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Re: svn commit: r1554800 - in /subversion/trunk/subversion: include/svn_fs.h libsvn_fs/fs-loader.c libsvn_fs/fs-loader.h libsvn_fs_base/tree.c libsvn_fs_fs/tree.c libsvn_fs_x/tree.c

From: Julian Foad <julianfoad_at_btopenworld.com>
Date: Fri, 28 Feb 2014 12:10:02 +0000 (GMT)

> Author: stefan2
> Date: Thu Jan  2 13:16:43 2014
> New Revision: 1554800
>
> URL: http://svn.apache.org/r1554800

Hi Stefan. I just noticed a few things in this commit...

> Log:
> Provide a path-based counterpart to svn_fs_base__id_compare.
> Most code can now compare nodes directly (next commit) using
> fewer LOCs and being faster for non-BDB repositories.
>
> It also introduces improvements over the id-based API:  An enum
> replaces the various magic return values and nodes from different
> repositories are reported as "unrelated" instead of yielding an
> undefined result.
>
> * subversion/include/svn_fs.h
>   (svn_fs_node_relation_t,
>    svn_fs_node_relation): Declare the new API.
>
> * subversion/libsvn_fs/fs-loader.h
>   (root_vtable_t): Add the corresponding vtable entry.
>
> * subversion/libsvn_fs/fs-loader.c
>   (svn_fs_node_relation): Implement as forwarding to the FS vtable.
>
> * subversion/libsvn_fs_base/tree.c
>   (base_node_relation): Naive implementation of the new API;
>                         basically what the users did in the past.
>   (root_vtable): Update.
>
> * subversion/libsvn_fs_fs/tree.c
>   (fs_node_relation): Optimized code based on fs_node_id() and
>                       svn_fs_fs__id_compare() using as few object
>                       copies as possible.  Since all logic is in
>                       one place now, it will be easier to refine
>                       in the future.
>   (root_vtable): Update.
>
> * subversion/libsvn_fs_x/tree.c
>   (x_node_relation): Implement similarly to FSFS.
>   (root_vtable): Update.

> Modified: subversion/trunk/subversion/include/svn_fs.h
> ==============================================================================
>
> +/** Defines the possible ways two arbitrary nodes may be related.

Would it be good to reference the old Boolean function svn_fs_check_related(id1, id2) here, saying how the three possible results of this function relate to that one? And/or maybe that function should reference this one.

> + *
> + * @since New in 1.9.
> + */
> +typedef enum svn_fs_node_relation_t
> +{
> +  /** The nodes are not related.
> +   * Nodes from different repositories are always unrelated. */
> +  svn_fs_node_unrelated = 0,
> +
> +  /** They are the same physical node, i.e. there is no intermittent change.
> +   * However, due to lazy copying, they may be intermittent parent copies.

A better word would be "intervening"; "intermittent" usually means "keeps on stopping and starting" or "occurring from time to time" ("mit" referring to "sending" rather than "middle").

Also s/they may/there may/ ?

> +   */
> +  svn_fs_node_same,
> +
> +  /** The nodes have a common ancestor (which may be one of these nodes)
> +   * but are not the same.
> +   */
> +  svn_fs_node_common_anchestor

"ancestor"

> + 
> +} svn_fs_node_relation_t;

So,
  svn_fs_compare_ids()
  id_vtable_t.compare
  svn_fs_base__id_compare()
  svn_fs_fs__id_compare()
  etc.

all return results that are analogous to svn_fs_node_relation_t, but using numeric codes instead. Maybe it would be
good to update those to use your new constants. There seem to be very few uses of each of them.

> +/** Determine how @a path_a under @a root_a and @a path_b under @a root_b
> + * are related and return the result in @a relation.  There is no restriction
> + * concerning the roots: They may refer to different repositories, be in
> + * arbitrary revision order and any of them may pertain to a transaction.
> + * @a pool is used for temporary allocations.
> + *
> + * @note The current implementation considers paths from different svn_fs_t
> + * as unrelated even if the underlying physical repository is the same.

We might as well decide that that's the promised and intended behaviour, and delete "current implementation", don't you think?

> + * @since New in 1.9.
> + */
> +svn_error_t *
> +svn_fs_node_relation(svn_fs_node_relation_t *relation,
> +                     svn_fs_root_t *root_a,
> +                     const char *path_a,
> +                     svn_fs_root_t *root_b,
> +                     const char *path_b,
> +                     apr_pool_t *pool);
> +

> Modified: subversion/trunk/subversion/libsvn_fs/fs-loader.c
> ==============================================================================
>
> svn_error_t *
> +svn_fs_node_relation(svn_fs_node_relation_t *relation,
> +                     svn_fs_root_t *root_a, const char *path_a,
> +                     svn_fs_root_t *root_b, const char *path_b,
> +                     apr_pool_t *pool)
> +{
> +  /* Different repository types? */
> +  if (root_a->vtable != root_b->vtable)

That test doesn't look robust. It may well be the case at the moment that the FSAP vtable is always at the same address for roots in a given FS, but wouldn't it be better to avoid relying on that and compare the FS object address directly?

    if (root_a->fs != root_b->fs)
      { return "unrelated" }
    /* Now the FS's are the same, so the FSAP vtables must be
       equivalent even if not allocated at the same address. */

> +    {
> +      *relation = svn_fs_node_unrelated;
> +      return SVN_NO_ERROR;
> +    }

Alternatively, but somehow not so good, we could leave the code above as it was and assert here that root_a->fs == root_b->fs.

