https://github.com/linkedin/cassette

An efficient, file-based FIFO Queue for iOS and macOS.
https://github.com/linkedin/cassette

Last synced: about 2 months ago
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An efficient, file-based FIFO Queue for iOS and macOS.

• Host: GitHub
• URL: https://github.com/linkedin/cassette
• Owner: linkedin
• License: bsd-2-clause
• Created: 2015-06-03T04:06:27.000Z (over 9 years ago)
• Default Branch: master
• Last Pushed: 2023-10-20T19:22:41.000Z (11 months ago)
• Last Synced: 2024-07-04T14:41:47.308Z (2 months ago)
• Language: Objective-C
• Homepage:
• Size: 444 KB
• Stars: 95
• Watchers: 44
• Forks: 17
• Open Issues: 10
• Metadata Files:
  • Readme: README.md
  • Contributing: CONTRIBUTING.md
  • License: LICENSE

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README

        
[![Build Status](https://dev.azure.com/lnkd-oss/cassette/_apis/build/status/linkedin.cassette?branchName=master)](https://dev.azure.com/lnkd-oss/cassette/_build/latest?definitionId=4&branchName=master)

# Cassette 

Cassette is a collection of queue-related classes for iOS and macOS. It is maintained by [LinkedIn](https://engineering.linkedin.com/). Cassette was originally implemented by [Segment](https://segment.com). Cassette was inspired by [Tape](https://github.com/square/tape).

`QueueFile` is an efficient, file-based FIFO queue. Addition and removal from an instance is an O(1) operation. Writes are synchronous; data will be written to disk before an operation returns. The queue is intended to be reliable and survive system or process crashes.

## Installing the Library

#### CocoaPods

```

target 'MyApp' do

  pod 'Cassette', '1.0.0-beta3'

end

```

#### Manual

Download the [latest binary](https://github.com/linkedin/cassette/releases) of the library.

## Usage

`CASObjectQueue` works with arbitrary objects that abide by the [NSCoding](https://developer.apple.com/documentation/foundation/nscoding?language=objc) protocol. An `CASObjectQueue` may be backed by a persistent `CASQueueFile`, or in memory. 

```

CASObjectQueue *queue;

// Persistent ObjectQueue

NSError *error;

queue = [[CASFileObjectQueue alloc] initWithRelativePath:@"Test-File" error:&error];

// In-Memory ObjectQueue

queue = [[CASInMemoryObjectQueue alloc] init];

```

Add some data to the end of the queue.

```

NSError *error;

if ([queue add:@1 error:&error]) {

  // Success

} else {

  NSLog(@"Error: %@", error);

}

```

Read data at the head of the queue.

```

// Peek the eldest element. Note that -peek:error: on an empty queue

// returns @[], but on error (e.g., I/O error) it returns nil.

NSNumber *data = [queue peek:1 error:&error].firstObject;

// Peek the eldest `n` elements.

NSArray *data = [queue peek:n error:&error];

```

Remove processed elements.

```

// Remove the eldest element.

if ([queue pop:1 error:&error]) { ... }

// Remove 'n' elements.

if ([queue pop:n error:&error]) { ... }

// Remove all elements.

if ([queue clearAndReturnError:&error]) { ... }

```