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refactor(CRDT): introduce CrdtNodeId type alias
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Replace ulong with CrdtNodeId for node identifiers throughout
the CRDT implementation. Update method signatures, comparisons,
and related logic to use the new type alias for clarity.
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@sinkingsugar
sinkingsugar committed Oct 15, 2024
1 parent a909d53 commit 9dc5818
Showing 1 changed file with 21 additions and 18 deletions.
39 changes: 21 additions & 18 deletions CRDT.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,8 @@

#nullable enable

using CrdtNodeId = ulong;

// Namespace for CRDT implementation
namespace ForSync.CRDT {
/// <summary>
Expand Down Expand Up @@ -52,10 +54,10 @@ public void SetTime(ulong t) {
public struct ColumnVersion {
public ulong ColVersion { get; set; }
public ulong DbVersion { get; set; }
public ulong NodeId { get; set; }
public CrdtNodeId NodeId { get; set; }
public ulong LocalDbVersion { get; set; }

public ColumnVersion(ulong c, ulong d, ulong n, ulong ldbVer = 0) {
public ColumnVersion(ulong c, ulong d, CrdtNodeId n, ulong ldbVer = 0) {
ColVersion = c;
DbVersion = d;
NodeId = n;
Expand Down Expand Up @@ -151,14 +153,15 @@ public class Change<K, V> {
public V? Value { get; set; } // null represents deletion of the column, not the record
public ulong ColVersion { get; set; }
public ulong DbVersion { get; set; }
public ulong NodeId { get; set; }
public CrdtNodeId NodeId { get; set; }
public ulong LocalDbVersion { get; set; }

public Change() {
RecordId = default!;
Value = default!;
}

public Change(K recordId, ColName<K>? colName, V? value, ulong colVersion, ulong dbVersion, ulong nodeId, ulong localDbVersion = 0) {
public Change(K recordId, ColName<K>? colName, V? value, ulong colVersion, ulong dbVersion, CrdtNodeId nodeId, ulong localDbVersion = 0) {
RecordId = recordId;
ColName = colName;
Value = value;
Expand Down Expand Up @@ -200,7 +203,7 @@ public int Compare(Change<K, V>? a, Change<K, V>? b) {
return a.DbVersion > b.DbVersion ? -1 : 1;

if (a.NodeId != b.NodeId)
return a.NodeId > b.NodeId ? -1 : 1;
return a.NodeId.CompareTo(b.NodeId);

return 0; // Consider equal if all fields match
}
Expand All @@ -210,19 +213,19 @@ public int Compare(Change<K, V>? a, Change<K, V>? b) {
/// Represents the CRDT structure, generic over key (K) and value (V) types.
/// </summary>
public class CRDT<K, V> {
private ulong _nodeId;
private CrdtNodeId _nodeId;
private LogicalClock _clock;
private Dictionary<K, Record<K, V>> _data;

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The type 'K' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'K' doesn't match 'notnull' constraint.

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The type 'K' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'K' doesn't match 'notnull' constraint.
private HashSet<K> _tombstones;

private CRDT<K, V>? _parent;
private ulong _baseVersion;

public ulong NodeId => _nodeId;
public CrdtNodeId NodeId => _nodeId;
public ulong Clock => _clock.CurrentTime;
public ulong BaseVersion => _baseVersion;

public CRDT(ulong nodeId, CRDT<K, V>? parent = null) {
public CRDT(CrdtNodeId nodeId, CRDT<K, V>? parent = null) {
_nodeId = nodeId;
_clock = new LogicalClock();
_data = new Dictionary<K, Record<K, V>>();

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The type 'K' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'K' doesn't match 'notnull' constraint.

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Expand All @@ -245,7 +248,7 @@ public CRDT(ulong nodeId, CRDT<K, V>? parent = null) {
/// <summary>
/// Creates a CRDT from a list of changes (e.g., loaded from disk).
/// </summary>
public CRDT(ulong nodeId, List<Change<K, V>> changes) {
public CRDT(CrdtNodeId nodeId, List<Change<K, V>> changes) {
_nodeId = nodeId;
_clock = new LogicalClock();
_data = new Dictionary<K, Record<K, V>>();

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Expand Down Expand Up @@ -278,7 +281,7 @@ public List<Change<K, V>> InvertChanges(List<Change<K, V>> changes, bool usePare

if (colName == null) {
// The change was a record deletion (tombstone)
Record<K, V>? recordPtr = useParent ? GetRecordPtr(recordId, true) : GetRecordPtr(recordId);
Record<K, V>? recordPtr = useParent ? GetRecord(recordId, true) : GetRecord(recordId);

if (recordPtr != null) {
// Restore all fields from the record
Expand All @@ -304,7 +307,7 @@ public List<Change<K, V>> InvertChanges(List<Change<K, V>> changes, bool usePare
} else {
// The change was an insertion or update of a column
ColName<K> col = colName.Value;
Record<K, V>? recordPtr = useParent ? GetRecordPtr(recordId, true) : GetRecordPtr(recordId);
Record<K, V>? recordPtr = useParent ? GetRecord(recordId, true) : GetRecord(recordId);

if (recordPtr != null) {
if (recordPtr.Fields.TryGetValue(col, out V existingValue)) {

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Converting null literal or possible null value to non-nullable type.
Expand Down Expand Up @@ -497,14 +500,14 @@ public List<Change<K, V>> MergeChanges(List<Change<K, V>> changes, bool ignorePa
ColName<K>? colName = change.ColName;
ulong remoteColVersion = change.ColVersion;
ulong remoteDbVersion = change.DbVersion;
ulong remoteNodeId = change.NodeId;
CrdtNodeId remoteNodeId = change.NodeId;
V? remoteValue = change.Value;

// Update the logical clock
ulong newLocalDbVersion = _clock.Update(remoteDbVersion);

// Retrieve local column version information
Record<K, V>? recordPtr = GetRecordPtr(recordId, ignoreParent);
Record<K, V>? recordPtr = GetRecord(recordId, ignoreParent);
ColumnVersion? localColInfo = null;

if (recordPtr != null) {
Expand Down Expand Up @@ -535,7 +538,7 @@ public List<Change<K, V>> MergeChanges(List<Change<K, V>> changes, bool ignorePa
shouldAccept = false;
} else {
// db_version is equal; use node_id for final tiebreaking
shouldAccept = remoteNodeId > localColInfo.Value.NodeId;
shouldAccept = remoteNodeId.CompareTo(localColInfo.Value.NodeId) > 0;
}
}
}
Expand Down Expand Up @@ -704,7 +707,7 @@ private void ApplyChanges(List<Change<K, V>> changes) {
ColName<K>? colName = change.ColName;
ulong remoteColVersion = change.ColVersion;
ulong remoteDbVersion = change.DbVersion;
ulong remoteNodeId = change.NodeId;
CrdtNodeId remoteNodeId = change.NodeId;
ulong remoteLocalDbVersion = change.LocalDbVersion;
V? remoteValue = change.Value;

Expand Down Expand Up @@ -757,12 +760,12 @@ private bool IsRecordTombstoned(K recordId, bool ignoreParent = false) {
/// <summary>
/// Retrieves a record pointer.
/// </summary>
private Record<K, V>? GetRecordPtr(K recordId, bool ignoreParent = false) {
public Record<K, V>? GetRecord(K recordId, bool ignoreParent = false) {
if (_data.TryGetValue(recordId, out Record<K, V>? record))
return record;

if (_parent != null && !ignoreParent)
return _parent.GetRecordPtr(recordId);
return _parent.GetRecord(recordId);

return null;
}
Expand All @@ -775,7 +778,7 @@ private Record<K, V> GetOrCreateRecordUnchecked(K recordId, bool ignoreParent =
_data[recordId] = new Record<K, V>();

if (_parent != null && !ignoreParent) {
Record<K, V>? parentRecord = _parent.GetRecordPtr(recordId);
Record<K, V>? parentRecord = _parent.GetRecord(recordId);
if (parentRecord != null)
_data[recordId] = new Record<K, V>(new Dictionary<ColName<K>, V>(parentRecord.Fields),
new Dictionary<ColName<K>, ColumnVersion>(parentRecord.ColumnVersions));
Expand Down

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