chunkbuffer: split big strings directly in chunkbuffer

mercurial/revlog.py

@@ -1193,13 +1193,6 b' class revlog(object):'
                 d = self.revdiff(a, b)
             yield changegroup.chunkheader(len(meta) + len(d))
             yield meta
-            if len(d) > 2**20:
-                pos = 0
-                while pos < len(d):
-                    pos2 = pos + 2 ** 18
-                    yield d[pos:pos2]
-                    pos = pos2
-            else:
                 yield d
 
         yield changegroup.closechunk()

mercurial/util.py

@@ -914,7 +914,17 b' class chunkbuffer(object):'
     def __init__(self, in_iter):
         """in_iter is the iterator that's iterating over the input chunks.
         targetsize is how big a buffer to try to maintain."""
-        self.iter = iter(in_iter)
+        def splitbig(chunks):
+            for chunk in chunks:
+                if len(chunk) > 2**20:
+                    pos = 0
+                    while pos < len(chunk):
+                        end = pos + 2 ** 18
+                        yield chunk[pos:end]
+                        pos = end
+                else:
+                    yield chunk
+        self.iter = splitbig(in_iter)
         self.buf = ''
 
     def read(self, l):