quill_sql/transaction/
txn_context.rs

1use std::sync::Arc;
2
3use crate::error::QuillSQLError;
4use crate::storage::{
5    page::{RecordId, TupleMeta},
6    tuple::Tuple,
7};
8use crate::transaction::{
9    CommandId, IsolationLevel, LockManager, LockMode, RowLockGuard, Transaction, TransactionId,
10    TransactionManager, TransactionSnapshot, TxnReadGuard,
11};
12use crate::utils::table_ref::TableReference;
13use log::warn;
14use sqlparser::ast::TransactionAccessMode;
15
16pub struct TxnContext<'a> {
17    txn: &'a mut Transaction,
18    manager: Arc<TransactionManager>,
19    snapshot: TransactionSnapshot,
20    command_id: CommandId,
21    lock_manager: Arc<LockManager>,
22}
23
24impl<'a> TxnContext<'a> {
25    pub fn new(manager: Arc<TransactionManager>, txn: &'a mut Transaction) -> Self {
26        let lock_manager = manager.lock_manager_arc();
27        let command_id = txn.begin_command();
28        let snapshot = match txn.isolation_level() {
29            IsolationLevel::RepeatableRead | IsolationLevel::Serializable => {
30                if let Some(existing) = txn.snapshot().cloned() {
31                    existing
32                } else {
33                    let snap = manager.snapshot(txn.id());
34                    txn.set_snapshot(snap.clone());
35                    snap
36                }
37            }
38            IsolationLevel::ReadCommitted | IsolationLevel::ReadUncommitted => {
39                let snap = manager.snapshot(txn.id());
40                txn.clear_snapshot();
41                snap
42            }
43        };
44        Self {
45            txn,
46            manager,
47            snapshot,
48            command_id,
49            lock_manager,
50        }
51    }
52
53    pub fn snapshot(&self) -> &TransactionSnapshot {
54        &self.snapshot
55    }
56
57    pub fn is_visible(&self, meta: &TupleMeta) -> bool {
58        self.snapshot.is_visible(meta, self.command_id, |txn_id| {
59            self.manager.transaction_status(txn_id)
60        })
61    }
62
63    pub fn read_visible_tuple(
64        &mut self,
65        table: &TableReference,
66        rid: RecordId,
67        meta: &TupleMeta,
68        tuple: Tuple,
69    ) -> crate::error::QuillSQLResult<Option<Tuple>> {
70        match self.transaction().isolation_level() {
71            crate::transaction::IsolationLevel::ReadUncommitted => {
72                if self.is_visible(meta) {
73                    Ok(Some(tuple))
74                } else {
75                    Ok(None)
76                }
77            }
78            _ => {
79                let guard = self.acquire_shared_guard(table, rid)?;
80                let visible = self.is_visible(meta);
81                guard.release();
82                if visible {
83                    Ok(Some(tuple))
84                } else {
85                    Ok(None)
86                }
87            }
88        }
89    }
90
91    pub fn acquire_shared_guard(
92        &mut self,
93        table: &TableReference,
94        rid: RecordId,
95    ) -> crate::error::QuillSQLResult<TxnReadGuard> {
96        if !self
97            .lock_manager
98            .lock_row(self.transaction(), LockMode::Shared, table.clone(), rid)
99        {
100            return Err(QuillSQLError::Execution(
101                "failed to acquire shared row lock".to_string(),
102            ));
103        }
104        Ok(TxnReadGuard::Temporary(RowLockGuard::new(
105            self.lock_manager.clone(),
106            self.transaction().id(),
107            table.clone(),
108            rid,
109        )))
110    }
111
112    pub fn lock_row_exclusive(
113        &mut self,
114        table: &TableReference,
115        rid: RecordId,
116    ) -> crate::error::QuillSQLResult<()> {
117        if !self
118            .manager
119            .try_acquire_row_lock(self.txn, table.clone(), rid, LockMode::Exclusive)?
120        {
121            return Err(QuillSQLError::Execution(
122                "failed to acquire row exclusive lock".to_string(),
123            ));
124        }
125        Ok(())
126    }
127
128    pub fn lock_table(
129        &mut self,
130        table: TableReference,
131        mode: LockMode,
132    ) -> crate::error::QuillSQLResult<()> {
133        self.manager
134            .acquire_table_lock(self.txn, table.clone(), mode)
135            .map_err(|e| QuillSQLError::Execution(format!("lock error: {}", e)))
136    }
137
138    pub fn ensure_writable(
139        &self,
140        table: &TableReference,
141        operation: &str,
142    ) -> crate::error::QuillSQLResult<()> {
143        if matches!(
144            self.transaction().access_mode(),
145            TransactionAccessMode::ReadOnly
146        ) {
147            warn!(
148                "read-only txn {} attempted '{}' on {}",
149                self.txn.id(),
150                operation,
151                table.to_log_string()
152            );
153            return Err(QuillSQLError::Execution(format!(
154                "operation '{}' on table {} is not allowed in READ ONLY transaction",
155                operation,
156                table.to_log_string()
157            )));
158        }
159        Ok(())
160    }
161
162    pub fn isolation_level(&self) -> IsolationLevel {
163        self.txn.isolation_level()
164    }
165
166    pub fn transaction(&self) -> &Transaction {
167        self.txn
168    }
169
170    pub fn transaction_mut(&mut self) -> &mut Transaction {
171        self.txn
172    }
173
174    pub fn manager(&self) -> &TransactionManager {
175        self.manager.as_ref()
176    }
177
178    pub fn txn_id(&self) -> TransactionId {
179        self.txn.id()
180    }
181
182    pub fn unlock_row(&self, table: &TableReference, rid: RecordId) {
183        self.manager.unlock_row(self.txn.id(), table, rid);
184    }
185
186    pub fn command_id(&self) -> CommandId {
187        self.command_id
188    }
189}
quill_sql/transaction/txn_context.rs

quill_sql/transaction/
txn_context.rs
