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package restful
// Copyright 2015 Ernest Micklei. All rights reserved.
// Use of this source code is governed by a license
// that can be found in the LICENSE file.
import (
"compress/gzip"
"compress/zlib"
)
// BoundedCachedCompressors is a CompressorProvider that uses a cache with a fixed amount
// of writers and readers (resources).
// If a new resource is acquired and all are in use, it will return a new unmanaged resource.
type BoundedCachedCompressors struct {
gzipWriters chan *gzip.Writer
gzipReaders chan *gzip.Reader
zlibWriters chan *zlib.Writer
writersCapacity int
readersCapacity int
}
// NewBoundedCachedCompressors returns a new, with filled cache, BoundedCachedCompressors.
func NewBoundedCachedCompressors(writersCapacity, readersCapacity int) *BoundedCachedCompressors {
b := &BoundedCachedCompressors{
gzipWriters: make(chan *gzip.Writer, writersCapacity),
gzipReaders: make(chan *gzip.Reader, readersCapacity),
zlibWriters: make(chan *zlib.Writer, writersCapacity),
writersCapacity: writersCapacity,
readersCapacity: readersCapacity,
}
for ix := 0; ix < writersCapacity; ix++ {
b.gzipWriters <- newGzipWriter()
b.zlibWriters <- newZlibWriter()
}
for ix := 0; ix < readersCapacity; ix++ {
b.gzipReaders <- newGzipReader()
}
return b
}
// AcquireGzipWriter returns an resettable *gzip.Writer. Needs to be released.
func (b *BoundedCachedCompressors) AcquireGzipWriter() *gzip.Writer {
var writer *gzip.Writer
select {
case writer, _ = <-b.gzipWriters:
default:
// return a new unmanaged one
writer = newGzipWriter()
}
return writer
}
// ReleaseGzipWriter accepts a writer (does not have to be one that was cached)
// only when the cache has room for it. It will ignore it otherwise.
func (b *BoundedCachedCompressors) ReleaseGzipWriter(w *gzip.Writer) {
// forget the unmanaged ones
if len(b.gzipWriters) < b.writersCapacity {
b.gzipWriters <- w
}
}
// AcquireGzipReader returns a *gzip.Reader. Needs to be released.
func (b *BoundedCachedCompressors) AcquireGzipReader() *gzip.Reader {
var reader *gzip.Reader
select {
case reader, _ = <-b.gzipReaders:
default:
// return a new unmanaged one
reader = newGzipReader()
}
return reader
}
// ReleaseGzipReader accepts a reader (does not have to be one that was cached)
// only when the cache has room for it. It will ignore it otherwise.
func (b *BoundedCachedCompressors) ReleaseGzipReader(r *gzip.Reader) {
// forget the unmanaged ones
if len(b.gzipReaders) < b.readersCapacity {
b.gzipReaders <- r
}
}
// AcquireZlibWriter returns an resettable *zlib.Writer. Needs to be released.
func (b *BoundedCachedCompressors) AcquireZlibWriter() *zlib.Writer {
var writer *zlib.Writer
select {
case writer, _ = <-b.zlibWriters:
default:
// return a new unmanaged one
writer = newZlibWriter()
}
return writer
}
// ReleaseZlibWriter accepts a writer (does not have to be one that was cached)
// only when the cache has room for it. It will ignore it otherwise.
func (b *BoundedCachedCompressors) ReleaseZlibWriter(w *zlib.Writer) {
// forget the unmanaged ones
if len(b.zlibWriters) < b.writersCapacity {
b.zlibWriters <- w
}
}
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