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overlookmotel
edc70eae97
#13622 and #13624 altered what happens when the `fixed_size` Cargo feature is enabled. Previously, enabling that feature altered behavior of `AllocatorPool`. Now the feature is additive - it does nothing on it's own, but only adds additional APIs, and *those APIs* can be used to alter behavior. The purpose of the `disable_fixed_size` Cargo feature was to prevent the `fixed_size` feature being activated when tests are run with `--all-features`. Now that enabling `fixed_size` feature doesn't alter behavior, we don't need to worry about it being enabled in tests. Therefore `disable_fixed_size` feature can be removed. This removes a bunch of `#[cfg]` boilerplate, and ugly hacks which were previously required to workaround feature unification.
40 lines
1.9 KiB
Markdown
40 lines
1.9 KiB
Markdown
# Oxc Allocator
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A high-performance memory allocator using bump-based arena allocation for fast AST node creation.
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## Overview
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Oxc uses a bump-based memory arena for faster AST allocations. This crate provides an [`Allocator`] that manages memory efficiently by allocating objects in a single contiguous memory region, avoiding the overhead of individual heap allocations.
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## Key Features
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- **Bump allocation**: Fast allocation by simply incrementing a pointer
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- **Arena-based memory management**: All allocations live for the same lifetime
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- **Zero-copy data structures**: Efficient `Box`, `Vec`, `String`, and `HashMap` implementations
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- **Optimal for AST operations**: Perfect for parse-transform-emit workflows
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## Architecture
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The allocator is designed specifically for AST processing workflows where:
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1. A large number of nodes are allocated during parsing
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2. All nodes have the same lifetime (tied to the AST)
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3. Memory is released all at once when the AST is dropped
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This approach is significantly faster than using the system allocator for AST operations.
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## Features
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- `serialize` - Enables serialization support for `Box` and `Vec` with `serde` and `oxc_estree`.
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- `pool` - Enables `AllocatorPool`.
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- `bitset` - Enables `BitSet`.
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- `from_raw_parts` - Adds unsafe `from_raw_parts` method (not recommended for general use).
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- `fixed_size` - Makes `AllocatorPool` create large fixed-size allocators, instead of flexibly-sized ones.
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Only supported on 64-bit little-endian platforms at present.
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Usage of this feature is not advisable, and it will be removed as soon as we're able to.
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- `track_allocations` - Count allocations and reallocations.
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For internal use only. The APIs provided by this feature are sketchy at best, and possibly
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undefined behavior. Do not enable this feature under any circumstances in production code.
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- `disable_track_allocations` - Disables `track_allocations` feature.
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Purpose is to prevent `--all-features` enabling allocation tracking.
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