diff --git a/include/Scrape.php b/include/Scrape.php
index 4f53effe92..b784650cd1 100644
--- a/include/Scrape.php
+++ b/include/Scrape.php
@@ -432,7 +432,7 @@ function probe_url($url, $mode = PROBE_NORMAL) {
intval(local_user())
);
if(count($x) && count($r)) {
- $mailbox = construct_mailbox_name($r[0]);
+ $mailbox = construct_mailbox_name($r[0]);
$password = '';
openssl_private_decrypt(hex2bin($r[0]['pass']),$password,$x[0]['prvkey']);
$mbox = email_connect($mailbox,$r[0]['user'],$password);
diff --git a/include/diaspora.php b/include/diaspora.php
index 5ab0ee6749..29846eedf6 100755
--- a/include/diaspora.php
+++ b/include/diaspora.php
@@ -5,6 +5,7 @@ require_once('include/items.php');
require_once('include/bb2diaspora.php');
require_once('include/contact_selectors.php');
require_once('include/queue_fn.php');
+require_once('include/lock.php');
function diaspora_dispatch_public($msg) {
@@ -113,27 +114,83 @@ function diaspora_get_contact_by_handle($uid,$handle) {
}
function find_diaspora_person_by_handle($handle) {
+
+ $person = false;
$update = false;
- $r = q("select * from fcontact where network = '%s' and addr = '%s' limit 1",
- dbesc(NETWORK_DIASPORA),
- dbesc($handle)
- );
- if(count($r)) {
- logger('find_diaspora_person_by handle: in cache ' . print_r($r,true), LOGGER_DEBUG);
- // update record occasionally so it doesn't get stale
- $d = strtotime($r[0]['updated'] . ' +00:00');
- if($d > strtotime('now - 14 days'))
- return $r[0];
- $update = true;
- }
- logger('find_diaspora_person_by_handle: refresh',LOGGER_DEBUG);
- require_once('include/Scrape.php');
- $r = probe_url($handle, PROBE_DIASPORA);
- if((count($r)) && ($r['network'] === NETWORK_DIASPORA)) {
- add_fcontact($r,$update);
- return ($r);
- }
- return false;
+ $got_lock = false;
+
+ do {
+ $r = q("select * from fcontact where network = '%s' and addr = '%s' limit 1",
+ dbesc(NETWORK_DIASPORA),
+ dbesc($handle)
+ );
+ if(count($r)) {
+ $person = $r[0];
+ logger('find_diaspora_person_by handle: in cache ' . print_r($r,true), LOGGER_DEBUG);
+
+ // update record occasionally so it doesn't get stale
+ $d = strtotime($person['updated'] . ' +00:00');
+ if($d < strtotime('now - 14 days'))
+ $update = true;
+ }
+
+
+ // FETCHING PERSON INFORMATION FROM REMOTE SERVER
+ //
+ // If the person isn't in our 'fcontact' table, or if he/she is but
+ // his/her information hasn't been updated for more than 14 days, then
+ // we want to fetch the person's information from the remote server.
+ //
+ // Note that $person isn't changed by this block of code unless the
+ // person's information has been successfully fetched from the remote
+ // server. So if $person was 'false' to begin with (because he/she wasn't
+ // in the local cache), it'll stay false, and if $person held the local
+ // cache information to begin with, it'll keep that information. That way
+ // if there's a problem with the remote fetch, we can at least use our
+ // cached information--it's better than nothing.
+
+ if((! $person) || ($update)) {
+ // Lock the function to prevent race conditions if multiple items
+ // come in at the same time from a person who doesn't exist in
+ // fcontact
+ $got_lock = lock_function('find_diaspora_person_by_handle', false);
+
+ if($got_lock) {
+ logger('find_diaspora_person_by_handle: create or refresh', LOGGER_DEBUG);
+ require_once('include/Scrape.php');
+ $r = probe_url($handle, PROBE_DIASPORA);
+
+ // Note that Friendica contacts can return a "Diaspora person"
+ // if Diaspora connectivity is enabled on their server
+ if((count($r)) && ($r['network'] === NETWORK_DIASPORA)) {
+ add_fcontact($r,$update);
+ $person = ($r);
+ }
+
+ unlock_function('find_diaspora_person_by_handle');
+ }
+ else {
+ logger('find_diaspora_person_by_handle: couldn\'t lock function', LOGGER_DEBUG);
+ if(! $person)
+ block_on_function_lock('find_diaspora_person_by_handle');
+ }
+ }
+ } while((! $person) && (! $got_lock));
+ // We need to try again if the person wasn't in 'fcontact' but the function was locked.
