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authorZach Prezkuta <fermion@gmx.com>2012-07-05 19:01:13 -0600
committerZach Prezkuta <fermion@gmx.com>2012-07-05 19:01:13 -0600
commit5dcce1ed9378c4a1ef2f5272e34baf8fee5cc8be (patch)
treeeff78b5232480b27b6b614fce3696132265c2279 /include
parent2edfc3b53902d1f666d239fbcb88492c57d81ca7 (diff)
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add some timeouts to prevent deadlock
Diffstat (limited to 'include')
-rwxr-xr-xinclude/diaspora.php12
-rw-r--r--include/lock.php15
2 files changed, 18 insertions, 9 deletions
diff --git a/include/diaspora.php b/include/diaspora.php
index 29846eedf..35cd66059 100755
--- a/include/diaspora.php
+++ b/include/diaspora.php
@@ -119,6 +119,9 @@ function find_diaspora_person_by_handle($handle) {
$update = false;
$got_lock = false;
+ $endlessloop = 0;
+ $maxloops = 10;
+
do {
$r = q("select * from fcontact where network = '%s' and addr = '%s' limit 1",
dbesc(NETWORK_DIASPORA),
@@ -153,7 +156,12 @@ function find_diaspora_person_by_handle($handle) {
// 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);
+ //
+ // Don't loop forever. On the last loop, try to create the contact
+ // whether the function is locked or not. Maybe the locking thread
+ // has died or something. At any rate, a duplicate in 'fcontact'
+ // is a much smaller problem than a deadlocked thread
+ $got_lock = (($endlessloop + 1) < $maxloops ? lock_function('find_diaspora_person_by_handle', false) : true );
if($got_lock) {
logger('find_diaspora_person_by_handle: create or refresh', LOGGER_DEBUG);
@@ -175,7 +183,7 @@ function find_diaspora_person_by_handle($handle) {
block_on_function_lock('find_diaspora_person_by_handle');
}
}
- } while((! $person) && (! $got_lock));
+ } while((! $person) && (! $got_lock) && (++$endlessloop < $maxloops));
// We need to try again if the person wasn't in 'fcontact' but the function was locked.
// The fact that the function was locked may mean that another process was creating the
// person's record. It could also mean another process was creating or updating an unrelated
diff --git a/include/lock.php b/include/lock.php
index 9bdb71125..5f1ca6323 100644
--- a/include/lock.php
+++ b/include/lock.php
@@ -3,11 +3,12 @@
// Provide some ability to lock a PHP function so that multiple processes
// can't run the function concurrently
if(! function_exists('lock_function')) {
-function lock_function($fn_name, $block = true, $wait_sec = 2) {
+function lock_function($fn_name, $block = true, $wait_sec = 2, $timeout = 30) {
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;
+ $start = time();
do {
q("LOCK TABLE locks WRITE");
@@ -33,19 +34,21 @@ function lock_function($fn_name, $block = true, $wait_sec = 2) {
if(($block) && (! $got_lock))
sleep($wait_sec);
- } while(($block) && (! $got_lock));
+ } while(($block) && (! $got_lock) && ((time() - $start) < $timeout));
- logger('lock_function: function ' . $fn_name . ' with blocking = ' . $block . ' got_lock = ' . $got_lock, LOGGER_DEBUG);
+ logger('lock_function: function ' . $fn_name . ' with blocking = ' . $block . ' got_lock = ' . $got_lock . ' time = ' . (time() - $start), LOGGER_DEBUG);
return $got_lock;
}}
if(! function_exists('block_on_function_lock')) {
-function block_on_function_lock($fn_name, $wait_sec = 2) {
+function block_on_function_lock($fn_name, $wait_sec = 2, $timeout = 30) {
if( $wait_sec == 0 )
$wait_sec = 2; // don't let the user pick a value that's likely to crash the system
+ $start = time();
+
do {
$r = q("SELECT locked FROM locks WHERE name = '%s' LIMIT 1",
dbesc($fn_name)
@@ -54,7 +57,7 @@ function block_on_function_lock($fn_name, $wait_sec = 2) {
if(count($r) && $r[0]['locked'])
sleep($wait_sec);
- } while(count($r) && $r[0]['locked']);
+ } while(count($r) && $r[0]['locked'] && ((time() - $start) < $timeout));
return;
}}
@@ -62,11 +65,9 @@ function block_on_function_lock($fn_name, $wait_sec = 2) {
if(! function_exists('unlock_function')) {
function unlock_function($fn_name) {
- //$r = q("LOCK TABLE lock WRITE");
$r = q("UPDATE locks SET locked = 0 WHERE name = '%s' LIMIT 1",
dbesc($fn_name)
);
- //$r = q("UNLOCK TABLES");
logger('unlock_function: released lock for function ' . $fn_name, LOGGER_DEBUG);