public class | source

SynchronousTransaction

Extends:

Transaction → SynchronousTransaction

Implements:

Indirect Implements:

Synchronous transactions avoid unnecessary async/await calls by preloading and caching all necessary key-value-pairs.

WARNING: If not all required key-value-pairs are preloaded, the results of any call on a synchronous transaction might be wrong. Only use synchronous transactions, if unavoidable.

Constructor Summary

Protected Constructor
protected	constructor(objectStore: ObjectStore, parent: IObjectStore, managingBackend: ICommittable, enableWatchdog: boolean) This constructor should only be called by an ObjectStore object.

Method Summary

Public Methods
public	async get(key: string, options: RetrievalConfig): *
public	getSync(key: string, options: SyncRetrievalConfig): * Returns the object stored under the given primary key.
public	isCached(key: string): boolean A check whether a certain key is cached.
public	isSynchronous(): boolean Checks whether an object store implements the ISynchronousObjectStore interface.
public	preload(keys: Array<string>): Promise This method preloads a set of keys and caches them.

Inherited Summary

From class Transaction
public get	connected: boolean
public get	dependency: CombinedTransaction
public get	id: number
public get	indices: Map<string, IIndex> A map of index names to indices.
public get	nested: boolean
public get	objectStore: ObjectStore
public get	state: Transaction.STATE: * The transaction's current state.
public	async abort(tx: Transaction): Promise<boolean> Aborts a transaction and (if this was the last open transaction) potentially persists the most recent, committed state.
public	close(): Promise Alias for abort.
public	async commit(tx: Transaction): Promise<boolean> Commits a transaction to the underlying backend.
public	async count(query: KeyRange): Promise<number> Returns the count of entries in the given range.
public	decode(value: , key: string): Method called to decode a single value.
public	encode(value: ): Method called to encode a single value.
public	async get(key: string, options: RetrievalConfig): Promise<*> Returns a promise of the object stored under the given primary key.
public	index(indexName: string): IIndex Returns the index of the given name.
public	isSynchronous(): boolean Checks whether an object store implements the ISynchronousObjectStore interface.
public	async keyStream(callback: function(key: string): boolean, ascending: boolean, query: KeyRange): Promise Iterates over the keys in a given range and direction.
public	async keys(query: Query \| KeyRange): Promise<Set<string>> Returns a promise of a set of keys fulfilling the given query.
public	async maxKey(query: KeyRange): Promise<string> Returns a promise of the key being maximal for the given range.
public	async maxValue(query: KeyRange): Promise<*> Returns a promise of the object whose primary key is maximal for the given range.
public	async minKey(query: KeyRange): Promise<string> Returns a promise of the key being minimal for the given range.
public	async minValue(query: KeyRange): Promise<*> Returns a promise of the object whose primary key is minimal for the given range.
public	async put(key: string, value: *): Promise Inserts or replaces a key-value pair.
public	putSync(key: string, value: *) Inserts or replaces a key-value pair.
public	async remove(key: string): Promise Removes the key-value pair of the given key from the object store.
public	removeSync(key: string) Removes the key-value pair of the given key from the object store.
public	snapshot(): Snapshot Creates an in-memory snapshot of this state.
public	synchronousTransaction(enableWatchdog: boolean): SynchronousTransaction Creates a nested synchronous transaction, ensuring read isolation.
public	toString(): string
public	toStringShort(): string
public	transaction(enableWatchdog: boolean): Transaction Creates a nested transaction, ensuring read isolation.
public	async truncate(): Promise Empties the object store.
public	async valueStream(callback: function(value: *, key: string): boolean, ascending: boolean, query: KeyRange): Promise Iterates over the keys and values in a given range and direction.
public	async values(query: Query \| KeyRange): Promise<Array<*>> Returns a promise of an array of objects whose primary keys fulfill the given query.
protected	async _apply(tx: Transaction): Promise Internally applies a transaction to the transaction's state. This needs to be done in batch (as a db level transaction), i.e., either the full state is updated or no changes are applied.
protected	_applySync(tx: Transaction) Non-async version of _apply that does not update snapshots.
protected	async _checkConstraints(): Promise<boolean> Is used to check constraints before committing.
protected	async _commitBackend(): Promise<boolean> Commits the transaction to the backend.
protected	async _commitInternal(tx: Transaction): Promise Is used to commit the transaction to the in memory state.
protected	_isCommittable(tx: Transaction): boolean Is used to probe whether a transaction can be committed.
protected	_put(key: string, value: *) Internal method for inserting/replacing a key-value pair.
protected	_remove(key: string) Internal method for removing a key-value pair.
protected	_setParent(parent: *) Allows to change the backend of a Transaction when the state has been flushed.
protected	truncateSync() Non-async variant to empty the object store.

Protected Constructors

protected constructor(objectStore: ObjectStore, parent: IObjectStore, managingBackend: ICommittable, enableWatchdog: boolean) source

This constructor should only be called by an ObjectStore object. Our transactions have a watchdog enabled by default, logging a warning after a certain time specified by WATCHDOG_TIMER. This helps to detect unclosed transactions preventing to store the state in the persistent backend.

Override:

Transaction#constructor

Params:

Name	Type	Attribute	Description
objectStore	ObjectStore		The object store this transaction belongs to.
parent	IObjectStore		The backend on which the transaction is based, i.e., another transaction or the real database.
managingBackend	ICommittable	optional	The object store managing the transactions, i.e., the ObjectStore object.
enableWatchdog	boolean	optional	If this is is set to true (default), a warning will be logged if left open for longer than WATCHDOG_TIMER.

Public Methods

public async get(key: string, options: RetrievalConfig): * source

Returns a promise of the object stored under the given primary key. Resolves to undefined if the key is not present in the object store.

Override:

Transaction#get

Params:

Name	Type	Attribute	Description
key	string
options	RetrievalConfig	optional	Advanced retrieval options.

Return:

public getSync(key: string, options: SyncRetrievalConfig): * source

Returns the object stored under the given primary key. Resolves to undefined if the key is not present in the object store.

Params:

Name	Type	Attribute	Description
key	string		The primary key to look for.
options	SyncRetrievalConfig	optional	Advanced retrieval options.

Return:

*	The object stored under the given key, or undefined if not present.

public isCached(key: string): boolean source

A check whether a certain key is cached.

Params:

Name	Type	Attribute	Description
key	string		The key to check.

Return:

boolean

A boolean indicating whether the key is already in the cache.

public isSynchronous(): boolean source

Checks whether an object store implements the ISynchronousObjectStore interface.

Override:

Transaction#isSynchronous

Return:

boolean

The transaction object.

public preload(keys: Array<string>): Promise source

This method preloads a set of keys and caches them. It can be called as often as needed.

Params:

Name	Type	Attribute	Description
keys	Array<string>		The keys to preload.

Return:

Promise