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WIP: Unlock Notification

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To do: unlock_notify_cb
This commit is contained in:
gwenn 2017-09-21 19:27:07 +02:00
parent 5d91fb088f
commit 455e7d4060
4 changed files with 104 additions and 52 deletions
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37
src/lib.rs
View File

@ -125,8 +125,7 @@ pub mod limits;
mod hooks;
#[cfg(feature = "hooks")]
pub use hooks::*;
#[cfg(feature = "unlock_notify")]
pub mod unlock_notify;
mod unlock_notify;
// Number of cached prepared statements we'll hold on to.
const STATEMENT_CACHE_DEFAULT_CAPACITY: usize = 16;
@ -864,16 +863,40 @@ impl InnerConnection {
}
let mut c_stmt: *mut ffi::sqlite3_stmt = unsafe { mem::uninitialized() };
let c_sql = try!(str_to_cstring(sql));
let r = unsafe {
let len_with_nul = (sql.len() + 1) as c_int;
ffi::sqlite3_prepare_v2(self.db(),
let r = unsafe {
if cfg!(feature = "unlock_notify") {
let mut rc;
loop {
rc = ffi::sqlite3_prepare_v2(
self.db(),
c_sql.as_ptr(),
len_with_nul,
&mut c_stmt,
ptr::null_mut())
ptr::null_mut(),
);
if rc != ffi::SQLITE_LOCKED {
break;
}
rc = unlock_notify::wait_for_unlock_notify(self.db);
if rc != ffi::SQLITE_OK {
break;
}
}
rc
} else {
ffi::sqlite3_prepare_v2(
self.db(),
c_sql.as_ptr(),
len_with_nul,
&mut c_stmt,
ptr::null_mut(),
)
}
};
self.decode_result(r)
.map(|_| Statement::new(conn, RawStatement::new(c_stmt)))
self.decode_result(r).map(|_| {
Statement::new(conn, RawStatement::new(c_stmt, self.db()))
})
}
fn changes(&mut self) -> c_int {

29
src/raw_statement.rs
View File

@ -2,14 +2,15 @@ use std::ffi::CStr;
use std::ptr;
use std::os::raw::c_int;
use super::ffi;
use super::unlock_notify;
// Private newtype for raw sqlite3_stmts that finalize themselves when dropped.
#[derive(Debug)]
pub struct RawStatement(*mut ffi::sqlite3_stmt);
pub struct RawStatement(*mut ffi::sqlite3_stmt, *mut ffi::sqlite3);
impl RawStatement {
pub fn new(stmt: *mut ffi::sqlite3_stmt) -> RawStatement {
RawStatement(stmt)
pub fn new(stmt: *mut ffi::sqlite3_stmt, db: *mut ffi::sqlite3) -> RawStatement {
RawStatement(stmt, db)
}
pub unsafe fn ptr(&self) -> *mut ffi::sqlite3_stmt {
@ -29,8 +30,30 @@ impl RawStatement {
}
pub fn step(&self) -> c_int {
if cfg!(feature = "unlock_notify") {
let mut rc;
loop {
rc = unsafe { ffi::sqlite3_step(self.0) };
if rc == ffi::SQLITE_LOCKED {
if unsafe { ffi::sqlite3_extended_errcode(self.1) } !=
ffi::SQLITE_LOCKED_SHAREDCACHE
{
break;
}
} else if rc != ffi::SQLITE_LOCKED_SHAREDCACHE {
break;
}
rc = unlock_notify::wait_for_unlock_notify(self.1);
if rc != ffi::SQLITE_OK {
break;
}
self.reset();
}
rc
} else {
unsafe { ffi::sqlite3_step(self.0) }
}
}
pub fn reset(&self) -> c_int {
unsafe { ffi::sqlite3_reset(self.0) }

4
src/statement.rs
View File

@ -462,7 +462,7 @@ impl<'conn> Statement<'conn> {
}
fn finalize_(&mut self) -> Result<()> {
let mut stmt = RawStatement::new(ptr::null_mut());
let mut stmt = RawStatement::new(ptr::null_mut(), ptr::null_mut());
mem::swap(&mut stmt, &mut self.stmt);
self.conn.decode_result(stmt.finalize())
}
@ -470,7 +470,7 @@ impl<'conn> Statement<'conn> {
impl<'conn> Into<RawStatement> for Statement<'conn> {
fn into(mut self) -> RawStatement {
let mut stmt = RawStatement::new(ptr::null_mut());
let mut stmt = RawStatement::new(ptr::null_mut(), ptr::null_mut());
mem::swap(&mut stmt, &mut self.stmt);
stmt
}

62
src/unlock_notify.rs
View File

@ -1,16 +1,20 @@
//! [Unlock Notification](http://sqlite.org/unlock_notify.html)
use std::sync::{Mutex, Condvar};
use std::os::raw::{c_char, c_int, c_void};
#[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;
use InnerConnection;
#[cfg(feature = "unlock_notify")]
struct UnlockNotification {
cond: Condvar, // Condition variable to wait on
mutex: Mutex<bool>, // Mutex to protect structure
}
#[cfg(feature = "unlock_notify")]
impl UnlockNotification {
fn new() -> UnlockNotification {
UnlockNotification {
@ -34,6 +38,7 @@ impl UnlockNotification {
}
/// 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) {
/*int i;
for(i=0; i<nArg; i++){
@ -45,36 +50,37 @@ unsafe extern "C" fn unlock_notify_cb(ap_arg: *mut *mut c_void, n_arg: c_int) {
}*/
}
impl InnerConnection {
fn blocking_prepare(&mut self,
z_sql: *const c_char,
n_byte: c_int,
pp_stmt: *mut *mut ffi::sqlite3_stmt,
pz_tail: *mut *const c_char) -> c_int {
let mut rc;
loop {
rc = unsafe {
ffi::sqlite3_prepare_v2(self.db, z_sql, n_byte, pp_stmt, pz_tail)
};
if rc != ffi::SQLITE_LOCKED {
break;
}
rc = self.wait_for_unlock_notify();
if rc != ffi::SQLITE_OK {
break;
}
}
rc
}
fn wait_for_unlock_notify(&mut self) -> c_int {
/// 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(self.db, Some(unlock_notify_cb), &mut un as *mut UnlockNotification as *mut c_void) };
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_OK);
if rc == ffi::SQLITE_OK {
un.wait();
}
rc
}
}
#[cfg(not(feature = "unlock_notify"))]
pub fn wait_for_unlock_notify(_db: *mut ffi::sqlite3) -> c_int {
unreachable!()
}