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author | 2024-09-16 11:06:00 +0200 | |
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committer | 2024-09-16 09:06:00 +0000 | |
commit | b2572b9e074ebbce8bcf1b9979d4d8ea066650d6 (patch) | |
tree | 0c2a08ed63b582676ce7661252a6917db751c62a /vendor/google.golang.org/grpc/mem/buffer_slice.go | |
parent | [chore]: Bump golang.org/x/net from 0.28.0 to 0.29.0 (#3303) (diff) | |
download | gotosocial-b2572b9e074ebbce8bcf1b9979d4d8ea066650d6.tar.xz |
[chore] Bump otel deps -> v1.30.0/v0.52.0 (#3307)
Diffstat (limited to 'vendor/google.golang.org/grpc/mem/buffer_slice.go')
-rw-r--r-- | vendor/google.golang.org/grpc/mem/buffer_slice.go | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/vendor/google.golang.org/grpc/mem/buffer_slice.go b/vendor/google.golang.org/grpc/mem/buffer_slice.go new file mode 100644 index 000000000..d7775cea6 --- /dev/null +++ b/vendor/google.golang.org/grpc/mem/buffer_slice.go @@ -0,0 +1,224 @@ +/* + * + * Copyright 2024 gRPC 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 mem + +import ( + "compress/flate" + "io" +) + +// BufferSlice offers a means to represent data that spans one or more Buffer +// instances. A BufferSlice is meant to be immutable after creation, and methods +// like Ref create and return copies of the slice. This is why all methods have +// value receivers rather than pointer receivers. +// +// Note that any of the methods that read the underlying buffers such as Ref, +// Len or CopyTo etc., will panic if any underlying buffers have already been +// freed. It is recommended to not directly interact with any of the underlying +// buffers directly, rather such interactions should be mediated through the +// various methods on this type. +// +// By convention, any APIs that return (mem.BufferSlice, error) should reduce +// the burden on the caller by never returning a mem.BufferSlice that needs to +// be freed if the error is non-nil, unless explicitly stated. +type BufferSlice []Buffer + +// Len returns the sum of the length of all the Buffers in this slice. +// +// # Warning +// +// Invoking the built-in len on a BufferSlice will return the number of buffers +// in the slice, and *not* the value returned by this function. +func (s BufferSlice) Len() int { + var length int + for _, b := range s { + length += b.Len() + } + return length +} + +// Ref invokes Ref on each buffer in the slice. +func (s BufferSlice) Ref() { + for _, b := range s { + b.Ref() + } +} + +// Free invokes Buffer.Free() on each Buffer in the slice. +func (s BufferSlice) Free() { + for _, b := range s { + b.Free() + } +} + +// CopyTo copies each of the underlying Buffer's data into the given buffer, +// returning the number of bytes copied. Has the same semantics as the copy +// builtin in that it will copy as many bytes as it can, stopping when either dst +// is full or s runs out of data, returning the minimum of s.Len() and len(dst). +func (s BufferSlice) CopyTo(dst []byte) int { + off := 0 + for _, b := range s { + off += copy(dst[off:], b.ReadOnlyData()) + } + return off +} + +// Materialize concatenates all the underlying Buffer's data into a single +// contiguous buffer using CopyTo. +func (s BufferSlice) Materialize() []byte { + l := s.Len() + if l == 0 { + return nil + } + out := make([]byte, l) + s.CopyTo(out) + return out +} + +// MaterializeToBuffer functions like Materialize except that it writes the data +// to a single Buffer pulled from the given BufferPool. As a special case, if the +// input BufferSlice only actually has one Buffer, this function has nothing to +// do and simply returns said Buffer. +func (s BufferSlice) MaterializeToBuffer(pool BufferPool) Buffer { + if len(s) == 1 { + s[0].Ref() + return s[0] + } + sLen := s.Len() + if sLen == 0 { + return emptyBuffer{} + } + buf := pool.Get(sLen) + s.CopyTo(*buf) + return NewBuffer(buf, pool) +} + +// Reader returns a new Reader for the input slice after taking references to +// each underlying buffer. +func (s BufferSlice) Reader() Reader { + s.Ref() + return &sliceReader{ + data: s, + len: s.Len(), + } +} + +// Reader exposes a BufferSlice's data as an io.Reader, allowing it to interface +// with other parts systems. It also provides an additional convenience method +// Remaining(), which returns the number of unread bytes remaining in the slice. +// Buffers will be freed as they are read. +type Reader interface { + flate.Reader + // Close frees the underlying BufferSlice and never returns an error. Subsequent + // calls to Read will return (0, io.EOF). + Close() error + // Remaining returns the number of unread bytes remaining in the slice. + Remaining() int +} + +type sliceReader struct { + data BufferSlice + len int + // The index into data[0].ReadOnlyData(). + bufferIdx int +} + +func (r *sliceReader) Remaining() int { + return r.len +} + +func (r *sliceReader) Close() error { + r.data.Free() + r.data = nil + r.len = 0 + return nil +} + +func (r *sliceReader) freeFirstBufferIfEmpty() bool { + if len(r.data) == 0 || r.bufferIdx != len(r.data[0].ReadOnlyData()) { + return false + } + + r.data[0].Free() + r.data = r.data[1:] + r.bufferIdx = 0 + return true +} + +func (r *sliceReader) Read(buf []byte) (n int, _ error) { + if r.len == 0 { + return 0, io.EOF + } + + for len(buf) != 0 && r.len != 0 { + // Copy as much as possible from the first Buffer in the slice into the + // given byte slice. + data := r.data[0].ReadOnlyData() + copied := copy(buf, data[r.bufferIdx:]) + r.len -= copied // Reduce len by the number of bytes copied. + r.bufferIdx += copied // Increment the buffer index. + n += copied // Increment the total number of bytes read. + buf = buf[copied:] // Shrink the given byte slice. + + // If we have copied all the data from the first Buffer, free it and advance to + // the next in the slice. + r.freeFirstBufferIfEmpty() + } + + return n, nil +} + +func (r *sliceReader) ReadByte() (byte, error) { + if r.len == 0 { + return 0, io.EOF + } + + // There may be any number of empty buffers in the slice, clear them all until a + // non-empty buffer is reached. This is guaranteed to exit since r.len is not 0. + for r.freeFirstBufferIfEmpty() { + } + + b := r.data[0].ReadOnlyData()[r.bufferIdx] + r.len-- + r.bufferIdx++ + // Free the first buffer in the slice if the last byte was read + r.freeFirstBufferIfEmpty() + return b, nil +} + +var _ io.Writer = (*writer)(nil) + +type writer struct { + buffers *BufferSlice + pool BufferPool +} + +func (w *writer) Write(p []byte) (n int, err error) { + b := Copy(p, w.pool) + *w.buffers = append(*w.buffers, b) + return b.Len(), nil +} + +// NewWriter wraps the given BufferSlice and BufferPool to implement the +// io.Writer interface. Every call to Write copies the contents of the given +// buffer into a new Buffer pulled from the given pool and the Buffer is added to +// the given BufferSlice. +func NewWriter(buffers *BufferSlice, pool BufferPool) io.Writer { + return &writer{buffers: buffers, pool: pool} +} |