[Feature #120782] Introduction of Happy Eyeballs Version 2 (RFC8305) in TCPSocket.new (#11653)

* Introduction of Happy Eyeballs Version 2 (RFC8305) in TCPSocket.new

This is an implementation of Happy Eyeballs version 2 (RFC 8305) in `TCPSocket.new`.
See https://github.com/ruby/ruby/pull/11653

1. Background
Prior to this implementation, I implemented Happy Eyeballs Version 2 (HEv2) for `Socket.tcp` in https://github.com/ruby/ruby/pull/9374.
HEv2 is an algorithm defined in [RFC 8305](https://datatracker.ietf.org/doc/html/rfc8305), aimed at improving network connectivity.
For more details on the specific cases that HEv2 helps, please refer to https://bugs.ruby-lang.org/issues/20108.

2. Proposal & Outcome
This proposal implements the same HEv2 algorithm in `TCPSocket.new`.
Since `TCPSocket.new` is used more widely than `Socket.tcp`, this change is expected to broaden the impact of HEv2's benefits.
Like `Socket.tcp`, I have also added `fast_fallback` keyword argument to `TCPSocket.new`.
This option is set to true by default, enabling the HEv2 functionality.
However, users can explicitly set it to false to disable HEv2 and use the previous behavior of `TCPSocket.new`.

It should be noted that HEv2 is enabled only in environments where pthreads are available.
This specification follows the approach taken in https://bugs.ruby-lang.org/issues/19965 , where name resolution can be interrupted.
(In environments where pthreads are not available, the `fast_fallback` option is ignored.)

3. Performance
Below is the benchmark of 100 requests to `www.ruby-lang.org` with the fast_fallback option set to true and false, respectively.
While there is a slight performance degradation when HEv2 is enabled, the degradation is smaller compared to that seen in `Socket.tcp`.

```
~/s/build ❯❯❯ ../install/bin/ruby ../ruby/test.rb
Rehearsal --------------------------------------------------------
fast_fallback: true    0.017588   0.097045   0.114633 (  1.460664)
fast_fallback: false   0.014033   0.078984   0.093017 (  1.413951)
----------------------------------------------- total: 0.207650sec

                           user     system      total        real
fast_fallback: true    0.020891   0.124054   0.144945 (  1.473816)
fast_fallback: false   0.018392   0.110852   0.129244 (  1.466014)
```

* Update debug prints

Co-authored-by: Nobuyoshi Nakada <[email protected]>

* Remove debug prints

* misc

* Disable HEv2 in Win

* Raise resolution error with hostname resolution

* Fix to handle errors

* Remove warnings

* Errors that do not need to be handled

* misc

* Improve doc

* Fix bug on cancellation

* Avoid EAI_ADDRFAMILY for resolving IPv6

* Follow upstream

* misc

* Refactor connection_attempt_fds management

- Introduced allocate_connection_attempt_fds and reallocate_connection_attempt_fds for improved memory allocation of connection_attempt_fds
- Added remove_connection_attempt_fd to resize connection_attempt_fds dynamically.
- Simplified the in_progress_fds function to only check the size of connection_attempt_fds.

* Rename do_pthread_create to raddrinfo_pthread_create to avoid conflicting

---------

Co-authored-by: Nobuyoshi Nakada <[email protected]>

1 files changed, 40 insertions, 1 deletions

diff --git a/ext/socket/rubysocket.h b/ext/socket/rubysocket.h
index b4daa66071..97f3bc55d7 100644
--- a/ext/socket/rubysocket.h
+++ b/ext/socket/rubysocket.h
@@ -354,7 +354,7 @@ int rsock_socket(int domain, int type, int proto);
 int rsock_detect_cloexec(int fd);
 VALUE rsock_init_sock(VALUE sock, int fd);
 VALUE rsock_sock_s_socketpair(int argc, VALUE *argv, VALUE klass);
-VALUE rsock_init_inetsock(VALUE sock, VALUE remote_host, VALUE remote_serv, VALUE local_host, VALUE local_serv, int type, VALUE resolv_timeout, VALUE connect_timeout);
+VALUE rsock_init_inetsock(VALUE sock, VALUE remote_host, VALUE remote_serv, VALUE local_host, VALUE local_serv, int type, VALUE resolv_timeout, VALUE connect_timeout, VALUE fast_fallback, VALUE test_mode_settings);
 VALUE rsock_init_unixsock(VALUE sock, VALUE path, int server);
 
 struct rsock_send_arg {
@@ -413,6 +413,45 @@ ssize_t rsock_recvmsg(int socket, struct msghdr *message, int flags);
 void rsock_discard_cmsg_resource(struct msghdr *mh, int msg_peek_p);
 #endif
 
+char *host_str(VALUE host, char *hbuf, size_t hbuflen, int *flags_ptr);
+char *port_str(VALUE port, char *pbuf, size_t pbuflen, int *flags_ptr);
+
+#ifndef FAST_FALLBACK_INIT_INETSOCK_IMPL
+#  if !defined(HAVE_PTHREAD_CREATE) || !defined(HAVE_PTHREAD_DETACH) || defined(__MINGW32__) || defined(__MINGW64__)
+#    define FAST_FALLBACK_INIT_INETSOCK_IMPL 0
+#  else
+#    include "ruby/thread_native.h"
+#    define FAST_FALLBACK_INIT_INETSOCK_IMPL 1
+#    define IPV6_HOSTNAME_RESOLVED '1'
+#    define IPV4_HOSTNAME_RESOLVED '2'
+#    define SELECT_CANCELLED '3'
+
+struct fast_fallback_getaddrinfo_shared
+{
+    int wait, notify, refcount, connection_attempt_fds_size;
+    int *connection_attempt_fds, *cancelled;
+    char *node, *service;
+    rb_nativethread_lock_t *lock;
+};
+
+struct fast_fallback_getaddrinfo_entry
+{
+    int family, err, refcount;
+    struct addrinfo hints;
+    struct addrinfo *ai;
+    struct fast_fallback_getaddrinfo_shared *shared;
+    int has_syserr;
+    long test_sleep_ms;
+    int test_ecode;
+};
+
+int raddrinfo_pthread_create(pthread_t *th, void *(*start_routine) (void *), void *arg);
+void *do_fast_fallback_getaddrinfo(void *ptr);
+void free_fast_fallback_getaddrinfo_entry(struct fast_fallback_getaddrinfo_entry **entry);
+void free_fast_fallback_getaddrinfo_shared(struct fast_fallback_getaddrinfo_shared **shared);
+#  endif
+#endif
+
 void rsock_init_basicsocket(void);
 void rsock_init_ipsocket(void);
 void rsock_init_tcpsocket(void);