libgo: Update to weekly.2012-03-04 release.

From-SVN: r185010

2 files changed, 11 insertions, 0 deletions

diff --git a/libgo/go/io/io.go b/libgo/go/io/io.go
index bbfa6c2..7074834 100644
--- a/libgo/go/io/io.go
+++ b/libgo/go/io/io.go
@@ -6,6 +6,10 @@
 // Its primary job is to wrap existing implementations of such primitives,
 // such as those in package os, into shared public interfaces that
 // abstract the functionality, plus some other related primitives.
+//
+// Because these interfaces and primitives wrap lower-level operations with
+// various implementations, unless otherwise informed clients should not
+// assume they are safe for parallel execution.
 package io
 
 import (
@@ -156,6 +160,9 @@ type WriterTo interface {
 // If ReadAt is reading from an input source with a seek offset,
 // ReadAt should not affect nor be affected by the underlying
 // seek offset.
+//
+// Clients of ReadAt can execute parallel ReadAt calls on the
+// same input source.
 type ReaderAt interface {
 	ReadAt(p []byte, off int64) (n int, err error)
 }
diff --git a/libgo/go/io/pipe.go b/libgo/go/io/pipe.go
index cf05e0c1..f3f0f17 100644
--- a/libgo/go/io/pipe.go
+++ b/libgo/go/io/pipe.go
@@ -175,6 +175,10 @@ func (w *PipeWriter) CloseWithError(err error) error {
 // with code expecting an io.Writer.
 // Reads on one end are matched with writes on the other,
 // copying data directly between the two; there is no internal buffering.
+// It is safe to call Read and Write in parallel with each other or with
+// Close. Close will complete once pending I/O is done. Parallel calls to
+// Read, and parallel calls to Write, are also safe:
+// the individual calls will be gated sequentially.
 func Pipe() (*PipeReader, *PipeWriter) {
 	p := new(pipe)
 	p.rwait.L = &p.l