> +  return svn_error_trace(root_a->vtable->node_relation(relation, root_a,
> +                                                       path_a, root_b,
> +                                                       path_b, pool));
> +}

> Modified: subversion/trunk/subversion/libsvn_fs/fs-loader.h
> ==============================================================================
> @@ -299,6 +299,10 @@ typedef struct root_vtable_t
>                                 apr_pool_t *pool);
>    svn_error_t *(*node_id)(const svn_fs_id_t **id_p, svn_fs_root_t *root,
>                            const char *path, apr_pool_t *pool);
> +  svn_error_t *(*node_relation)(svn_fs_node_relation_t *relation,
> +                                svn_fs_root_t *root_a, const char *path_a,
> +                                svn_fs_root_t *root_b, const char *path_b,
> +                                apr_pool_t *pool);
>    svn_error_t *(*node_created_rev)(svn_revnum_t *revision,
>                                     svn_fs_root_t *root, const char *path,
>                                     apr_pool_t *pool);
>
> Modified: subversion/trunk/subversion/libsvn_fs_base/tree.c
> ==============================================================================
>
> +static svn_error_t *
> +base_node_relation(svn_fs_node_relation_t *relation,
> +                   svn_fs_root_t *root_a, const char *path_a,
> +                   svn_fs_root_t *root_b, const char *path_b,
> +                   apr_pool_t *pool)
> +{
> +  const svn_fs_id_t *id_a, *id_b;
> +
> +  /* Paths from different repository are never related. */
> +  if (root_a->fs != root_b->fs)
> +    {
> +      *relation = svn_fs_node_unrelated;
> +      return SVN_NO_ERROR;
> +    }
> +
> +  /* Naive implementation. */
> +  SVN_ERR(base_node_id(&id_a, root_a, path_a, pool));
> +  SVN_ERR(base_node_id(&id_b, root_b, path_b, pool));
> +
> +  switch (svn_fs_base__id_compare(id_a, id_b))
> +    {
> +      case 0:  *relation = svn_fs_node_same;
> +               break;
> +      case 1:  *relation = svn_fs_node_common_anchestor;
> +               break;
> +      default: *relation = svn_fs_node_unrelated;
> +               break;
> +    }
> +
> +  return SVN_NO_ERROR;
> +}
> +
>
> struct node_created_rev_args {
>    svn_revnum_t revision;
> @@ -5400,6 +5432,7 @@ static root_vtable_t root_vtable = {
>    base_check_path,
>    base_node_history,
>    base_node_id,
> +  base_node_relation,
>    base_node_created_rev,
>    base_node_origin_rev,
>    base_node_created_path,
>
> Modified: subversion/trunk/subversion/libsvn_fs_fs/tree.c
> ==============================================================================
>
> +static svn_error_t *
> +fs_node_relation(svn_fs_node_relation_t *relation,
> +                 svn_fs_root_t *root_a, const char *path_a,
> +                 svn_fs_root_t *root_b, const char *path_b,
> +                 apr_pool_t *pool)
> +{
> +  dag_node_t *node;
> +  const svn_fs_id_t *id;
> +  svn_fs_fs__id_part_t rev_item_a, rev_item_b, node_id_a, node_id_b;
> +
> +  /* Root paths are a common special case. */
> +  svn_boolean_t a_is_root_dir
> +    = (path_a[0] == '\0') || ((path_a[0] == '/') &&
> (path_a[1] == '\0'));
> +  svn_boolean_t b_is_root_dir
> +    = (path_b[0] == '\0') || ((path_b[0] == '/') &&
> (path_b[1] == '\0'));
> +
> +  /* Root paths are never related to non-root paths and path from different
> +   * repository are always unrelated. */

It's possible to copy the root (svn cp ^/@123 ^/copy-of-old-root). Does a copy not count as "related"? I'm not sure precisely what "related" means.

