Module: crdt

The main module for CRDTs:

  • Read and write CRDT objects
  • Generate CRDT metadata
  • merge CRDTs
  • how to resolve references
Source:

Methods

(static) storeVersionedObjectCRDT(obj, objBase) → {Promise.<VersionedObjectResult.<T>>}

Parameters:
Name Type Description
obj T
objBase SHA256Hash.<T>

This stores a new version for a crdt based data type.

Functionality:

  1. A diff is calculated between ob and objBase.
  2. The metadata is updated based on the changes. The details depend on the CRDT implementation. For a set a list of add / remove objects might be generated, or for a LWWRegister the current time might be recorded for the new value ...
  3. This metadata is then merged into the latest version generating a new version for the versioned object.

The interface differs from the normal storeVersionedObject only by one additional parameter: objBase. For most CRDTs we need to calculate the changes that have happened since the last version. So you have to specify on which version you based your new object on. We can't just use the latest version that is stored, because other changes might have arrived via chum in the meantime.

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Returns:

Type: Promise.<VersionedObjectResult.<T>>

(static) storeVersionedObjectCRDTMergeOnly(metadata) → {Promise.<VersionedObjectResult.<T>>}

Parameters:
Name Type Description
metadata CRDTMetaData.<T.$type$>

Generate a new version of the versioned object by merging the passed information. The data is referenced by the metadata object, so effectively you pass in metadata and data.

Source:
Returns:

Type: Promise.<VersionedObjectResult.<T>>

(async, inner) generateCrdtMetaData(obj, objBaseHash) → {Promise.<unknown>}

Parameters:
Name Type Description
obj T

The new version of the object that shall be written
objBaseHash SHA256Hash.<T>

The base object. It is used to see what changes were made in the original object.

This generates / updates metadata for all crdt variables.

This function diffs the obj against the base object in order to see what data was added / removed from the object. Then it computes new metadata that then can be merged into the versioned object with the mergeCRDTData call.

Note: This call does not write anything at the moment. It just gets the base version, compares it to the new version and returns the metadata that reflects this diff.

Source:
Returns:
  • This

Type: Promise.<unknown>

(static) generateCrdtMetadataForRule(rule, obj, objBaseopt, metadataBaseopt, crdtConfigopt) → {Promise.<(undefined|{itemprop:string, metaDataPart: *})>}

Parameters:
Name Type Attributes Description
rule RecipeRule
obj Record.<string, any>
objBase Record.<string, any> <optional>
metadataBase Record.<string, any> <optional>
crdtConfig Recipe.crdtConfig <optional>

Generate the metadata for the given rule. If case, it is recursive for unversioned reference objects.

Source:
Returns:

Type: Promise.<(undefined|{itemprop:string, metaDataPart: *})>

(async, inner) mergeCRDTData(obj, metadata, source) → {Promise.<VersionedObjectResult.<T>>}

Parameters:
Name Type Description
obj T
metadata CRDTMetaData.<T.$type$>
source "local" | "remote"

Merges an object with CRDT Annotations into a versioned object

This will generate a new version of the versioned object (if necessary).

Source:
Returns:

Type: Promise.<VersionedObjectResult.<T>>

(static) mergeCRDTDataForRule(objLatestVersion, metadataLatestVersion, objToMerge, metadataToMerge, rule, crdtConfig) → {Promise.<(undefined|{itemprop:string, data: *, metadata: *})>}

Parameters:
Name Type Description
objLatestVersion Record.<string, any> | undefined
metadataLatestVersion Record.<string, any> | undefined
objToMerge Record.<string, any> | undefined
metadataToMerge Record.<string, any> | undefined
rule RecipeRule
crdtConfig Recipe.crdtConfig

Merge CRDT data for given rule. If case, it is recursive for unversioned referenced objects.

Source:
Returns:

Type: Promise.<(undefined|{itemprop:string, data: *, metadata: *})>

(async, inner) getCrdtAndMetaObjectByIdHash(idHash) → {Object}

Parameters:
Name Type Description
idHash SHA256IdHash.<T>

Loads the latest data and metadata object for the versioned object.

Source:
Returns:

Type: Object

(async, inner) getCrdtAndMetaObject(hash) → {Object}

Parameters:
Name Type Description
hash SHA256Hash.<T>

The hash of a specific object version for which to load data and metadata.

