IO#write: return early if slice is empty

src/crystal/system/win32/file_descriptor.cr

@@ -14,13 +14,14 @@ module Crystal::System::FileDescriptor
 
   private def unbuffered_write(slice : Bytes)
     loop do
+      return if slice.empty?
+
       bytes_written = LibC._write(@fd, slice, slice.size)
       if bytes_written == -1
         raise Errno.new("Error writing file")
       end
 
       slice += bytes_written
-      return if slice.size == 0
     end
   end
 

src/flate/writer.cr

@@ -48,6 +48,8 @@ class Flate::Writer < IO
   def write(slice : Bytes)
     check_open
 
+    return if slice.empty?
+
     @stream.avail_in = slice.size
     @stream.next_in = slice
     consume_output LibZ::Flush::NO_FLUSH

src/gzip/writer.cr

@@ -68,6 +68,8 @@ class Gzip::Writer < IO
   def write(slice : Bytes) : Nil
     check_open
 
+    return if slice.empty?
+
     flate_io = write_header
     flate_io.write(slice)
 

src/http/server/response.cr

@@ -63,6 +63,8 @@ class HTTP::Server
 
     # See `IO#write(slice)`.
     def write(slice : Bytes)
+      return if slice.empty?
+
       @output.write(slice)
     end
 
@@ -159,6 +161,8 @@ class HTTP::Server
       end
 
       private def unbuffered_write(slice : Bytes)
+        return if slice.empty?
+
         unless response.wrote_headers?
           if response.version != "HTTP/1.0" && !response.headers.has_key?("Content-Length")
             response.headers["Transfer-Encoding"] = "chunked"

src/http/web_socket/protocol.cr

@@ -50,6 +50,8 @@ class HTTP::WebSocket::Protocol
     end
 
     def write(slice : Bytes)
+      return if slice.empty?
+
       count = Math.min(@buffer.size - @pos, slice.size)
       (@buffer + @pos).copy_from(slice.pointer(count), count)
       @pos += count

src/io/buffered.cr

@@ -113,6 +113,8 @@ module IO::Buffered
   def write(slice : Bytes)
     check_open
 
+    return if slice.empty?
+
     count = slice.size
 
     if sync?

src/io/hexdump.cr

@@ -33,6 +33,8 @@ class IO::Hexdump < IO
   end
 
   def write(buf : Bytes)
+    return if buf.empty?
+
     @io.write(buf).tap do
       @output.puts buf.hexdump if @write
     end

src/io/multi_writer.cr

@@ -32,6 +32,8 @@ class IO::MultiWriter < IO
   def write(slice : Bytes)
     check_open
 
+    return if slice.empty?
+
     @writers.each { |writer| writer.write(slice) }
   end
 

src/io/stapled.cr

@@ -68,6 +68,8 @@ class IO::Stapled < IO
   def write(slice : Bytes) : Nil
     check_open
 
+    return if slice.empty?
+
     @writer.write(slice)
   end
 

src/io/syscall.cr

@@ -62,22 +62,26 @@ module IO::Syscall
   end
 
   def write_syscall_helper(slice : Bytes, errno_msg : String) : Nil
-    loop do
-      bytes_written = yield slice
-      if bytes_written != -1
-        slice += bytes_written
-        return if slice.size == 0
-      else
-        if Errno.value == Errno::EAGAIN
-          wait_writable
+    return if slice.empty?
+
+    begin
+      loop do
+        bytes_written = yield slice
+        if bytes_written != -1
+          slice += bytes_written
+          return if slice.size == 0
         else
-          raise Errno.new(errno_msg)
+          if Errno.value == Errno::EAGAIN
+            wait_writable
+          else
+            raise Errno.new(errno_msg)
+          end
         end
       end
-    end
-  ensure
-    if (writers = @writers) && !writers.empty?
-      add_write_event
+    ensure
+      if (writers = @writers) && !writers.empty?
+        add_write_event
+      end
     end
   end
 

src/openssl/digest/digest_io.cr

@@ -43,6 +43,8 @@ module OpenSSL
     end
 
     def write(slice : Bytes)
+      return if slice.empty?
+
       if @mode.write?
         digest_algorithm.update(slice)
       end

src/openssl/ssl/socket.cr

@@ -107,6 +107,8 @@ abstract class OpenSSL::SSL::Socket < IO
   def unbuffered_write(slice : Bytes)
     check_open
 
+    return if slice.empty?
+
     count = slice.size
     bytes = LibSSL.ssl_write(@ssl, slice.pointer(count), count)
     unless bytes > 0

src/string/builder.cr

@@ -39,6 +39,8 @@ class String::Builder < IO
   end
 
   def write(slice : Bytes)
+    return if slice.empty?
+
     count = slice.size
     new_bytesize = real_bytesize + count
     if new_bytesize > @capacity

src/zip/checksum_writer.cr

@@ -14,6 +14,8 @@ module Zip
     end
 
     def write(slice : Bytes)
+      return if slice.empty?
+
       @count += slice.size
       @crc32 = CRC32.update(slice, @crc32) if @compute_crc32
       io.write(slice)

src/zlib/writer.cr

@@ -47,6 +47,8 @@ class Zlib::Writer < IO
   def write(slice : Bytes) : Nil
     check_open
 
+    return if slice.empty?
+
     write_header unless @wrote_header
 
     @flate_io.write(slice)