# HG changeset patch
# User Bryan O'Sullivan <bryano@fb.com>
# Date 1340657773 25200
# Node ID 1028a1c9077aaa547f423eb8b5f2d5d9c4d1a26a
# Parent  9e1616307c4cca80d177203afc39e5eecda60c84
revlog: make compress a method

This allows an extension to optionally use a new compression type based
on the options applied by the repo to the revlog's opener.

(decompress doesn't need the same treatment, as it can be replaced using
extensions.wrapfunction, and can figure out which compression algorithm
is in use based on the first byte of the compressed payload.)

diff -r 9e1616307c4c -r 1028a1c9077a mercurial/revlog.py
--- a/mercurial/revlog.py	Sun Jun 24 20:36:22 2012 +0200
+++ b/mercurial/revlog.py	Mon Jun 25 13:56:13 2012 -0700
@@ -75,35 +75,6 @@
     s.update(text)
     return s.digest()
 
-def compress(text):
-    """ generate a possibly-compressed representation of text """
-    if not text:
-        return ("", text)
-    l = len(text)
-    bin = None
-    if l < 44:
-        pass
-    elif l > 1000000:
-        # zlib makes an internal copy, thus doubling memory usage for
-        # large files, so lets do this in pieces
-        z = zlib.compressobj()
-        p = []
-        pos = 0
-        while pos < l:
-            pos2 = pos + 2**20
-            p.append(z.compress(text[pos:pos2]))
-            pos = pos2
-        p.append(z.flush())
-        if sum(map(len, p)) < l:
-            bin = "".join(p)
-    else:
-        bin = _compress(text)
-    if bin is None or len(bin) > l:
-        if text[0] == '\0':
-            return ("", text)
-        return ('u', text)
-    return ("", bin)
-
 def decompress(bin):
     """ decompress the given input """
     if not bin:
@@ -1008,6 +979,35 @@
                 dfh.close()
             ifh.close()
 
+    def compress(self, text):
+        """ generate a possibly-compressed representation of text """
+        if not text:
+            return ("", text)
+        l = len(text)
+        bin = None
+        if l < 44:
+            pass
+        elif l > 1000000:
+            # zlib makes an internal copy, thus doubling memory usage for
+            # large files, so lets do this in pieces
+            z = zlib.compressobj()
+            p = []
+            pos = 0
+            while pos < l:
+                pos2 = pos + 2**20
+                p.append(z.compress(text[pos:pos2]))
+                pos = pos2
+            p.append(z.flush())
+            if sum(map(len, p)) < l:
+                bin = "".join(p)
+        else:
+            bin = _compress(text)
+        if bin is None or len(bin) > l:
+            if text[0] == '\0':
+                return ("", text)
+            return ('u', text)
+        return ("", bin)
+
     def _addrevision(self, node, text, transaction, link, p1, p2,
                      cachedelta, ifh, dfh):
         """internal function to add revisions to the log
@@ -1040,7 +1040,7 @@
                 t = buildtext()
                 ptext = self.revision(self.node(rev))
                 delta = mdiff.textdiff(ptext, t)
-            data = compress(delta)
+            data = self.compress(delta)
             l = len(data[1]) + len(data[0])
             if basecache[0] == rev:
                 chainbase = basecache[1]
@@ -1084,7 +1084,7 @@
             textlen = len(text)
         if d is None or dist > textlen * 2:
             text = buildtext()
-            data = compress(text)
+            data = self.compress(text)
             l = len(data[1]) + len(data[0])
             base = chainbase = curr