# @sailplane/expiring-value - on-demand value with timeout

## What?

The `ExpringValue` generic class is a container for a value that is instantiated on-demand (lazy-loaded via factory) and cached for a limited
time. Once the cache expires, the factory is used again on next demand to get a fresh version.

This is part of the [sailplane](https://github.com/rackspace/sailplane) library of
utilities for AWS Serverless in Node.js.

## Why?

`ExpiringValue` is a container for a value that is instantiated on-demand (lazy-loaded via factory)
and cached for a limited time.
Once the cache expires, the factory is used again on next demand to get a fresh version.

In Lambda functions, it is useful to cache some data in instance memory to avoid
recomputing or fetching data on every invocation. In the early days of Lambda, instances only lasted 15 minutes
and thus set an upper-limit on how stale the cached data could be. With instances now seen to last for
many hours, a mechanism is needed to deal with refreshing stale content - thus `ExpiringValue` was born.

`ExpiringValue` is not limited to Lambdas, though. Use it anywhere you want to cache a value for
a limited time. It even works in the browser for client code.

## How?

See the [docs](https://github.com/rackspace/sailplane/blob/master/README.md) for usage and examples.


Container for a value that is instantiated on-demand (lazy-loaded via factory) and cached for a limited time. 

@sailplane/expiring-value

Container for a value that is instantiated on-demand (lazy-loaded via factory) and cached for a limited time.

expiring-value

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Ambiguous License Classifier

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Bad text encoding

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Bad semver

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Bad dependency semver

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Bidirectional unicode control characters

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Bin script confusion

This Chrome extension includes content scripts that execute JavaScript on specified websites.

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Chrome Extension Content Script

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Chrome Extension Host Permission

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Chrome Extension Permission

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Chrome Extension Wildcard Host Permission

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Chronological version anomaly

Project maintainer's SSH key has been compromised.

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Compromised SSH key

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Copyleft License

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Title

Critical CVE

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High CVE

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Debug access

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Deprecated

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Deprecated license

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Empty package

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File dependency

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Filesystem access

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Wildcard dependency

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GitHub dependency

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AI-detected potential malware

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AI-detected potential security risk

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Native code

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High entropy strings

Contains unicode homoglyphs which can be used in supply chain confusion attacks.

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Unicode homoglyphs

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HTTP dependency

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Install scripts

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Invalid manifest file

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Invisible chars

(Experimental) Package license has recently changed.

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License exception

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License Policy Violation

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Long strings

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Major refactor

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Manifest confusion

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Mixed license

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Modified license exception

(Experimental) Package contains a modified version of an SPDX license. Please read carefully before using this code.

What is a modified license?

Modified license

What is network access?

Network access

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What is new author?

New author

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Why is contributor and author data important?

No contributors or author data

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@sailplane/expiring-value

@sailplane/expiring-value - on-demand value with timeout

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