Loads the latest data and metadata object for the versioned object.

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Returns:

Type: Object

(static) getCrdtMetaObjectWithType(hash, type) → {Promise.<OneUnversionedObjectTypes>}

Parameters:
Name Type Description
hash SHA256Hash.<T>
type OneCrdtObjectTypeNames

Obtain the meta-object of a certain type for the passed object hash.

Source:
Returns:

Type: Promise.<OneUnversionedObjectTypes>

(static) getCrdtMetaObject(hash, type) → {Promise.<OneCrdtMetaObjectTypes>}

Parameters:
Name Type Description
hash SHA256Hash.<T>
type OneCrdtObjectTypeNames

Obtain the meta-object for the passed object hash.

Source:
Returns:

Type: Promise.<OneCrdtMetaObjectTypes>

(static) getCrdtMetaObjectAsMicrodata(hash, type) → {Promise.<{microdata:string, hash:SHA256Hash.<OneCrdtMetaObjectTypes>}>}

Parameters:
Name Type Description
hash SHA256Hash.<T>
type OneCrdtObjectTypeNames

Obtain the meta-object for the passed object hash.

Source:
Returns:

Type: Promise.<{microdata:string, hash:SHA256Hash.<OneCrdtMetaObjectTypes>}>

(async, inner) storeCrdtAndMetaObject(metadata) → {Promise.<VersionedObjectResult.<T>>}

Parameters:
Name Type Description
metadata CRDTMetaData.<T.$type$>

Stores a new version of the data and metadata.

The data is not part of the interface because we expect the data object already be written to disk - but without being recorded in the version map. This can be achieved with the call storeVersionedObjectOmitVersionMap.

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Returns:

Type: Promise.<VersionedObjectResult.<T>>

(async, inner) generateMetadataForListRule(rule, objBaseChild, objChild, metadataBaseChild, crdtConfig) → {Object}

Parameters:
Name Type Description
rule RecipeRule
objBaseChild unknown
objChild unknown
metadataBaseChild unknown
crdtConfig Recipe.crdtConfig

Generate the metadata object for the given list rule.

Source:
Returns:

Type: Object

(async, inner) generateMetadataForRuleWithReferenceToObj(rule, objBaseChild, objChild, metadataBaseChild, crdtConfig) → {Promise.<{itemprop: string, metaDataPart: unknown}>}

Parameters:
Name Type Description
rule RecipeRule
objBaseChild unknown
objChild unknown
metadataBaseChild unknown
crdtConfig Recipe.crdtConfig

Generate the metadata object for the given rule with a 'referenceToObject' property. The metadata generation will go recursively if:

  • the referenced object is unversioned
  • the referenced object has only one single type
  • the referenced object has a concrete type ('*' - not accepted; it is handled with CRDT-Register algorithm)
Source:
Returns:

Type: Promise.<{itemprop: string, metaDataPart: unknown}>

(async, inner) mergeCRDTDataForListRule(rule, objLatestVersionChildHash, metadataLatestVersionChild, objToMergeChild, metadataToMergeChild, crdtConfig) → {Promise.<{itemprop:string, data: *, metadata: *}>}

Parameters:
Name Type Description
rule RecipeRule
objLatestVersionChildHash unknown
metadataLatestVersionChild unknown
objToMergeChild unknown
metadataToMergeChild unknown
crdtConfig Recipe.crdtConfig

Merge CRDT data for list rule.

Source:
Returns:

Type: Promise.<{itemprop:string, data: *, metadata: *}>

(async, inner) mergeCRDTDataForRuleWithReferenceToObj(rule, objLatestVersionChild, metadataLatestVersionChild, metadataToMergeChild, objToMergeChild, crdtConfig) → {Promise.<{itemprop: string, data: unknown, metadata: unknown}>}

Parameters:
Name Type Description
rule RecipeRule
objLatestVersionChild unknown
metadataLatestVersionChild unknown
metadataToMergeChild unknown
objToMergeChild unknown
crdtConfig Recipe.crdtConfig

Merge CRDT data for the given rule with a 'referenceToObject' property. The data is merging is done recursively if:

  • the referenced object is unversioned
  • the referenced object has only one single type
  • the referenced object has a concrete type ('*' - not accepted; it is handled with CRDT-Register algorithm)
Source:
Returns:

Type: Promise.<{itemprop: string, data: unknown, metadata: unknown}>