diff options
Diffstat (limited to 'pkg/buffer')
| -rw-r--r-- | pkg/buffer/BUILD | 7 | ||||
| -rw-r--r-- | pkg/buffer/buffer.go | 35 | ||||
| -rw-r--r-- | pkg/buffer/pool.go | 83 | ||||
| -rw-r--r-- | pkg/buffer/pool_test.go | 51 | ||||
| -rw-r--r-- | pkg/buffer/safemem.go | 4 | ||||
| -rw-r--r-- | pkg/buffer/safemem_test.go | 2 | ||||
| -rw-r--r-- | pkg/buffer/view.go | 13 | ||||
| -rw-r--r-- | pkg/buffer/view_test.go | 77 |
8 files changed, 237 insertions, 35 deletions
diff --git a/pkg/buffer/BUILD b/pkg/buffer/BUILD index b03d46d18..1186f788e 100644 --- a/pkg/buffer/BUILD +++ b/pkg/buffer/BUILD @@ -20,6 +20,7 @@ go_library( srcs = [ "buffer.go", "buffer_list.go", + "pool.go", "safemem.go", "view.go", "view_unsafe.go", @@ -37,9 +38,13 @@ go_test( name = "buffer_test", size = "small", srcs = [ + "pool_test.go", "safemem_test.go", "view_test.go", ], library = ":buffer", - deps = ["//pkg/safemem"], + deps = [ + "//pkg/safemem", + "//pkg/state", + ], ) diff --git a/pkg/buffer/buffer.go b/pkg/buffer/buffer.go index c6d089fd9..311808ae9 100644 --- a/pkg/buffer/buffer.go +++ b/pkg/buffer/buffer.go @@ -14,36 +14,26 @@ // Package buffer provides the implementation of a buffer view. // -// A view is an flexible buffer, backed by a pool, supporting the safecopy -// operations natively as well as the ability to grow via either prepend or -// append, as well as shrink. +// A view is an flexible buffer, supporting the safecopy operations natively as +// well as the ability to grow via either prepend or append, as well as shrink. package buffer -import ( - "sync" -) - -const bufferSize = 8144 // See below. - // buffer encapsulates a queueable byte buffer. // -// Note that the total size is slightly less than two pages. This is done -// intentionally to ensure that the buffer object aligns with runtime -// internals. We have no hard size or alignment requirements. This two page -// size will effectively minimize internal fragmentation, but still have a -// large enough chunk to limit excessive segmentation. -// // +stateify savable type buffer struct { - data [bufferSize]byte + data []byte read int write int bufferEntry } -// reset resets internal data. -// -// This must be called before returning the buffer to the pool. +// init performs in-place initialization for zero value. +func (b *buffer) init(size int) { + b.data = make([]byte, size) +} + +// Reset resets read and write locations, effectively emptying the buffer. func (b *buffer) Reset() { b.read = 0 b.write = 0 @@ -85,10 +75,3 @@ func (b *buffer) WriteMove(n int) { func (b *buffer) WriteSlice() []byte { return b.data[b.write:] } - -// bufferPool is a pool for buffers. -var bufferPool = sync.Pool{ - New: func() interface{} { - return new(buffer) - }, -} diff --git a/pkg/buffer/pool.go b/pkg/buffer/pool.go new file mode 100644 index 000000000..7ad6132ab --- /dev/null +++ b/pkg/buffer/pool.go @@ -0,0 +1,83 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package buffer + +const ( + // embeddedCount is the number of buffer structures embedded in the pool. It + // is also the number for overflow allocations. + embeddedCount = 8 + + // defaultBufferSize is the default size for each underlying storage buffer. + // + // It is slightly less than two pages. This is done intentionally to ensure + // that the buffer object aligns with runtime internals. This two page size + // will effectively minimize internal fragmentation, but still have a large + // enough chunk to limit excessive segmentation. + defaultBufferSize = 8144 +) + +// pool allocates buffer. +// +// It contains an embedded buffer storage for fast path when the number of +// buffers needed