Struct DictionaryHandle

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pub struct DictionaryHandle { /* private fields */ }

Expand description

Shared pre-parsed dictionary handle for repeated decoding.

Uses Arc on targets with atomics and falls back to Rc otherwise.

Implementations§

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impl DictionaryHandle

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pub fn from_dictionary(dict: Dictionary) -> Self

Wrap an already-parsed dictionary in a shared handle.

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pub fn heap_size(&self) -> usize

Heap bytes the handle keeps alive: the shared allocation the dictionary lives in and the dictionary’s own content and tables. Clones share all of it.

§Examples

use structured_zstd::decoding::{Dictionary, DictionaryHandle};

let handle = DictionaryHandle::from_dictionary(
    Dictionary::from_raw_content(0, vec![7u8; 1024]).unwrap(),
);
assert!(handle.heap_size() > handle.as_dict().heap_bytes());
assert!(handle.heap_size() <= DictionaryHandle::max_heap_size(1024));

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pub fn max_heap_size(content_len: usize) -> usize

Most Self::heap_size a handle over a dictionary of content_len bytes can report, serialized header included, for budgeting before the dictionary is parsed.

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pub fn exclusive_heap_size<'a, I>(handles: I) -> usize
where I: IntoIterator<Item = &'a DictionaryHandle>, I::IntoIter: Clone,

Heap bytes that handles alone keep alive: each distinct dictionary among them once, and only when no handle outside them shares it. For an owner holding several handles, such as a decoding context that keeps a dictionary attached and its decoder keeps the last frame’s.

§Examples

use structured_zstd::decoding::{Dictionary, DictionaryHandle};

let handle = DictionaryHandle::from_dictionary(
    Dictionary::from_raw_content(0, vec![7u8; 64]).unwrap(),
);
let copy = handle.clone();
// Both handles are in the set: counted once.
assert_eq!(
    DictionaryHandle::exclusive_heap_size([&handle, &copy]),
    handle.heap_size()
);
// `copy` is held elsewhere: nothing is this set's alone.
assert_eq!(DictionaryHandle::exclusive_heap_size([&handle]), 0);

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pub fn decode_dict(raw: &[u8]) -> Result<Self, DictionaryDecodeError>

Parse a serialized dictionary and return a reusable shared handle.

With the legacy feature a dictionary in the v0.5 or v0.6 layout is taken too, whole as content with no ID: frames of its format parse its tables from it, as libzstd’s ZSTD_decompress_usingDict does.

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pub fn from_serialized_or_raw_content( raw: &[u8], ) -> Result<Self, DictionaryDecodeError>

Load whichever kind of dictionary raw holds, as ZSTD_createDDict does: a serialized dictionary, or raw content. See Dictionary::from_serialized_or_raw_content.

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