From 0060f88c4599c5cda1c6d5a7f6eb345a496e382f Mon Sep 17 00:00:00 2001
From: "M.Dent" <dentm42@dm42.net>
Date: Mon, 29 Oct 2018 23:04:13 -0400
Subject: Add tracking of deleted pconfig variables

---
 Zotlabs/Lib/PConfig.php | 44 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 40 insertions(+), 4 deletions(-)

diff --git a/Zotlabs/Lib/PConfig.php b/Zotlabs/Lib/PConfig.php
index 8bc5681f0..b9384cf6b 100644
--- a/Zotlabs/Lib/PConfig.php
+++ b/Zotlabs/Lib/PConfig.php
@@ -135,6 +135,16 @@ class PConfig {
 			$updated = datetime_convert();
 		}
 
+		$hash = hash('sha256',$family.':'.$key);
+
+		if (self::Get($uid, 'hz_delpconfig', $hash) !== false) {
+			if (Get($uid, 'hz_delpconfig', $hash) > $updated) {
+				logger('Refusing to update pconfig with outdated info (Item deleted more recently).', LOGGER_NORMAL, LOG_ERR);
+				return self::Get($uid,$family,$key);
+			} else {
+				self::Delete($uid,'hz_delpconfig',$hash);
+			}
+		}
 
 		if(self::Get($uid, $family, $key) === false) {
 			if(! array_key_exists($uid, \App::$config))
@@ -142,6 +152,7 @@ class PConfig {
 			if(! array_key_exists($family, \App::$config[$uid]))
 				\App::$config[$uid][$family] = array();
 
+
 			$ret = q("INSERT INTO pconfig ( uid, cat, k, v, updated ) VALUES ( %d, '%s', '%s', '%s', '%s' ) ",
 				intval($uid),
 				dbesc($family),
@@ -150,6 +161,14 @@ class PConfig {
 				dbesc($updated)
 			);
 
+			// There is a possible race condition if another process happens
+			// to insert something after this thread has Loaded and now.  We should
+			// at least make a note of it if it happens.
+
+			if (!$ret) {
+				logger("Error: Insert to pconfig failed.",LOGGER_NORMAL, LOG_ERR);
+			}
+
 			\App::$config[$uid][$family]['pcfgud:'.$key] = $updated;
 
 		}
@@ -157,6 +176,12 @@ class PConfig {
 			$new = (\App::$config[$uid][$family]['pcfgud:'.$key] < $updated);
 
 			if ($new) {
+
+				// @NOTE There is still a possible race condition under limited circumstances
+				// where a value will be updated by another thread with more current data than
+				// we have.  At this point there is no easy way to test for it, so we update
+				// and hope for the best.
+
 				$ret = q("UPDATE pconfig SET v = '%s', updated = '%s' WHERE uid = %d and cat = '%s' AND k = '%s' ",
 					dbesc($dbvalue),
 					dbesc($updated),
@@ -164,12 +189,16 @@ class PConfig {
 					dbesc($family),
 					dbesc($key)
 				);
+
+				\App::$config[$uid][$family]['pcfgud:'.$key] = $updated;
+
 			} else {
 				logger('Refusing to update pconfig with outdated info.', LOGGER_NORMAL, LOG_ERR);
 				return self::Get($uid, $family, $key);
 			}
 		}
 
+
 		// keep a separate copy for all variables which were
 		// set in the life of this page. We need this to
 		// synchronise channel clones.
@@ -223,11 +252,13 @@ class PConfig {
 
 		$ret = false;
 
-		if(array_key_exists($uid,\App::$config)
-			&& is_array(\App::$config['uid'])
-			&& array_key_exists($family,\App::$config['uid'])
-			&& array_key_exists($key, \App::$config[$uid][$family]))
+		if (isset(\App::$config[$uid][$family][$key])) {
 			unset(\App::$config[$uid][$family][$key]);
+		}
+
+		if (isset(\App::$config[$uid][$family]['pcfgud:'.$key])) {
+			unset(\App::$config[$uid][$family]['pcfgud:'.$key]);
+		}
 
 		$ret = q("DELETE FROM pconfig WHERE uid = %d AND cat = '%s' AND k = '%s'",
 			intval($uid),
@@ -235,6 +266,11 @@ class PConfig {
 			dbesc($key)
 		);
 
+		if ($family != 'hz_delpconfig') {
+			$hash = hash('sha256',$family.':'.$key);
+			set_pconfig($uid,'hz_delpconfig',$hash,$updated);
+		}
+
 		// Synchronize delete with clones.
 
 		if(! array_key_exists('transient', \App::$config[$uid]))
-- 
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