# HG changeset patch # User Gregory Szorc # Date 2019-01-10 01:41:36 # Node ID e7a2cc84dbc00deacaef6d4f13d6334c10a6903e # Parent 6439cefaeb64bcd97a2b74aff6b0faa006719058 revlog: always enable generaldelta on version 2 revlogs This commit starts the process of diverging version 2 revlogs from version 1 revlogs. generaldelta is a useful feature and has been enabled by default for ages. I can't think of a good reason why the feature should be disabled. Yes, it is true changelogs today don't have generaldelta enabled. But that's because they don't have delta chains enabled, so generaldelta makes no sense there. This commit makes generaldelta always enabled on version 2 revlogs. As part of this, one-off code in changelog.py mucking with revlog.version had to be made conditional on the revlog version, as we don't want to change revlog feature flags on version 2 revlogs. The fact this code exists is horrible and stems from revlog options being shared by the opener. We probably want a better API here. But that can wait for another patch. Differential Revision: https://phab.mercurial-scm.org/D5561 diff --git a/mercurial/changelog.py b/mercurial/changelog.py --- a/mercurial/changelog.py +++ b/mercurial/changelog.py @@ -295,8 +295,9 @@ class changelog(revlog.revlog): revlog.revlog.__init__(self, opener, indexfile, datafile=datafile, checkambig=True, mmaplargeindex=True) - if self._initempty: - # changelogs don't benefit from generaldelta + if self._initempty and (self.version & 0xFFFF == revlog.REVLOGV1): + # changelogs don't benefit from generaldelta. + self.version &= ~revlog.FLAG_GENERALDELTA self._generaldelta = False diff --git a/mercurial/help/internals/revlogs.txt b/mercurial/help/internals/revlogs.txt --- a/mercurial/help/internals/revlogs.txt +++ b/mercurial/help/internals/revlogs.txt @@ -66,8 +66,6 @@ Version 2 revlogs have the following fla 0 Store revision data inline. -1 - Generaldelta encoding. The following header values are common: @@ -159,8 +157,10 @@ Version 2 Format (In development. Format not finalized or stable.) -Version 2 is currently identical to version 1. This will obviously -change. +Version 2 is identical to version 2 with the following differences. + +There is no dedicated *generaldelta* revlog format flag. Instead, +the feature is implied enabled by default. Delta Chains ============ diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py --- a/mercurial/localrepo.py +++ b/mercurial/localrepo.py @@ -363,7 +363,7 @@ class locallegacypeer(localpeer): # Increment the sub-version when the revlog v2 format changes to lock out old # clients. -REVLOGV2_REQUIREMENT = 'exp-revlogv2.0' +REVLOGV2_REQUIREMENT = 'exp-revlogv2.1' # A repository with the sparserevlog feature will have delta chains that # can spread over a larger span. Sparse reading cuts these large spans into diff --git a/mercurial/revlog.py b/mercurial/revlog.py --- a/mercurial/revlog.py +++ b/mercurial/revlog.py @@ -387,8 +387,7 @@ class revlog(object): opts = getattr(opener, 'options', {}) or {} if 'revlogv2' in opts: - # version 2 revlogs always use generaldelta. - versionflags = REVLOGV2 | FLAG_GENERALDELTA | FLAG_INLINE_DATA + versionflags = REVLOGV2 | FLAG_INLINE_DATA elif 'revlogv1' in opts: versionflags = REVLOGV1 | FLAG_INLINE_DATA if 'generaldelta' in opts: @@ -451,25 +450,38 @@ class revlog(object): raise self.version = versionflags - self._inline = versionflags & FLAG_INLINE_DATA - self._generaldelta = versionflags & FLAG_GENERALDELTA + flags = versionflags & ~0xFFFF fmt = versionflags & 0xFFFF + if fmt == REVLOGV0: if flags: raise error.RevlogError(_('unknown flags (%#04x) in version %d ' 'revlog %s') % (flags >> 16, fmt, self.indexfile)) + + self._inline = False + self._generaldelta = False + elif fmt == REVLOGV1: if flags & ~REVLOGV1_FLAGS: raise error.RevlogError(_('unknown flags (%#04x) in version %d ' 'revlog %s') % (flags >> 16, fmt, self.indexfile)) + + self._inline = versionflags & FLAG_INLINE_DATA + self._generaldelta = versionflags & FLAG_GENERALDELTA + elif fmt == REVLOGV2: if flags & ~REVLOGV2_FLAGS: raise error.RevlogError(_('unknown flags (%#04x) in version %d ' 'revlog %s') % (flags >> 16, fmt, self.indexfile)) + + self._inline = versionflags & FLAG_INLINE_DATA + # generaldelta implied by version 2 revlogs. + self._generaldelta = True + else: raise error.RevlogError(_('unknown version (%d) in revlog %s') % (fmt, self.indexfile)) diff --git a/mercurial/revlogutils/constants.py b/mercurial/revlogutils/constants.py --- a/mercurial/revlogutils/constants.py +++ b/mercurial/revlogutils/constants.py @@ -20,13 +20,15 @@ REVLOGV1 = 1 # Dummy value until file format is finalized. # Reminder: change the bounds check in revlog.__init__ when this is changed. REVLOGV2 = 0xDEAD +# Shared across v1 and v2. FLAG_INLINE_DATA = (1 << 16) +# Only used by v1, implied by v2. FLAG_GENERALDELTA = (1 << 17) REVLOG_DEFAULT_FLAGS = FLAG_INLINE_DATA REVLOG_DEFAULT_FORMAT = REVLOGV1 REVLOG_DEFAULT_VERSION = REVLOG_DEFAULT_FORMAT | REVLOG_DEFAULT_FLAGS REVLOGV1_FLAGS = FLAG_INLINE_DATA | FLAG_GENERALDELTA -REVLOGV2_FLAGS = REVLOGV1_FLAGS +REVLOGV2_FLAGS = FLAG_INLINE_DATA # revlog index flags diff --git a/tests/test-revlog-v2.t b/tests/test-revlog-v2.t --- a/tests/test-revlog-v2.t +++ b/tests/test-revlog-v2.t @@ -22,7 +22,7 @@ Can create and open repo with revlog v2 $ cd empty-repo $ cat .hg/requires dotencode - exp-revlogv2.0 + exp-revlogv2.1 fncache sparserevlog store @@ -54,7 +54,7 @@ Writing a simple revlog v2 works date: Thu Jan 01 00:00:00 1970 +0000 summary: initial -Header written as expected (changelog always disables generaldelta) +Header written as expected $ f --hexdump --bytes 4 .hg/store/00changelog.i .hg/store/00changelog.i: @@ -62,4 +62,4 @@ Header written as expected (changelog al $ f --hexdump --bytes 4 .hg/store/data/foo.i .hg/store/data/foo.i: - 0000: 00 03 de ad |....| + 0000: 00 01 de ad |....|