Add queue cleanup. [#CLICKHOUSE-5]

dbms/src/Interpreters/DDLWorker.cpp

@@ -24,6 +24,8 @@
 #include <Columns/ColumnArray.h>
 
 #include <zkutil/ZooKeeper.h>
+#include <Poco/Timestamp.h>
+
 
 namespace DB
 {
@@ -107,7 +109,6 @@ DDLWorker::~DDLWorker()
 void DDLWorker::processTasks()
 {
     LOG_DEBUG(log, "processTasks");
-    zookeeper->createAncestors(root_dir + "/");
 
     Strings queue_nodes = zookeeper->getChildren(root_dir, nullptr, event_queue_updated);
     if (queue_nodes.empty())
@@ -172,6 +173,62 @@ void DDLWorker::processTasks()
     }
 }
 
+void DDLWorker::cleanupQueue(const Strings * node_names_to_check)
+{
+    /// Both ZK and Poco use Unix epoch
+    size_t current_time_seconds = Poco::Timestamp().epochTime();
+    constexpr size_t zookeeper_time_resolution = 1000;
+
+    // Too early to check
+    if (!last_cleanup_time_seconds && current_time_seconds < last_cleanup_time_seconds + 10)
+        return;
+
+    last_cleanup_time_seconds = current_time_seconds;
+
+    String data;
+    zkutil::Stat stat;
+    DDLLogEntry node;
+    Strings failed_hosts, sucess_hosts;
+
+    Strings node_names_fetched = node_names_to_check ? Strings{} : zookeeper->getChildren(root_dir);
+    const Strings & node_names = (node_names_to_check) ? *node_names_to_check : node_names_fetched;
+
+    for (const String & node_name : node_names)
+    {
+        /// TODO: Add /root/locks/node_name lock to avoid rare race counditions.
+        try
+        {
+            String node_path = root_dir + "/" + node_name;
+            if (!zookeeper->tryGet(node_path, data, &stat))
+                continue;
+
+            node.parse(data);
+
+            size_t zookeeper_time_seconds = stat.mtime / zookeeper_time_resolution;
+            if (zookeeper_time_seconds + node_max_lifetime_seconds < current_time_seconds)
+            {
+                size_t lifetime_seconds = current_time_seconds - zookeeper_time_seconds;
+                LOG_INFO(log, "Lifetime of node " << node_name << " (" << lifetime_seconds << " sec.) is expired, deleting it");
+                zookeeper->removeRecursive(node_path);
+                continue;
+            }
+
+            Strings sucess_nodes = zookeeper->getChildren(node_path + "/sucess");
+            Strings failed_nodes = zookeeper->getChildren(node_path + "/failed");
+
+            if (sucess_nodes.size() + failed_nodes.size() >= node.hosts.size())
+            {
+                LOG_INFO(log, "Node " << node_name << " had been executed by each host, deleting it");
+                zookeeper->removeRecursive(node_path);
+            }
+        }
+        catch (...)
+        {
+            tryLogCurrentException(log, "An error occured while checking and cleaning node " + node_name + " from queue");
+        }
+    }
+}
+
 
 /// Try to create unexisting "status" dirs for a node
 void DDLWorker::createStatusDirs(const std::string & node_path)
@@ -260,6 +317,7 @@ void DDLWorker::run()
 {
     using namespace std::chrono_literals;
 
+    zookeeper->createAncestors(root_dir + "/");
     LOG_DEBUG(log, "Started DDLWorker thread");
 
     while (!stop_flag)
@@ -275,6 +333,15 @@ void DDLWorker::run()
             tryLogCurrentException(log);
         }
 
+        try
+        {
+            cleanupQueue();
+        }
+        catch (...)
+        {
+            tryLogCurrentException(log);
+        }
+
         //std::unique_lock<std::mutex> g(lock);
         //cond_var.wait_for(g, 10s);
 
@@ -287,6 +354,7 @@ void DDLWorker::run()
 class DDLQueryStatusInputSream : public IProfilingBlockInputStream
 {
 public:
+
     DDLQueryStatusInputSream(const String & zk_node_path, Context & context, size_t num_hosts)
     : node_path(zk_node_path), context(context)
     {
@@ -364,10 +432,12 @@ public:
         for (const String & elem : cur_list)
         {
             if (!prev.count(elem))
+            {
                 diff.emplace_back(elem);
+                prev.emplace(elem);
+            }
         }
 
-        prev.insert(diff.cbegin(), diff.cend());
         return diff;
     }
 

dbms/src/Interpreters/DDLWorker.h

@@ -39,8 +39,8 @@ private:
 
     void createStatusDirs(const std::string & node_name);
 
-    void processQueries();
-    bool processQuery(const std::string & task);
+    /// Checks and cleanups queue's nodes
+    void cleanupQueue(const Strings * node_names_to_check = nullptr);
 
     void run();
 
@@ -62,6 +62,10 @@ private:
     std::mutex lock;
     std::thread thread;
 
+    size_t last_cleanup_time_seconds = 0;
+    static constexpr size_t node_max_lifetime_seconds = 10; // 7 * 24 * 60 * 60;
+    static constexpr size_t cleanup_after_seconds = 10;
+
     friend class DDLQueryStatusInputSream;
 };