Reimplement IO.select with poll(2)

* This avoids the issue of file descriptors >= 1024 that FD_ZERO does not handle.
* Fixes #3201
* Skip TestIO#test_select_exceptfds on macOS, macOS's poll(2) is buggy with TCP MSG_OOB or macOS does not really support MSG_OOB:
  For a fd to which out-of-band data has been sent,
  poll() with POLLIN|POLLPRI returns POLLRDNORM|POLLPRI|POLLIN on Linux (correct) but POLLRDNORM|POLLIN on macOS (bug).
  poll() with just POLLPRI works fine on Linux but hangs on macOS (bug).
  It seems a bug of macOS poll() not handling TCP MSG_OOB.
  The man page of poll() on macOS talks about: "The distinction between normal, priority, and high-priority data
  is specific to particular file types or devices." but gives no details, it seems a mess.
  MSG_OOB is poorly supported across platforms anyway and extremely rarely if ever used.

CHANGELOG.md

@@ -13,6 +13,7 @@ Bug fixes:
 * Fix `super` method lookup for unbounded attached methods (#3131,  @itarato).
 * Fix `Module#define_method(name, Method)` to respect `module_function` visibility (#3181, @andrykonchin).
 * Fix stack overflow with `Kernel.require` and `zeitwerk` (#3224, @eregon).
+* Reimplement `IO.select` with `poll(2)` to support file descriptors >= 1024 (#3201, @eregon).
 
 Compatibility:
 

spec/ruby/core/io/select_spec.rb

@@ -55,15 +55,26 @@
     end
   end
 
-  it "returns supplied objects correctly even when monitoring the same object in different arrays" do
-    filename = tmp("IO_select_pipe_file") + $$.to_s
+  it "returns supplied objects correctly when monitoring the same object in different arrays" do
+    filename = tmp("IO_select_pipe_file")
     io = File.open(filename, 'w+')
     result = IO.select [io], [io], nil, 0
     result.should == [[io], [io], []]
     io.close
     rm_r filename
   end
 
+  it "returns the pipe read end in read set if the pipe write end is closed concurrently" do
+    main = Thread.current
+    t = Thread.new {
+      Thread.pass until main.stop?
+      @wr.close
+    }
+    IO.select([@rd]).should == [[@rd], [], []]
+  ensure
+    t.join
+  end
+
   it "invokes to_io on supplied objects that are not IO and returns the supplied objects" do
     # make some data available
     @wr.write("foobar")

spec/truffle/io/read_spec.rb

@@ -29,10 +29,10 @@
     w.write "b"
     w.flush
 
-    select_ignoring_iobuffer([r], 1_000_000).should == [r]
+    select_ignoring_iobuffer([r], 100).should == [r]
     r.read(1).should == "a"
 
-    select_ignoring_iobuffer([r], 1_000_000).should == [r]
+    select_ignoring_iobuffer([r], 1000).should == [r]
     r.read(1).should == "b"
   end
 
@@ -42,17 +42,17 @@
     @w.flush
 
     @r.gets.should == "a\n"
-    select_ignoring_iobuffer([@r], 100_000).should == nil
+    select_ignoring_iobuffer([@r], 100).should == nil
   end
 
-  def select_ignoring_iobuffer(ios, timeout_us)
+  def select_ignoring_iobuffer(ios, timeout_ms)
     return IO.select(ios)[0] unless defined?(::TruffleRuby)
 
     result = Truffle::IOOperations.select(
       ios, ios,
       [], [],
       [], [],
-      timeout_us, timeout_us)
+      timeout_ms)
     result and result[0]
   end
 end

src/main/c/truffleposix/truffleposix.c

@@ -60,7 +60,6 @@ SUCH DAMAGE.
 #include <sys/file.h>
 #include <sys/resource.h>
 #include <sys/stat.h>
-#include <sys/select.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/wait.h>
@@ -91,27 +90,7 @@ struct truffleposix_stat {
 
 static void copy_stat(struct stat *stat, struct truffleposix_stat* buffer);
 
