as nilskch points out in #1807, Rust 1.88.0 is stricter about
alignment.
because rust integers default to `i32`, we were casting a pointer
to an `i32` as a pointer to an `i64` causing a panic when dereferenced
due to misalignment as rust expects it to be 8 byte aligned.
The following code reproduces the leak, with memory usage increasing
over time:
```
#[tokio::main]
async fn main() {
let db = Builder::new_local(":memory:").build().await.unwrap();
let conn = db.connect().unwrap();
conn.execute("SELECT load_extension('./target/debug/liblimbo_series');", ())
.await
.unwrap();
loop {
conn.execute("SELECT * FROM generate_series(1,10,2);", ())
.await
.unwrap();
}
}
```
After switching to the system allocator, the leak becomes detectable
with Valgrind:
```
32,000 bytes in 1,000 blocks are definitely lost in loss record 24 of 24
at 0x538580F: malloc (vg_replace_malloc.c:446)
by 0x62E15FA: alloc::alloc::alloc (alloc.rs:99)
by 0x62E172C: alloc::alloc::Global::alloc_impl (alloc.rs:192)
by 0x62E1530: allocate (alloc.rs:254)
by 0x62E1530: alloc::alloc::exchange_malloc (alloc.rs:349)
by 0x62E0271: new<limbo_series::GenerateSeriesCursor> (boxed.rs:257)
by 0x62E0271: open_GenerateSeriesVTab (lib.rs:19)
by 0x425D8FA: limbo_core::VirtualTable::open (lib.rs:732)
by 0x4285DDA: limbo_core::vdbe::execute::op_vopen (execute.rs:890)
by 0x42351E8: limbo_core::vdbe::Program::step (mod.rs:396)
by 0x425C638: limbo_core::Statement::step (lib.rs:610)
by 0x40DB238: limbo::Statement::execute::{{closure}} (lib.rs:181)
by 0x40D9EAF: limbo::Connection::execute::{{closure}} (lib.rs:109)
by 0x40D54A1: example::main::{{closure}} (example.rs:26)
```
Interestingly, when using mimalloc, neither Valgrind nor mimalloc’s
internal statistics report the leak.
I keep having 3+ PR's in at the same time and always deal with crazy
conflicts because everything in the `ext` library is together in one
file.
This PR moves each category of extension into its own file, and
separates the `vfs` functionality in Core into the `ext/dynamic` module,
so that it can be more easily separated from wasm (or non feature =
"fs") targets to prevent build issues.
The only semantic changes made in this PR is the feature gating of vfs,
the rest is simply organizing and cleaning up imports.
Was unsure if `vfs` should be a feature on the `core` side too, or to
just enable it with the `fs` feature which seemed reasonable, as that
was already the current behavior. But let me know if we want it entirely
behind it's own feature.
Reviewed-by: Pere Diaz Bou <pere-altea@homail.com>
Closes#1124
This PR cleans up some comments in the extension API and prevents
extensions themselves from calling 'free' on Value types that are
exposed to the user facing traits, as well as changes the `from_ffi`
method for OwnedValues to take ownership and automatically free the
values to prevent memory leaks.
This PR also finds the name of the `args: &[Value]` argument for scalar
functions in extensions, and uses that in the proc macro, instead of
relying on documentation to communicate that the parameter must be named
`args`.
Closes#1054
