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49 lines
1.3 KiB
49 lines
1.3 KiB
4 years ago
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// Package buffer implements a series of Buffers which can be composed to implement complicated buffering strategies
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package buffer
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import (
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"io"
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"os"
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)
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// Buffer is used to Write() data which will be Read() later.
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type Buffer interface {
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Len() int64 // How much data is Buffered in bytes
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Cap() int64 // How much data can be Buffered at once in bytes.
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io.Reader // Read() will read from the top of the buffer [io.EOF if empty]
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io.Writer // Write() will write to the end of the buffer [io.ErrShortWrite if not enough space]
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Reset() // Truncates the buffer, Len() == 0.
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}
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// BufferAt is a buffer which supports io.ReaderAt and io.WriterAt
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type BufferAt interface {
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Buffer
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io.ReaderAt
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io.WriterAt
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}
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func len64(p []byte) int64 {
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return int64(len(p))
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}
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// Gap returns buf.Cap() - buf.Len()
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func Gap(buf Buffer) int64 {
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return buf.Cap() - buf.Len()
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}
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// Full returns true iff buf.Len() == buf.Cap()
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func Full(buf Buffer) bool {
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return buf.Len() == buf.Cap()
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}
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// Empty returns false iff buf.Len() == 0
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func Empty(buf Buffer) bool {
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return buf.Len() == 0
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}
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// NewUnboundedBuffer returns a Buffer which buffers "mem" bytes to memory
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// and then creates file's of size "file" to buffer above "mem" bytes.
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func NewUnboundedBuffer(mem, file int64) Buffer {
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return NewMulti(New(mem), NewPartition(NewFilePool(file, os.TempDir())))
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}
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