[PATCH 1/2] buffer/splice: prepare for IO::Splice::WAITALL removal

[PATCH 1/2] buffer/splice: prepare for IO::Splice::WAITALL removal

[Eric Wong]

This feature in the io_splice was probably a bad idea
and slated for removal at some point in the future.
Anyways, do not rely on it since it is undocumented.
---
 lib/dtas/buffer/splice.rb | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/lib/dtas/buffer/splice.rb b/lib/dtas/buffer/splice.rb
index c83b87b..b987f3a 100644
--- a/lib/dtas/buffer/splice.rb
+++ b/lib/dtas/buffer/splice.rb
@@ -12,7 +12,6 @@ module DTAS::Buffer::Splice # :nodoc:
   MAX_SIZE = File.read("/proc/sys/fs/pipe-max-size").to_i
   DEVNULL = File.open("/dev/null", "r+")
   F_MOVE = IO::Splice::F_MOVE
-  WAITALL = IO::Splice::WAITALL
 
   def buffer_size
     @to_io.pipe_size
@@ -44,6 +43,26 @@ def broadcast_one(targets)
     nil # do not return error here, we already spewed an error message
   end
 
+  def __tee_in_full(src, dst, bytes)
+    rv = 0
+    while bytes > 0
+      s = IO.tee(src, dst, bytes)
+      bytes -= s
+      rv += s
+    end
+    rv
+  end
+
+  def __splice_in_full(src, dst, bytes, flags)
+    rv = 0
+    while bytes > 0
+      s = IO.splice(src, nil, dst, nil, bytes, flags)
+      rv += s
+      bytes -= s
+    end
+    rv
+  end
+
   # returns the largest value we teed
   def __broadcast_tee(blocked, targets, chunk_size)
     most_teed = 0
@@ -51,7 +70,7 @@ def __broadcast_tee(blocked, targets, chunk_size)
       begin
         t = (dst.nonblock? || most_teed == 0) ?
             IO.trytee(@to_io, dst, chunk_size) :
-            IO.tee(@to_io, dst, chunk_size, WAITALL)
+            __tee_in_full(@to_io, dst, chunk_size)
         if Integer === t
           if t > most_teed
             chunk_size = t if most_teed == 0
@@ -117,7 +136,7 @@ def broadcast_inf(targets)
         end
       else
         # the blocking case is simple
-        s = IO.splice(@to_io, nil, last, nil, bytes, WAITALL|F_MOVE)
+        s = __splice_in_full(@to_io, last, bytes, F_MOVE)
       end
       @bytes_xfer += s
 
-- 
EW

[PATCH 2/2] buffer: allow limiting the amount of bytes output

[Eric Wong]

This will aid in allowing us to create effects which affect
only a certain part of a track.
---
 lib/dtas/buffer.rb            | 6 +++---
 lib/dtas/buffer/read_write.rb | 9 +++++----
 lib/dtas/buffer/splice.rb     | 9 +++++----
 3 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/lib/dtas/buffer.rb b/lib/dtas/buffer.rb
index b03ed8a..23b0b77 100644
--- a/lib/dtas/buffer.rb
+++ b/lib/dtas/buffer.rb
@@ -48,14 +48,14 @@ def __dst_error(dst, e)
   # - subset of targets array for :wait_writable
   # - some type of StandardError
   # - nil
-  def broadcast(targets)
+  def broadcast(targets, limit = nil)
     case targets.size
     when 0
       :ignore # this will pause decoders
     when 1
-      broadcast_one(targets)
+      broadcast_one(targets, limit)
     else # infinity
-      broadcast_inf(targets)
+      broadcast_inf(targets, limit)
     end
   end
 
diff --git a/lib/dtas/buffer/read_write.rb b/lib/dtas/buffer/read_write.rb
index a27b823..64ad297 100644
--- a/lib/dtas/buffer/read_write.rb
+++ b/lib/dtas/buffer/read_write.rb
@@ -26,9 +26,9 @@ def discard(bytes)
   end
 
   # always block when we have a single target
-  def broadcast_one(targets)
+  def broadcast_one(targets, limit = nil)
     buf = _rbuf
-    @to_io.read_nonblock(MAX_AT_ONCE, buf)
+    @to_io.read_nonblock(limit || MAX_AT_ONCE, buf)
     n = targets[0].write(buf) # IO#write has write-in-full behavior
     @bytes_xfer += n
     :wait_readable
@@ -42,7 +42,7 @@ def broadcast_one(targets)
     nil # do not return error here, we already spewed an error message
   end
 
-  def broadcast_inf(targets)
+  def broadcast_inf(targets, limit = nil)
     nr_nb = targets.count(&:nonblock?)
     if nr_nb == 0 || nr_nb == targets.size
       # if all targets are full, don't start until they're all writable
@@ -61,7 +61,8 @@ def broadcast_inf(targets)
 
     # don't pin too much on one target
     bytes = inflight
-    bytes = bytes > MAX_AT_ONCE ? MAX_AT_ONCE : bytes
+    limit ||= MAX_AT_ONCE
+    bytes = bytes > limit ? limit : bytes
     buf = _rbuf
     @to_io.read(bytes, buf)
     n = buf.bytesize
diff --git a/lib/dtas/buffer/splice.rb b/lib/dtas/buffer/splice.rb
index b987f3a..02ce877 100644
--- a/lib/dtas/buffer/splice.rb
+++ b/lib/dtas/buffer/splice.rb
@@ -28,9 +28,10 @@ def discard(bytes)
     IO.splice(@to_io, nil, DEVNULL, nil, bytes)
   end
 
-  def broadcast_one(targets)
+  def broadcast_one(targets, limit = nil)
     # single output is always non-blocking
-    s = IO.trysplice(@to_io, nil, targets[0], nil, MAX_AT_ONCE_1, F_MOVE)
+    limit ||= MAX_AT_ONCE_1
+    s = IO.trysplice(@to_io, nil, targets[0], nil, limit, F_MOVE)
     if Symbol === s
       targets # our one and only target blocked on write
     else
@@ -88,7 +89,7 @@ def __broadcast_tee(blocked, targets, chunk_size)
     most_teed
   end
 
-  def broadcast_inf(targets)
+  def broadcast_inf(targets, limit = nil)
     if targets.all?(&:ready_write_optimized?)
       blocked = []
     elsif targets.none?(&:nonblock?)
@@ -105,7 +106,7 @@ def broadcast_inf(targets)
     end
 
     # don't pin too much on one target
-    bytes = MAX_AT_ONCE
+    bytes = limit || MAX_AT_ONCE
     last = targets.pop # we splice to the last one, tee to the rest
 
     # this may return zero if all targets were non-blocking
-- 
EW