is small. +// +// +stateify savable +type pool struct { + bufferSize int + avail []buffer `state:"nosave"` + embeddedStorage [embeddedCount]buffer `state:"wait"` +} + +// get gets a new buffer from p. +func (p *pool) get() *buffer { + if p.avail == nil { + p.avail = p.embeddedStorage[:] + } + if len(p.avail) == 0 { + p.avail = make([]buffer, embeddedCount) + } + if p.bufferSize <= 0 { + p.bufferSize = defaultBufferSize + } + buf := &p.avail[0] + buf.init(p.bufferSize) + p.avail = p.avail[1:] + return buf +} + +// put releases buf. +func (p *pool) put(buf *buffer) { + // Remove reference to the underlying storage, allowing it to be garbage + // collected. + buf.data = nil +} + +// setBufferSize sets the size of underlying storage buffer for future +// allocations. It can be called at any time. +func (p *pool) setBufferSize(size int) { + p.bufferSize = size +} + +// afterLoad is invoked by stateify. +func (p *pool) afterLoad() { + // S/R does not save subslice into embeddedStorage correctly. Restore + // available portion of embeddedStorage manually. Restore as nil if none used. + for i := len(p.embeddedStorage); i > 0; i-- { + if p.embeddedStorage[i-1].data != nil { + p.avail = p.embeddedStorage[i:] + break + } + } +} diff --git a/pkg/buffer/pool_test.go b/pkg/buffer/pool_test.go new file mode 100644 index 000000000..8584bac89 --- /dev/null +++ b/pkg/buffer/pool_test.go @@ -0,0 +1,51 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package buffer + +import ( + "testing" +) + +func TestGetDefaultBufferSize(t *testing.T) { + var p pool + for i := 0; i < embeddedCount*2; i++ { + buf := p.get() + if got, want := len(buf.data), defaultBufferSize; got != want { + t.Errorf("#%d len(buf.data) = %d, want %d", i, got, want) + } + } +} + +func TestGetCustomBufferSize(t *testing.T) { + const size = 100 + + var p pool + p.setBufferSize(size) + for i := 0; i < embeddedCount*2; i++ { + buf := p.get() + if got, want := len(buf.data), size; got != want { + t.Errorf("#%d len(buf.data) = %d, want %d", i, got, want) + } + } +} + +func TestPut(t *testing.T) { + var p pool + buf := p.get() + p.put(buf) + if buf.data != nil { + t.Errorf("buf.data = %x, want nil", buf.data) + } +} diff --git a/pkg/buffer/safemem.go b/pkg/buffer/safemem.go index b789e56e9..8b42575b4 100644 --- a/pkg/buffer/safemem.go +++ b/pkg/buffer/safemem.go @@ -44,7 +44,7 @@ func (v *View) WriteFromSafememReader(r safemem.Reader, count uint64) (uint64, e // Need at least one buffer. firstBuf := v.data.Back() if firstBuf == nil { - firstBuf = bufferPool.Get().(*buffer) + firstBuf = v.pool.get() v.data.PushBack(firstBuf) } @@ -56,7 +56,7 @@ func (v *View) WriteFromSafememReader(r safemem.Reader, count uint64) (uint64, e count -= l blocks = append(blocks, firstBuf.WriteBlock()) for count > 0 { - emptyBuf := bufferPool.Get().(*buffer) + emptyBuf := v.pool.get() v.data.PushBack(emptyBuf) block := emptyBuf.WriteBlock().TakeFirst64(count) count -= uint64(block.Len()) diff --git a/pkg/buffer/safemem_test.go b/pkg/buffer/safemem_test.go index 47f357e0c..721cc5934 100644 --- a/pkg/buffer/safemem_test.go +++ b/pkg/buffer/safemem_test.go @@ -23,6 +23,8 @@ import ( ) func TestSafemem(t *testing.T) { + const bufferSize = defaultBufferSize + testCases := []struct { name string input string diff --git a/pkg/buffer/view.go b/pkg/buffer/view.go index e6901eadb..00652d675 100644 --- a/pkg/buffer/view.go +++ b/pkg/buffer/view.go @@ -27,6 +27,7 @@ import ( type View struct { data bufferList size int64 + pool pool } // TrimFront removes the first count bytes from the buffer. @@ -81,7 +82,7 @@ func (v *View) advanceRead(count int64) { buf = buf.Next() // Iterate. v.data.Remove(oldBuf) oldBuf.Reset() - bufferPool.Put(oldBuf) + v.pool.put(oldBuf) // Update counts. count -= sz @@ -118,7 +119,7 @@ func (v *View) Truncate(length int64) { // Drop the buffer completely; see above. v.data.Remove(buf) buf.Reset() - bufferPool.Put(buf) + v.pool.put(buf) v.size -= sz } } @@ -137,7 +138,7 @@ func (v *View) Grow(length int64, zero bool) { // Is there some space in the last buffer? if buf == nil || buf.Full() { - buf = bufferPool.Get().