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Merge pull request #349 from gwenn/unlock-notify
Unlock notify
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,129 @@ | ||
| //! [Unlock Notification](http://sqlite.org/unlock_notify.html) | ||
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| #[cfg(feature = "unlock_notify")] | ||
| use std::sync::{Condvar, Mutex}; | ||
| use std::os::raw::c_int; | ||
| #[cfg(feature = "unlock_notify")] | ||
| use std::os::raw::c_void; | ||
|
|
||
| use ffi; | ||
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| #[cfg(feature = "unlock_notify")] | ||
| struct UnlockNotification { | ||
| cond: Condvar, // Condition variable to wait on | ||
| mutex: Mutex<bool>, // Mutex to protect structure | ||
| } | ||
|
|
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| #[cfg(feature = "unlock_notify")] | ||
| impl UnlockNotification { | ||
| fn new() -> UnlockNotification { | ||
| UnlockNotification { | ||
| cond: Condvar::new(), | ||
| mutex: Mutex::new(false), | ||
| } | ||
| } | ||
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| fn fired(&mut self) { | ||
| *self.mutex.lock().unwrap() = true; | ||
| self.cond.notify_one(); | ||
| } | ||
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|
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| fn wait(&mut self) { | ||
| let mut fired = self.mutex.lock().unwrap(); | ||
| while !*fired { | ||
| fired = self.cond.wait(fired).unwrap(); | ||
| } | ||
| } | ||
| } | ||
|
|
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| /// This function is an unlock-notify callback | ||
| #[cfg(feature = "unlock_notify")] | ||
| unsafe extern "C" fn unlock_notify_cb(ap_arg: *mut *mut c_void, n_arg: c_int) { | ||
| use std::slice::from_raw_parts; | ||
| let args = from_raw_parts(ap_arg, n_arg as usize); | ||
| for arg in args { | ||
| let un: &mut UnlockNotification = &mut *(*arg as *mut UnlockNotification); | ||
| un.fired(); | ||
| } | ||
| } | ||
|
|
||
| #[cfg(feature = "unlock_notify")] | ||
| pub fn is_locked(db: *mut ffi::sqlite3, rc: c_int) -> bool { | ||
| rc == ffi::SQLITE_LOCKED_SHAREDCACHE || (rc & 0xFF) == ffi::SQLITE_LOCKED && unsafe { | ||
| ffi::sqlite3_extended_errcode(db) | ||
| } | ||
| == ffi::SQLITE_LOCKED_SHAREDCACHE | ||
| } | ||
|
|
||
| /// This function assumes that an SQLite API call (either `sqlite3_prepare_v2()` | ||
| /// or `sqlite3_step()`) has just returned `SQLITE_LOCKED`. The argument is the | ||
| /// associated database connection. | ||
| /// | ||
| /// This function calls `sqlite3_unlock_notify()` to register for an | ||
| /// unlock-notify callback, then blocks until that callback is delivered | ||
| /// and returns `SQLITE_OK`. The caller should then retry the failed operation. | ||
| /// | ||
| /// Or, if `sqlite3_unlock_notify()` indicates that to block would deadlock | ||
| /// the system, then this function returns `SQLITE_LOCKED` immediately. In | ||
| /// this case the caller should not retry the operation and should roll | ||
| /// back the current transaction (if any). | ||
| #[cfg(feature = "unlock_notify")] | ||
| pub fn wait_for_unlock_notify(db: *mut ffi::sqlite3) -> c_int { | ||
| let mut un = UnlockNotification::new(); | ||
| /* Register for an unlock-notify callback. */ | ||
| let rc = unsafe { | ||
| ffi::sqlite3_unlock_notify( | ||
| db, | ||
| Some(unlock_notify_cb), | ||
| &mut un as *mut UnlockNotification as *mut c_void, | ||
| ) | ||
| }; | ||
| debug_assert!( | ||
| rc == ffi::SQLITE_LOCKED || rc == ffi::SQLITE_LOCKED_SHAREDCACHE || rc == ffi::SQLITE_OK | ||
| ); | ||
| if rc == ffi::SQLITE_OK { | ||
| un.wait(); | ||
| } | ||
| rc | ||
| } | ||
|
|
||
| #[cfg(not(feature = "unlock_notify"))] | ||
| pub fn is_locked(_db: *mut ffi::sqlite3, _rc: c_int) -> bool { | ||
| unreachable!() | ||
| } | ||
|
|
||
| #[cfg(not(feature = "unlock_notify"))] | ||
| pub fn wait_for_unlock_notify(_db: *mut ffi::sqlite3) -> c_int { | ||
| unreachable!() | ||
| } | ||
|
|
||
| #[cfg(feature = "unlock_notify")] | ||
| #[cfg(test)] | ||
| mod test { | ||
| use std::sync::mpsc::sync_channel; | ||
| use std::thread; | ||
| use std::time; | ||
| use {Connection, OpenFlags, Result, Transaction, TransactionBehavior}; | ||
|
|
||
| #[test] | ||
| fn test_unlock_notify() { | ||
| let url = "file::memory:?cache=shared"; | ||
| let flags = OpenFlags::SQLITE_OPEN_READ_WRITE | OpenFlags::SQLITE_OPEN_URI; | ||
| let db1 = Connection::open_with_flags(url, flags).unwrap(); | ||
| db1.execute_batch("CREATE TABLE foo (x)").unwrap(); | ||
| let (rx, tx) = sync_channel(0); | ||
| let child = thread::spawn(move || { | ||
| let mut db2 = Connection::open_with_flags(url, flags).unwrap(); | ||
| let tx2 = Transaction::new(&mut db2, TransactionBehavior::Immediate).unwrap(); | ||
| tx2.execute_batch("INSERT INTO foo VALUES (42)").unwrap(); | ||
| rx.send(1).unwrap(); | ||
| let ten_millis = time::Duration::from_millis(10); | ||
| thread::sleep(ten_millis); | ||
| tx2.commit().unwrap(); | ||
| }); | ||
| assert_eq!(tx.recv().unwrap(), 1); | ||
| let the_answer: Result<i64> = db1.query_row("SELECT x FROM foo", &[], |r| r.get(0)); | ||
| assert_eq!(42i64, the_answer.unwrap()); | ||
| child.join().unwrap(); | ||
| } | ||
| } |