-
Notifications
You must be signed in to change notification settings - Fork 29.6k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
lib,src: fix a few typos in comments
PR-URL: #46835 Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Moshe Atlow <moshe@atlow.co.il> Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com> Reviewed-By: Richard Lau <rlau@redhat.com> Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
- Loading branch information
1 parent
b08687f
commit 7f9e60a
Showing
5 changed files
with
299 additions
and
5 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,294 @@ | ||
#pragma once | ||
|
||
#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS | ||
|
||
#include <base_object.h> | ||
#include <memory_tracker.h> | ||
#include <node.h> | ||
#include <node_bob.h> | ||
#include <node_file.h> | ||
#include <stream_base.h> | ||
#include <uv.h> | ||
#include <v8.h> | ||
|
||
#include <memory> | ||
#include <optional> | ||
#include <vector> | ||
|
||
namespace node { | ||
|
||
// Represents a sequenced collection of data sources that can be | ||
// consumed as a single logical stream of data. Sources can be | ||
// memory-resident or streaming. | ||
// | ||
// There are two essential kinds of DataQueue: | ||
// | ||
// * Idempotent - Multiple reads always produce the same result. | ||
// This is even the case if individual sources | ||
// are not memory-resident. Reads never change | ||
// the state of the DataQueue. Every entry in | ||
// an Idempotent DataQueue must also be idempotent. | ||
// | ||
// * Non-idempotent - Reads are destructive of the internal state. | ||
// A non-idempotent DataQueue can be read at | ||
// most once and only by a single reader. | ||
// Entries in a non-idempotent DataQueue can | ||
// be a mix of idempotent and non-idempotent | ||
// entries. | ||
// | ||
// The DataQueue is essentially a collection of DataQueue::Entry | ||
// instances. A DataQueue::Entry is a single logical source of | ||
// data. The data may be memory-resident or streaming. The entry | ||
// can be idempotent or non-idempotent. An entry cannot be read | ||
// by itself, it must be part of a DataQueue to be consumed. | ||
// | ||
// Example of creating an idempotent DataQueue: | ||
// | ||
// std::shared_ptr<v8::BackingStore> store1 = getBackingStoreSomehow(); | ||
// std::shared_ptr<v8::BackingStore> store2 = getBackingStoreSomehow(); | ||
// | ||
// std::vector<std::unique_ptr<DataQueue::Entry>> list; | ||
// list.push_back(DataQueue::CreateInMemoryEntryFromBackingStore( | ||
// store1, 0, len1)); | ||
// list.push_back(DataQueue::CreateInMemoryEntryFromBackingStore( | ||
// store2, 0, len2)); | ||
// | ||
// std::shared_ptr<DataQueue> data_queue = | ||
// DataQueue::CreateIdempotent(std::move(list)); | ||
// | ||
// Importantly, idempotent DataQueue's are immutable and all entries | ||
// must be provided when the DataQueue is constructed. Every entry | ||
// must be idempotent with known sizes. The entries may be memory | ||
// resident or streaming. Streaming entries must be capable of | ||
// being read multiple times. | ||
// | ||
// Because idempotent DataQueue's will always produce the same results | ||
// when read, they can be sliced. Slices yield a new DataQueue instance | ||
// that is a subset view over the original: | ||
// | ||
// std::shared_ptr<DataQueue> slice = data_queue.slice( | ||
// 5, v8::Just(10UL)); | ||
// | ||
// Example of creating a non-idempotent DataQueue: | ||
// | ||
// std::shared_ptr<v8::BackingStore> store1 = getBackingStoreSomehow(); | ||
// std::shared_ptr<v8::BackingStore> store2 = getBackingStoreSomehow(); | ||
// | ||
// std::shared_ptr<DataQueue> data_queue = DataQueue::Create(); | ||
// | ||
// data_queue->append(DataQueue::CreateInMemoryEntryFromBackingStore( | ||
// store1, 0, len1)); | ||
// | ||
// data_queue->append(DataQueue::CreateInMemoryEntryFromBackingStore( | ||
// store2, 0, len2)); | ||
// | ||
// These data-queues can have new entries appended to them. Entries can | ||
// be memory-resident or streaming. Streaming entries might not have | ||
// a known size. Entries may not be capable of being read multiple | ||
// times. | ||
// | ||
// A non-idempotent data queue will, by default, allow any amount of | ||
// entries to be appended to it. To limit the size of the DataQueue, | ||
// or the close the DataQueue (preventing new entries from being | ||
// appending), use the cap() method. The DataQueue can be capped | ||
// at a specific size or whatever size it currently it. | ||
// | ||
// It might not be possible for a non-idempotent DataQueue to provide | ||
// a size because it might not know how much data a streaming entry | ||
