Streamlines a common middleware pattern and provides foundations for avoiding variably sized v8::ExternalReferences & enabling fully monomorphic op callpaths
This note about how `v8::SnapshotCreator::create_blob` must not be
called from a `HandleScope` stopped being relevant in #6801, and was
now attached to code that had nothing to do with `HandleScope`s.
When an exception is thrown during the processing of streaming WebAssembly,
`op_wasm_streaming_abort` is called. This op calls into V8, which synchronously
rejects the promise and calls into the promise rejection handler, if applicable.
But calling an op borrows the isolate's `JsRuntimeState` for the duration of the
op, which means it is borrowed when V8 calls into `promise_reject_callback`,
which tries to borrow it again, panicking.
This change changes `op_wasm_streaming_abort` from an op to a binding
(`Deno.core.abortWasmStreaming`). Although that binding must borrow the
`JsRuntimeState` in order to access the `WasmStreamingResource` stored in the
`OpTable`, it also takes ownership of that `WasmStreamingResource` instance,
which means it can drop any borrows of the `JsRuntimeState` before calling into
V8.
In the implementation of structured serialization in
`Deno.core.serialize`, whenever there is a serialization error, an
exception will be thrown with the message "Failed to serialize
response", even though V8 provides a message to use in such cases.
This change instead throws an exception with the V8-provided message,
if there is one.
This commit adds "--trace-ops" flag to "deno test" subcommand.
This flag enables saving of stack traces for async ops, that before were always
saved. While the feature proved to be very useful it comes with a significant performance
hit, it's caused by excessive source mapping of stack frames.
This commit improves the error messages for the `deno test` async op
sanitizer. It does this in two ways:
- it uses handwritten error messages for each op that could be leaking
- it includes traces showing where each op was started
This "async op tracing" functionality is a new feature in deno_core.
It likely has a significant performance impact, which is why it is only
enabled in tests.