+ // The fact that the function was locked may mean that another process was creating the
+ // person's record. It could also mean another process was creating or updating an unrelated
+ // person.
+ //
+ // At any rate, we need to keep trying until we've either got the person or had a chance to
+ // try to fetch his/her remote information. But we don't want to block on locking the
+ // function, because if the other process is creating the record, then when we acquire the lock
+ // we'll dive right into creating another, duplicate record. We DO want to at least wait
+ // until the lock is released, so we don't flood the database with requests.
+ //
+ // If the person was in the 'fcontact' table, don't try again. It's not worth the time, since
+ // we do have some information for the person
+
+ return $person;
}
diff --git a/include/lock.php b/include/lock.php
new file mode 100644
index 0000000000..be6130e1d0
--- /dev/null
+++ b/include/lock.php
@@ -0,0 +1,76 @@
+<?php
+
+// Provide some ability to lock a PHP function so that multiple processes
+// can't run the function concurrently
+// The function must have a line inserted into the 'lock' table with the
+// function's name in the 'name' field
+if(! function_exists('lock_function')) {
+function lock_function($fn_name, $block = true, $wait_sec = 2) {
+ if( $wait_sec == 0 )
+ $wait_sec = 2; // don't let the user pick a value that's likely to crash the system
+
+ $got_lock = false;
+
+ do {
+ q("LOCK TABLE lock WRITE");
+ $r = q("SELECT locked FROM lock WHERE name = '%s' LIMIT 1",
+ dbesc($fn_name)
+ );
+
+ if((count($r)) && (! $r[0]['locked'])) {
+ q("UPDATE lock SET locked = 1 WHERE name = '%s' LIMIT 1",
+ dbesc($fn_name)
+ );
+ $got_lock = true;
+ }
+ elseif(! $r) { // the Boolean value for count($r) should be equivalent to the Boolean value of $r
+ q("INSERT INTO lock ( name, locked ) VALUES ( '%s', 1 )",
+ dbesc($fn_name)
+ );
+ $got_lock = true;
+ }
+
+ q("UNLOCK TABLES");
+
+ if(($block) && (! $got_lock))
+ sleep($wait_sec);
+
+ } while(($block) && (! $got_lock));
+
+ logger('lock_function: function ' . $fn_name . ' with blocking = ' . $block . ' got_lock = ' . $got_lock, LOGGER_DEBUG);
+
+ return $got_lock;
+}}
+
+
+if(! function_exists('block_on_function_lock')) {
+function block_on_function_lock($fn_name, $wait_sec = 2) {
+ if( $wait_sec == 0 )
+ $wait_sec = 2; // don't let the user pick a value that's likely to crash the system
+
+ do {
+ $r = q("SELECT locked FROM lock WHERE name = '%s' LIMIT 1",
+ dbesc(fn_name)
+ );
+
+ if(count($r) && $r[0]['locked'])
+ sleep($wait_sec);
+
+ } while(count($r) && $r[0]['locked']);
+
+ return;
+}}
+
+
+if(! function_exists('unlock_function')) {
+function unlock_function(fn_name) {
+ //$r = q("LOCK TABLE lock WRITE");
+ $r = q("UPDATE lock SET locked = 0 WHERE name = '%s' LIMIT 1",
+ dbesc(fn_name)
+ );
+ //$r = q("UNLOCK TABLES");
+
+ logger('unlock_function: released lock for function ' . fn_name, LOGGER_DEBUG);
+
+ return;
+}}
diff --git a/update.php b/update.php
index b8e247f57c..5e5ec3e865 100644
--- a/update.php
+++ b/update.php
@@ -1307,3 +1307,15 @@ function update_1150() {
return UPDATE_SUCCESS;
}
+
+function update_1151() {
+ $r = q("CREATE TABLE IF NOT EXISTS lock (
+ id INT NOT NULL AUTO_INCREMENT PRIMARY KEY ,
+ name CHAR(128) NOT NULL ,
+ locked TINYINT(1) NOT NULL DEFAULT '0'
+ ) ENGINE = MYISAM DEFAULT CHARSET=utf8 ");
+ if (!$r)
+ return UPDATE_FAILED;
+ return UPDATE_SUCCESS;
+}
+