Fix assertion failed: assert(m_in_use) MP-603
[metaproxy-moved-to-github.git] / src / filter_session_shared.cpp
index 4d4606a..dbfa491 100644 (file)
@@ -1,5 +1,5 @@
 /* This file is part of Metaproxy.
-   Copyright (C) 2005-2011 Index Data
+   Copyright (C) Index Data
 
 Metaproxy is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free
@@ -31,6 +31,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 #include <metaproxy/util.hpp>
 #include "filter_session_shared.hpp"
 
+#include <yaz/copy_types.h>
 #include <yaz/log.h>
 #include <yaz/zgdu.h>
 #include <yaz/otherinfo.h>
@@ -40,6 +41,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 #include <map>
 #include <iostream>
 #include <time.h>
+#include <limits.h>
 
 namespace mp = metaproxy_1;
 namespace yf = metaproxy_1::filter;
@@ -74,15 +76,21 @@ namespace metaproxy_1 {
         public:
             std::string m_result_set_id;
             Databases m_databases;
-            int m_result_set_size;
+            Odr_int m_result_set_size;
             yazpp_1::Yaz_Z_Query m_query;
             time_t m_time_last_use;
             void timestamp();
             yazpp_1::RecordCache m_record_cache;
+
+            Z_OtherInformation *additionalSearchInfoRequest;
+            Z_OtherInformation *additionalSearchInfoResponse;
+            NMEM mem_additionalSearchInfo;
             BackendSet(
                 const std::string &result_set_id,
                 const Databases &databases,
-                const yazpp_1::Yaz_Z_Query &query);
+                const yazpp_1::Yaz_Z_Query &query,
+                Z_OtherInformation *additionalSearchInfoRequest);
+            ~BackendSet();
             bool search(
                 Package &frontend_package,
                 Package &search_package,
@@ -117,19 +125,27 @@ namespace metaproxy_1 {
             BackendInstancePtr get_backend(const Package &package);
             void use_backend(BackendInstancePtr b);
             void release_backend(BackendInstancePtr b);
-            void expire_class();
+            bool expire_instances();
             yazpp_1::GDU m_init_request;
             yazpp_1::GDU m_init_response;
             boost::mutex m_mutex_backend_class;
+            boost::condition m_cond_set_ready;
             int m_sequence_top;
             time_t m_backend_set_ttl;
             time_t m_backend_expiry_ttl;
             size_t m_backend_set_max;
+            Odr_int m_preferredMessageSize;
+            Odr_int m_maximumRecordSize;
+            int m_no_failed;
+            int m_no_succeeded;
+            int m_no_init;
         public:
             BackendClass(const yazpp_1::GDU &init_request,
                          int resultset_ttl,
                          int resultset_max,
-                         int session_ttl);
+                         int session_ttl,
+                         Odr_int preferredRecordSize,
+                         Odr_int maximumRecordSize);
             ~BackendClass();
         };
         // frontend result set
@@ -155,6 +171,9 @@ namespace metaproxy_1 {
             void present(Package &package, Z_APDU *apdu);
             void scan(Package &package, Z_APDU *apdu);
 
+            int result_set_ref(ODR o,
+                               const Databases &databases,
+                               Z_RPNStructure *s, std::string &rset);
             void get_set(mp::Package &package,
                          const Z_APDU *apdu_req,
                          const Databases &databases,
@@ -162,28 +181,34 @@ namespace metaproxy_1 {
                          BackendInstancePtr &found_backend,
                          BackendSetPtr &found_set);
             void override_set(BackendInstancePtr &found_backend,
-                              std::string &result_set_id);
+                              std::string &result_set_id,
+                              const Databases &databases,
+                              bool out_of_sessions);
 
             Rep *m_p;
             BackendClassPtr m_backend_class;
             FrontendSets m_frontend_sets;
-        };            
+        };
         // representation
         class SessionShared::Rep {
             friend class SessionShared;
             friend struct Frontend;
-            
+
             FrontendPtr get_frontend(Package &package);
             void release_frontend(Package &package);
             Rep();
         public:
+            ~Rep();
             void expire();
         private:
+            void expire_classes();
+            void stat();
             void init(Package &package, const Z_GDU *gdu,
                       FrontendPtr frontend);
             void start();
             boost::mutex m_mutex;
             boost::condition m_cond_session_ready;
+            boost::condition m_cond_expire_ready;
             std::map<mp::Session, FrontendPtr> m_clients;
 
