This change adds support for weak handles that don't prevent GC of the
referenced objects, through the `v8::Weak<T>` API. A weak handle can
be empty (if it was created empty or its object was GC'd) or
non-empty, and if non-empty it allows getting its object as a global
or local.
When creating a `v8::Weak` you can also set a finalizer that will be
called at some point after the object is GC'd, as long as the weak
handle is still alive at that point. This finalization corresponds to
the second-pass callback in `kParameter` mode in the C++ API, so it
will only be called after the object is GC'd. The finalizer function
is a `FnOnce` that may close over data, and which takes a
`&mut Isolate` as an argument.
The C++ finalization API doesn't guarantee _when_ or even _if_ the
finalizer will ever be called, but in order to prevent memory leaks,
the rusty_v8 wrapper ensures that it will be called at some point,
even if it's just before the isolate gets dropped.
`v8::Weak<T>` implements `Clone`, but a finalizer is tied to a single
weak handle, so its clones won't be able to keep the finalizer alive.
And in fact, cloning will create a new weak handle that isn't tied to
a finalizer at all. `v8::Weak::clone_with_finalizer` can be used to
make a clone of a weak handle which has a finalizer tied to it.
Note that `v8::Weak<T>` doesn't implement `Hash`, because the hash
would have to change once the handle's object is GC'd, which is a big
gotcha and would break some of the algorithms that rely on hashes,
such as the Rust std's `HashMap`.
This fixes in a segmentation fault when dropping a `BackingStore`
constructed through `ArrayBuffer::new_backing_store_from_boxed_slice()`
from an empty slice, since zero length boxed slices are invalid
(dangling) pointers, while Rust expects a `Box<c_void>` to always be a
valid pointer.
Fixes: #849
The pointer returned by `BackingStore::data` might be null if the
backing store has zero length, but the return type `*mut c_void` does
not force the user to consider this case. This change makes the return
type `Option<NonNull<c_void>>`, which is semantically equivalent, but
which forces users of the API to handle the `None` case.
This is a breaking API change.
For zero-size `BackingStore`s, it seems like `BackingStore::data` always
returns a null pointer. The `Deref` impl for `BackingStore` called
`std::slice::from_raw_parts` on that pointer, even though it is UB to
call that function on a null pointer even for empty slices. This change
fixes that by obtaining a valid pointer from `NonNull::dangling()` if
the original is null.
Reported in
https://github.com/denoland/rusty_v8/issues/711#issuecomment-950637136.
Best case, it produces serialized output that cannot be deserialized.
Worst case, it hits this assert in V8:
# Fatal error in v8::FromJust
# Maybe value is Nothing.
This commit adds the following methods:
* `FunctionTemplate::inherit()`
* `FunctionTemplate::prototype_template()`
* `FunctionTemplate::read_only_prototype()`
* `FunctionTemplate::remove_prototype()`
* We are floating a revert of v8/v8@7f9d7f0 because of the issue described in #694.
* Upgrade ICU 68 -> 69
* Upgrade //build and //buildtools
* set v8_enable_shared_ro_heap = false to fix tests
v8::Location is the size of two ints, not the size of one size_t.
`2 * sizeof(int) == sizeof(size_t)` on 64 bits architectures but not on
32 bits architectures.
Fixes #667.
This commit adds support for import assertions.
Major changes include:
- removal of "ResolveCallback" (deprecated in V8)
in favor of "ModuleResolveCallback"
- removal of "HostImportModuleDynamicallyCallback" (deprecated in V8)
in favor of "HostImportModuleDynamicallyWithImportAssertionsCallback"
This commit removes the set_flags_from_command_line_with_usage and puts
it in an example code section instead.
The motivation for doing this is that the test output currently contains
the usage string and all the V8 options which creates a lot of output
when the tests is run regardless if --nocapture is used or not.
The blanket `std:#️⃣:Hash` impl for instances of `v8::Data` invokes
`v8::internal::Object::GetHash()` but that crashes for `v8::Module`
objects. Use a custom impl that calls `v8::Module::get_identity_hash()`.
Fixes the following runtime assertion:
# Fatal error in ../../../v8/src/objects/objects-inl.h, line 1043
# Debug check failed: object.IsJSReceiver().
Refs: https://github.com/denoland/deno/pull/8354#discussion_r522157813
This commit removes mut from the script variable to avoid the following
warning if used:
25 | let mut script = v8::Script::compile(scope, code, None).unwrap();
| ----^^^^^^
| |
| help: remove this `mut`
|
= note: `#[warn(unused_mut)]` on by default
warning: 1 warning emitted
* The `Default` trait did not actually get derived for `SharedPtr<T>`.
This is solved by implementing `Default` manually.
* Trait function `Shared::get()` used to return a mutable raw pointer
(`*mut Self`), but it would be inconceivable to ever mutate the
referenced value. It was changed to return a const pointer instead.
