io.permazen.kv.mvcc

Class Reads

java.lang.Object

io.permazen.kv.KeyRanges

io.permazen.kv.mvcc.Reads

All Implemented Interfaces:

KeyFilter, Cloneable, Iterable<KeyRange>

public class Reads
extends KeyRanges

Holds a set of reads from a KVStore.

Only the (ranges of) keys read are retained, not the values.

Instances are not thread safe.

Constructor Summary

Constructors

Constructor and Description
Reads() Construct an empty instance.
Reads(InputStream input) Constructor to deserialize an instance created by serialize().
Reads(KeyRanges ranges) Construct an instance containing the given key ranges.

Method Summary

Modifier and Type	Method and Description
Reads	clone() Clone this instance.
List<String>	getConflicts(Mutations mutations) List the conflicts between the given mutations and any of the keys read by this instance.
Reads	immutableSnapshot() Return an immutable snapshot of this instance.
boolean	isConflict(Mutations mutations) Determine whether any of the given mutations conflict with any of the keys read by this instance.

Methods inherited from class io.permazen.kv.KeyRanges

add, add, asList, asSet, clear, contains, contains, contains, deserializeIterator, empty, equals, findKey, forPrefix, full, getMax, getMin, hashCode, intersect, intersect, intersects, inverse, isEmpty, isFull, iterator, prefixedBy, remove, remove, seekHigher, seekLower, serialize, serializedLength, size, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

Reads

public Reads()

Construct an empty instance.

Reads

public Reads(KeyRanges ranges)

Construct an instance containing the given key ranges.

Parameters:

ranges - initial key ranges

Throws:

IllegalArgumentException - if ranges is null

Reads

public Reads(InputStream input)
      throws IOException

Constructor to deserialize an instance created by serialize().

Parameters:

input - input stream containing data from serialize()

Throws:

IOException - if an I/O error occurs

EOFException - if the input ends unexpectedly

IllegalArgumentException - if input is null

IllegalArgumentException - if input is invalid

Method Detail

isConflict

public boolean isConflict(Mutations mutations)

Determine whether any of the given mutations conflict with any of the keys read by this instance.

If this method returns false, then if two transactions T1 and T2 are based on the same underlying KVStore snapshot, and T1 writes mutations and T2 reads according to this instance, then T2 can be ordered after T1 while still preserving linearizable semantics. That is, the given mutations are invisible to this instance.

This method guarantees that it will access the given mutations in this order: removes, puts, adjusts.

Parameters:

mutations - mutations to check for conflicts

Returns:

true if the mutations are invisible to this instance, false if there is a read/write conflict

Throws:

IllegalArgumentException - if mutations is null

getConflicts

public List<String> getConflicts(Mutations mutations)

List the conflicts between the given mutations and any of the keys read by this instance.

This gives descriptive details about the conflicts reported by isConflict(); see that method for information on these conflicts. This method returns an empty list if and only if isConflict() returns false.

Parameters:

mutations - mutations to check for conflicts with this instance

Returns:

a description of each conflict between this instance and the given mutations

Throws:

IllegalArgumentException - if mutations is null

clone

public Reads clone()

Description copied from class: KeyRanges

Clone this instance.

The returned clone will always be mutable, even if this instance is not.

Overrides:

clone in class KeyRanges

immutableSnapshot

public Reads immutableSnapshot()

Description copied from class: KeyRanges

Return an immutable snapshot of this instance.

Overrides:

immutableSnapshot in class KeyRanges

Returns:

immutable snapshot