feat: implement MSSQL cancelQuery and applyQueryTimeout

Author: datlechin

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Copy as INSERT/UPDATE SQL statements from data grid context menu
 - Plugin download count display in Browse Plugins — fetched from GitHub Releases API and cached for 1 hour
+- MSSQL query cancellation (`cancelQuery`) and lock timeout (`applyQueryTimeout`) support
 
 ### Fixed
 

Plugins/MSSQLDriverPlugin/MSSQLPlugin.swift

@@ -92,6 +92,7 @@ private final class FreeTDSConnection: @unchecked Sendable {
     private let database: String
     private let lock = NSLock()
     private var _isConnected = false
+    private var _isCancelled = false
 
     var isConnected: Bool {
         lock.lock()
@@ -172,6 +173,16 @@ private final class FreeTDSConnection: @unchecked Sendable {
         }
     }
 
+    func cancelCurrentQuery() {
+        lock.lock()
+        _isCancelled = true
+        let proc = dbproc
+        lock.unlock()
+
+        guard let proc else { return }
+        dbcancel(proc)
+    }
+
     func executeQuery(_ query: String) async throws -> FreeTDSQueryResult {
         let queryToRun = String(query)
         return try await pluginDispatchAsync(on: queue) { [self] in
@@ -186,6 +197,10 @@ private final class FreeTDSConnection: @unchecked Sendable {
 
         _ = dbcanquery(proc)
 
+        lock.lock()
+        _isCancelled = false
+        lock.unlock()
+
         freetdsLastError = ""
         if dbcmd(proc, query) == FAIL {
             throw MSSQLPluginError.queryFailed("Failed to prepare query")
@@ -232,6 +247,14 @@ private final class FreeTDSConnection: @unchecked Sendable {
                 if rowCode == Int32(NO_MORE_ROWS) { break }
                 if rowCode == FAIL { break }
 
+                lock.lock()
+                let cancelled = _isCancelled
+                if cancelled { _isCancelled = false }
+                lock.unlock()
+                if cancelled {
+                    throw MSSQLPluginError.queryFailed("Query cancelled")
+                }
+
                 var row: [String?] = []
                 for i in 1...numCols {
                     let len = dbdatlen(proc, Int32(i))
@@ -386,6 +409,16 @@ final class MSSQLPluginDriver: PluginDatabaseDriver, @unchecked Sendable {
         )
     }
 
+    func cancelQuery() throws {
+        freeTDSConn?.cancelCurrentQuery()
+    }
+
+    func applyQueryTimeout(_ seconds: Int) async throws {
+        guard seconds > 0 else { return }
+        let ms = seconds * 1_000
+        _ = try await execute(query: "SET LOCK_TIMEOUT \(ms)")
+    }
+
     func executeParameterized(query: String, parameters: [String?]) async throws -> PluginQueryResult {
         guard !parameters.isEmpty else {
             return try await execute(query: query)