-static void init_fd_set(fd_set *set, int nfds, int *fds, int *maxfd) {
-  FD_ZERO(set);
-  for (int i = 0; i < nfds; i++) {
-    int fd = fds[i];
-    FD_SET(fd, set);
-    if (fd > *maxfd) {
-      *maxfd = fd;
-    }
-  }
-}
-
-static void mark_ready_from_set(fd_set *set, int nfds, int *fds) {
-  for (int i = 0; i < nfds; i++) {
-    int fd = fds[i];
-    if (!FD_ISSET(fd, set)) {
-      fds[i] = -1;
-    }
-  }
-}
-
-int truffleposix_poll(int fd, int events, int timeout_ms) {
+int truffleposix_poll_single_fd(int fd, int events, int timeout_ms) {
   struct pollfd fds;
 
   fds.fd = fd;
@@ -120,32 +99,6 @@ int truffleposix_poll(int fd, int events, int timeout_ms) {
   return poll(&fds, 1, timeout_ms) >= 0 ? fds.revents : -1;
 }
 
-int truffleposix_select(int nread, int *readfds, int nwrite, int *writefds,
-                        int nexcept, int *exceptfds, long timeout_us) {
-  struct timeval timeout;
-  struct timeval *timeout_ptr = NULL;
-
-  if (timeout_us >= 0) {
-    timeout.tv_sec = (timeout_us / 1000000);
-    timeout.tv_usec = (timeout_us % 1000000);
-    timeout_ptr = &timeout;
-  }
-
-  int maxfd = 0;
-  fd_set readset, writeset, exceptset;
-  init_fd_set(&readset, nread, readfds, &maxfd);
-  init_fd_set(&writeset, nwrite, writefds, &maxfd);
-  init_fd_set(&exceptset, nexcept, exceptfds, &maxfd);
-
-  int ret = select(maxfd+1, &readset, &writeset, &exceptset, timeout_ptr);
-  if (ret > 0) {
-    mark_ready_from_set(&readset, nread, readfds);
-    mark_ready_from_set(&writeset, nwrite, writefds);
-    mark_ready_from_set(&exceptset, nexcept, exceptfds);
-  }
-  return ret;
-}
-
 int truffleposix_utimes(const char *filename, long atime_sec, int atime_nsec,
                         long mtime_sec, int mtime_nsec) {
   struct timespec timespecs[2];

src/main/java/org/truffleruby/platform/DarwinAArch64NativeConfiguration.java

@@ -407,6 +407,12 @@ public static void load(NativeConfiguration configuration, RubyContext context)
         configuration.config("platform.poll.POLLIN", 1);
         configuration.config("platform.poll.POLLPRI", 2);
         configuration.config("platform.poll.POLLOUT", 4);
+        configuration.config("platform.poll.POLLERR", 8);
+        configuration.config("platform.poll.POLLHUP", 16);
+        configuration.config("platform.poll.POLLRDNORM", 64);
+        configuration.config("platform.poll.POLLRDBAND", 128);
+        configuration.config("platform.poll.POLLWRNORM", 4);
+        configuration.config("platform.poll.POLLWRBAND", 256);
         configuration.config("platform.socket.AF_APPLETALK", 16);
         configuration.config("platform.socket.PF_APPLETALK", 16);
         configuration.config("platform.socket.AF_INET", 2);

src/main/java/org/truffleruby/platform/DarwinAMD64NativeConfiguration.java

@@ -407,6 +407,12 @@ public static void load(NativeConfiguration configuration, RubyContext context)
         configuration.config("platform.poll.POLLIN", 1);
         configuration.config("platform.poll.POLLPRI", 2);
         configuration.config("platform.poll.POLLOUT", 4);
+        configuration.config("platform.poll.POLLERR", 8);
+        configuration.config("platform.poll.POLLHUP", 16);
+        configuration.config("platform.poll.POLLRDNORM", 64);
+        configuration.config("platform.poll.POLLRDBAND", 128);
+        configuration.config("platform.poll.POLLWRNORM", 4);
+        configuration.config("platform.poll.POLLWRBAND", 256);
         configuration.config("platform.socket.AF_APPLETALK", 16);
         configuration.config("platform.socket.PF_APPLETALK", 16);
         configuration.config("platform.socket.AF_INET", 2);

src/main/java/org/truffleruby/platform/LinuxAArch64NativeConfiguration.java

@@ -418,6 +418,12 @@ public static void load(NativeConfiguration configuration, RubyContext context)
         configuration.config("platform.poll.POLLIN", 1);
         configuration.config("platform.poll.POLLPRI", 2);
         configuration.config("platform.poll.POLLOUT", 4);
+        configuration.config("platform.poll.POLLERR", 8);
+        configuration.config("platform.poll.POLLHUP", 16);
+        configuration.config("platform.poll.POLLRDNORM", 64);
+        configuration.config("platform.poll.POLLRDBAND", 128);
+        configuration.config("platform.poll.POLLWRNORM", 256);
+        configuration.config("platform.poll.POLLWRBAND", 512);
         configuration.config("platform.socket.AF_APPLETALK", 5);
         configuration.config("platform.socket.PF_APPLETALK", 5);
         configuration.config("platform.socket.AF_AX25", 3);

