IPersistence Class Reference

#include <persistence.hpp>

Inheritance diagram for IPersistence:

Public Member Functions
virtual void	Set (std::string storage_namespace, std::string key, std::string data) noexcept=0
virtual void	Remove (std::string storage_namespace, std::string key) noexcept=0
virtual std::optional< std::string >	Read (std::string storage_namespace, std::string key) noexcept=0

Detailed Description

Interface for a data store that holds feature flag data and other SDK properties in a serialized form.

This interface should be used for platform-specific integrations that store data somewhere other than in memory. The SDK defaults to using only in-memory storage. Each data item is uniquely identified by the combination of a "namespace" and a "key", and has a string value. These are defined as follows:

• Both the namespace and the key are non-empty string.
• Both the namespace and the key contain only alphanumeric characters, hyphens, and underscores.
• The namespace always starts with "LaunchDarkly".
• The value can be any string, including an empty string.

The SDK assumes that the persistence is only being used by a single instance of the SDK per SDK key (two different SDK instances, with 2 different SDK keys could use the same persistence instance). It does not implement read-through behavior. It reads values at SDK initialization or when changing contexts.

The SDK, with correct usage, will not have overlapping writes to the same key. The Read/Write methods may not always be called from the same thread.

This interface does not depend on the ability to list the contents of the store or namespaces. This is to maintain the simplicity of implementing a key-value store on many platforms.

Member Function Documentation

Read()

virtual std::optional<std::string> IPersistence::Read ( std::string  storage_namespace, std::string  key  )

pure virtualnoexcept

Attempt to read a value from the store.

Parameters

storage_namespace	The namespace of the data.
key	The key of the data.

Returns

The read value, or std::nullopt if the value does not exist or could not be read.

Implemented in PersistenceImplementationWrapper.

Remove()

virtual void IPersistence::Remove ( std::string  storage_namespace, std::string  key  )

pure virtualnoexcept

Remove a value from the store. If the value cannot be removed, then the function should complete normally.

Parameters

storage_namespace	The namespace of the data.
key	The key of the data.

Implemented in PersistenceImplementationWrapper.

Set()

virtual void IPersistence::Set ( std::string  storage_namespace, std::string  key, std::string  data  )

pure virtualnoexcept

Add or update a value in the store. If the value cannot be set, then the function should complete normally.

Parameters

storage_namespace	The namespace for the data.
key	The key for the data.
data	The data to add or update.

Implemented in PersistenceImplementationWrapper.

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The documentation for this class was generated from the following file:

• /home/runner/work/cpp-sdks/cpp-sdks/libs/common/include/launchdarkly/persistence/persistence.hpp