// will ultimately provide. | ||
// | ||
// Non-idempotent DataQueues cannot be sliced. | ||
// | ||
// To read from a DataQueue, we use the node::bob::Source API | ||
// (see src/node_bob.h). | ||
// | ||
// std::shared_ptr<DataQueue::Reader> reader = data_queue->get_reader(); | ||
// | ||
// reader->Pull( | ||
// [](int status, const DataQueue::Vec* vecs, | ||
// uint64_t count, Done done) { | ||
// // status is one of node::bob::Status | ||
// // vecs is zero or more data buffers containing the read data | ||
// // count is the number of vecs | ||
// // done is a callback to be invoked when done processing the data | ||
// }, options, nullptr, 0, 16); | ||
// | ||
// Keep calling Pull() until status is equal to node::bob::Status::STATUS_EOS. | ||
// | ||
// For idempotent DataQueues, any number of readers can be created and | ||
// pull concurrently from the same DataQueue. The DataQueue can be read | ||
// multiple times. Successful reads should always produce the same result. | ||
// If, for whatever reason, the implementation cannot ensure that the | ||
// data read will remain the same, the read must fail with an error status. | ||
// | ||
// For non-idempotent DataQueues, only a single reader is ever allowed for | ||
// the DataQueue, and the data can only ever be read once. | ||
|
||
class DataQueue : public MemoryRetainer { | ||
public: | ||
struct Vec { | ||
uint8_t* base; | ||
uint64_t len; | ||
}; | ||
|
||
// A DataQueue::Reader consumes the DataQueue. If the data queue is | ||
// idempotent, multiple Readers can be attached to the DataQueue at | ||
// any given time, all guaranteed to yield the same result when the | ||
// data is read. Otherwise, only a single Reader can be attached. | ||
class Reader : public MemoryRetainer, public bob::Source<Vec> { | ||
public: | ||
using Next = bob::Next<Vec>; | ||
using Done = bob::Done; | ||
}; | ||
|
||
// A DataQueue::Entry represents a logical chunk of data in the queue. | ||
// The entry may or may not represent memory-resident data. It may | ||
// or may not be consumable more than once. | ||
class Entry : public MemoryRetainer { | ||
public: | ||
// Returns a new Entry that is a view over this entries data | ||
// from the start offset to the ending offset. If the end | ||
// offset is omitted, the slice extends to the end of the | ||
// data. | ||
// | ||
// Creating a slice is only possible if is_idempotent() returns | ||
// true. This is because consuming either the original entry or | ||
// the new entry would change the state of the other in non- | ||
// deterministic ways. When is_idempotent() returns false, slice() | ||
// must return a nulled unique_ptr. | ||
// | ||
// Creating a slice is also only possible if the size of the | ||
// entry is known. If size() returns std::nullopt, slice() | ||
// must return a nulled unique_ptr. | ||
virtual std::unique_ptr<Entry> slice( | ||
uint64_t start, std::optional<uint64_t> end = std::nullopt) = 0; | ||
|
||
// Returns the number of bytes represented by this Entry if it is | ||
// known. Certain types of entries, such as those backed by streams | ||
// might not know the size in advance and therefore cannot provide | ||
// a value. In such cases, size() must return v8::Nothing<uint64_t>. | ||
// | ||
// If the entry is idempotent, a size should always be available. | ||
virtual std::optional<uint64_t> size() const = 0; | ||
|
||
// When true, multiple reads on the object must produce the exact | ||
// same data or the reads will fail. Some sources of entry data, | ||
// such as streams, may not be capable of preserving idempotency | ||
// and therefore must not claim to be. If an entry claims to be | ||
// idempotent and cannot preserve that quality, subsequent reads | ||
// must fail with an error when a variance is detected. | ||
virtual bool is_idempotent() const = 0; | ||
}; | ||
|
||
// Creates an idempotent DataQueue with a pre-established collection | ||
// of entries. All of the entries must also be idempotent otherwise | ||
// an empty std::unique_ptr will be returned. | ||
static std::shared_ptr<DataQueue> CreateIdempotent( | ||
std::vector<std::unique_ptr<Entry>> list); | ||
|
||
// Creates a non-idempotent DataQueue. This kind of queue can be | ||
// mutated and updated such that multiple reads are not guaranteed | ||
// to produce the same result. The entries added can be of any type. | ||
static std::shared_ptr<DataQueue> Create( | ||
std::optional<uint64_t> capped = std::nullopt); | ||
|
||
// Creates an idempotent Entry from a v8::ArrayBufferView. To help | ||
// ensure idempotency, the underlying ArrayBuffer is detached from | ||
