucket with a given ID

try {

    $bucket = new Bucket('bucket_id', $adapter, [
        'capacity' => 10, // Total drop capacity
        'leak' => 10 // Number of drops to leak per minute
    ]);

} catch (AdapterException | BucketException $e) {
    die($e->getMessage());
}

// Work with the bucket

$bucket->leak();

if ($bucket->hasCapacity()) {

    try {

        $bucket->fill()->save();

    } catch (AdapterException $e) {
        die($e->getMessage());
    }

}

NOTE: Be sure to leak() the bucket before attempting to do any calculations regarding its capacity. Also, the save() method must be used to store the current bucket settings for future use.

Public methods

• exists
• save
• get
• reset
• delete
• isFull
• getCapacity
• getCapacityUsed
• getCapacityRemaining
• hasCapacity
• getLeakPerSecond
• getSecondsPerDrop
• getSecondsUntilCapacity
• getSecondsUntilEmpty
• touch
• getLastTime
• fill
• leak
• spill
• overflow
• dump
• hasData
• setData
• getData
• forgetData

---

exists

Description:

Checks if this bucket ID already exists in storage.

Parameters:

• None

Returns:

• (bool)

Example:

if ($bucket->exists()) {
    // Do something
}

---

save

Description:

Saves the bucket.

Parameters:

• None

Returns:

• (self)

Throws:

Bayfront\LeakyBucket\AdapterException

Example:

try {

    $bucket->save();

} catch (AdapterException $e) {
    die($e->getMessage());
}

---

get

Description:

Returns entire bucket contents.

Parameters:

• None

Returns:

• (array)

Example:

$contents = $bucket->get();

---

reset

Description:

Reset all bucket information and data.

Parameters:

• None

Returns:

• (self)

Example:

$bucket->reset();

---

delete

Description:

Resets bucket and deletes the file in storage.

Parameters:

• None

Returns:

• (self)

Throws:

Bayfront\LeakyBucket\AdapterException

Example:

try {

    $bucket->delete();

} catch (AdapterException $e) {
    die($e->getMessage());
}

---

isFull

Description:

Checks if bucket is full.

Parameters:

• None

Returns:

• (bool)

Example:

if ($bucket->isFull()) {
    // Do something
}

---

getCapacity

Description:

Returns the total bucket capacity.

Parameters:

• None

Returns:

• (int)

Example:

echo $bucket->getCapacity();

---

getCapacityUsed

Description:

Returns the number of drops in the bucket.

Parameters:

• None

Returns:

• (float)

Example:

echo $bucket->getCapacityUsed();

---

getCapacityRemaining

Description:

Returns the remaining bucket capacity.

Parameters:

• None

Returns:

• (float)

Example:

echo $bucket->getCapacityRemaining();

---

hasCapacity

Description:

Checks if bucket has the capacity fo fill by a given number of drops.

Parameters:

• $drops = 1 (int)

Returns:

• (bool)

Example:

if ($bucket->hasCapacity(5)) {
    // Do something
}

---

getLeakPerSecond

Description:

Returns the number of drops per second the bucket will leak.

Parameters:

• None

Returns:

• (float)

Example:

echo $bucket->getLeakPerSecond();

---

getSecondsPerDrop

Description:

Returns the number of seconds required to leak one drop.

Parameters:

• None

Returns:

• (float)

Example:

echo $bucket->getSecondsPerDrop();

---

getSecondsUntilCapacity

Description:

Returns the number of seconds until bucket has capacity for number of drops. Returns 0 if bucket has capacity.

Parameters:

• $drops = 1 (int)

Returns:

• (float)

Example:

echo $bucket->getSecondsPerDrop();

---

getSecondsUntilEmpty

Description:

Returns the number of seconds until bucket would be empty.

Parameters:

• None

Returns:

• (float)

Example:

echo $bucket->getSecondsUntilEmpty();

---

touch

Description:

Manually update the bucket's timestamp.

The bucket's timestamp is automatically updated when any of the following methods are called:

• fill
• leak
• spill
• dump

Parameters:

• None

Returns:

• (self)

Example:

$bucket->touch();

---

getLastTime

Description:

Returns the bucket's last timestamp.

Parameters:

• None

Returns:

• (int)

Example:

echo $bucket->getLastTime();

---

fill

Description:

Fills the bucket with a given number of drops.

If not allowed to overflow, and the bucket does not have the required capacity, a Bayfront\LeakyBucket\BucketException will be thrown. Otherwise, the bucket will be allowed to overflow.

Parameters:

• $drops = 1 (int)
• $allow_overflow = false (bool)

Returns:

• (self)

Throws:

• Bayfront\LeakyBucket\BucketException

Example:

try {
    
    $bucket->fill();
    
} catch (BucketException $e) {
    die($e->getMessage());
}

---

leak

Description:

Updates the bucket by calculating how many drops to leak since it's last timestamp.

Parameters:

• None

Returns:

• (self)

Example:

$bucket->leak();

---

spill

Description:

Spills a given number of drops from the bucket.

Parameters:

• $drops = 1 (int)

Returns:

• (self)

Example:

$bucket->spill(5);

---

overflow

Description:

Dumps (empties) all drops from the bucket in excess of its capacity.

Parameters:

• None

Returns:

• (self)

Example:

$bucket->overflow();

---

dump

Description:

Dumps (empties) all drops from the bucket.

Parameters:

• None

Returns:

• (self)

Example:

$bucket->dump();

---

hasData

Description:

Checks if this bucket contains any additional data, or a specific key in dot notation.

Parameters:

• $key = NULL (string|null): If NULL, checks if any additional data exists

Returns:

• (bool)

Example:

if ($bucket->hasData('client_id')) {
    // Do something
}

---

setData

Description:

Sets additional data for this bucket in dot notation.

Parameters:

• $key (string)
• $value (mixed)

Returns:

• (self)

Example:

$bucket->setData('client_id', 5);

---

getData

Description:

Returns this bucket's additional data key in dot notation, or an optional default value if not found.

Parameters:

• $key = NULL (string|null): Returns the entire data array when NULL
• $default = NULL (mixed)

Returns:

• (mixed)

Example:

$client_id = $bucket->getData('client_id');

---

forgetData

Description:

Removes additional data key in dot notation for this bucket.

Parameters:

• $key = NULL (string|null): Removes the entire data array when NULL

Returns:

• (self)

Example:

$bucket->forgetData('client_id');