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Index ¶
Constants ¶
This section is empty.
Variables ¶
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var ( // ErrStoreNotFound is returned when a store is not found. ErrStoreNotFound = errors.New("store not found") // ErrDataNotFound is returned when data is not found. ErrDataNotFound = errors.New("data not found") // ErrDuplicateKey is returned when a call is made to Store.Batch using the IsNewKey PutOption with a key that // already exists in the database. ErrDuplicateKey = errors.New("duplicate key") )
Functions ¶
This section is empty.
Types ¶
type Iterator ¶
type Iterator interface {
// Next moves the pointer to the next entry in the iterator.
// Note that it must be called before accessing the first entry.
// It returns false if the iterator is exhausted - this is not considered an error.
Next() (bool, error)
// Key returns the key of the current entry.
Key() (string, error)
// Value returns the value of the current entry.
Value() ([]byte, error)
// Tags returns the tags associated with the key of the current entry.
// As of writing, aries-framework-go code does not use this, but it may be useful for custom solutions.
Tags() ([]Tag, error)
// TotalItems returns a count of the number of entries (key + value + tags triplets) matched by the query
// that generated this Iterator. This count is not affected by the page settings used (i.e. the count is of all
// results as if you queried starting from the first page and with an unlimited page size).
// Depending on the storage implementation, you may need to ensure that the TagName used in the query is in the
// Store's StoreConfiguration before trying to call this method (or it may be optional, but recommended).
// As of writing, aries-framework-go code does not use this, but it may be useful for custom solutions.
TotalItems() (int, error)
// Close closes this iterator object, freeing resources.
Close() error
}
Iterator allows for iteration over a collection of entries in a store.
type MultiError ¶
type MultiError interface {
error
Errors() []error // Errors returns the error objects for all operations.
}
MultiError represents the errors that occurred during a bulk operation.
type Operation ¶
type Operation struct {
Key string `json:"key,omitempty"`
Value []byte `json:"value,omitempty"` // A nil value will result in a delete operation.
Tags []Tag `json:"tags,omitempty"` // Optional.
PutOptions *PutOptions `json:"putOptions,omitempty"` // Optional. Only used for Put Operations.
}
Operation represents an operation to be performed in the Batch method.
type Provider ¶
type Provider interface {
// OpenStore opens a Store with the given name and returns it.
// Depending on the store implementation, this may or may not create an underlying database.
// The store implementation may defer creating the underlying database until SetStoreConfig is called or
// data is inserted using Store.Put or Store.Batch.
// Store names are not case-sensitive. If name is blank, then an error will be returned.
OpenStore(name string) (Store, error)
// SetStoreConfig sets the configuration on a Store. It's recommended calling this method at some point before
// calling Store.Query if your store contains a large amount of data. The underlying database will use this to
// create indexes to make querying via the Store.Query method faster. If you don't need to use Store.Query, then
// you don't need to call this method. OpenStore must be called first before calling this method. If not, then an
// error wrapping ErrStoreNotFound will be returned. This method will not open the store automatically.
// If name is blank, then an error will be returned.
SetStoreConfig(name string, config StoreConfiguration) error
// GetStoreConfig gets the current Store configuration.
// This method operates a bit differently in that it directly checks the underlying storage implementation to see
// if the underlying database exists for the given name, rather than checking the currently known list of
// open stores in memory. If no underlying database can be found, then an error wrapping ErrStoreNotFound will be
// returned. This means that this method can be used to determine whether an underlying database for a Store
// already exists or not. This method will not create the database automatically.
// If name is blank, then an error will be returned.
// As of writing, aries-framework-go code does not use this, but it may be useful for custom solutions.
GetStoreConfig(name string) (StoreConfiguration, error)
// GetOpenStores returns all Stores that are currently open in memory from calling OpenStore.
// It does not check for all databases that have been created before. They have to have been opened in this Provider
// object's lifetime from a call to OpenStore.