> +  if (a_is_root_dir ^ b_is_root_dir || root_a->fs != root_b->fs)
> +    {
> +      *relation = svn_fs_node_unrelated;
> +      return SVN_NO_ERROR;
> +    }
> +
> +  /* Nodes from different transactions are never related. */
> +  if (root_a->is_txn_root && root_b->is_txn_root
> +      && strcmp(root_a->txn, root_b->txn))
> +    {
> +      *relation = svn_fs_node_unrelated;
> +      return SVN_NO_ERROR;
> +    }
> +
> +  /* Are both (!) root paths? Then, they are related and we only test how
> +   * direct the relation is. */
> +  if (a_is_root_dir)
> +    {
> +      *relation = root_a->rev == root_b->rev
> +                ? svn_fs_node_same
> +                : svn_fs_node_common_anchestor;
> +      return SVN_NO_ERROR;
> +    }
> +
> +  /* We checked for all separations between ID spaces (repos, txn).
> +   * Now, we can simply test for the ID values themselves. */
> +  SVN_ERR(get_dag(&node, root_a, path_a, FALSE, pool));
> +  id = svn_fs_fs__dag_get_id(node);
> +  rev_item_a = *svn_fs_fs__id_rev_item(id);
> +  node_id_a = *svn_fs_fs__id_node_id(id);
> +
> +  SVN_ERR(get_dag(&node, root_b, path_b, FALSE, pool));
> +  id = svn_fs_fs__dag_get_id(node);
> +  rev_item_b = *svn_fs_fs__id_rev_item(id);
> +  node_id_b = *svn_fs_fs__id_node_id(id);
> +
> +  if (svn_fs_fs__id_part_eq(&rev_item_a, &rev_item_b))
> +    *relation = svn_fs_node_same;
> +  else if (svn_fs_fs__id_part_eq(&node_id_a, &node_id_b))
> +    *relation = svn_fs_node_common_anchestor;
> +  else
> +    *relation = svn_fs_node_unrelated;
> +
> +  return SVN_NO_ERROR;
> +}
>
> svn_error_t *
> svn_fs_fs__node_created_rev(svn_revnum_t *revision,
> @@ -4275,6 +4338,7 @@ static root_vtable_t root_vtable = {
>    svn_fs_fs__check_path,
>    fs_node_history,
>    svn_fs_fs__node_id,
> +  fs_node_relation,
>    svn_fs_fs__node_created_rev,
>    fs_node_origin_rev,
>    fs_node_created_path,
>
> Modified: subversion/trunk/subversion/libsvn_fs_x/tree.c
> ==============================================================================
>
> +static svn_error_t *
> +x_node_relation(svn_fs_node_relation_t *relation,
> +                svn_fs_root_t *root_a, const char *path_a,
> +                svn_fs_root_t *root_b, const char *path_b,
> +                apr_pool_t *pool)
> +{
> +  dag_node_t *node;
> +  const svn_fs_id_t *id;
> +  svn_fs_x__id_part_t rev_item_a, rev_item_b, node_id_a, node_id_b;
> +
> +  /* Root paths are a common special case. */
> +  svn_boolean_t a_is_root_dir
> +    = (path_a[0] == '\0') || ((path_a[0] == '/') &&
> (path_a[1] == '\0'));
> +  svn_boolean_t b_is_root_dir
> +    = (path_b[0] == '\0') || ((path_b[0] == '/') &&
> (path_b[1] == '\0'));
> +
> +  /* Root paths are never related to non-root paths and path from different
> +   * repository are always unrelated. */
> +  if (a_is_root_dir ^ b_is_root_dir || root_a->fs != root_b->fs)
> +    {
> +      *relation = svn_fs_node_unrelated;
> +      return SVN_NO_ERROR;
> +    }
> +
> +  /* Nodes from different transactions are never related. */
> +  if (root_a->is_txn_root && root_b->is_txn_root
> +      && strcmp(root_a->txn, root_b->txn))
> +    {
> +      *relation = svn_fs_node_unrelated;
> +      return SVN_NO_ERROR;
> +    }
> +
> +  /* Are both (!) root paths? Then, they are related and we only test how
> +   * direct the relation is. */
> +  if (a_is_root_dir)
> +    {
> +      *relation = root_a->rev == root_b->rev
> +                ? svn_fs_node_same
> +                : svn_fs_node_common_anchestor;
> +      return SVN_NO_ERROR;
> +    }
> +
> +  /* We checked for all separations between ID spaces (repos, txn).
> +   * Now, we can simply test for the ID values themselves. */
> +  SVN_ERR(get_dag(&node, root_a, path_a, FALSE, pool));
> +  id = svn_fs_x__dag_get_id(node);
> +  rev_item_a = *svn_fs_x__id_rev_item(id);
> +  node_id_a = *svn_fs_x__id_node_id(id);
> +
> +  SVN_ERR(get_dag(&node, root_b, path_b, FALSE, pool));
> +  id = svn_fs_x__dag_get_id(node);
> +  rev_item_b = *svn_fs_x__id_rev_item(id);
> +  node_id_b = *svn_fs_x__id_node_id(id);
> +
> +  if (svn_fs_x__id_part_eq(&rev_item_a, &rev_item_b))
> +    *relation = svn_fs_node_same;
> +  else if (svn_fs_x__id_part_eq(&node_id_a, &node_id_b))
> +    *relation = svn_fs_node_common_anchestor;
> +  else
> +    *relation = svn_fs_node_unrelated;
> +
> +  return SVN_NO_ERROR;
> +}
>
> svn_error_t *
> svn_fs_x__node_created_rev(svn_revnum_t *revision,
> @@ -4199,6 +4262,7 @@ static root_vtable_t root_vtable = {
>    svn_fs_x__check_path,
>    x_node_history,
>    svn_fs_x__node_id,
> +  x_node_relation,
>    svn_fs_x__node_created_rev,
>    x_node_origin_rev,
>    x_node_created_path,
>

- Julian
Received on 2014-02-28 13:10:40 CET

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