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LibAudio: New error propagation API in Loader and Buffer

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Previously, a libc-like out-of-line error information was used in the
loader and its plugins. Now, all functions that may fail to do their job
return some sort of Result. The universally-used error type ist the new
LoaderError, which can contain information about the general error
category (such as file format, I/O, unimplemented features), an error
description, and location information, such as file index or sample
index.

Additionally, the loader plugins try to do as little work as possible in
their constructors. Right after being constructed, a user should call
initialize() and check the errors returned from there. (This is done
transparently by Loader itself.) If a constructor caused an error, the
call to initialize should check and return it immediately.

This opportunity was used to rework a lot of the internal error
propagation in both loader classes, especially FlacLoader. Therefore, a
couple of other refactorings may have sneaked in as well.

The adoption of LibAudio users is minimal. Piano's adoption is not
important, as the code will receive major refactoring in the near future
anyways. SoundPlayer's adoption is also less important, as changes to
refactor it are in the works as well. aplay's adoption is the best and
may serve as an example for other users. It also includes new buffering
behavior.

Buffer also gets some attention, making it OOM-safe and thereby also
propagating its errors to the user.
This commit is contained in:
kleines Filmröllchen 2021-11-27 17:00:19 +01:00 • committed by Brian Gianforcaro
parent ec8bd8116d
commit 96d02a3e75
19 changed files with 406 additions and 397 deletions
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16
Userland/Libraries/LibAudio/WavLoader.h
View file

@ -36,20 +36,17 @@ public:
explicit WavLoaderPlugin(StringView path);
explicit WavLoaderPlugin(const ByteBuffer& buffer);
virtual bool sniff() override { return valid; }
virtual bool has_error() override { return !m_error_string.is_null(); }
virtual const String& error_string() override { return m_error_string; }
virtual MaybeLoaderError initialize() override;
// The Buffer returned contains input data resampled at the
// destination audio device sample rate.
virtual RefPtr<Buffer> get_more_samples(size_t max_bytes_to_read_from_input = 128 * KiB) override;
virtual LoaderSamples get_more_samples(size_t max_bytes_to_read_from_input = 128 * KiB) override;
virtual void reset() override { return seek(0); }
virtual MaybeLoaderError reset() override { return seek(0); }
// sample_index 0 is the start of the raw audio sample data
// within the file/stream.
virtual void seek(const int sample_index) override;
virtual MaybeLoaderError seek(const int sample_index) override;
virtual int loaded_samples() override { return m_loaded_samples; }
virtual int total_samples() override { return m_total_samples; }
@ -59,13 +56,12 @@ public:
virtual RefPtr<Core::File> file() override { return m_file; }
private:
bool parse_header();
MaybeLoaderError parse_header();
bool valid { false };
RefPtr<Core::File> m_file;
OwnPtr<AK::InputStream> m_stream;
AK::InputMemoryStream* m_memory_stream;
String m_error_string;
Optional<LoaderError> m_error {};
u32 m_sample_rate { 0 };
u16 m_num_channels { 0 };