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74 lines
2.8 KiB
Go
74 lines
2.8 KiB
Go
// Copyright 2014 The b Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package b implements the B+tree flavor of a BTree.
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//
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// Changelog
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//
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// 2016-07-16: Update benchmark results to newer Go version. Add a note on
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// concurrency.
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//
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// 2014-06-26: Lower GC presure by recycling things.
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//
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// 2014-04-18: Added new method Put.
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//
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// Concurrency considerations
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//
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// Tree.{Clear,Delete,Put,Set} mutate the tree. One can use eg. a
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// sync.Mutex.Lock/Unlock (or sync.RWMutex.Lock/Unlock) to wrap those calls if
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// they are to be invoked concurrently.
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//
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// Tree.{First,Get,Last,Len,Seek,SeekFirst,SekLast} read but do not mutate the
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// tree. One can use eg. a sync.RWMutex.RLock/RUnlock to wrap those calls if
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// they are to be invoked concurrently with any of the tree mutating methods.
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//
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// Enumerator.{Next,Prev} mutate the enumerator and read but not mutate the
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// tree. One can use eg. a sync.RWMutex.RLock/RUnlock to wrap those calls if
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// they are to be invoked concurrently with any of the tree mutating methods. A
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// separate mutex for the enumerator, or the whole tree in a simplified
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// variant, is necessary if the enumerator's Next/Prev methods per se are to
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// be invoked concurrently.
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//
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// Generic types
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//
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// Keys and their associated values are interface{} typed, similar to all of
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// the containers in the standard library.
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//
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// Semiautomatic production of a type specific variant of this package is
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// supported via
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//
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// $ make generic
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//
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// This command will write to stdout a version of the btree.go file where every
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// key type occurrence is replaced by the word 'KEY' and every value type
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// occurrence is replaced by the word 'VALUE'. Then you have to replace these
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// tokens with your desired type(s), using any technique you're comfortable
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// with.
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//
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// This is how, for example, 'example/int.go' was created:
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//
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// $ mkdir example
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// $ make generic | sed -e 's/KEY/int/g' -e 's/VALUE/int/g' > example/int.go
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//
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// No other changes to int.go are necessary, it compiles just fine.
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//
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// Running the benchmarks for 1000 keys on a machine with Intel i5-4670 CPU @
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// 3.4GHz, Go 1.7rc1.
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//
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// $ go test -bench 1e3 example/all_test.go example/int.go
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// BenchmarkSetSeq1e3-4 20000 78265 ns/op
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// BenchmarkGetSeq1e3-4 20000 67980 ns/op
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// BenchmarkSetRnd1e3-4 10000 172720 ns/op
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// BenchmarkGetRnd1e3-4 20000 89539 ns/op
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// BenchmarkDelSeq1e3-4 20000 87863 ns/op
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// BenchmarkDelRnd1e3-4 10000 130891 ns/op
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// BenchmarkSeekSeq1e3-4 10000 100118 ns/op
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// BenchmarkSeekRnd1e3-4 10000 121684 ns/op
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// BenchmarkNext1e3-4 200000 6330 ns/op
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// BenchmarkPrev1e3-4 200000 9066 ns/op
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// PASS
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// ok command-line-arguments 42.531s
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// $
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package b
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