src: implement DataQueue and non-memory resident Blob

[jasnell]

This is the start of work being collaboratively done by myself and @flakey5 to update the implementation of Blob to support non-memory resident data sources such as files as well as enable proper streaming support.

It is a work in progress and remain draft status until it is ready to go. Opening it for transparency.

Some background:

Currently, Blob objects consist solely of memory-resident data, backed by a collection of v8::BackingStore instances. While this behavior is correct standard/spec defined behavior, it is extremely inefficient. To support other use cases of Blob, we want to be able to efficiently and effectively support non-memory resident data sources such as files. To do so will require a number of key changes on the internals of the Blob class.

Further, the current implementation of Blob suffers from an overly simplistic streaming model where the entire Blob is first read into a single ArrayBuffer before passing the data on to the stream API. Effectively meaning Blobs are never actually streamed.

While going through this evaluation, we came to realization that many of the underlying requirements for Blob are (surprisingly) shared by the internal data management requirements for the QUIC implementation that is in progress, and can enable a range of other use cases also, so we have decided to take an approach that addresses those multiple use cases.

When complete, this PR is going to do two things:

This PR does three things:

1. Introduces a new C++ data structure called DataQueue which acts as a sequence of memory-resident and non-memory-resident data sources that can be consumed as a single logical stream of data. This is designed to meet the needs of both Blob and QUIC initially (the bits relevant to QUIC will come later)
2. Update the current Blob implementation to use DataQueue internally in support of the existing all-memory-resident model.
3. Provides an API for acquiring a File-backed Blob that will support efficient, non-memory resident use cases.

This PR is far from complete. I would strongly recommend that you hold off performing any review on it at all until after we flip the bit to mark it ready for review. We are opening this draft PR now purely for the sake of transparency so that folks can be aware of what we are working on.

I also want to avoid any and all bikeshedding on the design until we at least have the updated Blob implementation ready to go, and many of the design decisions made will likely not be clear until that concrete case is implemented.

Specifically for Blob, this PR will enable enables:

1. Proper streaming support. No longer will the Blob data be collected into a single ArrayBuffer and then passed on to the stream, but data will flow into the stream as one would actually expect.
2. File-backed Blob. The ability to acquire a Blob that is backed by an on-disc file. As well as the ability to use such Blob instances efficiently within other Blob instances, e.g. new Blob(['string', fileBackedBlob])

For QUIC, eventually the DataQueue implemented here will replace the Stream::Queue mechanism implemented in that PR. DataQueue will not completely replace that mechanism but covers a sizable chunk of it, which should further simplify and reduce the size of that rather complex bit of work.

As for other use cases of DataQueue... we'll address those later, but we do have a range of cases in mind (including the recent discussions around Node.js providing an efficient http static file server).

/cc @mcollina (who prompted this work due to Undici and Fetch use case requirements)

[jasnell]

@mcollina ... this is ready for review!

[mcollina]

cc @KhafraDev

[mcollina]

lgtm

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/48655/

[jasnell]

Moving this back to Draft status. Trying to work through @addaleax's feedback and wanted to make it so that the FdEntry Reader is using FileHandle as a StreamBase but for some reason I'm having a difficult time getting it to work to perform parallel reads of the same file with two separate fds. Will move back out of draft status once I've got it working.

[juanarbol]

Would you mind to backporting this to v18.x?

[jimmywarting]

I notice that blobs transfered over workers aren't readable at all.

• it only applies to blobs coming from fs.openAsBlob
• in-memory constructed blobs works fine.

mini repro:

import { Worker } from 'worker_threads'
new Worker('./worker.js').once('message', blob => blob.text())

// worker.js
import { parentPort } from 'node:worker_threads'
import { openAsBlob } from 'node:fs'

const blob = await openAsBlob(import.meta.url.slice(7)) // file:// doesn't work
parentPort.postMessage(blob)

I would assume that if you also closed the worker it would still work just fine to read the blob, even if it came from another thread...