src/main/java/org/truffleruby/platform/LinuxAMD64NativeConfiguration.java

@@ -418,6 +418,12 @@ public static void load(NativeConfiguration configuration, RubyContext context)
         configuration.config("platform.poll.POLLIN", 1);
         configuration.config("platform.poll.POLLPRI", 2);
         configuration.config("platform.poll.POLLOUT", 4);
+        configuration.config("platform.poll.POLLERR", 8);
+        configuration.config("platform.poll.POLLHUP", 16);
+        configuration.config("platform.poll.POLLRDNORM", 64);
+        configuration.config("platform.poll.POLLRDBAND", 128);
+        configuration.config("platform.poll.POLLWRNORM", 256);
+        configuration.config("platform.poll.POLLWRBAND", 512);
         configuration.config("platform.socket.AF_APPLETALK", 5);
         configuration.config("platform.socket.PF_APPLETALK", 5);
         configuration.config("platform.socket.AF_AX25", 3);

src/main/ruby/truffleruby/core/io.rb

@@ -735,10 +735,8 @@ def self.select(readables = nil, writables = nil, errorables = nil, timeout = ni
 
       raise ArgumentError, 'timeout must be positive' if timeout < 0
 
-      # Microseconds, rounded down
-      timeout = remaining_timeout = Integer(timeout * 1_000_000)
-    else
-      remaining_timeout = -1
+      # Milliseconds, rounded down
+      timeout = Integer(timeout * 1_000)
     end
 
     if readables
@@ -782,7 +780,7 @@ def self.select(readables = nil, writables = nil, errorables = nil, timeout = ni
         readables, readable_ios,
         writables, writable_ios,
         errorables, errorable_ios,
-        timeout, remaining_timeout)
+        timeout)
   end
 
   ##

src/main/ruby/truffleruby/core/posix.rb

@@ -214,7 +214,9 @@ def self.attach_function_eagerly(native_name, argument_types, return_type,
   attach_function :open, [:string, :int, varargs(:mode_t)], :int
   attach_function :opendir, [:string], :pointer
   attach_function :pipe, [:pointer], :int
-  attach_function :truffleposix_poll, [:pointer, :long, :int], :int, LIBTRUFFLEPOSIX, true
+  # blocking=false for both poll because the timeout needs to be decreased on EINTR
+  attach_function :truffleposix_poll_single_fd, [:pointer, :long, :int], :int, LIBTRUFFLEPOSIX
+  attach_function :poll, [:pointer, :long, :int], :int
   attach_function :read, [:int, :pointer, :size_t], :ssize_t, LIBC, true
   attach_function :readlink, [:string, :pointer, :size_t], :ssize_t
   attach_function :realpath, [:string, :pointer], :pointer
@@ -224,8 +226,6 @@ def self.attach_function_eagerly(native_name, argument_types, return_type,
   attach_function :truffleposix_rewinddir, [:pointer], :void, LIBTRUFFLEPOSIX
   attach_function :rmdir, [:string], :int
   attach_function :seekdir, [:pointer, :long], :void
-  select_args = [:int, :pointer, :int, :pointer, :int, :pointer, :long]
-  attach_function :truffleposix_select, select_args, :int, LIBTRUFFLEPOSIX
   attach_function :truffleposix_stat, [:string, :pointer], :int, LIBTRUFFLEPOSIX
   attach_function :truffleposix_stat_mode, [:string], :mode_t, LIBTRUFFLEPOSIX
   attach_function :truffleposix_stat_size, [:string], :long, LIBTRUFFLEPOSIX
@@ -240,8 +240,8 @@ def self.attach_function_eagerly(native_name, argument_types, return_type,
   Truffle::Boot.delay do
     if NATIVE
       # We should capture the non-lazy method
-      attach_function_eagerly :truffleposix_select, select_args, :int, LIBTRUFFLEPOSIX, false, :truffleposix_select, self
-      SELECT = method(:truffleposix_select)
+      attach_function_eagerly :poll, [:pointer, :long, :int], :int, LIBC, false, :poll, self
+      POLL = method(:poll)
     end
   end