Author: stefan2
Date: Wed Jun 17 14:55:02 2015
New Revision: 1686039
URL: http://svn.apache.org/r1686039
Log:
On the fsx-1.10 branch:
Use the fsync batch for the revision data file in FSX.
As soon as the commit process begins, the protorev file is (potentially)
tainted by adding tree data (noderevs, directories) and metadata to it.
Instead of modifying it in the original location and then moving it to
the shard, we first move it to the shard and then modify it. Due to the
'current' file not being bumped, yet, the intermediate contents will not
be accessed by readers.
So with this patch, we prevent commit attempts on previously failed txns
and at the same time eliminate the fsync-after rename issue for the
revision data file.
* subversion/libsvn_fs_x/transaction.c
(get_writable_final_rev): New function.
(commit_body): Call the new function instead of handling renames and
fsyncs for the revision data file here.
Modified:
subversion/branches/fsx-1.10/subversion/libsvn_fs_x/transaction.c
Modified: subversion/branches/fsx-1.10/subversion/libsvn_fs_x/transaction.c
URL:
http://svn.apache.org/viewvc/subversion/branches/fsx-1.10/subversion/libsvn_fs_x/transaction.c?rev=1686039&r1=1686038&r2=1686039&view=diff
==============================================================================
--- subversion/branches/fsx-1.10/subversion/libsvn_fs_x/transaction.c (original)
+++ subversion/branches/fsx-1.10/subversion/libsvn_fs_x/transaction.c Wed Jun
17 14:55:02 2015
@@ -3327,6 +3327,73 @@ auto_create_shard(svn_fs_t *fs,
return SVN_NO_ERROR;
}
+/* Move the protype revision file of transaction TXN_ID in FS to the final
+ location for REVISION and return a handle to it in *FILE. Schedule any
+ fsyncs in BATCH and use SCRATCH_POOL for temporaries.
+
+ Note that the lifetime of *FILE is determined by BATCH instead of
+ SCRATCH_POOL. It will be invalidated by either BATCH being cleaned up
+ itself of by running svn_fs_x__batch_fsync_run on it.
+
+ This function will "destroy" the transaction by removing its prototype
+ revision file, so it can at most be called once per transaction. Also,
+ later attempts to modify this txn will fail due to get_writable_proto_rev
+ not finding the protorev file. Therefore, we will take out the lock for
+ it only until we move the file to its final location.
+
+ If the prototype revision file is already locked, return error
+ SVN_ERR_FS_REP_BEING_WRITTEN. */
+static svn_error_t *
+get_writable_final_rev(apr_file_t **file,
+ svn_fs_t *fs,
+ svn_fs_x__txn_id_t txn_id,
+ svn_revnum_t revision,
+ svn_fs_x__batch_fsync_t *batch,
+ apr_pool_t *scratch_pool)
+{
+ get_writable_proto_rev_baton_t baton;
+ apr_off_t end_offset = 0;
+ void *lockcookie;
+
+ const char *proto_rev_filename
+ = svn_fs_x__path_txn_proto_rev(fs, txn_id, scratch_pool);
+ const char *final_rev_filename
+ = svn_fs_x__path_rev(fs, revision, scratch_pool);
+
+ /* Acquire exclusive access to the proto-rev file. */
+ baton.lockcookie = &lockcookie;
+ baton.txn_id = txn_id;
+
+ SVN_ERR(with_txnlist_lock(fs, get_writable_proto_rev_body, &baton,
+ scratch_pool));
+
+ /* Move the proto-rev file to its final location as revision data file.
+ After that, we don't need to protect it anymore and can unlock it. */
+ SVN_ERR(svn_error_compose_create(svn_io_file_rename(proto_rev_filename,
+ final_rev_filename,
+ scratch_pool),
+ unlock_proto_rev(fs, txn_id, lockcookie,
+ scratch_pool)));
+ SVN_ERR(svn_fs_x__batch_fsync_new_path(batch, final_rev_filename,
+ scratch_pool));
+
+ /* Now open the prototype revision file and seek to the end.
