Author: danielsh
Date: Thu Jul 7 14:21:08 2011
New Revision: 1143841
URL: http://svn.apache.org/viewvc?rev=1143841&view=rev
Log:
On the 'revprop-sharding' branch:
Begin documenting the design plan.
* BRANCH-README: Point to 'structure'.
* subversion/libsvn_fs_fs/structure:
Document the directory and file structure.
TBD: locking, readers/writers algorithm.
Modified:
subversion/branches/revprop-packing/BRANCH-README
subversion/branches/revprop-packing/subversion/libsvn_fs_fs/structure
Modified: subversion/branches/revprop-packing/BRANCH-README
URL:
http://svn.apache.org/viewvc/subversion/branches/revprop-packing/BRANCH-README?rev=1143841&r1=1143840&r2=1143841&view=diff
==============================================================================
--- subversion/branches/revprop-packing/BRANCH-README (original)
+++ subversion/branches/revprop-packing/BRANCH-README Thu Jul 7 14:21:08 2011
@@ -1,3 +1,9 @@
-This branch exists to reimplement the revprop-packing without SQLite. Several
-strategies have been discussed on the mailing list here:
+This branch exists to reimplement the revprop-packing in FSFS f5 without
+SQLite. Several strategies have been discussed on the mailing list here:
http://svn.haxx.se/dev/archive-2011-07/0134.shtml
+
+The concrete design proposal has been patched into the 'structure' file; you
+may review it via
+
+ svn diff ^/subversion/trunk/subversion/libsvn_fs_fs/structure@r1143816 \
+
^/subversion/branches/revprop-packing/subversion/libsvn_fs_fs/structure
Modified: subversion/branches/revprop-packing/subversion/libsvn_fs_fs/structure
URL:
http://svn.apache.org/viewvc/subversion/branches/revprop-packing/subversion/libsvn_fs_fs/structure?rev=1143841&r1=1143840&r2=1143841&view=diff
==============================================================================
--- subversion/branches/revprop-packing/subversion/libsvn_fs_fs/structure
(original)
+++ subversion/branches/revprop-packing/subversion/libsvn_fs_fs/structure Thu
Jul 7 14:21:08 2011
@@ -40,7 +40,9 @@ repository) is:
revprops/ Subdirectory containing rev-props
<shard>/ Shard directory, if sharding is in use (see below)
<revnum> File containing rev-props for <revnum>
- revprops.db SQLite database of the packed revision properties
+ <shard>.revpack/ Pack directory, if the repo has been packed (see below)
+ revpack Revprops pack file, contains inline manifest (see below)
+ lock Revprops shard lock file (see below)
transactions/ Subdirectory containing transactions
<txnid>.txn/ Directory containing transaction <txnid>
txn-protorevs/ Subdirectory containing transaction proto-revision files
@@ -63,8 +65,8 @@ repository) is:
min-unpacked-revprop File containing the oldest revision of unpacked revprop
rep-cache.db SQLite database mapping rep checksums to locations
-Files in the revprops directory are in the hash dump format used by
-svn_hash_write.
+Non-packed files in the revprops directory are in the hash dump format used by
+svn_hash_write.
The format of the "current" file is:
@@ -171,6 +173,10 @@ Revision changed paths list:
Format 1-3: Does not contain the node's kind.
Format 4-5: Contains the node's kind.
+Revprop packing:
+ Format 1-4: revprops are not packed
+ Format 5: revprops are packed
+
# Incomplete list. See SVN_FS_FS__MIN_*_FORMAT
@@ -225,13 +231,27 @@ Packing revision properties
---------------------------
Revprop shards may be packed too. The packing process moves all revprops from
-a the oldest unpacked shard to the SQLite database "revprops/revprops.db". The
-sequel documents the schema of FSFS format 5, which corresponds to schema
-version USER_VERSION=1:
-
-The database maps revision numbers to serialized "proplist" skels. Every
-packed revision must have a mapping entry (a table row), even if it maps the
-revnum to an empty skel.
+each completed shard S to a single pack file. As a special-case, r0 revprops
+are never packed, in consideration of performance of 'svnsync' and other
+consumers that propedit r0.
+
+The pack+manifest file consists of:
+
+* A 32-bit sequence number
+* A list of offsets, one for each revision's hunk in the pack file.
+* The concatenated hunks for all revisions in the shard.
+
+The sequence number and the offsets are stored as ASCII decimal, followed by
+newline. They are space-padded from the left such that the least-significant
+digit is on the tenth byte of the line for the sequence number, and on the
+twentieth byte of the line for the offsets. Each revprop's hunk takes the same
+format as an unpacked revprop file: namely, it is a svn_hash_write()-serialized
+revprops hash.
+
+The manifest for the zeroth shard contains the literal ASCII text "zerothshard"
+(with no following newline) in place of the offset for the zeroth revision of
+the shard.
+
Node-revision IDs
-----------------
