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[PATCH] Re: Flushing directory log accumulator during pool cleanup (Re: svn commit: r23342 - trunk/subversion/libsvn_wc)

From: David Glasser <glasser_at_davidglasser.net>
Date: 2007-11-02 21:51:48 CET

Here's a simple patch that makes the test I added in r27575 pass. The
whole test suite passes with this patch applied, but since this bug
involves error behavior, the test suite might not actually cover it
well. I would like review before I commit.

(An alternate implementation, which would still allow *some* in-memory
logs to be run during cleanup, would be to have a boolean
"logs_ok_to_run" flag on the directory baton, which is cleared every
time the accumulator is appended to and set only when the accumulator
is definitely runnable.)

--dave

[[[
Fix wc corruption caused by flushing potentially-incomplete logs
during baton cleanup on error, by just not flushing logs during baton
cleanup. Makes the new update test #42 pass.

* subversion/libsvn_wc/update_editor.c
  (cleanup_dir_baton): Don't call flush_log.

* subversion/tests/cmdline/update_tests.py
  (test_list): eof_in_interactive_conflict_resolver now passes.
]]]

On 11/2/07, David Glasser <glasser@davidglasser.net> wrote:
> Super-late commit review!
>
> In r23342, a log accumulator was added to the directory baton; instead
> of making one "log" file per entry, there's one big log accumulator in
> each directory baton, which is flushed at various times (before
> descending into subtrees, etc) and executed at "close_directory" time.
>
> That's fine. Except there's one issue here: this revision also adds a
> flush_log call to the cleanup_dir_baton APR pool cleanup handler. And
> this can be called when Subversion is dying due to an error or signal.
> This means that something like merge_file could have only added some
> of its loggy entries to the accumulator, but the log can be executed
> anyway! This causes the problem Hyrum reported at
>
> http://svn.haxx.se/dev/archive-2007-11/0078.shtml
>
> I think we should just remove flush_log from the cleanup handler so
> that the cleanup handler only runs logs that are guaranteed to be
> "complete". (Honestly, I'm not sure how good an idea it is to be
> running logs during cleanup anyway... seems like a lot of work to be
> doing after an error is found.) I am going to do that and see if the
> tests still pass. I've noted the particular line in the diff below.
>
> (Completely orthogonally, it doesn't look like the any of the file or
> directory baton pools are ever cleared/destroyed until the main edit
> baton is. Is that acceptable memory usage?)
>
> --dave
>
> On 2/4/07, lundblad@tigris.org <lundblad@tigris.org> wrote:
> > Author: lundblad
> > Date: Sun Feb 4 12:09:32 2007
> > New Revision: 23342
> >
> > Log:
> > For checkout/update etc., avoid creating one working copy 'log' file per
> > versioned file by accumulating log entries in memory, flushing it
> > when closing the directory and before going into subdirectories.
> >
> > For large working copies, this saves a lot of creation/reading/removing small
> > files, which turns out to be rather expensive, especially on remote
> > filesystems.
> >
> > Suggested by: Henner Zeller <hzeller@google.com>
> > me
> >
> >
> > * subversion/libsvn_wc/update_editor.c
> > (struct dir_baton): Add log_accum field.
> > (make_dir_baton): Initialize the log_accum field.
> > (flush_log): New function.
> > (cleanup_dir_baton): Flush the current log before running logs.
> > (open_directory, add_directory): Flush parent directory's log before
