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net: move context cancellation logic of blocking calls to a common function.

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Change-Id: I5f7219a111436e3d6a4685df9461f5a8f8bcb000
GitHub-Last-Rev: e420129bad
GitHub-Pull-Request: golang/go#58108
Reviewed-on: https://go-review.googlesource.com/c/go/+/463231
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
This commit is contained in:
Mateusz Poliwczak 2023-01-31 08:34:13 +00:00 committed by Gopher Robot
parent 7d7fd6d362
commit 00e7fdc077
1 changed files with 41 additions and 87 deletions
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128
src/net/cgo_unix.go
View file

@ -29,20 +29,33 @@ func (eai addrinfoErrno) Error() string { return _C_gai_strerror(_C_int(eai))
func (eai addrinfoErrno) Temporary() bool { return eai == _C_EAI_AGAIN }
func (eai addrinfoErrno) Timeout() bool { return false }
type portLookupResult struct {
port int
err error
}
// doBlockingWithCtx executes a blocking function in a separate goroutine when the provided
// context is cancellable. It is intended for use with calls that don't support context
// cancellation (cgo, syscalls). blocking func may still be running after this function finishes.
func doBlockingWithCtx[T any](ctx context.Context, blocking func() (T, error)) (T, error) {
if ctx.Done() == nil {
return blocking()
}
type ipLookupResult struct {
addrs []IPAddr
cname string
err error
}
type result struct {
res T
err error
}
type reverseLookupResult struct {
names []string
err error
res := make(chan result, 1)
go func() {
var r result
r.res, r.err = blocking()
res <- r
}()
select {
case r := <-res:
return r.res, r.err
case <-ctx.Done():
var zero T
return zero, mapErr(ctx.Err())
}
}
func cgoLookupHost(ctx context.Context, name string) (hosts []string, err error, completed bool) {
@ -72,20 +85,11 @@ func cgoLookupPort(ctx context.Context, network, service string) (port int, err
case '6':
*_C_ai_family(&hints) = _C_AF_INET6
}
if ctx.Done() == nil {
port, err := cgoLookupServicePort(&hints, network, service)
return port, err, true
}
result := make(chan portLookupResult, 1)
go cgoPortLookup(result, &hints, network, service)
select {
case r := <-result:
return r.port, r.err, true
case <-ctx.Done():
// Since there isn't a portable way to cancel the lookup,
// we just let it finish and write to the buffered channel.
return 0, mapErr(ctx.Err()), false
}
port, err = doBlockingWithCtx(ctx, func() (int, error) {
return cgoLookupServicePort(&hints, network, service)
})
return port, err, true
}
func cgoLookupServicePort(hints *_C_struct_addrinfo, network, service string) (port int, err error) {
@ -127,11 +131,6 @@ func cgoLookupServicePort(hints *_C_struct_addrinfo, network, service string) (p
return 0, &DNSError{Err: "unknown port", Name: network + "/" + service}
}
func cgoPortLookup(result chan<- portLookupResult, hints *_C_struct_addrinfo, network, service string) {
port, err := cgoLookupServicePort(hints, network, service)
result <- portLookupResult{port, err}
}
func cgoLookupIPCNAME(network, name string) (addrs []IPAddr, cname string, err error) {
acquireThread()
defer releaseThread()
@ -206,24 +205,12 @@ func cgoLookupIPCNAME(network, name string) (addrs []IPAddr, cname string, err e
return addrs, cname, nil
}
func cgoIPLookup(result chan<- ipLookupResult, network, name string) {
addrs, cname, err := cgoLookupIPCNAME(network, name)
result <- ipLookupResult{addrs, cname, err}
}
func cgoLookupIP(ctx context.Context, network, name string) (addrs []IPAddr, err error, completed bool) {
if ctx.Done() == nil {
addrs, err = doBlockingWithCtx(ctx, func() ([]IPAddr, error) {
addrs, _, err = cgoLookupIPCNAME(network, name)
return addrs, err, true
}
result := make(chan ipLookupResult, 1)
go cgoIPLookup(result, network, name)
select {
case r := <-result:
return r.addrs, r.err, true
case <-ctx.Done():
return nil, mapErr(ctx.Err()), true
}
return addrs, err
})
return addrs, err, true
}
// These are roughly enough for the following:
@ -252,18 +239,11 @@ func cgoLookupPTR(ctx context.Context, addr string) (names []string, err error,
if sa == nil {
return nil, &DNSError{Err: "invalid address " + ip.String(), Name: addr}, true
}
if ctx.Done() == nil {
names, err := cgoLookupAddrPTR(addr, sa, salen)
return names, err, true
}
result := make(chan reverseLookupResult, 1)
go cgoReverseLookup(result, addr, sa, salen)
select {
case r := <-result:
return r.names, r.err, true
case <-ctx.Done():
return nil, mapErr(ctx.Err()), true
}
names, err = doBlockingWithCtx(ctx, func() ([]string, error) {
return cgoLookupAddrPTR(addr, sa, salen)
})
return names, err, true
}
func cgoLookupAddrPTR(addr string, sa *_C_struct_sockaddr, salen _C_socklen_t) (names []string, err error) {
@ -301,11 +281,6 @@ func cgoLookupAddrPTR(addr string, sa *_C_struct_sockaddr, salen _C_socklen_t) (
return []string{absDomainName(string(b))}, nil
}
func cgoReverseLookup(result chan<- reverseLookupResult, addr string, sa *_C_struct_sockaddr, salen _C_socklen_t) {
names, err := cgoLookupAddrPTR(addr, sa, salen)
result <- reverseLookupResult{names, err}
}
func cgoSockaddr(ip IP, zone string) (*_C_struct_sockaddr, _C_socklen_t) {
if ip4 := ip.To4(); ip4 != nil {
return cgoSockaddrInet4(ip4), _C_socklen_t(syscall.SizeofSockaddrInet4)
@ -331,30 +306,9 @@ func cgoLookupCNAME(ctx context.Context, name string) (cname string, err error,
// resSearch will make a call to the 'res_nsearch' routine in the C library
// and parse the output as a slice of DNS resources.
func resSearch(ctx context.Context, hostname string, rtype, class int) ([]dnsmessage.Resource, error) {
if ctx.Done() == nil {
return doBlockingWithCtx(ctx, func() ([]dnsmessage.Resource, error) {
return cgoResSearch(hostname, rtype, class)
}
type result struct {
res []dnsmessage.Resource
err error
}
res := make(chan result, 1)
go func() {
r, err := cgoResSearch(hostname, rtype, class)
res <- result{
res: r,
err: err,
}
}()
select {
case res := <-res:
return res.res, res.err
case <-ctx.Done():
return nil, mapErr(ctx.Err())
}
})
}
func cgoResSearch(hostname string, rtype, class int) ([]dnsmessage.Resource, error) {