[PATCH 1 of 2] revlog: return offset from _chunkraw()

[Gregory Szorc]

# HG changeset patch
# User Gregory Szorc <gregory.szorc at gmail.com>
# Date 1452052311 28800
#      Tue Jan 05 19:51:51 2016 -0800
# Node ID 2506af2e83054d590b9b12912c91074f5f58a274
# Parent  b8405d739149cdd6d8d9bd5e3dd2ad8487b1f09a
revlog: return offset from _chunkraw()

A subsequent patch will refactor _chunks() and the calculation of the
offset will no longer occur in that function. Prepare by returning the
offset from _chunkraw().

diff --git a/contrib/perf.py b/contrib/perf.py
--- a/contrib/perf.py
+++ b/contrib/perf.py
@@ -563,17 +563,17 @@ def perfrevlogrevision(ui, repo, file_, 
         r._checkhash(text, node, rev)
 
     def dorevision():
         if not cache:
             r.clearcaches()
         r.revision(node)
 
     chain = r._deltachain(rev)[0]
-    data = r._chunkraw(chain[0], chain[-1])
+    data = r._chunkraw(chain[0], chain[-1])[1]
     bins = r._chunks(chain)
     text = str(bins[0])
     bins = bins[1:]
     text = mdiff.patches(text, bins)
 
     benches = [
         (lambda: dorevision(), 'full'),
         (lambda: dodeltachain(rev), 'deltachain'),
diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -1066,38 +1066,42 @@ class revlog(object):
         """Obtain a segment of raw data corresponding to a range of revisions.
 
         Accepts the start and end revisions and an optional already-open
         file handle to be used for reading. If the file handle is read, its
         seek position will not be preserved.
 
         Requests for data may be satisfied by a cache.
 
-        Returns a str or a buffer instance of raw byte data. Callers will
-        need to call ``self.start(rev)`` and ``self.length()`` to determine
-        where each revision's data begins and ends.
+        Returns a 2-tuple of (offset, data) for the requested range of
+        revisions. Offset is the integer offset from the beginning of the
+        revlog and data is a str or buffer of the raw byte data.
+
+        Callers will need to call ``self.start(rev)`` and ``self.length(rev)``
+        to determine where each revision's data begins and ends.
         """
         start = self.start(startrev)
         end = self.end(endrev)
         if self._inline:
             start += (startrev + 1) * self._io.size
             end += (endrev + 1) * self._io.size
         length = end - start
-        return self._getchunk(start, length, df=df)
+
+        return start, self._getchunk(start, length, df=df)
 
     def _chunk(self, rev, df=None):
         """Obtain a single decompressed chunk for a revision.
 
         Accepts an integer revision and an optional already-open file handle
         to be used for reading. If used, the seek position of the file will not
         be preserved.
 
         Returns a str holding uncompressed data for the requested revision.
         """
-        return decompress(self._chunkraw(rev, rev, df=df))
+        return decompress(self._chunkraw(rev, rev, df=df)[1])
 
     def _chunks(self, revs, df=None):
         """Obtain decompressed chunks for the specified revisions.
 
         Accepts an iterable of numeric revisions that are assumed to be in
         ascending order. Also accepts an optional already-open file handle
         to be used for reading. If used, the seek position of the file will
         not be preserved.
@@ -1118,17 +1122,17 @@ class revlog(object):
         l = []
         ladd = l.append
 
         # preload the cache
         try:
             while True:
                 # ensure that the cache doesn't change out from under us
                 _cache = self._chunkcache
-                self._chunkraw(revs[0], revs[-1], df=df)
+                self._chunkraw(revs[0], revs[-1], df=df)[1]
                 if _cache == self._chunkcache:
                     break
             offset, data = _cache
         except OverflowError:
             # issue4215 - we can't cache a run of chunks greater than
             # 2G on Windows
             return [self._chunk(rev, df=df) for rev in revs]
 
@@ -1262,17 +1266,17 @@ class revlog(object):
 
         if fp:
             fp.flush()
             fp.close()
 
         df = self.opener(self.datafile, 'w')
         try:
             for r in self:
-                df.write(self._chunkraw(r, r))
+                df.write(self._chunkraw(r, r)[1])
         finally:
             df.close()
 
         fp = self.opener(self.indexfile, 'w', atomictemp=True)
         self.version &= ~(REVLOGNGINLINEDATA)
         self._inline = False
         for i in self:
             e = self._io.packentry(self.index[i], self.node, self.version, i)