Display range-diff by default

Don't make developers do copy-pasting unnecessarily. Switch to
outputting the diff by default, with flag options to save to file or
just show what needs to be done.

Additionally, adds caching to lookups and remember previously generated
fake-am ranges so we don't continuously generate loose objects on repeat
runs.

Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>

1 files changed, 88 insertions, 9 deletions

diff --git a/b4/diff.py b/b4/diff.py
index 0ce2283..36bdfd6 100644
--- a/b4/diff.py
+++ b/b4/diff.py
@@ -10,6 +10,9 @@ import sys
 import b4
 import b4.mbox
 import mailbox
+import shutil
+import urllib.parse
+
 from tempfile import mkstemp
 
 
@@ -17,6 +20,45 @@ logger = b4.logger
 
 
 def make_fake_commit_range(gitdir, lser):
+    start_commit = end_commit = None
+    # Do we have it in cache already?
+    cachedir = b4.get_cache_dir()
+    # Use the msgid of the first non-None patch in the series
+    msgid = None
+    for lmsg in lser.patches:
+        if lmsg is not None:
+            msgid = lmsg.msgid
+            break
+    if msgid is None:
+        logger.critical('Cannot operate on an empty series')
+        return None, None
+    cachefile = os.path.join(cachedir, '%s.fakeam' % urllib.parse.quote_plus(msgid))
+    if os.path.exists(cachefile):
+        stalecache = False
+        with open(cachefile, 'r') as fh:
+            cachedata = fh.read()
+            chunks = cachedata.strip().split()
+            if len(chunks) == 2:
+                start_commit, end_commit = chunks
+            else:
+                stalecache = True
+        if start_commit is not None and end_commit is not None:
+            # Make sure they are still there
+            ecode, out = b4.git_run_command(gitdir, ['cat-file', '-e', start_commit])
+            if ecode > 0:
+                stalecache = True
+            else:
+                ecode, out = b4.git_run_command(gitdir, ['cat-file', '-e', end_commit])
+                if ecode > 0:
+                    stalecache = True
+                else:
+                    logger.debug('Using previously generated range')
+                    return start_commit, end_commit
+
+        if stalecache:
+            logger.debug('Stale cache for [v%s] %s', lser.revision, lser.subject)
+            os.unlink(cachefile)
+
     logger.info('Preparing fake-am for v%s: %s', lser.revision, lser.subject)
     with b4.git_temp_worktree(gitdir):
         # We are in a temporary chdir at this time, so writing to a known file should be safe
@@ -73,6 +115,11 @@ def make_fake_commit_range(gitdir, lser):
         end_commit = out.strip()
         logger.info('  range: %.12s..%.12s', start_commit, end_commit)
 
+    with open(cachefile, 'w') as fh:
+        logger.debug('Saving into cache: %s', cachefile)
+        logger.debug('    %s..%s', start_commit, end_commit)
+        fh.write(f'{start_commit} {end_commit}\n')
+
     return start_commit, end_commit
 
 
@@ -84,12 +131,26 @@ def main(cmdargs):
 
     # start by grabbing the mbox provided
     savefile = mkstemp('b4-diff-to')[1]
-    mboxfile = b4.get_pi_thread_by_msgid(msgid, savefile, useproject=cmdargs.useproject, nocache=cmdargs.nocache)
-    if mboxfile is None:
-        logger.critical('Unable to retrieve thread: %s', msgid)
-        return
-    logger.info('Retrieved %s messages in the thread', len(mboxfile))
-    b4.mbox.get_extra_series(mboxfile, direction=-1, wantvers=cmdargs.wantvers)
+    # Do we have a cache of this lookup?
+    cachedir = b4.get_cache_dir()
+    if cmdargs.wantvers:
+        cachefile = os.path.join(cachedir,
+                                 '%s-%s.diff.mbx' % (urllib.parse.quote_plus(msgid), '-'.join(cmdargs.wantvers)))
+    else:
+        cachefile = os.path.join(cachedir, '%s-latest.diff.mbx' % urllib.parse.quote_plus(msgid))
+    if os.path.exists(cachefile) and not cmdargs.nocache:
+        logger.info('Using cached copy of the lookup')
+        shutil.copyfile(cachefile, savefile)
+        mboxfile = savefile
+    else:
+        mboxfile = b4.get_pi_thread_by_msgid(msgid, savefile, useproject=cmdargs.useproject, nocache=cmdargs.nocache)
+        if mboxfile is None:
+            logger.critical('Unable to retrieve thread: %s', msgid)
+            return
+        logger.info('Retrieved %s messages in the thread', len(mboxfile))
+        b4.mbox.get_extra_series(mboxfile, direction=-1, wantvers=cmdargs.wantvers)
+
+    shutil.copyfile(mboxfile, cachefile)
     mbx = mailbox.mbox(mboxfile)
     count = len(mbx)
     logger.info('---')
@@ -136,6 +197,24 @@ def main(cmdargs):
         os.unlink(mboxfile)
         sys.exit(1)
     logger.info('---')
-    logger.info('Success, you may now run:')
-    logger.info('    git range-diff %.12s..%.12s %.12s..%.12s', lsc, lec, usc, uec)
-
+    grdcmd = 'git range-diff %.12s..%.12s %.12s..%.12s' % (lsc, lec, usc, uec)
+    if cmdargs.nodiff:
+        logger.info('Success, to compare v%s and v%s:', lower, upper)
+        logger.info(f'    {grdcmd}')
+        sys.exit(0)
+    logger.info('Running: %s', grdcmd)
+    gitargs = ['range-diff', f'{lsc}..{lec}', f'{usc}..{uec}']
+    if cmdargs.outdiff is None or cmdargs.color:
+        gitargs.append('--color')
+    ecode, rdiff = b4.git_run_command(cmdargs.gitdir, gitargs)
+    if ecode > 0:
+        logger.critical('Unable to generate diff')
+        logger.critical('Try running it yourself:')
+        logger.critical(f'    {grdcmd}')
+        sys.exit(1)
+    if cmdargs.outdiff is not None:
+        logger.info('Writing %s', cmdargs.outdiff)
+        fh = open(cmdargs.outdiff, 'w')
+    else:
+        fh = sys.stdout
+    fh.write(rdiff)