Overview
| Comment: | Extracted SizedWriter to a sizedWriter struct with a Write() method. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
46da7a6ae933a799da23fba4c3d096e5 |
| User & Date: | spaskalev on 2014-12-25 00:26:02 |
| Other Links: | manifest | tags |
Context
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2014-12-25
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| 00:43 | Extracted predictor's compressor and decompressor code into separate structs that embed Sized{Writer,Reader} check-in: 50507bd510 user: spaskalev tags: trunk | |
| 00:26 | Extracted SizedWriter to a sizedWriter struct with a Write() method. check-in: 46da7a6ae9 user: spaskalev tags: trunk | |
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2014-12-24
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| 23:58 | 0dev.org/ioutil/SizedReader is now as fast as bufio.Reader if not faster for a buffer of 4096 bytes. Switched pdc to use it for decompression buffering and removed profiling code from the former check-in: 2cec92909f user: spaskalev tags: trunk | |
Changes
Modified src/0dev.org/ioutil/ioutil.go from [9862ea3396] to [c11fdb5a53].
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// Returns a writer that delegates calls to Write(...) while ensuring
// that it is never called with less bytes than the specified amount.
//
// Calls with fewer bytes are buffered while a call with a nil slice
// causes the buffer to be flushed to the underlying writer.
func SizedWriter(writer io.Writer, size int) io.Writer {
| > > | > > > | > > > > | > | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | < < < < < < < < < > > > > > > | 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 |
// Returns a writer that delegates calls to Write(...) while ensuring
// that it is never called with less bytes than the specified amount.
//
// Calls with fewer bytes are buffered while a call with a nil slice
// causes the buffer to be flushed to the underlying writer.
func SizedWriter(writer io.Writer, size int) io.Writer {
var sw sizedWriter
sw.writer = writer
sw.buffer = make([]byte, 0, size)
sw.size = size
return &sw
}
type sizedWriter struct {
writer io.Writer
buffer []byte
size int
}
func (sw *sizedWriter) Write(input []byte) (int, error) {
var (
count int
err error
)
// Flush the buffer when called with no bytes to write
if input == nil {
// Call the writer with whatever we have in store..
count, err = sw.writer.Write(sw.buffer)
// Advance the buffer
sw.buffer = sw.buffer[:copy(sw.buffer, sw.buffer[count:])]
return 0, err
}
// Delegate to the writer if the size is right
if len(sw.buffer) == 0 && len(input) >= sw.size {
reduced := (len(input) / sw.size) * sw.size
count, err = sw.writer.Write(input[:reduced])
if count < reduced || err != nil {
return count, err
}
// Stage any remaining data in the buffer
sw.buffer = append(sw.buffer, input[count:]...)
return len(input), nil
}
// Append data to the buffer
count = copy(sw.buffer[len(sw.buffer):sw.size], input)
sw.buffer = sw.buffer[:len(sw.buffer)+count]
// Return if we don't have enough bytes to write
if len(sw.buffer) < sw.size {
return len(input), nil
}
// Flush the buffer as it is filled
_, err = sw.Write(nil)
if err != nil {
return count, err
}
// Handle the rest of the input
return sw.Write(input[count:])
}
// Returns a reader that delegates calls to Read(...) while ensuring
// that the output buffer is never smaller than the required size
// and is downsized to a multiple of the required size if larger.
func SizedReader(reader io.Reader, size int) io.Reader {
var sr sizedReader
sr.reader = reader
sr.buffer = make([]byte, size)
sr.size, sr.from, sr.to = size, 0, 0
return &sr
}
type sizedReader struct {
reader io.Reader
buffer []byte
from, to, size int
}
func (sr *sizedReader) Read(output []byte) (int, error) {
var (
count int
err error
)
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