Error stacktrace

FATAL ERROR: v8::HandleScope::CreateHandle() Cannot create a handle without a HandleScope
 1: 0x104e1df7c node::Abort() [/opt/homebrew/Cellar/node/19.8.1/bin/node]
 2: 0x104e1f33c node::OOMErrorHandler(char const*, v8::OOMDetails const&) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
 3: 0x104f7a064 v8::Utils::ReportApiFailure(char const*, char const*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
 4: 0x1050cb130 v8::internal::HandleScope::Extend(v8::internal::Isolate*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
 5: 0x104f7bf04 v8::EscapableHandleScope::EscapableHandleScope(v8::Isolate*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
 6: 0x104f98978 v8::ObjectTemplate::NewInstance(v8::Local<v8::Context>) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
 7: 0x104e241dc node::fs::FileHandle::New(node::fs::BindingData*, int, v8::Local<v8::Object>, std::__1::optional<long long>, std::__1::optional<long long>) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
 8: 0x104d869ec node::(anonymous namespace)::FdEntry::get_reader() [/opt/homebrew/Cellar/node/19.8.1/bin/node]
 9: 0x104d847b8 node::(anonymous namespace)::IdempotentDataQueueReader::Pull(std::__1::function<void (int, node::DataQueue::Vec const*, unsigned long, std::__1::function<void (unsigned long)>)>, int, node::DataQueue::Vec*, unsigned long, unsigned long) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
10: 0x104d86518 node::(anonymous namespace)::DataQueueEntry::ReaderImpl::Pull(std::__1::function<void (int, node::DataQueue::Vec const*, unsigned long, std::__1::function<void (unsigned long)>)>, int, node::DataQueue::Vec*, unsigned long, unsigned long) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
11: 0x104d84928 node::(anonymous namespace)::IdempotentDataQueueReader::Pull(std::__1::function<void (int, node::DataQueue::Vec const*, unsigned long, std::__1::function<void (unsigned long)>)>, int, node::DataQueue::Vec*, unsigned long, unsigned long) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
12: 0x104defcf8 node::Blob::Reader::Pull(v8::FunctionCallbackInfo<v8::Value> const&) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
13: 0x104fd8a58 v8::internal::FunctionCallbackArguments::Call(v8::internal::CallHandlerInfo) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
14: 0x104fd8858 v8::internal::MaybeHandle<v8::internal::Object> v8::internal::(anonymous namespace)::HandleApiCallHelper<false>(v8::internal::Isolate*, v8::internal::Handle<v8::internal::HeapObject>, v8::internal::Handle<v8::internal::FunctionTemplateInfo>, v8::internal::Handle<v8::internal::Object>, unsigned long*, int) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
15: 0x104fd82b8 v8::internal::Builtin_HandleApiCall(int, unsigned long*, v8::internal::Isolate*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
16: 0x104c733ec Builtins_CEntry_Return1_DontSaveFPRegs_ArgvOnStack_BuiltinExit [/opt/homebrew/Cellar/node/19.8.1/bin/node]
17: 0x104bf0064 Builtins_InterpreterEntryTrampoline [/opt/homebrew/Cellar/node/19.8.1/bin/node]
18: 0x104bf0064 Builtins_InterpreterEntryTrampoline [/opt/homebrew/Cellar/node/19.8.1/bin/node]
19: 0x104bf0064 Builtins_InterpreterEntryTrampoline [/opt/homebrew/Cellar/node/19.8.1/bin/node]
20: 0x104bf0064 Builtins_InterpreterEntryTrampoline [/opt/homebrew/Cellar/node/19.8.1/bin/node]
21: 0x104c28ab0 Builtins_GeneratorPrototypeNext [/opt/homebrew/Cellar/node/19.8.1/bin/node]
22: 0x104bee4f0 Builtins_JSEntryTrampoline [/opt/homebrew/Cellar/node/19.8.1/bin/node]
23: 0x104bee184 Builtins_JSEntry [/opt/homebrew/Cellar/node/19.8.1/bin/node]
24: 0x10509aa90 v8::internal::(anonymous namespace)::Invoke(v8::internal::Isolate*, v8::internal::(anonymous namespace)::InvokeParams const&) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
25: 0x10509b1a8 v8::internal::(anonymous namespace)::InvokeWithTryCatch(v8::internal::Isolate*, v8::internal::(anonymous namespace)::InvokeParams const&) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
26: 0x1053a0c8c v8::internal::SourceTextModule::ExecuteModule(v8::internal::Isolate*, v8::internal::Handle<v8::internal::SourceTextModule>) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
27: 0x1053a067c v8::internal::SourceTextModule::InnerModuleEvaluation(v8::internal::Isolate*, v8::internal::Handle<v8::internal::SourceTextModule>, v8::internal::ZoneForwardList<v8::internal::Handle<v8::internal::SourceTextModule> >*, unsigned int*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
