PhosphorConfig::MigrationRunner Class Reference

Executes a Schema's migration chain against a JSON document. More...

#include <phosphor-config/include/PhosphorConfig/MigrationRunner.h>

Public Member Functions
	MigrationRunner (const Schema &schema)
	MigrationRunner (Schema &&)=delete
	Forbid construction from a temporary Schema — the runner stores a const reference, which would dangle the moment the temporary expires.
void	runInMemory (QJsonObject &root) const
	Apply the full migration chain in memory.
bool	runOnFile (const QString &jsonPath) const
	Read the file at jsonPath, run the chain, and — if the version advanced — atomically write the result back.
int	readVersion (const QJsonObject &root) const
	Current version persisted in root, or 1 if unset / invalid.
void	stampVersion (QJsonObject &root) const
	Stamp root with the schema's current version.

Detailed Description

Executes a Schema's migration chain against a JSON document.

Typical use: call runOnFile() once at startup, before opening a JsonBackend against the same path. The runner is idempotent — if the on-disk version already matches Schema::version it returns without rewriting the file.

Constructor & Destructor Documentation

MigrationRunner() [1/2]

PhosphorConfig::MigrationRunner::MigrationRunner ( const Schema &  schema )

explicit

MigrationRunner() [2/2]

PhosphorConfig::MigrationRunner::MigrationRunner ( Schema &&  )

explicitdelete

Forbid construction from a temporary Schema — the runner stores a const reference, which would dangle the moment the temporary expires.

Callers must own the schema for the runner's full lifetime.

Member Function Documentation

readVersion()

int PhosphorConfig::MigrationRunner::readVersion

(

const QJsonObject &

root

)

const

Current version persisted in root, or 1 if unset / invalid.

runInMemory()

void PhosphorConfig::MigrationRunner::runInMemory

(

QJsonObject &

root

)

const

Apply the full migration chain in memory.

Steps whose fromVersion matches the current Schema::versionKey are invoked in declared order; each step MUST bump the version by one. On a bump mismatch the chain aborts and an error is logged.

runOnFile()

bool PhosphorConfig::MigrationRunner::runOnFile

(

const QString &

jsonPath

)

const

Read the file at jsonPath, run the chain, and — if the version advanced — atomically write the result back.

Returns true on success, on "nothing to do", or on "file doesn't exist" (fresh install). Returns false only on parse or write errors.

Not safe against concurrent writers — the read-migrate-write sequence has no file lock. Assumes single-process single-user desktop-config usage; a second process mutating the file between our read and our atomic rename would silently have its edits overwritten.

stampVersion()

void PhosphorConfig::MigrationRunner::stampVersion

(

QJsonObject &

root

)

const

Stamp root with the schema's current version.

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

• phosphor-config/include/PhosphorConfig/MigrationRunner.h