com.google.gerrit.server.notedb

Class NotesMigration

java.lang.Object

com.google.gerrit.server.notedb.NotesMigration

Direct Known Subclasses:

ConfigNotesMigration

public abstract class NotesMigration
extends Object

Holds the current state of the NoteDb migration.

The migration will proceed one root entity type at a time. A root entity is an entity stored in ReviewDb whose key's getParentKey() method returns null. For an example of the entity hierarchy rooted at Change, see the diagram in com.google.gerrit.reviewdb.client.Change.

During a transitional period, each root entity group from ReviewDb may be either written to or both written to and read from NoteDb.

This class controls the state of the migration according to options in gerrit.config. In general, any changes to these options should only be made by adventurous administrators, who know what they're doing, on non-production data, for the purposes of testing the NoteDb implementation. Changing options quite likely requires re-running RebuildNoteDb. For these reasons, the options remain undocumented.

Constructor Summary

Constructors

Constructor and Description
NotesMigration()

Method Summary

Modifier and Type	Method and Description
abstract NoteDbChangeState.PrimaryStorage	changePrimaryStorage()
boolean	commitChangeWrites()
abstract boolean	disableChangeReviewDb() Disable ReviewDb access for changes.
boolean	enabled()
boolean	failChangeWrites()
boolean	failOnLoad() Whether to fail when reading any data from NoteDb.
abstract boolean	readChanges() Read changes from NoteDb.
abstract boolean	readChangeSequence() Read sequential change ID numbers from NoteDb.
protected abstract boolean	writeChanges() Write changes to NoteDb.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

NotesMigration

public NotesMigration()

Method Detail

readChanges

public abstract boolean readChanges()

Read changes from NoteDb.

Change data is read from NoteDb refs, but ReviewDb is still the source of truth. If the loader determines NoteDb is out of date, the change data in NoteDb will be transparently rebuilt. This means that some code paths that look read-only may in fact attempt to write.

If true and writeChanges() = false, changes can still be read from NoteDb, but any attempts to write will generate an error.

writeChanges

protected abstract boolean writeChanges()

Write changes to NoteDb.

Updates to change data are written to NoteDb refs, but ReviewDb is still the source of truth. Change data will not be written unless the NoteDb refs are already up to date, and the write path will attempt to rebuild the change if not.

If false, the behavior when attempting to write depends on readChanges(). If readChanges() = false, writes to NoteDb are simply ignored; if true, any attempts to write will generate an error.

readChangeSequence

public abstract boolean readChangeSequence()

Read sequential change ID numbers from NoteDb.

If true, change IDs are read from refs/sequences/changes in All-Projects. If false, change IDs are read from ReviewDb's native sequences.

changePrimaryStorage

public abstract NoteDbChangeState.PrimaryStorage changePrimaryStorage()

Returns:

default primary storage for new changes.

disableChangeReviewDb

public abstract boolean disableChangeReviewDb()

Disable ReviewDb access for changes.

When set, ReviewDb operations involving the Changes table become no-ops. Lookups return no results; updates do nothing, as does opening, committing, or rolling back a transaction on the Changes table.

failOnLoad

public boolean failOnLoad()

Whether to fail when reading any data from NoteDb.

Used in conjunction with readChanges() for tests.

commitChangeWrites

public boolean commitChangeWrites()

failChangeWrites

public boolean failChangeWrites()

enabled

public boolean enabled()