[GR-17457] Implement poll for waiting on io.

PullRequest: truffleruby/3285

Author: aardvark179

CHANGELOG.md

@@ -35,6 +35,7 @@ Performance:
 * Replace a call of `-"string"` with frozen string literal at parse time (@andrykonchin).
 * Report polymorphism inside `Hash#[]` to recover performance (@aardvark179).
 * Improved interpreter performance by optimizing for better host inlining (@eregon).
+* Use `poll` instead of `select` for simple IO waiting to reduce overheads (#1584, @aardvark179).
 
 Changes:
 

lib/truffle/io/wait.rb

@@ -13,16 +13,19 @@ def nread
   end
 
   def ready?
-    not Kernel.select([self], [], [], 0).nil?
+    ensure_open_and_readable
+    Truffle::IOOperations.poll(self, Truffle::IOOperations::POLLIN, 0)
   end
 
   def wait(timeout = nil)
-    Kernel.select([self], [], [], timeout).nil? ? nil : self
+    ensure_open_and_readable
+    Truffle::IOOperations.poll(self, Truffle::IOOperations::POLLIN, timeout) ? self : nil
   end
 
   alias_method :wait_readable, :wait
 
   def wait_writable(timeout = nil)
-    Kernel.select([], [self], [], timeout).nil? ? nil : self
+    ensure_open_and_writable
+    Truffle::IOOperations.poll(self, Truffle::IOOperations::POLLOUT, timeout) ? self : nil
   end
 end

src/main/c/truffleposix/truffleposix.c

@@ -46,6 +46,7 @@ SUCH DAMAGE.
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <poll.h>
 #include <pwd.h>
 #include <spawn.h>
 #include <stdint.h>
@@ -110,6 +111,15 @@ static void mark_ready_from_set(fd_set *set, int nfds, int *fds) {
   }
 }
 
+int truffleposix_poll(int fd, int events, int timeout_ms) {
+  struct pollfd fds;
+
+  fds.fd = fd;
+  fds.events = events;
+
+  return poll(&fds, 1, timeout_ms);
+}
+
 int truffleposix_select(int nread, int *readfds, int nwrite, int *writefds,
                         int nexcept, int *exceptfds, long timeout_us) {
   struct timeval timeout;

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

@@ -402,6 +402,9 @@ public static void load(NativeConfiguration configuration, RubyContext context)
         configuration.config("platform.fcntl.F_GLOBAL_NOCACHE", 55);
         configuration.config("platform.fcntl.F_ALLOCATECONTIG", 2);
         configuration.config("platform.fcntl.F_ALLOCATEALL", 4);
+        configuration.config("platform.poll.POLLIN", 1);
+        configuration.config("platform.poll.POLLPRI", 2);
+        configuration.config("platform.poll.POLLOUT", 4);
         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

@@ -402,6 +402,9 @@ public static void load(NativeConfiguration configuration, RubyContext context)
         configuration.config("platform.fcntl.F_GLOBAL_NOCACHE", 55);
         configuration.config("platform.fcntl.F_ALLOCATECONTIG", 2);
         configuration.config("platform.fcntl.F_ALLOCATEALL", 4);
+        configuration.config("platform.poll.POLLIN", 1);
+        configuration.config("platform.poll.POLLPRI", 2);
+        configuration.config("platform.poll.POLLOUT", 4);
         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

@@ -413,6 +413,9 @@ public static void load(NativeConfiguration configuration, RubyContext context)
         configuration.config("platform.fcntl.F_RDLCK", 0);
         configuration.config("platform.fcntl.F_UNLCK", 2);
         configuration.config("platform.fcntl.F_WRLCK", 1);
+        configuration.config("platform.poll.POLLIN", 1);
+        configuration.config("platform.poll.POLLPRI", 2);
+        configuration.config("platform.poll.POLLOUT", 4);
         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

@@ -413,6 +413,9 @@ public static void load(NativeConfiguration configuration, RubyContext context)
         configuration.config("platform.fcntl.F_RDLCK", 0);
         configuration.config("platform.fcntl.F_UNLCK", 2);
         configuration.config("platform.fcntl.F_WRLCK", 1);
+        configuration.config("platform.poll.POLLIN", 1);
+        configuration.config("platform.poll.POLLPRI", 2);
+        configuration.config("platform.poll.POLLOUT", 4);
         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/posix.rb

@@ -214,6 +214,7 @@ 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
   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

src/main/ruby/truffleruby/core/truffle/io_operations.rb

@@ -10,6 +10,11 @@
 
 module Truffle
   module IOOperations
+
+    POLLIN = Truffle::Config['platform.poll.POLLIN']
+    POLLPRI = Truffle::Config['platform.poll.POLLPRI']
+    POLLOUT = Truffle::Config['platform.poll.POLLOUT']
+
     def self.print(io, args, last_line_storage)
       if args.empty?
         raise 'last_line_binding is required' if Primitive.nil? last_line_storage
@@ -191,6 +196,58 @@ def self.select(readables, readable_ios, writables, writable_ios, errorables, er
 
     end
 
+    # This method will return a true if poll returned without error
+    # with an event within the timeout, false if the timeout expired,
+    # or raises an exception for an errno.
+    def self.poll(io, event_mask, timeout)
+      if (event_mask & POLLIN) != 0
+        return 1 unless io.__send__(:buffer_empty?)
+      end
+
+      if timeout
+        unless Primitive.object_kind_of? timeout, Numeric
+          raise TypeError, 'Timeout must be numeric'
+        end
+
+        raise ArgumentError, 'timeout must be positive' if timeout < 0
+
+        # Milliseconds, rounded down
+        timeout = remaining_timeout = (timeout * 1_000).to_i
+        start = Process.clock_gettime(Process::CLOCK_MONOTONIC, :millisecond)
+        deadline = start + timeout
+      else
+        remaining_timeout = -1
+      end
+
+      begin
+        primitive_result = Truffle::POSIX.truffleposix_poll(Primitive.io_fd(io), event_mask, remaining_timeout)
+        result =
+          if primitive_result < 0
+            errno = Errno.errno
+            if errno == Errno::EINTR::Errno
+              if timeout
+                # Update timeout
+                now = Process.clock_gettime(Process::CLOCK_MONOTONIC, :millisecond)
+                if now >= deadline
+                  false # timeout
+                else
+                  remaining_timeout = deadline - now
+                  :retry
+                end
+              else
+                :retry
+              end
+            else
+              Errno.handle_errno(errno)
+            end
+          else
+            primitive_result > 0
+          end
+      end while result == :retry
+
+      result
+    end
+
     # The constants used to express a mode for the opening of files are
     # different to the fmode constants used to express the mode of an
     # opened file used by C extensions. Thus we will need to translate

tool/generate-native-config.rb

@@ -636,6 +636,13 @@ def constants(name)
   ]
 end
 
+constants 'poll' do |cg|
+  cg.include 'poll.h'
+  cg.consts %w[
+    POLLIN POLLPRI POLLOUT
+  ]
+end
+
 constants 'socket' do |cg|
   cg.include 'sys/types.h'
   cg.include 'sys/socket.h'