28: 0x1053a03e0 v8::internal::SourceTextModule::InnerModuleEvaluation(v8::internal::Isolate*, v8::internal::Handle<v8::internal::SourceTextModule>, v8::internal::ZoneForwardList<v8::internal::Handle<v8::internal::SourceTextModule> >*, unsigned int*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
29: 0x10539ff6c v8::internal::SourceTextModule::Evaluate(v8::internal::Isolate*, v8::internal::Handle<v8::internal::SourceTextModule>) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
30: 0x105355240 v8::internal::Module::Evaluate(v8::internal::Isolate*, v8::internal::Handle<v8::internal::Module>) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
31: 0x104f849f8 v8::Module::Evaluate(v8::Local<v8::Context>) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
32: 0x104de085c node::loader::ModuleWrap::Evaluate(v8::FunctionCallbackInfo<v8::Value> const&) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
33: 0x104fd8a58 v8::internal::FunctionCallbackArguments::Call(v8::internal::CallHandlerInfo) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
34: 0x104fd8858 v8::internal::MaybeHandle<v8::internal::Object> v8::internal::(anonymous namespace)::HandleApiCallHelper<false>(v8::internal::Isolate*, v8::internal::Handle<v8::internal::HeapObject>, v8::internal::Handle<v8::internal::FunctionTemplateInfo>, v8::internal::Handle<v8::internal::Object>, unsigned long*, int) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
35: 0x104fd82b8 v8::internal::Builtin_HandleApiCall(int, unsigned long*, v8::internal::Isolate*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
36: 0x104c733ec Builtins_CEntry_Return1_DontSaveFPRegs_ArgvOnStack_BuiltinExit [/opt/homebrew/Cellar/node/19.8.1/bin/node]
37: 0x104bf0064 Builtins_InterpreterEntryTrampoline [/opt/homebrew/Cellar/node/19.8.1/bin/node]
38: 0x104c268b4 Builtins_AsyncFunctionAwaitResolveClosure [/opt/homebrew/Cellar/node/19.8.1/bin/node]
39: 0x104cc6e38 Builtins_PromiseFulfillReactionJob [/opt/homebrew/Cellar/node/19.8.1/bin/node]
40: 0x104c16834 Builtins_RunMicrotasks [/opt/homebrew/Cellar/node/19.8.1/bin/node]
41: 0x104bee3c4 Builtins_JSRunMicrotasksEntry [/opt/homebrew/Cellar/node/19.8.1/bin/node]
42: 0x10509aa60 v8::internal::(anonymous namespace)::Invoke(v8::internal::Isolate*, v8::internal::(anonymous namespace)::InvokeParams const&) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
43: 0x10509b1a8 v8::internal::(anonymous namespace)::InvokeWithTryCatch(v8::internal::Isolate*, v8::internal::(anonymous namespace)::InvokeParams const&) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
44: 0x1050bdc7c v8::internal::MicrotaskQueue::RunMicrotasks(v8::internal::Isolate*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
45: 0x1050bdaac v8::internal::MicrotaskQueue::PerformCheckpointInternal(v8::Isolate*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
46: 0x104d50ae8 node::InternalCallbackScope::Close() [/opt/homebrew/Cellar/node/19.8.1/bin/node]
47: 0x104e25864 node::fs::FileHandle::CloseReq::Resolve() [/opt/homebrew/Cellar/node/19.8.1/bin/node]
48: 0x104e26304 node::fs::FileHandle::ClosePromise()::$_0::__invoke(uv_fs_s*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
49: 0x104e182b4 node::MakeLibuvRequestCallback<uv_fs_s, void (*)(uv_fs_s*)>::Wrapper(uv_fs_s*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
50: 0x10784aff8 uv__work_done [/opt/homebrew/Cellar/libuv/1.44.2/lib/libuv.1.dylib]
51: 0x10784e3d0 uv__async_io [/opt/homebrew/Cellar/libuv/1.44.2/lib/libuv.1.dylib]
52: 0x10785e1e0 uv__io_poll [/opt/homebrew/Cellar/libuv/1.44.2/lib/libuv.1.dylib]
53: 0x10784e7d0 uv_run [/opt/homebrew/Cellar/libuv/1.44.2/lib/libuv.1.dylib]
54: 0x104d518a8 node::SpinEventLoopInternal(node::Environment*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
55: 0x104e60068 node::NodeMainInstance::Run(node::ExitCode*, node::Environment*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
56: 0x104e5fde8 node::NodeMainInstance::Run() [/opt/homebrew/Cellar/node/19.8.1/bin/node]
57: 0x104de6654 node::LoadSnapshotDataAndRun(node::SnapshotData const**, node::InitializationResultImpl const*) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
58: 0x104de67d8 node::Start(int, char**) [/opt/homebrew/Cellar/node/19.8.1/bin/node]
59: 0x1a2cd7e50 start [/usr/lib/dyld]

[jasnell]

Oops, yeah just a bug. Will take a look in the next day or so.

[targos]

I also noticed that the new method is on fs, not fs.promises, which is weird since it returns a promise.