* Added some basic unit tests for types `SharedPtr` and `SharedRef`.
Isolate::run_microtasks() already exists but the microtasks queue
is also flushed on script entry and exit. Some embedders want strict
control over when microtasks run, which is set by the policy.
And deprecate Isolate::run_microtasks(). The corresponding V8 API is
tagged with V8_DEPRECATE_SOON.
Certain callbacks (e.g. `WasmLoadSourceMapCallback`) expect the
embedder to return a local handle (a `Local<String>` in this case), but
do not provide a `Local<Context>` as an argument, nor does it provide
any other argument that we might obtain a context from. This is not
unexpected - WASM execution as such is not tied to a context, and a
`Local<String>` can be created without a context too because it's a
primitive value that has no JavaScript prototype.
It turns out that using `v8::internal::MaybeObject` was, although
harmless, not appropriate here, because this function does not deal
deal with (potentially) weak handles.
* Merged all handle type implementations into one file ('handle.h').
* Made it so that `Global` handles cannot be empty.
* Renamed the `AsHandle` trait to `Handle`, and made it more generally
useful.
* Simplified how `PartialEq` is implemented for V8 heap objects and/or
the `Local`/`Global` handles that reference them.
Local handles never need to be mutable. This patch also rounds up the
last few places where we were still asking the user to pass an `&mut T`
to an API method.
According to v8.h, "the returned handle is valid until this TryCatch
block has been destroyed". This is incorrect, as can be demonstrated
with the test below. In practice the return value lives no longer and
no shorter than the active HandleScope at the time these methods are
called. An issue has been opened about this in the V8 bug tracker:
https://bugs.chromium.org/p/v8/issues/detail?id=10537.
```rust
fn try_catch_bad_lifetimes() {
let _setup_guard = setup();
let mut isolate = v8::Isolate::new(Default::default());
let mut hs = v8::HandleScope::new(&mut isolate);
let scope = hs.enter();
let context = v8::Context::new(scope);
let mut cs = v8::ContextScope::new(scope, context);
let scope = cs.enter();
let caught_msg_2 = {
let mut try_catch = v8::TryCatch::new(scope);
let try_catch = try_catch.enter();
let caught_msg_1 = {
let mut hs = v8::HandleScope::new(scope);
let scope = hs.enter();
// Throw exception #1.
let msg_1 = v8::String::new(scope, "BOOM!").unwrap();
let exc_1 = v8::Exception::type_error(scope, msg_1);
scope.isolate().throw_exception(exc_1);
// Catch exception #1.
let caught_msg_1 = try_catch.message().unwrap();
let caught_str_1 =
caught_msg_1.get(scope).to_rust_string_lossy(scope);
assert!(caught_str_1.contains("BOOM"));
// Move `caught_msg_1` out of the HandleScope it was created in.
// The borrow checker allows this because `caught_msg_1`'s
// lifetime is contrained to not outlive the TryCatch, but it is
// allowed to outlive the HandleScope that was active when the
// exception was caught.
caught_msg_1
};
// Next line crashes.
let caught_str_1 =
caught_msg_1.get(scope).to_rust_string_lossy(scope);
assert!(caught_str_1.contains("BOOM"));
// Throws exception #2.
let msg_2 = v8::String::new(scope, "DANG!").unwrap();
let exc_2 = v8::Exception::type_error(scope, msg_2);
scope.isolate().throw_exception(exc_2);
// Catch exception #2.
let caught_msg_2 = try_catch.message().unwrap();
let caught_str_2 =
caught_msg_2.get(scope).to_rust_string_lossy(scope);
assert!(caught_str_2.contains("DANG"));
// Move `caught_msg_2` out of the extent of the TryCatch, but still
// within the extent of its HandleScope. This is unnecessarily
// rejected at compile time.
caught_msg_2
};
let caught_str_2 =
caught_msg_2.get(scope).to_rust_string_lossy(scope);
assert!(caught_str_2.contains("DANG"));
}
```
* Add `SharedPtr` as a nullable sibling to `SharedRef`.
* Add `Borrow`, `AsRef` and `AsMut` implementations as appropriate.
* `SharedRef<T>` now derefs to `T` rather than to `UnsafeCell<T>`.
* `array_buffer::BackingStore` now derefs to `[Cell<u8>]`.
In v8.h, not all heap object classes actually derive from `v8::Data`,
but this seems to be a mistake, because this hierarchy does definitely
exists in V8's internal source code.
The file naming in the current src/inspector/ directory is inconsistent and difficult to
navigate. It will be simpler if we just put them all in one place since they're rather
interconnected.
This doesn't really follow the current V8 API (it's pretty close to how
V8 used to be back in 2012 though.) However:
1. The C++ API is very C++-y and doesn't carry over well to Rust, and
2. It addresses the immediate need of being able to take heap snapshots.
Refs #298