> > opening the new directory.
> > (close_directory): Write to the accumulated log of the dir baton instead
> > of a local strinbuf. Flush the accumulated log before running the logs.
> > (close_file): Write to the accumulated log of the parent directory instead
> > of creating our own log file.
> >
> >
> > Modified:
> > trunk/subversion/libsvn_wc/update_editor.c
> >
> > Modified: trunk/subversion/libsvn_wc/update_editor.c
> > URL: http://svn.collab.net/viewvc/svn/trunk/subversion/libsvn_wc/update_editor.c?pathrev=23342&r1=23341&r2=23342
> > ==============================================================================
> > --- trunk/subversion/libsvn_wc/update_editor.c (original)
> > +++ trunk/subversion/libsvn_wc/update_editor.c Sun Feb 4 12:09:32 2007
> > @@ -162,6 +162,9 @@
> > /* The current log file number. */
> > int log_number;
> >
> > + /* The current log buffer. */
> > + svn_stringbuf_t *log_accum;
> > +
> > /* The pool in which this baton itself is allocated. */
> > apr_pool_t *pool;
> > };
> > @@ -235,6 +238,27 @@
> > return entry->url;
> > }
> >
> > +/* Flush accumulated log entries to a log file on disk for DIR_BATON and
> > + * increase the log number of the dir baton.
> > + * Use POOL for temporary allocations. */
> > +static svn_error_t *
> > +flush_log(struct dir_baton *db, apr_pool_t *pool)
> > +{
> > + if (! svn_stringbuf_isempty(db->log_accum))
> > + {
> > + svn_wc_adm_access_t *adm_access;
> > +
> > + SVN_ERR(svn_wc_adm_retrieve(&adm_access, db->edit_baton->adm_access,
> > + db->path, pool));
> > + SVN_ERR(svn_wc__write_log(adm_access, db->log_number, db->log_accum,
> > + pool));
> > + db->log_number++;
> > + svn_stringbuf_setempty(db->log_accum);
> > + }
> > +
> > + return SVN_NO_ERROR;
> > +}
> > +
> > /* An APR pool cleanup handler. This runs the log file for a
> > directory baton. */
> > static apr_status_t
> > @@ -244,23 +268,27 @@
> > svn_error_t *err;
> > apr_status_t apr_err;
> > svn_wc_adm_access_t *adm_access;
> > + apr_pool_t *pool = apr_pool_parent_get(db->pool);
> >
> > - /* If there are no log files to write, return immediately. */
> > - if (db->log_number == 0)
> > - return APR_SUCCESS;
> > -
> > - err = svn_wc_adm_retrieve(&adm_access, db->edit_baton->adm_access,
> > - db->path, apr_pool_parent_get(db->pool));
> > -
> > - if (! err)
> > + err = flush_log(db, pool);
>
> The above line is the one that concerns me.
>
> > + if (! err && db->log_number > 0)
> > {
> > - err = svn_wc__run_log(adm_access, NULL, apr_pool_parent_get(db->pool));
> > -
> > + err = svn_wc_adm_retrieve(&adm_access, db->edit_baton->adm_access,
> > + db->path, pool);
> > +
> > if (! err)
> > - return APR_SUCCESS;
> > + {
> > + err = svn_wc__run_log(adm_access, NULL, pool);
> > +
> > + if (! err)
> > + return APR_SUCCESS;
> > + }
> > }
> > -
> > - apr_err = err->apr_err;
> > +
> > + if (err)
> > + apr_err = err->apr_err;
> > + else
> > + apr_err = APR_SUCCESS;
> > svn_error_clear(err);
> > return apr_err;
> > }
> > @@ -363,6 +391,7 @@
> > d->add_existed = FALSE;
> > d->bump_info = bdi;
> > d->log_number = 0;
> > + d->log_accum = svn_stringbuf_create("", pool);
> >
> > apr_pool_cleanup_register(d->pool, d, cleanup_dir_baton,
> > cleanup_dir_baton_child);
> > @@ -513,8 +542,6 @@
> > return SVN_NO_ERROR;
> > }
> >
> > -
> > -
> > struct file_baton
> > {
> > /* The global edit baton. */
> > @@ -1100,6 +1127,9 @@
> > struct dir_baton *db = make_dir_baton(path, eb, pb, TRUE, pool);
> > svn_node_kind_t kind;
> >
> > + /* Flush the log for the parent directory before going into this subtree. */
> > + SVN_ERR(flush_log(pb, pool));
> > +
