Merge "Protect SparseImage._GetRangeData() with lock"

tools/releasetools/blockimgdiff.py

@@ -776,8 +776,6 @@ class BlockImageDiff(object):
             src_ranges = xf.src_ranges
             tgt_ranges = xf.tgt_ranges
 
-            # Needs lock since WriteRangeDataToFd() is stateful (calling seek).
-            with lock:
             src_file = common.MakeTempFile(prefix="src-")
             with open(src_file, "wb") as fd:
               self.src.WriteRangeDataToFd(src_ranges, fd)
@@ -1430,7 +1428,6 @@ class BlockImageDiff(object):
 
         src_file = common.MakeTempFile(prefix="src-")
         tgt_file = common.MakeTempFile(prefix="tgt-")
-        with transfer_lock:
         with open(src_file, "wb") as src_fd:
           self.src.WriteRangeDataToFd(src_ranges, src_fd)
         with open(tgt_file, "wb") as tgt_fd:

tools/releasetools/sparse_img.py

@@ -15,6 +15,7 @@
 import bisect
 import os
 import struct
+import threading
 from hashlib import sha1
 
 import rangelib
@@ -111,6 +112,8 @@ class SparseImage(object):
         raise ValueError("Unknown chunk type 0x%04X not supported" %
                          (chunk_type,))
 
+    self.generator_lock = threading.Lock()
+
     self.care_map = rangelib.RangeSet(care_data)
     self.offset_index = [i[0] for i in offset_map]
 
@@ -173,11 +176,11 @@ class SparseImage(object):
     particular is not necessarily equal to the number of ranges in
     'ranges'.
 
-    This generator is stateful -- it depends on the open file object
-    contained in this SparseImage, so you should not try to run two
+    Use a lock to protect the generator so that we will not run two
     instances of this generator on the same object simultaneously."""
 
     f = self.simg_f
+    with self.generator_lock:
       for s, e in ranges:
         to_read = e-s
         idx = bisect.bisect_right(self.offset_index, s) - 1