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	Fixes #9105 Signed-off-by: Julien Pivotto <roidelapluie@o11y.eu> Signed-off-by: Julien <roidelapluie@o11y.eu>
		
			
				
	
	
		
			125 lines
		
	
	
		
			3.1 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			125 lines
		
	
	
		
			3.1 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
// Copyright 2024 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 netconnlimit
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import (
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	"io"
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	"net"
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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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func TestSharedLimitListenerConcurrency(t *testing.T) {
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	testCases := []struct {
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		name        string
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		semCapacity int
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		connCount   int
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		expected    int // Expected number of connections processed simultaneously.
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	}{
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		{
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			name:        "Single connection allowed",
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			semCapacity: 1,
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			connCount:   3,
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			expected:    1,
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		},
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		{
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			name:        "Two connections allowed",
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			semCapacity: 2,
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			connCount:   3,
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			expected:    2,
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		},
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		{
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			name:        "Three connections allowed",
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			semCapacity: 3,
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			connCount:   3,
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			expected:    3,
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		},
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	}
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	for _, tc := range testCases {
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		t.Run(tc.name, func(t *testing.T) {
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			sem := NewSharedSemaphore(tc.semCapacity)
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			listener, err := net.Listen("tcp", "127.0.0.1:0")
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			require.NoError(t, err, "failed to create listener")
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			defer listener.Close()
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			limitedListener := SharedLimitListener(listener, sem)
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			var wg sync.WaitGroup
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			var activeConnCount int64
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			var mu sync.Mutex
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			wg.Add(tc.connCount)
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			// Accept connections.
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			for i := 0; i < tc.connCount; i++ {
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				go func() {
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					defer wg.Done()
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					conn, err := limitedListener.Accept()
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					require.NoError(t, err, "failed to accept connection")
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					defer conn.Close()
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					// Simulate work and track the active connection count.
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					mu.Lock()
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					activeConnCount++
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					require.LessOrEqual(t, activeConnCount, int64(tc.expected), "too many simultaneous connections")
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					mu.Unlock()
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					time.Sleep(100 * time.Millisecond)
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					mu.Lock()
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					activeConnCount--
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					mu.Unlock()
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				}()
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			}
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			// Create clients that attempt to connect to the listener.
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			for i := 0; i < tc.connCount; i++ {
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				go func() {
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					conn, err := net.Dial("tcp", listener.Addr().String())
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					require.NoError(t, err, "failed to connect to listener")
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					defer conn.Close()
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					_, _ = io.WriteString(conn, "hello")
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				}()
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			}
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			wg.Wait()
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			// Ensure all connections are released and semaphore is empty.
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			require.Empty(t, sem)
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		})
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	}
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}
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func TestSharedLimitListenerClose(t *testing.T) {
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	sem := NewSharedSemaphore(2)
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	listener, err := net.Listen("tcp", "127.0.0.1:0")
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	require.NoError(t, err, "failed to create listener")
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	limitedListener := SharedLimitListener(listener, sem)
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	// Close the listener and ensure it does not accept new connections.
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	err = limitedListener.Close()
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	require.NoError(t, err, "failed to close listener")
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	conn, err := limitedListener.Accept()
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	require.Error(t, err, "expected error on accept after listener closed")
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	if conn != nil {
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		conn.Close()
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	}
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}
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