Darnell Andries
f3bea37356
* Create `SSEParser` util in `api_request_helper` namespace * Refactor `ObliviousHttpAPIClient` to use `SSEParser` * Address PR feedback
69 lines
2.4 KiB
C++
69 lines
2.4 KiB
C++
/* Copyright (c) 2026 The Brave Authors. All rights reserved.
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at https://mozilla.org/MPL/2.0/. */
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#ifndef BRAVE_COMPONENTS_API_REQUEST_HELPER_SSE_PARSER_H_
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#define BRAVE_COMPONENTS_API_REQUEST_HELPER_SSE_PARSER_H_
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#include <string>
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#include <string_view>
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#include "base/functional/callback.h"
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#include "base/memory/scoped_refptr.h"
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#include "base/memory/weak_ptr.h"
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#include "base/task/sequenced_task_runner.h"
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#include "base/types/expected.h"
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#include "base/values.h"
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namespace api_request_helper {
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using ValueOrError = base::expected<base::Value, std::string>;
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// Parses a Server-Sent Events (SSE) byte stream delivered in arbitrary chunks.
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//
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// Callers feed chunks via Process(). Complete lines starting with "data: {"
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// are parsed as JSON asynchronously on |task_runner|. For each successfully
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// recognised event the |on_event| callback is invoked with the parsed value
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// (or an error). Callers can check IsDecoding() to determine whether async
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// parse operations are still in flight.
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//
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// Bytes that arrive after the last line-ending in a chunk are kept in an
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// internal line buffer and prepended to the next chunk so lines split across
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// network chunks are reassembled correctly.
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class SSEParser {
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public:
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SSEParser(scoped_refptr<base::SequencedTaskRunner> task_runner,
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base::RepeatingCallback<void(ValueOrError)> on_event);
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~SSEParser();
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SSEParser(const SSEParser&) = delete;
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SSEParser& operator=(const SSEParser&) = delete;
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// Feed the next chunk of raw SSE bytes. May dispatch async JSON parse
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// operations and synchronously advance the line buffer.
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void Process(std::string_view chunk);
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// Clears the partial-line buffer (e.g. on retry or stream completion).
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void Clear();
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// Returns true while there are JSON parse operations still in flight.
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bool IsDecoding() const;
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private:
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void ProcessLine(std::string_view line);
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void OnJsonParsed(ValueOrError result);
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scoped_refptr<base::SequencedTaskRunner> task_runner_;
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base::RepeatingCallback<void(ValueOrError)> on_event_;
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std::string line_buffer_;
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size_t decoding_count_ = 0;
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base::WeakPtrFactory<SSEParser> weak_ptr_factory_{this};
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};
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} // namespace api_request_helper
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#endif // BRAVE_COMPONENTS_API_REQUEST_HELPER_SSE_PARSER_H_
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