106 lines
2.4 KiB
Go
106 lines
2.4 KiB
Go
/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package ioutil
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import (
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"errors"
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"io"
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"sync"
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)
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// WriterGroup is a group of writers. Writer could be dynamically
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// added and removed.
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type WriterGroup struct {
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mu sync.Mutex
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writers map[string]io.WriteCloser
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closed bool
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}
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var _ io.Writer = &WriterGroup{}
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// NewWriterGroup creates an empty writer group.
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func NewWriterGroup() *WriterGroup {
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return &WriterGroup{
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writers: make(map[string]io.WriteCloser),
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}
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}
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// Add adds a writer into the group. The writer will be closed
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// if the writer group is closed.
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func (g *WriterGroup) Add(key string, w io.WriteCloser) {
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g.mu.Lock()
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defer g.mu.Unlock()
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if g.closed {
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w.Close()
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return
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}
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g.writers[key] = w
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}
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// Get gets a writer from the group, returns nil if the writer
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// doesn't exist.
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func (g *WriterGroup) Get(key string) io.WriteCloser {
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g.mu.Lock()
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defer g.mu.Unlock()
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return g.writers[key]
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}
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// Remove removes a writer from the group.
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func (g *WriterGroup) Remove(key string) {
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g.mu.Lock()
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defer g.mu.Unlock()
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w, ok := g.writers[key]
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if !ok {
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return
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}
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w.Close()
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delete(g.writers, key)
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}
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// Write writes data into each writer. If a writer returns error,
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// it will be closed and removed from the writer group. It returns
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// error if writer group is empty.
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func (g *WriterGroup) Write(p []byte) (int, error) {
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g.mu.Lock()
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defer g.mu.Unlock()
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for k, w := range g.writers {
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n, err := w.Write(p)
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if err == nil && len(p) == n {
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continue
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}
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// The writer is closed or in bad state, remove it.
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w.Close()
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delete(g.writers, k)
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}
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if len(g.writers) == 0 {
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return 0, errors.New("writer group is empty")
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}
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return len(p), nil
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}
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// Close closes the writer group. Write will return error after
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// closed.
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func (g *WriterGroup) Close() {
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g.mu.Lock()
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defer g.mu.Unlock()
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for _, w := range g.writers {
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w.Close()
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}
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g.writers = nil
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g.closed = true
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}
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