diff options
| author | Marek Habersack <grendel@twistedcode.net> | 2019-11-25 19:52:58 +0300 |
|---|---|---|
| committer | Zoltan Varga <vargaz@gmail.com> | 2019-11-25 19:52:58 +0300 |
| commit | 10795da1c065c5349bf78ca4d39cfc7992fe5f7c (patch) | |
| tree | 39a06ca7270643ddc67503acb1a6c57de8f3dc43 | |
| parent | f47b7bbf4f0d1a63accab932ec1c8c5fffb4cd3f (diff) | |
[WIP] Make debugger agent startup faster (#17898)
Mono SDB's debugger agent takes a `host:port` parameter to specify the host and
port on which to listen for debugger connection. `host` is passed, via
`mono_get_address_info`, to the `getaddrinfo(3)` standard library call which
does the job of translating the name to the IP address. However, there's no
special treatment for situations when `host` is already an IP address. In this
case `getaddrinfo` takes a lot of time to perform at least two DNS lookups (if
there's just a single DNS server configured) which will time out as the IP
address in `host` will not be resolved by any of the servers.
`getaddrinfo` takes a "hints" parameter where caller can specify some
information about the `host:port` pair to make the lookup faster/easier.
However, Mono doesn't specify the address family in the `hints` parameter, thus
forcing the slow path of DNS lookups on `getaddrinfo`.
This commit adds a new hint named `MONO_HINT_NUMERIC_HOST` (which maps to
`AI_NUMERICHOST` for `getaddrinfo`) which will allow, if set, `getaddrinfo` to
take a faster route in address discovery. Debugger agent will, in most cases,
get an IP address to instead of host name so we call `mono_get_address_info` up
to 3 times (IPv4, IPv6 and unspecified) in order to make the lookup faster.
| -rw-r--r-- | mono/mini/debugger-agent.c | 13 | ||||
| -rw-r--r-- | mono/utils/networking-posix.c | 2 | ||||
| -rw-r--r-- | mono/utils/networking.h | 1 |
3 files changed, 14 insertions, 2 deletions
diff --git a/mono/mini/debugger-agent.c b/mono/mini/debugger-agent.c index 566646362a7..0a2c1dd806f 100644 --- a/mono/mini/debugger-agent.c +++ b/mono/mini/debugger-agent.c @@ -1234,11 +1234,20 @@ socket_transport_connect (const char *address) listen_fd = -1; if (host) { + int hints[] = { + MONO_HINT_IPV4 | MONO_HINT_NUMERIC_HOST, + MONO_HINT_IPV6 | MONO_HINT_NUMERIC_HOST, + MONO_HINT_UNSPECIFIED + }; mono_network_init (); - /* Obtain address(es) matching host/port */ - s = mono_get_address_info (host, port, MONO_HINT_UNSPECIFIED, &result); + for (int i = 0; i < sizeof(hints) / sizeof(int); i++) { + /* Obtain address(es) matching host/port */ + s = mono_get_address_info (host, port, hints[i], &result); + if (s == 0) + break; + } if (s != 0) { g_printerr ("debugger-agent: Unable to resolve %s:%d: %d\n", host, port, s); // FIXME add portable error conversion functions exit (1); diff --git a/mono/utils/networking-posix.c b/mono/utils/networking-posix.c index 59889328372..e307a728fa3 100644 --- a/mono/utils/networking-posix.c +++ b/mono/utils/networking-posix.c @@ -84,6 +84,8 @@ mono_get_address_info (const char *hostname, int port, int flags, MonoAddressInf if (flags & MONO_HINT_CANONICAL_NAME) hints.ai_flags = AI_CANONNAME; + if (flags & MONO_HINT_NUMERIC_HOST) + hints.ai_flags |= AI_NUMERICHOST; /* Some ancient libc don't define AI_ADDRCONFIG */ #ifdef AI_ADDRCONFIG diff --git a/mono/utils/networking.h b/mono/utils/networking.h index 357c2993398..4f6a0f5d733 100644 --- a/mono/utils/networking.h +++ b/mono/utils/networking.h @@ -43,6 +43,7 @@ typedef enum { MONO_HINT_IPV6 = 2, MONO_HINT_CANONICAL_NAME = 4, MONO_HINT_CONFIGURED_ONLY = 8, + MONO_HINT_NUMERIC_HOST = 16, } MonoGetAddressHints; typedef struct _MonoAddressEntry MonoAddressEntry; |