(*buffer) + buf = v.pool.get() v.data.PushBack(buf) } @@ -181,7 +182,7 @@ func (v *View) Prepend(data []byte) { for len(data) > 0 { // Do we need an empty buffer? - buf := bufferPool.Get().(*buffer) + buf := v.pool.get() v.data.PushFront(buf) // The buffer is empty; copy last chunk. @@ -211,7 +212,7 @@ func (v *View) Append(data []byte) { // Ensure there's a buffer with space. if buf == nil || buf.Full() { - buf = bufferPool.Get().(*buffer) + buf = v.pool.get() v.data.PushBack(buf) } @@ -297,7 +298,7 @@ func (v *View) WriteFromReader(r io.Reader, count int64) (int64, error) { // Ensure we have an empty buffer. if buf == nil || buf.Full() { - buf = bufferPool.Get().(*buffer) + buf = v.pool.get() v.data.PushBack(buf) } diff --git a/pkg/buffer/view_test.go b/pkg/buffer/view_test.go index 3db1bc6ee..839af0223 100644 --- a/pkg/buffer/view_test.go +++ b/pkg/buffer/view_test.go @@ -16,11 +16,16 @@ package buffer import ( "bytes" + "context" "io" "strings" "testing" + + "gvisor.dev/gvisor/pkg/state" ) +const bufferSize = defaultBufferSize + func fillAppend(v *View, data []byte) { v.Append(data) } @@ -50,6 +55,30 @@ var fillFuncs = map[string]func(*View, []byte){ "writeFromReaderEnd": fillWriteFromReaderEnd, } +func BenchmarkReadAt(b *testing.B) { + b.ReportAllocs() + var v View + v.Append(make([]byte, 100)) + + buf := make([]byte, 10) + for i := 0; i < b.N; i++ { + v.ReadAt(buf, 0) + } +} + +func BenchmarkWriteRead(b *testing.B) { + b.ReportAllocs() + var v View + sz := 1000 + wbuf := make([]byte, sz) + rbuf := bytes.NewBuffer(make([]byte, sz)) + for i := 0; i < b.N; i++ { + v.Append(wbuf) + rbuf.Reset() + v.ReadToWriter(rbuf, int64(sz)) + } +} + func testReadAt(t *testing.T, v *View, offset int64, n int, wantStr string, wantErr error) { t.Helper() d := make([]byte, n) @@ -465,3 +494,51 @@ func TestView(t *testing.T) { } } } + +func doSaveAndLoad(t *testing.T, toSave, toLoad *View) { + t.Helper() + var buf bytes.Buffer + ctx := context.Background() + if _, err := state.Save(ctx, &buf, toSave); err != nil { + t.Fatal("state.Save:", err) + } + if _, err := state.Load(ctx, bytes.NewReader(buf.Bytes()), toLoad); err != nil { + t.Fatal("state.Load:", err) + } +} + +func TestSaveRestoreViewEmpty(t *testing.T) { + var toSave View + var v View + doSaveAndLoad(t, &toSave, &v) + + if got := v.pool.avail; got != nil { + t.Errorf("pool is not in zero state: v.pool.avail = %v, want nil", got) + } + if got := v.Flatten(); len(got) != 0 { + t.Errorf("v.Flatten() = %x, want []", got) + } +} + +func TestSaveRestoreView(t *testing.T) { + // Create data that fits 2.5 slots. + data := bytes.Join([][]byte{ + bytes.Repeat([]byte{1, 2}, defaultBufferSize), + bytes.Repeat([]byte{3}, defaultBufferSize/2), + }, nil) + + var toSave View + toSave.Append(data) + + var v View + doSaveAndLoad(t, &toSave, &v) + + // Next available slot at index 3; 0-2 slot are used. + i := 3 + if got, want := &v.pool.avail[0], &v.pool.embeddedStorage[i]; got != want { + t.Errorf("next available buffer points to %p, want %p (&v.pool.embeddedStorage[%d])", got, want, i) + } + if got := v.Flatten(); !bytes.Equal(got, data) { + t.Errorf("v.Flatten() = %x, want %x", got, data) + } +} |