39 lines
2 KiB
Markdown
39 lines
2 KiB
Markdown
treap
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=====
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[](https://travis-ci.org/btcsuite/btcd)
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[](http://copyfree.org)
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[](http://godoc.org/github.com/btcsuite/btcd/database/internal/treap)
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Package treap implements a treap data structure that is used to hold ordered
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key/value pairs using a combination of binary search tree and heap semantics.
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It is a self-organizing and randomized data structure that doesn't require
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complex operations to maintain balance. Search, insert, and delete
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operations are all O(log n). Both mutable and immutable variants are provided.
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The mutable variant is typically faster since it is able to simply update the
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treap when modifications are made. However, a mutable treap is not safe for
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concurrent access without careful use of locking by the caller and care must be
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taken when iterating since it can change out from under the iterator.
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The immutable variant works by creating a new version of the treap for all
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mutations by replacing modified nodes with new nodes that have updated values
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while sharing all unmodified nodes with the previous version. This is extremely
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useful in concurrent applications since the caller only has to atomically
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replace the treap pointer with the newly returned version after performing any
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mutations. All readers can simply use their existing pointer as a snapshot
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since the treap it points to is immutable. This effectively provides O(1)
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snapshot capability with efficient memory usage characteristics since the old
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nodes only remain allocated until there are no longer any references to them.
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Package treap is licensed under the copyfree ISC license.
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## Usage
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This package is only used internally in the database code and as such is not
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available for use outside of it.
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## License
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Package treap is licensed under the [copyfree](http://copyfree.org) ISC
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License.
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