// As of writing, aries-framework-go code does not use this, but it may be useful for custom solutions.
GetOpenStores() []Store
// Close closes all open Stores in this Provider
// For persistent Store implementations, this does not delete any data in the underlying databases.
Close() error
}
Provider represents a storage provider.
type PutOptions ¶
type PutOptions struct {
// This is an optimization for a Put Operation. Some storage providers may be able to store data faster if they
// know beforehand that this key does not currently exist in the database. Unexpected behaviour may occur if
// this is set to true and the key already exists. See the documentation for the specific storage provider to
// see if and how this option is used.
IsNewKey bool `json:"isNewKey,omitempty"`
}
PutOptions represents options for a Put Operation.
type QueryOption ¶
type QueryOption func(opts *QueryOptions)
QueryOption represents an option for a Store.Query call.
func WithInitialPageNum ¶
func WithInitialPageNum(initialPageNum int) QueryOption
WithInitialPageNum sets the page number for an Iterator to start from. If this option isn't used, then the Iterator will start from the first page. Page number counting starts from 0 (i.e. initialPageNum=0 means that the iterator will start from the first page).
func WithPageSize ¶
func WithPageSize(size int) QueryOption
WithPageSize sets the maximum page size for data retrievals done within the Iterator returned by the Query call. Paging is handled internally by the Iterator. Higher values may reduce CPU time and the number of database calls at the expense of higher memory usage.
func WithSortOrder ¶
func WithSortOrder(sortOptions *SortOptions) QueryOption
WithSortOrder sets the sort order used by a Store.Query call. See SortOptions for more information. If this option isn't used, then the result order from the Iterator will be determined (perhaps arbitrarily) by the underlying database implementation. As of writing, aries-framework-go code does not use this, but it may be useful for custom solutions.
type QueryOptions ¶
type QueryOptions struct {
// PageSize sets the page size used by the Store.Query method.
PageSize int
// InitialPageNum sets the page for the iterator returned from Store.Query to start from.
// InitialPageNum=0 means start from the first page.
InitialPageNum int
// SortOptions defines the sort order.
SortOptions *SortOptions
}
QueryOptions represents various options for Query calls in a store.
type SortOptions ¶
SortOptions sets the order that results from an Iterator will be returned in. Sorting is based on the tag values associated with the TagName chosen below. The TagName you use below can be the same as the one you're querying on, or it can be a different one. Depending on the storage implementation, you may need to ensure that the TagName set below is in the Store's StoreConfiguration before trying to use it for sorting (or it may be optional, but recommended). If tag value strings are decimal numbers, then the sorting must be based on their numerical value instead of the string representations of those numbers (i.e. numerical sorting, not lexicographic). TagName cannot be blank.
type Store ¶
type Store interface {
// Put stores the key + value pair along with the (optional) tags. If the key already exists in the database,
// then the value and tags will be overwritten silently.
// If value is a JSON-formatted object, then an underlying storage implementation may store it in a way that
// does not preserve the order of the fields. Therefore, you should avoid doing direct byte-for-byte comparisons
// with data put in and data retrieved, as the marshalled representation may be different - always unmarshal data
// first before comparing.
// If key is empty or value is nil, then an error will be returned.
// A single key-value pair cannot have multiple tags that share the same tag name.
Put(key string, value []byte, tags ...Tag) error
// Get fetches the value associated with the given key.
// If key cannot be found, then an error wrapping ErrDataNotFound will be returned.
// If key is empty, then an error will be returned.
Get(key string) ([]byte, error)
// GetTags fetches all tags associated with the given key.
// If key cannot be found, then an error wrapping ErrDataNotFound will be returned.
// If key is empty, then an error will be returned.
// As of writing, aries-framework-go code does not use this, but it may be useful for custom solutions.
GetTags(key string) ([]Tag, error)
// GetBulk fetches the values associated with the given keys.
