BTreeDBM class

B+tree implementation of SortedDBM. Stores tree nodes as entries in an underlying DBM (typically HashDBM).

Node IDs are sequential uint64s encoded as 8-byte big-endian keys. ID 0 is reserved for the meta record.

Implemented types

• SortedDBM

Constructors

BTreeDBM(RandomAccessFile file, {int order = 128, int buckets = 49999, bool flush = true, bool crc = false, int cache = 256, KeyComparator? comparator})

Create a new BTreeDBM that owns a HashDBM built from file.

BTreeDBM.wrap(DBM store, {int order = 128, int cache = 256, KeyComparator? comparator})

Wrap an existing DBM as storage. The caller retains ownership of store and is responsible for closing it.

Properties

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

ceiling(Uint8List key) → MapEntry<Uint8List, Uint8List>?

Return the smallest entry with key greater than or equal to key, or null if no such entry exists.

override

clear() → void

Erases all data and resets the internal structure, but does not reclaim storage.

override

close() → void

flush() and close the underlying file.

override

compact() → int

Truncate trailing free blocks at end-of-file and return bytes reclaimed.

override

count() → int

Get the number of records stored in the database as a Uint64

override

entries() → Iterator<MapEntry<Uint8List, Uint8List>>

Iterate over all keys and values in the database

override

first() → MapEntry<Uint8List, Uint8List>?

Return the first (smallest) entry, or null if empty.

override

floor(Uint8List key) → MapEntry<Uint8List, Uint8List>?

Return the greatest entry with key less than or equal to key, or null if no such entry exists.

override

flush() → void

Flush all data to external storage.

override

get(Uint8List key) → Uint8List?

Get a value from the database using key, or else return null

override

last() → MapEntry<Uint8List, Uint8List>?

Return the last (largest) entry, or null if empty.

override

modified() → DateTime

Get the last time the database was opened or modified.

override

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

put(Uint8List key, Uint8List value) → Uint8List?

Add a key, value pair to the underlying store, overwriting any existing values. Returns the old value if one existed, otherwise returns the new value.

override

putIfAbsent(Uint8List key, Uint8List value) → Uint8List

Add a key, value pair to the underlying store if not key is in the underlying store. Returns the old value if key existed, otherwise value is returned.

override

range({Uint8List? start, Uint8List? end}) → Iterator<MapEntry<Uint8List, Uint8List>>

Iterate entries in sorted order from start (inclusive) to end (exclusive). If start is null, iteration begins at the first key. If end is null, iteration continues through the last key.

override

remove(Uint8List key) → Uint8List?

Remove a value from the database using key. If the key had an associated value, return the value or else return null

override

size() → int

Get the size, in bytes, of data stored. This is intended to track approximate data size and will differ from the size of the file itself.

override

toString() → String

A string representation of this object.

inherited

version() → int

Get the version of the underlying implementation as a 32bit integer.

override

Operators

operator ==(Object other) → bool

The equality operator.

inherited