> > /* Semantic check. Either both "copyfrom" args are valid, or they're
> > NULL and SVN_INVALID_REVNUM. A mixture is illegal semantics. */
> > if ((copyfrom_path && (! SVN_IS_VALID_REVNUM(copyfrom_revision)))
> > @@ -1299,6 +1329,9 @@
> >
> > svn_wc_adm_access_t *adm_access;
> >
> > + /* Flush the log for the parent directory before going into this subtree. */
> > + SVN_ERR(flush_log(pb, pool));
> > +
> > /* kff todo: check that the dir exists locally, find it somewhere if
> > its not there? Yes, all this and more... And ancestor_url and
> > ancestor_revision need to get used. */
> > @@ -1419,9 +1452,6 @@
> > to deal with them. */
> > if (regular_props->nelts || entry_props->nelts || wc_props->nelts)
> > {
> > - /* to hold log messages: */
> > - svn_stringbuf_t *entry_accum = svn_stringbuf_create("", db->pool);
> > -
> > if (regular_props->nelts)
> > {
> > /* If recording traversal info, then see if the
> > @@ -1478,25 +1508,23 @@
> > adm_access, NULL,
> > NULL /* use baseprops */,
> > regular_props, TRUE, FALSE,
> > - db->pool, &entry_accum),
> > + db->pool, &db->log_accum),
> > _("Couldn't do property merge"));
> > }
> >
> > - SVN_ERR(accumulate_entry_props(entry_accum, NULL,
> > + SVN_ERR(accumulate_entry_props(db->log_accum, NULL,
> > adm_access, SVN_WC_ENTRY_THIS_DIR,
> > entry_props, pool));
> >
> > - SVN_ERR(accumulate_wcprops(entry_accum, adm_access,
> > + SVN_ERR(accumulate_wcprops(db->log_accum, adm_access,
> > SVN_WC_ENTRY_THIS_DIR, wc_props, pool));
> > -
> > - /* Write our accumulation of log entries into a log file */
> > - SVN_ERR(svn_wc__write_log(adm_access, db->log_number, entry_accum, pool));
> > }
> >
> > - /* Run the log. */
> > + /* Flush and run the log. */
> > + SVN_ERR(flush_log(db, pool));
> > SVN_ERR(svn_wc__run_log(adm_access, db->edit_baton->diff3_cmd, db->pool));
> > db->log_number = 0;
> > -
> > +
> > /* We're done with this directory, so remove one reference from the
> > bump information. This may trigger a number of actions. See
> > maybe_bump_dir_info() for more information. */
> > @@ -2503,7 +2531,6 @@
> > svn_wc_notify_state_t content_state, prop_state;
> > svn_wc_notify_lock_state_t lock_state;
> > svn_wc_adm_access_t *adm_access;
> > - svn_stringbuf_t *log_accum;
> >
> > if (fb->skipped)
> > {
> > @@ -2531,11 +2558,7 @@
> > SVN_ERR(svn_wc_adm_retrieve(&adm_access, eb->adm_access,
> > parent_path, pool));
> >
> > - /* Accumulate log commands in this buffer until we're ready to
> > - write the log. */
> > - log_accum = svn_stringbuf_create("", pool);
> > -
> > - SVN_ERR(merge_file(log_accum,
> > + SVN_ERR(merge_file(fb->dir_baton->log_accum,
> > &content_state,
> > &prop_state,
> > &lock_state,
> > @@ -2551,12 +2574,6 @@
> > fb->last_changed_date,
> > pool));
> >
> > - /* Write our accumulation of log entries into a log file */
> > - SVN_ERR(svn_wc__write_log(adm_access, fb->dir_baton->log_number,
> > - log_accum, pool));
> > -
> > - fb->dir_baton->log_number++;
> > -
> > /* We have one less referrer to the directory's bump information. */
> > SVN_ERR(maybe_bump_dir_info(eb, fb->bump_info, pool));
> >
> >
> > ---------------------------------------------------------------------
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> > For additional commands, e-mail: svn-help@subversion.tigris.org
> >
> >
>
>
> --
> David Glasser | glasser_at_davidglasser.net | http://www.davidglasser.net/
>

-- 
David Glasser | glasser_at_davidglasser.net | http://www.davidglasser.net/


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Received on Fri Nov 2 21:52:25 2007

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