// the BackingStore. It is the callers responsibility to ensure that | ||
// the BackingStore is not otherwise modified through any other | ||
// means. If the ArrayBuffer is not detachable, nullptr will be | ||
// returned. | ||
static std::unique_ptr<Entry> CreateInMemoryEntryFromView( | ||
v8::Local<v8::ArrayBufferView> view); | ||
|
||
// Creates an idempotent Entry from a v8::BackingStore. It is the | ||
// callers responsibility to ensure that the BackingStore is not | ||
// otherwise modified through any other means. If the ArrayBuffer | ||
// is not detachable, nullptr will be returned. | ||
static std::unique_ptr<Entry> CreateInMemoryEntryFromBackingStore( | ||
std::shared_ptr<v8::BackingStore> store, | ||
uint64_t offset, | ||
uint64_t length); | ||
|
||
static std::unique_ptr<Entry> CreateDataQueueEntry( | ||
std::shared_ptr<DataQueue> data_queue); | ||
|
||
static std::unique_ptr<Entry> CreateFdEntry(Environment* env, | ||
v8::Local<v8::Value> path); | ||
|
||
// Creates a Reader for the given queue. If the queue is idempotent, | ||
// any number of readers can be created, all of which are guaranteed | ||
// to provide the same data. Otherwise, only a single reader is | ||
// permitted. | ||
virtual std::shared_ptr<Reader> get_reader() = 0; | ||
|
||
// Append a single new entry to the queue. Appending is only allowed | ||
// when is_idempotent() is false. std::nullopt will be returned | ||
// if is_idempotent() is true. std::optional(false) will be returned if the | ||
// data queue is not idempotent but the entry otherwise cannot be added. | ||
virtual std::optional<bool> append(std::unique_ptr<Entry> entry) = 0; | ||
|
||
// Caps the size of this DataQueue preventing additional entries to | ||
// be added if those cause the size to extend beyond the specified | ||
// limit. | ||
// | ||
// If limit is zero, or is less than the known current size of the | ||
// data queue, the limit is set to the current known size, meaning | ||
// that no additional entries can be added at all. | ||
// | ||
// If the size of the data queue is not known, the limit will be | ||
// ignored and no additional entries will be allowed at all. | ||
// | ||
// If is_idempotent is true capping is unnecessary because the data | ||
// queue cannot be appended to. In that case, cap() is a non-op. | ||
// | ||
// If the data queue has already been capped, cap can be called | ||
// again with a smaller size. | ||
virtual void cap(uint64_t limit = 0) = 0; | ||
|
||
// Returns a new DataQueue that is a view over this queues data | ||
// from the start offset to the ending offset. If the end offset | ||
// is omitted, the slice extends to the end of the data. | ||
// | ||
// The slice will coverage a range from start up to, but excluding, end. | ||
// | ||
// Creating a slice is only possible if is_idempotent() returns | ||
// true. This is because consuming either the original DataQueue or | ||
// the new queue would change the state of the other in non- | ||
// deterministic ways. When is_idempotent() returns false, slice() | ||
// must return a nulled unique_ptr. | ||
// | ||
// Creating a slice is also only possible if the size of the | ||
// DataQueue is known. If size() returns std::nullopt, slice() | ||
// must return a null unique_ptr. | ||
virtual std::shared_ptr<DataQueue> slice( | ||
uint64_t start, std::optional<uint64_t> end = std::nullopt) = 0; | ||
|
||
// The size of DataQueue is the total size of all of its member entries. | ||
// If any of the entries is not able to specify a size, the DataQueue | ||
// will also be incapable of doing so, in which case size() must return | ||
// std::nullopt. | ||
virtual std::optional<uint64_t> size() const = 0; | ||
|
||
// A DataQueue is idempotent only if all of its member entries are | ||
// idempotent. | ||
virtual bool is_idempotent() const = 0; | ||
|
||
// True only if cap is called or the data queue is a limited to a | ||
// fixed size. | ||
virtual bool is_capped() const = 0; | ||
|
||
// If the data queue has been capped, and the size of the data queue | ||
// is known, maybeCapRemaining will return the number of additional | ||
// bytes the data queue can receive before reaching the cap limit. | ||
// If the size of the queue cannot be known, or the cap has not | ||
// been set, maybeCapRemaining() will return std::nullopt. | ||
virtual std::optional<uint64_t> maybeCapRemaining() const = 0; | ||
|
||
static void Initialize(Environment* env, v8::Local<v8::Object> target); | ||
static void RegisterExternalReferences(ExternalReferenceRegistry* registry); | ||
}; | ||
|
||
} // namespace node | ||
|
||
#endif // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters