dson 0.3.0

A delta-state CRDT implementation
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370

//! Tests for transaction rollback behavior.
//!
//! When a transaction is dropped without calling commit(), all changes
//! should be rolled back, leaving the original store unchanged.

use dson::{
    CausalDotStore, Identifier, OrArray, OrMap,
    crdts::mvreg::MvRegValue,
    transaction::{ArrayTransaction, CrdtValue, MapTransaction},
};

#[test]
fn map_transaction_rollback_register() {
    let mut store = CausalDotStore::<OrMap<String>>::default();
    let id = Identifier::new(0, 0);

    // Create initial state
    {
        let mut tx = MapTransaction::new(&mut store, id);
        tx.write_register("name", MvRegValue::String("Alice".to_string()));
        let _delta = tx.commit();
    }

    // Clone store to compare later
    let original_store = store.clone();

    // Start transaction and make changes but DON'T commit
    {
        let mut tx = MapTransaction::new(&mut store, id);
        tx.write_register("name", MvRegValue::String("Bob".to_string()));
        tx.write_register("age", MvRegValue::U64(30));
        // Drop tx without calling commit() - should rollback
    }

    // Store should be unchanged
    assert_eq!(store, original_store);

    // Verify original value still present
    let tx = MapTransaction::new(&mut store, id);
    match tx.get(&"name".to_string()) {
        Some(CrdtValue::Register(reg)) => {
            use dson::crdts::snapshot::ToValue;
            assert_eq!(
                reg.value().unwrap(),
                &MvRegValue::String("Alice".to_string())
            );
        }
        _ => panic!("Expected register with original value"),
    }

    // Verify new key was NOT added
    assert!(tx.get(&"age".to_string()).is_none());
}

#[test]
fn map_transaction_rollback_nested_map() {
    let mut store = CausalDotStore::<OrMap<String>>::default();
    let id = Identifier::new(0, 0);

    // Create initial state with nested map
    {
        let mut tx = MapTransaction::new(&mut store, id);
        tx.in_map("config", |cfg_tx| {
            cfg_tx.write_register("version", MvRegValue::U64(1));
        });
        let _delta = tx.commit();
    }

    let original_store = store.clone();

    // Modify nested map but don't commit
    {
        let mut tx = MapTransaction::new(&mut store, id);
        tx.in_map("config", |cfg_tx| {
            cfg_tx.write_register("version", MvRegValue::U64(2));
            cfg_tx.write_register("debug", MvRegValue::Bool(true));
        });
        // Drop without commit
    }

    // Store should be unchanged
    assert_eq!(store, original_store);

    // Verify original nested value
    use dson::crdts::snapshot::ToValue;
    let config = store.store.get(&"config".to_string()).unwrap();
    let version = config.map.get(&"version".to_string()).unwrap();
    assert_eq!(version.reg.value().unwrap(), &MvRegValue::U64(1));
    assert!(config.map.get(&"debug".to_string()).is_none());
}

#[test]
fn map_transaction_rollback_array() {
    let mut store = CausalDotStore::<OrMap<String>>::default();
    let id = Identifier::new(0, 0);

    // Create initial state with array
    {
        let mut tx = MapTransaction::new(&mut store, id);
        tx.in_array("items", |arr_tx| {
            arr_tx.insert_register(0, MvRegValue::String("first".to_string()));
        });
        let _delta = tx.commit();
    }

    let original_store = store.clone();

    // Modify array but don't commit
    {
        let mut tx = MapTransaction::new(&mut store, id);
        tx.in_array("items", |arr_tx| {
            arr_tx.insert_register(1, MvRegValue::String("second".to_string()));
            arr_tx.insert_register(2, MvRegValue::String("third".to_string()));
        });
        // Drop without commit
    }

    // Store should be unchanged
    assert_eq!(store, original_store);

    // Verify array still has only one element
    use dson::crdts::snapshot::ToValue;
    let items = store.store.get(&"items".to_string()).unwrap();
    assert_eq!(items.array.len(), 1);
    assert_eq!(
        items.array.get(0).unwrap().reg.value().unwrap(),
        &MvRegValue::String("first".to_string())
    );
}

#[test]
fn array_transaction_rollback_register() {
    let mut store = CausalDotStore::<OrArray>::default();
    let id = Identifier::new(0, 0);

    // Create initial state
    {
        let mut tx = ArrayTransaction::new(&mut store, id);
        tx.insert_register(0, MvRegValue::U64(1));
        tx.insert_register(1, MvRegValue::U64(2));
        let _delta = tx.commit();
    }

    let original_store = store.clone();

    // Modify array but don't commit
    {
        let mut tx = ArrayTransaction::new(&mut store, id);
        tx.insert_register(2, MvRegValue::U64(3));
        tx.insert_register(3, MvRegValue::U64(4));
        // Drop without commit
    }

    // Store should be unchanged
    assert_eq!(store, original_store);

    // Verify array still has only 2 elements
    use dson::crdts::snapshot::ToValue;
    assert_eq!(store.store.len(), 2);
    assert_eq!(
        store.store.get(0).unwrap().reg.value().unwrap(),
        &MvRegValue::U64(1)
    );
    assert_eq!(
        store.store.get(1).unwrap().reg.value().unwrap(),
        &MvRegValue::U64(2)
    );
}

#[test]
fn array_transaction_rollback_nested_array() {
    let mut store = CausalDotStore::<OrArray>::default();
    let id = Identifier::new(0, 0);

    // Create initial state with nested array
    {
        let mut tx = ArrayTransaction::new(&mut store, id);
        tx.insert_array(0, |inner_tx| {
            inner_tx.insert_register(0, MvRegValue::U64(1));
        });
        let _delta = tx.commit();
    }

    let original_store = store.clone();

