diff options
Diffstat (limited to 'src/H5Oattribute.c')
| -rw-r--r-- | src/H5Oattribute.c | 72 |
1 files changed, 64 insertions, 8 deletions
diff --git a/src/H5Oattribute.c b/src/H5Oattribute.c index b1e8d31..ea77e26 100644 --- a/src/H5Oattribute.c +++ b/src/H5Oattribute.c @@ -235,9 +235,54 @@ HDfprintf(stderr, "%s: adding attribute, attr->name = '%s'\n", FUNC, attr->name) HDassert(attr); /* Should this message be written as a SOHM? */ - if((shared_mesg = H5SM_try_share(loc->file, dxpl_id, H5O_ATTR_ID, attr)) > 0) + if((shared_mesg = H5SM_try_share(loc->file, dxpl_id, H5O_ATTR_ID, attr)) > 0) { + hsize_t attr_rc; /* Attribute's ref count in shared message storage */ + /* Mark the message as shared */ mesg_flags |= H5O_MSG_FLAG_SHARED; + + /* Check whether datatype is committed */ + /* (to maintain ref. count incr/decr similarity with "shared message" + * type of datatype sharing) + */ + if(H5T_committed(attr->dt)) { + /* Increment the reference count on the shared datatype */ + if(H5T_link(attr->dt, 1, dxpl_id) < 0) + HGOTO_ERROR(H5E_OHDR, H5E_LINKCOUNT, FAIL, "unable to adjust shared datatype link count") + } /* end if */ + + /* Retrieve ref count for shared attribute */ + if(H5SM_get_refcount(loc->file, dxpl_id, H5O_ATTR_ID, &attr->sh_loc, &attr_rc) < 0) + HGOTO_ERROR(H5E_ATTR, H5E_CANTGET, FAIL, "can't retrieve shared message ref count") + + /* If this is not the first copy of the attribute in the shared message + * storage, decrement the reference count on any shared components + * of the attribute. This is done because the shared message + * storage's "try delete" call doesn't call the message class's + * "delete" callback until the reference count drops to zero. + * However, attributes have already increased the reference + * count on shared components before passing the attribute + * to the shared message code to manage, causing an assymetry + * in the reference counting for any shared components. + * + * The alternate solution is to have the shared message's "try + * delete" code always call the message class's "delete" callback, + * even when the reference count is positive. This can be done + * without an appreciable performance hit (by using H5HF_op() in + * the shared message comparison v2 B-tree callback), but it has + * the undesirable side-effect of leaving the reference count on + * the attribute's shared components artificially (and possibly + * misleadingly) high, because there's only one shared attribute + * referencing the shared components, not <refcount for the + * shared attribute> objects referencing the shared components. + * + * *ick* -QAK, 2007/01/08 + */ + if(attr_rc > 1) { + if(H5O_attr_delete(loc->file, dxpl_id, attr, TRUE) < 0) + HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete attribute") + } /* end if */ + } /* end if */ else if(shared_mesg < 0) HGOTO_ERROR(H5E_ATTR, H5E_WRITEERROR, FAIL, "error determining if message should be shared") @@ -535,6 +580,7 @@ herr_t H5O_attr_update_shared(H5F_t *f, hid_t dxpl_id, H5A_t *attr, const H5O_shared_t *sh_mesg) { + hsize_t attr_rc; /* Attribute's ref count in shared message storage */ htri_t shared_mesg; /* Whether the message should be shared */ herr_t ret_value = SUCCEED; /* Return value */ @@ -545,13 +591,6 @@ H5O_attr_update_shared(H5F_t *f, hid_t dxpl_id, H5A_t *attr, HDassert(attr); HDassert(sh_mesg); - /* Increment reference count on attribute components */ - /* (Otherwise they may be deleted when the old attribute - * message is removed from the shared message storage.) - */ - if(H5O_attr_link(f, dxpl_id, attr) < 0) - HGOTO_ERROR(H5E_ATTR, H5E_LINKCOUNT, FAIL, "unable to adjust attribute link count") - /* Store new version of message as a SOHM */ /* (should always work, since we're not changing the size of the attribute) */ if((shared_mesg = H5SM_try_share(f, dxpl_id, H5O_ATTR_ID, attr)) == 0) @@ -559,6 +598,23 @@ H5O_attr_update_shared(H5F_t *f, hid_t dxpl_id, H5A_t *attr, else if(shared_mesg < 0) HGOTO_ERROR(H5E_ATTR, H5E_BADMESG, FAIL, "can't share attribute") + /* Retrieve shared message storage ref count for new shared attribute */ + if(H5SM_get_refcount(f, dxpl_id, H5O_ATTR_ID, &attr->sh_loc, &attr_rc) < 0) + HGOTO_ERROR(H5E_ATTR, H5E_CANTGET, FAIL, "can't retrieve shared message ref count") + + /* If the newly shared attribute needs to share "ownership" of the shared + * components (ie. its reference count is 1), increment the reference + * count on any shared components of the attribute, so that they won't + * be removed from the file. (Essentially a "copy on write" operation). + * + * *ick* -QAK, 2007/01/08 + */ + if(attr_rc == 1) { + /* Increment reference count on attribute components */ + if(H5O_attr_link(f, dxpl_id, attr) < 0) + HGOTO_ERROR(H5E_ATTR, H5E_LINKCOUNT, FAIL, "unable to adjust attribute link count") + } /* end if */ + /* Remove the old attribute from the SOHM storage */ if(H5SM_try_delete(f, dxpl_id, H5O_ATTR_ID, sh_mesg) < 0) HGOTO_ERROR(H5E_ATTR, H5E_CANTFREE, FAIL, "unable to delete shared attribute in shared storage") |