mirror of
https://github.com/prometheus-community/windows_exporter.git
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115 lines
2.4 KiB
Go
115 lines
2.4 KiB
Go
// SPDX-License-Identifier: Apache-2.0
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//
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// Copyright The Prometheus 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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package log
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import (
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"sync"
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"testing"
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"time"
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"github.com/stretchr/testify/require"
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)
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type blockingWriter struct {
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started chan struct{}
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release chan struct{}
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mu sync.Mutex
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writes [][]byte
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}
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func (w *blockingWriter) Write(p []byte) (int, error) {
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select {
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case <-w.started:
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default:
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close(w.started)
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}
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<-w.release
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w.mu.Lock()
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defer w.mu.Unlock()
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w.writes = append(w.writes, append([]byte(nil), p...))
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return len(p), nil
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}
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func (w *blockingWriter) Writes() [][]byte {
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w.mu.Lock()
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defer w.mu.Unlock()
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result := make([][]byte, len(w.writes))
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copy(result, w.writes)
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return result
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}
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func TestNonBlockingWriterDropsInsteadOfBlocking(t *testing.T) {
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t.Parallel()
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writer := &blockingWriter{
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started: make(chan struct{}),
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release: make(chan struct{}),
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}
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var cleanupOnce sync.Once
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nonBlockingWriter := newNonBlockingWriter(writer, 1)
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t.Cleanup(func() {
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cleanupOnce.Do(func() {
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close(writer.release)
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require.NoError(t, nonBlockingWriter.Close())
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})
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})
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_, err := nonBlockingWriter.Write([]byte("first"))
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require.NoError(t, err)
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select {
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case <-writer.started:
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case <-time.After(time.Second):
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t.Fatal("timed out waiting for background write to start")
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}
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_, err = nonBlockingWriter.Write([]byte("second"))
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require.NoError(t, err)
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done := make(chan struct{})
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go func() {
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defer close(done)
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_, err := nonBlockingWriter.Write([]byte("third"))
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require.NoError(t, err)
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}()
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select {
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case <-done:
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case <-time.After(100 * time.Millisecond):
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t.Fatal("write blocked while output writer was stalled")
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}
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cleanupOnce.Do(func() {
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close(writer.release)
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require.NoError(t, nonBlockingWriter.Close())
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})
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writes := writer.Writes()
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require.Len(t, writes, 2)
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require.Equal(t, []byte("first"), writes[0])
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require.Equal(t, []byte("second"), writes[1])
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}
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