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Diffstat (limited to 'vendor/golang.org/x/net/http2/databuffer.go')
-rw-r--r-- | vendor/golang.org/x/net/http2/databuffer.go | 149 |
1 files changed, 0 insertions, 149 deletions
diff --git a/vendor/golang.org/x/net/http2/databuffer.go b/vendor/golang.org/x/net/http2/databuffer.go deleted file mode 100644 index e6f55cbd1..000000000 --- a/vendor/golang.org/x/net/http2/databuffer.go +++ /dev/null @@ -1,149 +0,0 @@ -// Copyright 2014 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -package http2 - -import ( - "errors" - "fmt" - "sync" -) - -// Buffer chunks are allocated from a pool to reduce pressure on GC. -// The maximum wasted space per dataBuffer is 2x the largest size class, -// which happens when the dataBuffer has multiple chunks and there is -// one unread byte in both the first and last chunks. We use a few size -// classes to minimize overheads for servers that typically receive very -// small request bodies. -// -// TODO: Benchmark to determine if the pools are necessary. The GC may have -// improved enough that we can instead allocate chunks like this: -// make([]byte, max(16<<10, expectedBytesRemaining)) -var dataChunkPools = [...]sync.Pool{ - {New: func() interface{} { return new([1 << 10]byte) }}, - {New: func() interface{} { return new([2 << 10]byte) }}, - {New: func() interface{} { return new([4 << 10]byte) }}, - {New: func() interface{} { return new([8 << 10]byte) }}, - {New: func() interface{} { return new([16 << 10]byte) }}, -} - -func getDataBufferChunk(size int64) []byte { - switch { - case size <= 1<<10: - return dataChunkPools[0].Get().(*[1 << 10]byte)[:] - case size <= 2<<10: - return dataChunkPools[1].Get().(*[2 << 10]byte)[:] - case size <= 4<<10: - return dataChunkPools[2].Get().(*[4 << 10]byte)[:] - case size <= 8<<10: - return dataChunkPools[3].Get().(*[8 << 10]byte)[:] - default: - return dataChunkPools[4].Get().(*[16 << 10]byte)[:] - } -} - -func putDataBufferChunk(p []byte) { - switch len(p) { - case 1 << 10: - dataChunkPools[0].Put((*[1 << 10]byte)(p)) - case 2 << 10: - dataChunkPools[1].Put((*[2 << 10]byte)(p)) - case 4 << 10: - dataChunkPools[2].Put((*[4 << 10]byte)(p)) - case 8 << 10: - dataChunkPools[3].Put((*[8 << 10]byte)(p)) - case 16 << 10: - dataChunkPools[4].Put((*[16 << 10]byte)(p)) - default: - panic(fmt.Sprintf("unexpected buffer len=%v", len(p))) - } -} - -// dataBuffer is an io.ReadWriter backed by a list of data chunks. -// Each dataBuffer is used to read DATA frames on a single stream. -// The buffer is divided into chunks so the server can limit the -// total memory used by a single connection without limiting the -// request body size on any single stream. -type dataBuffer struct { - chunks [][]byte - r int // next byte to read is chunks[0][r] - w int // next byte to write is chunks[len(chunks)-1][w] - size int // total buffered bytes - expected int64 // we expect at least this many bytes in future Write calls (ignored if <= 0) -} - -var errReadEmpty = errors.New("read from empty dataBuffer") - -// Read copies bytes from the buffer into p. -// It is an error to read when no data is available. -func (b *dataBuffer) Read(p []byte) (int, error) { - if b.size == 0 { - return 0, errReadEmpty - } - var ntotal int - for len(p) > 0 && b.size > 0 { - readFrom := b.bytesFromFirstChunk() - n := copy(p, readFrom) - p = p[n:] - ntotal += n - b.r += n - b.size -= n - // If the first chunk has been consumed, advance to the next chunk. - if b.r == len(b.chunks[0]) { - putDataBufferChunk(b.chunks[0]) - end := len(b.chunks) - 1 - copy(b.chunks[:end], b.chunks[1:]) - b.chunks[end] = nil - b.chunks = b.chunks[:end] - b.r = 0 - } - } - return ntotal, nil -} - -func (b *dataBuffer) bytesFromFirstChunk() []byte { - if len(b.chunks) == 1 { - return b.chunks[0][b.r:b.w] - } - return b.chunks[0][b.r:] -} - -// Len returns the number of bytes of the unread portion of the buffer. -func (b *dataBuffer) Len() int { - return b.size -} - -// Write appends p to the buffer. -func (b *dataBuffer) Write(p []byte) (int, error) { - ntotal := len(p) - for len(p) > 0 { - // If the last chunk is empty, allocate a new chunk. Try to allocate - // enough to fully copy p plus any additional bytes we expect to - // receive. However, this may allocate less than len(p). - want := int64(len(p)) - if b.expected > want { - want = b.expected - } - chunk := b.lastChunkOrAlloc(want) - n := copy(chunk[b.w:], p) - p = p[n:] - b.w += n - b.size += n - b.expected -= int64(n) - } - return ntotal, nil -} - -func (b *dataBuffer) lastChunkOrAlloc(want int64) []byte { - if len(b.chunks) != 0 { - last := b.chunks[len(b.chunks)-1] - if b.w < len(last) { - return last - } - } - chunk := getDataBufferChunk(want) - b.chunks = append(b.chunks, chunk) - b.w = 0 - return chunk -} |