wsgi: Fix handling partial writes on Python 3partial-write-fix-2

Closes https://github.com/eventlet/eventlet/issues/295 (in the wsgi
module we use a custom writelines implementation now).

Those write() calls might write only part of the data (and even if they
don't - it's more readable to make sure all data is written
explicitly).

I changed the test code so that the write() implementation returns the
number of characters logged and it cooperates nicely with writeall()
now.

1 files changed, 17 insertions, 0 deletions

diff --git a/eventlet/support/__init__.py b/eventlet/support/__init__.py
index 4c2b75d..d78ac15 100644
--- a/eventlet/support/__init__.py
+++ b/eventlet/support/__init__.py
@@ -53,3 +53,20 @@ def capture_stderr():
     finally:
         sys.stderr = original
         stream.seek(0)
+
+
+def safe_writelines(fd, to_write):
+    # Standard Python 3 writelines() is not reliable because it doesn't care if it
+    # loses data. See CPython bug report: http://bugs.python.org/issue26292
+    for item in to_write:
+        writeall(fd, item)
+
+
+if six.PY2:
+    def writeall(fd, buf):
+        fd.write(buf)
+else:
+    def writeall(fd, buf):
+        written = 0
+        while written < len(buf):
+            written += fd.write(buf[written:])