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

Method Summary

Modifier and Type	Method	Description
Reads	clone()	Clone this instance.
Conflict	findConflict(Mutations mutations)	Determine whether any of the given mutations conflict with any of the keys read by this instance, and report the first conflict found.
List<Conflict>	getAllConflicts(Mutations mutations)	List all of the conflicts between the given mutations and any of the keys read by this instance.
List<String>	getConflicts(Mutations mutations)	List all of the conflicts between the given mutations and any of the keys read by this instance, in String form.
boolean	isConflict(Mutations mutations)	Determine whether any of the given mutations conflict with any of the keys read by this instance.
Reads	readOnlySnapshot()	Return an immutable snapshot of 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 Details

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 Details

isConflict

public boolean isConflict(Mutations mutations)

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

This method is equivalent to invoking findConflict() and checking whether it returns non-null.

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 this instance contains a key modified by mutations

Throws:

IllegalArgumentException - if mutations is null

See Also:

• findConflict()
• getAllConflicts()

findConflict

public Conflict findConflict(Mutations mutations)

Determine whether any of the given mutations conflict with any of the keys read by this instance, and report the first conflict found.

If this method returns null, 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:

the first Conflict found, or null if there are no conflicts

Throws:

IllegalArgumentException - if mutations is null

See Also:

• getAllConflicts()
• isConflict()

getConflicts

public List<String> getConflicts(Mutations mutations)

List all of the conflicts between the given mutations and any of the keys read by this instance, in String form.

This method simply invokes getAllConflicts() and returns the resulting list converted into String objects via Object.toString().

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

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

See Also:

• getAllConflicts()

getAllConflicts

public List<Conflict> getAllConflicts(Mutations mutations)

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

Returns:

list of each conflict between this instance and the given mutations

Throws:

IllegalArgumentException - if mutations is null

See Also:

• findConflict()
• isConflict()

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

readOnlySnapshot

public Reads readOnlySnapshot()

Description copied from class: KeyRanges

Return an immutable snapshot of this instance.

Overrides:

readOnlySnapshot in class KeyRanges

Returns:

immutable snapshot