c9ab713f59
Instead of letting the OS pick a random port for us in a way that wasn't concurrency safe, we use an atomically incremented port to avoid collisions.
100 lines
2.5 KiB
Go
100 lines
2.5 KiB
Go
// +build kvdb_etcd
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package etcd
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import (
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"context"
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"fmt"
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"net"
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"net/url"
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"sync/atomic"
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"time"
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"github.com/coreos/etcd/embed"
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)
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const (
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// readyTimeout is the time until the embedded etcd instance should start.
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readyTimeout = 10 * time.Second
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// defaultEtcdPort is the start of the range for listening ports of
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// embedded etcd servers. Ports are monotonically increasing starting
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// from this number and are determined by the results of getFreePort().
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defaultEtcdPort = 2379
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)
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var (
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// lastPort is the last port determined to be free for use by a new
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// embedded etcd server. It should be used atomically.
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lastPort uint32 = defaultEtcdPort
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)
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// getFreePort returns the first port that is available for listening by a new
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// embedded etcd server. It panics if no port is found and the maximum available
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// TCP port is reached.
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func getFreePort() int {
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port := atomic.AddUint32(&lastPort, 1)
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for port < 65535 {
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// If there are no errors while attempting to listen on this
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// port, close the socket and return it as available.
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addr := fmt.Sprintf("127.0.0.1:%d", port)
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l, err := net.Listen("tcp4", addr)
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if err == nil {
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err := l.Close()
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if err == nil {
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return int(port)
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}
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}
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port = atomic.AddUint32(&lastPort, 1)
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}
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// No ports available? Must be a mistake.
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panic("no ports available for listening")
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}
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// NewEmbeddedEtcdInstance creates an embedded etcd instance for testing,
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// listening on random open ports. Returns the backend config and a cleanup
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// func that will stop the etcd instance.
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func NewEmbeddedEtcdInstance(path string) (*BackendConfig, func(), error) {
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cfg := embed.NewConfig()
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cfg.Dir = path
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// To ensure that we can submit large transactions.
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cfg.MaxTxnOps = 8192
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cfg.MaxRequestBytes = 16384 * 1024
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// Listen on random free ports.
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clientURL := fmt.Sprintf("127.0.0.1:%d", getFreePort())
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peerURL := fmt.Sprintf("127.0.0.1:%d", getFreePort())
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cfg.LCUrls = []url.URL{{Host: clientURL}}
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cfg.LPUrls = []url.URL{{Host: peerURL}}
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etcd, err := embed.StartEtcd(cfg)
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if err != nil {
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return nil, nil, err
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}
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select {
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case <-etcd.Server.ReadyNotify():
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case <-time.After(readyTimeout):
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etcd.Close()
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return nil, nil,
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fmt.Errorf("etcd failed to start after: %v", readyTimeout)
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}
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ctx, cancel := context.WithCancel(context.Background())
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connConfig := &BackendConfig{
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Ctx: ctx,
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Host: "http://" + peerURL,
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User: "user",
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Pass: "pass",
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InsecureSkipVerify: true,
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}
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return connConfig, func() {
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cancel()
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etcd.Close()
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}, nil
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}
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