diff options
Diffstat (limited to 'vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go')
| -rw-r--r-- | vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go | 52 |
1 files changed, 34 insertions, 18 deletions
diff --git a/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go b/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go index 048fde6..084bdbf 100644 --- a/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go +++ b/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go @@ -33,6 +33,7 @@ import ( "golang.org/x/net/context" "google.golang.org/grpc/grpclog" + "google.golang.org/grpc/internal/backoff" "google.golang.org/grpc/internal/grpcrand" "google.golang.org/grpc/resolver" ) @@ -51,17 +52,23 @@ const ( ) var ( - errMissingAddr = errors.New("missing address") + errMissingAddr = errors.New("dns resolver: missing address") + + // Addresses ending with a colon that is supposed to be the separator + // between host and port is not allowed. E.g. "::" is a valid address as + // it is an IPv6 address (host only) and "[::]:" is invalid as it ends with + // a colon as the host and port separator + errEndsWithColon = errors.New("dns resolver: missing port after port-separator colon") ) // NewBuilder creates a dnsBuilder which is used to factory DNS resolvers. func NewBuilder() resolver.Builder { - return &dnsBuilder{freq: defaultFreq} + return &dnsBuilder{minFreq: defaultFreq} } type dnsBuilder struct { - // frequency of polling the DNS server. - freq time.Duration + // minimum frequency of polling the DNS server. + minFreq time.Duration } // Build creates and starts a DNS resolver that watches the name resolution of the target. @@ -92,7 +99,8 @@ func (b *dnsBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts // DNS address (non-IP). ctx, cancel := context.WithCancel(context.Background()) d := &dnsResolver{ - freq: b.freq, + freq: b.minFreq, + backoff: backoff.Exponential{MaxDelay: b.minFreq}, host: host, port: port, ctx: ctx, @@ -148,12 +156,14 @@ func (i *ipResolver) watcher() { // dnsResolver watches for the name resolution update for a non-IP target. type dnsResolver struct { - freq time.Duration - host string - port string - ctx context.Context - cancel context.CancelFunc - cc resolver.ClientConn + freq time.Duration + backoff backoff.Exponential + retryCount int + host string + port string + ctx context.Context + cancel context.CancelFunc + cc resolver.ClientConn // rn channel is used by ResolveNow() to force an immediate resolution of the target. rn chan struct{} t *time.Timer @@ -192,8 +202,15 @@ func (d *dnsResolver) watcher() { case <-d.rn: } result, sc := d.lookup() - // Next lookup should happen after an interval defined by d.freq. - d.t.Reset(d.freq) + // Next lookup should happen within an interval defined by d.freq. It may be + // more often due to exponential retry on empty address list. + if len(result) == 0 { + d.retryCount++ + d.t.Reset(d.backoff.Backoff(d.retryCount)) + } else { + d.retryCount = 0 + d.t.Reset(d.freq) + } d.cc.NewServiceConfig(sc) d.cc.NewAddress(result) } @@ -297,7 +314,6 @@ func formatIP(addr string) (addrIP string, ok bool) { // target: "ipv4-host:80" returns host: "ipv4-host", port: "80" // target: "[ipv6-host]" returns host: "ipv6-host", port: "443" // target: ":80" returns host: "localhost", port: "80" -// target: ":" returns host: "localhost", port: "443" func parseTarget(target string) (host, port string, err error) { if target == "" { return "", "", errMissingAddr @@ -307,15 +323,15 @@ func parseTarget(target string) (host, port string, err error) { return target, defaultPort, nil } if host, port, err = net.SplitHostPort(target); err == nil { + if port == "" { + // If the port field is empty (target ends with colon), e.g. "[::1]:", this is an error. + return "", "", errEndsWithColon + } // target has port, i.e ipv4-host:port, [ipv6-host]:port, host-name:port if host == "" { // Keep consistent with net.Dial(): If the host is empty, as in ":80", the local system is assumed. host = "localhost" } - if port == "" { - // If the port field is empty(target ends with colon), e.g. "[::1]:", defaultPort is used. - port = defaultPort - } return host, port, nil } if host, port, err = net.SplitHostPort(target + ":" + defaultPort); err == nil { |