// If no data exists under a given key, then a nil []byte is returned for that value. It is not considered an error.
// Depending on the implementation, this method may be faster than calling Get for each key individually.
// If any of the given keys are empty, then an error will be returned.
// As of writing, aries-framework-go code does not use this, but it may be useful for custom solutions.
GetBulk(keys ...string) ([][]byte, error)
// Query returns all data that satisfies the expression. Basic expression format: TagName:TagValue.
// If TagValue is not provided, then all data associated with the TagName will be returned, regardless of their
// tag values.
// At a minimum, a store implementation must be able to support querying with a single basic expression, but a
// store implementation may also support a more advanced expression format.
// Advanced expression format: [Criterion1][Operator][Criterion2][Operator]...[CriterionN]. Square brackets are
// used here for visual clarity. Omit them from the actual expression string.
// Each Criterion follows the rules for the basic expression format described above.
// Each operator must be either "&&" or "||" (without quotes). "&&" indicates an AND operator while "||"
// indicates an OR operator. The order of operations are ANDs followed by ORs.
// This method also supports a number of QueryOptions. If none are provided, then defaults will be used.
// If your store contains a large amount of data, then it's recommended calling Provider.SetStoreConfig at some
// point before calling this method in order to create indexes which will speed up queries.
Query(expression string, options ...QueryOption) (Iterator, error)
// Delete deletes the key + value pair (and all tags) associated with key.
// If key is empty, then an error will be returned.
Delete(key string) error
// Batch performs multiple Put and/or Delete operations in order. The Puts and Deletes here follow the same rules
// as described in the Put and Delete method documentation. The only exception is if the operation makes use of
// the PutOptions.IsNewKey optimization, in which case an error wrapping an ErrDuplicateKey may be returned if it's
// enabled and a key is used that already exists in the database.
// Depending on the implementation, this method may be faster than repeated Put and/or Delete calls.
// If any of the given keys are empty, or the operations slice is empty or nil, then an error will be returned.
// As of writing, aries-framework-go code does not use this, but it may be useful for custom solutions.
Batch(operations []Operation) error
// Flush forces any queued up Put and/or Delete operations to execute.
// If the Store implementation doesn't queue up operations, then this method is a no-op.
// As of writing, aries-framework-go code does not use this, but it may be useful for custom solutions.
Flush() error
// Close closes this store object, freeing resources. For persistent store implementations, this does not delete
// any data in the underlying databases.
// Close can be called repeatedly on the same store multiple times without causing an error.
Close() error
}
Store represents a storage database.
type StoreConfiguration ¶
type StoreConfiguration struct {
// TagNames is a list of Tag names to create indexes on.
// Tag names cannot contain any ':' characters.
TagNames []string `json:"tagNames,omitempty"`
}
StoreConfiguration represents the configuration of a store. Currently, it's only used for creating indexes in underlying storage databases.
type Tag ¶
type Tag struct {
// Name can be used to tag a given key + value pair as belonging to some sort of common
// group. Example: Identifying a key+value pair as being a Verifiable Credential by storing it
// with a tag Name called "VC". When used with the optional Value (see below), tag Name + Value can be used to
// specify metadata for a given key + value pair. Example: Identifying a Verifiable Credential (stored as a
// key+value pair) as belonging to a user account by using a tag Name called "UserAccount" and a tag Value called
// "bob@example.com". Tag Names are intended to be static values that the store is configured with in order to build
// indexes for queries (see TagNames in StoreConfiguration).
// Tag Names cannot contain any ':' characters.
Name string `json:"name,omitempty"`
// Value can optionally be used to indicate some metadata associated with a tag name for a given key + value pair.
// See Name above for an example of how this can be used.
// Tag Values are dynamic and are not specified in a StoreConfiguration.
// Tag Values cannot contain any ':' characters.
Value string `json:"value,omitempty"`
}
Tag represents a Name + Value pair that can be associated with a key + value pair for querying later.
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