+ Note that BATCH always seeks to position 0 before returning the file. */
+ SVN_ERR(svn_fs_x__batch_fsync_open_file(file, batch, final_rev_filename,
+ scratch_pool));
+ SVN_ERR(svn_io_file_seek(*file, APR_END, &end_offset, scratch_pool));
+
+ /* We don't want unused sections (such as leftovers from failed delta
+ stream) in our file. If we use log addressing, we would need an
+ index entry for the unused section and that section would need to
+ be all NUL by convention. So, detect and fix those cases by truncating
+ the protorev file. */
+ SVN_ERR(auto_truncate_proto_rev(fs, *file, end_offset, txn_id,
+ scratch_pool));
+
+ return SVN_NO_ERROR;
+}
+
/* Baton used for commit_body below. */
typedef struct commit_baton_t {
svn_revnum_t *new_rev_p;
@@ -3346,12 +3413,11 @@ commit_body(void *baton,
{
commit_baton_t *cb = baton;
svn_fs_x__data_t *ffd = cb->fs->fsap_data;
- const char *old_rev_filename, *rev_filename, *proto_filename;
+ const char *old_rev_filename, *rev_filename;
const char *revprop_filename, *final_revprop;
svn_fs_x__id_t root_id, new_root_id;
svn_revnum_t old_rev, new_rev;
apr_file_t *proto_file, *revprop_file;
- void *proto_file_lockcookie;
apr_off_t initial_offset, changed_path_offset;
svn_fs_x__txn_id_t txn_id = svn_fs_x__txn_get_id(cb->txn);
apr_hash_t *changed_paths;
@@ -3410,10 +3476,15 @@ commit_body(void *baton,
/* Set up the target directory. */
SVN_ERR(auto_create_shard(cb->fs, new_rev, batch, subpool));
- /* Get a write handle on the proto revision file. */
- SVN_ERR(get_writable_proto_rev(&proto_file, &proto_file_lockcookie,
- cb->fs, txn_id, scratch_pool));
+ /* Get a write handle on the proto revision file.
+
+ ### This "breaks" the transaction by removing the protorev file
+ ### but the revision is not yet complete. If this commit does
+ ### not complete for any reason the transaction will be lost. */
+ SVN_ERR(get_writable_final_rev(&proto_file, cb->fs, txn_id, new_rev,
+ batch, subpool));
SVN_ERR(svn_fs_x__get_file_offset(&initial_offset, proto_file, subpool));
+ svn_pool_clear(subpool);
/* Write out all the node-revisions and directory contents. */
svn_fs_x__init_txn_root(&root_id, txn_id);
@@ -3435,30 +3506,10 @@ commit_body(void *baton,
new_rev, subpool));
svn_pool_clear(subpool);
- SVN_ERR(svn_io_file_flush_to_disk(proto_file, subpool));
- SVN_ERR(svn_io_file_close(proto_file, subpool));
-
- /* We don't unlock the prototype revision file immediately to avoid a
- race with another caller writing to the prototype revision file
- before we commit it. */
-
- /* Move the finished rev file into place.
-
- ### This "breaks" the transaction by removing the protorev file
- ### but the revision is not yet complete. If this commit does
- ### not complete for any reason the transaction will be lost. */
+ /* Set the correct permissions. */
old_rev_filename = svn_fs_x__path_rev_absolute(cb->fs, old_rev, subpool);
-
rev_filename = svn_fs_x__path_rev(cb->fs, new_rev, subpool);
- proto_filename = svn_fs_x__path_txn_proto_rev(cb->fs, txn_id, subpool);
- SVN_ERR(svn_fs_x__move_into_place(proto_filename, rev_filename,
- old_rev_filename, subpool));
-
- /* Now that we've moved the prototype revision file out of the way,
- we can unlock it (since further attempts to write to the file
- will fail as it no longer exists). We must do this so that we can
- remove the transaction directory later. */
- SVN_ERR(unlock_proto_rev(cb->fs, txn_id, proto_file_lockcookie, subpool));
+ SVN_ERR(svn_io_copy_perms(rev_filename, old_rev_filename, subpool));
/* Move the revprops file into place. */
SVN_ERR_ASSERT(! svn_fs_x__is_packed_revprop(cb->fs, new_rev));
