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accesslib: get_assignable_roles() reworked to be constant-queries

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get_assignable_roles() was calling user_can_assign() (cost of 1~2 DBq)
once-per-role. Instead, we can do a single DB query that answers
all our questions in one go.

On a Moodle w 8 roles defined, saves 19 DB queries for the course page
for teachers/admins.

NOTE NOTE NOTE! With this patch we drop the insane strip/escape bit.
Only the caller knows if this is for display on html or for other uses,
so we'll be true and not mangle the data.

A review of all callers in 1.8 shows no problem - the strings were being
strip/escaped already.
This commit is contained in:
martinlanghoff 2007-09-19 07:27:46 +00:00
parent dfbf98cdb3
commit 2dff3a0681
1 changed files with 33 additions and 7 deletions
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40
lib/accesslib.php
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@ -3831,20 +3831,46 @@ function allow_assign($sroleid, $troleid) {
/**
* Gets a list of roles that this user can assign in this context
* @param object $context
* @param string $field
* @return array
*/
function get_assignable_roles ($context, $field="name") {
$options = array();
global $CFG;
if ($roles = get_all_roles()) {
foreach ($roles as $role) {
if (user_can_assign($context, $role->id)) {
$options[$role->id] = strip_tags(format_string($role->{$field}, true));
}
// this users RAs
$ras = get_user_roles($context);
$roleids = array();
foreach ($ras as $ra) {
$roleids[] = $ra->roleid;
}
unset($ra);
if (count($roleids)===0) {
return array();
}
$roleids = implode(',',$roleids);
// The subselect scopes the DISTINCT down to
// the role ids - a DISTINCT over the whole of
// the role table is much more expensive on some DBs
$sql = "SELECT r.id, r.$field
FROM {$CFG->prefix}role r
JOIN ( SELECT DISTINCT allowassign as allowedrole
FROM {$CFG->prefix}role_allow_assign raa
WHERE raa.roleid IN ($roleids) ) ar
ON r.id=ar.allowedrole
ORDER BY sortorder ASC";
$rs = get_recordset_sql($sql);
$roles = array();
if ($rs->RecordCount()) {
while ($r = rs_fetch_next_record($rs)) {
$roles[$r->id] = $r->{$field};
}
}
return $options;
return $roles;
}
/**