mirror of
https://github.com/ceph/ceph-csi.git
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75 lines
2.2 KiB
Go
75 lines
2.2 KiB
Go
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/*
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Copyright 2022 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package runtime
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import (
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"sync"
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)
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// AllocatorPool simply stores Allocator objects to avoid additional memory allocations
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// by caching created but unused items for later reuse, relieving pressure on the garbage collector.
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//
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// Usage:
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// memoryAllocator := runtime.AllocatorPool.Get().(*runtime.Allocator)
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// defer runtime.AllocatorPool.Put(memoryAllocator)
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//
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// A note for future:
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// consider introducing multiple pools for storing buffers of different sizes
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// perhaps this could allow us to be more efficient.
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var AllocatorPool = sync.Pool{
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New: func() interface{} {
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return &Allocator{}
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},
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}
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// Allocator knows how to allocate memory
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// It exists to make the cost of object serialization cheaper.
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// In some cases, it allows for allocating memory only once and then reusing it.
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// This approach puts less load on GC and leads to less fragmented memory in general.
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type Allocator struct {
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buf []byte
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}
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var _ MemoryAllocator = &Allocator{}
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// Allocate reserves memory for n bytes only if the underlying array doesn't have enough capacity
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// otherwise it returns previously allocated block of memory.
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//
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// Note that the returned array is not zeroed, it is the caller's
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// responsibility to clean the memory if needed.
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func (a *Allocator) Allocate(n uint64) []byte {
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if uint64(cap(a.buf)) >= n {
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a.buf = a.buf[:n]
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return a.buf
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}
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// grow the buffer
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size := uint64(2*cap(a.buf)) + n
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a.buf = make([]byte, size, size)
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a.buf = a.buf[:n]
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return a.buf
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}
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// SimpleAllocator a wrapper around make([]byte)
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// conforms to the MemoryAllocator interface
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type SimpleAllocator struct{}
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var _ MemoryAllocator = &SimpleAllocator{}
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func (sa *SimpleAllocator) Allocate(n uint64) []byte {
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return make([]byte, n, n)
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}
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