    // Modify nested array but don't commit
    {
        let mut tx = ArrayTransaction::new(&mut store, id);
        tx.insert_array(1, |inner_tx| {
            inner_tx.insert_register(0, MvRegValue::U64(2));
        });
        // Drop without commit
    }

    // Store should be unchanged
    assert_eq!(store, original_store);

    // Verify only original nested array exists
    use dson::crdts::snapshot::ToValue;
    assert_eq!(store.store.len(), 1);
    let nested = &store.store.get(0).unwrap().array;
    assert_eq!(nested.len(), 1);
    assert_eq!(
        nested.get(0).unwrap().reg.value().unwrap(),
        &MvRegValue::U64(1)
    );
}

#[test]
fn array_transaction_rollback_map() {
    let mut store = CausalDotStore::<OrArray>::default();
    let id = Identifier::new(0, 0);

    // Create initial state with map
    {
        let mut tx = ArrayTransaction::new(&mut store, id);
        tx.insert_map(0, |map_tx| {
            map_tx.write_register("id", MvRegValue::U64(1));
        });
        let _delta = tx.commit();
    }

    let original_store = store.clone();

    // Modify map but don't commit
    {
        let mut tx = ArrayTransaction::new(&mut store, id);
        tx.insert_map(1, |map_tx| {
            map_tx.write_register("id", MvRegValue::U64(2));
        });
        // Drop without commit
    }

    // Store should be unchanged
    assert_eq!(store, original_store);

    // Verify only original map exists
    use dson::crdts::snapshot::ToValue;
    assert_eq!(store.store.len(), 1);
    let map = &store.store.get(0).unwrap().map;
    let id_val = map.get(&"id".to_string()).unwrap();
    assert_eq!(id_val.reg.value().unwrap(), &MvRegValue::U64(1));
}

#[test]
fn map_transaction_commit_after_rollback() {
    // Ensure that after a rollback, a new transaction can still commit successfully
    let mut store = CausalDotStore::<OrMap<String>>::default();
    let id = Identifier::new(0, 0);

    // First transaction: commit
    {
        let mut tx = MapTransaction::new(&mut store, id);
        tx.write_register("count", MvRegValue::U64(1));
        let _delta = tx.commit();
    }

    // Second transaction: rollback
    {
        let mut tx = MapTransaction::new(&mut store, id);
        tx.write_register("count", MvRegValue::U64(999));
        // Drop without commit
    }

    // Third transaction: commit
    {
        let mut tx = MapTransaction::new(&mut store, id);
        tx.write_register("count", MvRegValue::U64(2));
        let _delta = tx.commit();
    }

    // Verify final value is from third transaction
    let tx = MapTransaction::new(&mut store, id);
    match tx.get(&"count".to_string()) {
        Some(CrdtValue::Register(reg)) => {
            use dson::crdts::snapshot::ToValue;
            assert_eq!(reg.value().unwrap(), &MvRegValue::U64(2));
        }
        _ => panic!("Expected register"),
    }
}

#[test]
fn array_transaction_commit_after_rollback() {
    // Ensure that after a rollback, a new transaction can still commit successfully
    let mut store = CausalDotStore::<OrArray>::default();
    let id = Identifier::new(0, 0);

    // First transaction: commit
    {
        let mut tx = ArrayTransaction::new(&mut store, id);
        tx.insert_register(0, MvRegValue::U64(1));
        let _delta = tx.commit();
    }

    // Second transaction: rollback
    {
        let mut tx = ArrayTransaction::new(&mut store, id);
        tx.insert_register(1, MvRegValue::U64(999));
        // Drop without commit
    }

    // Third transaction: commit
    {
        let mut tx = ArrayTransaction::new(&mut store, id);
        tx.insert_register(1, MvRegValue::U64(2));
        let _delta = tx.commit();
    }

    // Verify array has both committed values
    use dson::crdts::snapshot::ToValue;
    assert_eq!(store.store.len(), 2);
    assert_eq!(
        store.store.get(0).unwrap().reg.value().unwrap(),
        &MvRegValue::U64(1)
    );
    assert_eq!(
        store.store.get(1).unwrap().reg.value().unwrap(),
        &MvRegValue::U64(2)
    );
}

#[test]
fn nested_transaction_panic_safety() {
    use dson::{
        CausalDotStore, Identifier, OrMap, crdts::mvreg::MvRegValue, transaction::MapTransaction,
    };

    // Verify that if a nested transaction panics, the parent transaction
    // is not corrupted and can still be rolled back cleanly
    let mut store = CausalDotStore::<OrMap<String>>::default();
    let id = Identifier::new(0, 0);

    // Create initial state
    {
        let mut tx = MapTransaction::new(&mut store, id);
        tx.write_register("root", MvRegValue::U64(1));
        let _delta = tx.commit();
    }

    let original_store = store.clone();

    // Transaction with nested panic
    let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
        let mut tx = MapTransaction::new(&mut store, id);
        tx.write_register("root", MvRegValue::U64(2));

        tx.in_map("nested", |nested_tx| {
            nested_tx.write_register("field", MvRegValue::String("test".to_string()));
            panic!("Simulated panic in nested transaction");
        });

        #[allow(unreachable_code)]
        tx.commit()
    }));

    // Verify panic occurred
    assert!(result.is_err());

    // Store should be unchanged - automatic rollback
    assert_eq!(store, original_store);

    // Verify original value still present
    use dson::crdts::snapshot::ToValue;
    let val = store.store.get(&"root".to_string()).unwrap();
    assert_eq!(val.reg.value().unwrap(), &MvRegValue::U64(1));

    // Verify nested map was not created
    assert!(store.store.get(&"nested".to_string()).is_none());
}