             BackendClassMap m_backend_map;
@@ -193,6 +218,11 @@ namespace metaproxy_1 {
             int m_resultset_max;
             int m_session_ttl;
             bool m_optimize_search;
+            bool m_restart;
+            int m_session_max;
+            Odr_int m_preferredMessageSize;
+            Odr_int m_maximumRecordSize;
+            bool close_down;
         };
     }
 }
@@ -204,7 +234,7 @@ yf::SessionShared::FrontendSet::FrontendSet(
 {
 }
 
-const yf::SessionShared::Databases & 
+const yf::SessionShared::Databases &
 yf::SessionShared::FrontendSet::get_databases()
 {
     return m_databases;
@@ -218,7 +248,7 @@ const yazpp_1::Yaz_Z_Query& yf::SessionShared::FrontendSet::get_query()
 yf::SessionShared::InitKey::InitKey(const InitKey &k)
 {
     m_odr = odr_createmem(ODR_ENCODE);
-    
+
     m_idAuthentication_size =  k.m_idAuthentication_size;
     m_idAuthentication_buf = (char*)odr_malloc(m_odr, m_idAuthentication_size);
     memcpy(m_idAuthentication_buf, k.m_idAuthentication_buf,
@@ -250,7 +280,7 @@ yf::SessionShared::InitKey::~InitKey()
 }
 
 bool yf::SessionShared::InitKey::operator < (const SessionShared::InitKey &k)
-    const 
+    const
 {
     int c;
     c = mp::util::memcmp2(
@@ -273,49 +303,52 @@ bool yf::SessionShared::InitKey::operator < (const SessionShared::InitKey &k)
 void yf::SessionShared::BackendClass::release_backend(BackendInstancePtr b)
 {
     boost::mutex::scoped_lock lock(m_mutex_backend_class);
+    m_cond_set_ready.notify_all();
     b->m_in_use = false;
 }
 
 
 void yf::SessionShared::BackendClass::remove_backend(BackendInstancePtr b)
 {
-    BackendInstanceList::iterator it = m_backend_list.begin();
-    
-    while (it != m_backend_list.end())
     {
-        if (*it == b)
+        boost::mutex::scoped_lock lock(m_mutex_backend_class);
+        BackendInstanceList::iterator it = m_backend_list.begin();
+        for (;;)
         {
-             mp::odr odr;
-            (*it)->m_close_package->response() = odr.create_close(
-                0, Z_Close_lackOfActivity, 0);
-            (*it)->m_close_package->session().close();
-            (*it)->m_close_package->move();
-            
-            it = m_backend_list.erase(it);
-        }
-        else
+            if (it == m_backend_list.end())
+                return;
+            if (*it == b)
+            {
+                it = m_backend_list.erase(it);
+                break;
+            }
             it++;
+        }
     }
+    mp::odr odr;
+    b->m_close_package->response() = odr.create_close(
+        0, Z_Close_lackOfActivity, 0);
+    b->m_close_package->session().close();
+    b->m_close_package->move();
 }
 
 
-
-yf::SessionShared::BackendInstancePtr 
+yf::SessionShared::BackendInstancePtr
 yf::SessionShared::BackendClass::get_backend(
     const mp::Package &frontend_package)
 {
     {
         boost::mutex::scoped_lock lock(m_mutex_backend_class);
-        
+
         BackendInstanceList::const_iterator it = m_backend_list.begin();
-        
+
         BackendInstancePtr backend1; // null
-        
+
         for (; it != m_backend_list.end(); it++)
         {
             if (!(*it)->m_in_use)
             {
-                if (!backend1 
+                if (!backend1
                     || (*it)->m_sequence_this < backend1->m_sequence_this)
                     backend1 = *it;
             }
@@ -343,15 +376,30 @@ void yf::SessionShared::BackendInstance::timestamp()
 
 yf::SessionShared::BackendInstance::~BackendInstance()
 {
+    if (m_close_package)
+    {
+        mp::odr odr;
+        m_close_package->response() = odr.create_close(
+            0, Z_Close_lackOfActivity, 0);
+        m_close_package->session().close();
+        m_close_package->move();
+    }
     delete m_close_package;
 }
 
 yf::SessionShared::BackendInstancePtr yf::SessionShared::BackendClass::create_backend(
     const mp::Package &frontend_package)
 {
-    BackendInstancePtr bp(new BackendInstance);
     BackendInstancePtr null;
-
+    {
+        boost::mutex::scoped_lock lock(m_mutex_backend_class);
+        if (m_no_failed && !m_no_succeeded)
+        {
+            m_no_failed++;
+            return null;
+        }
+    }
+    BackendInstancePtr bp(new BackendInstance);
     bp->m_close_package =
         new mp::Package(bp->m_session, frontend_package.origin());
     bp->m_close_package->copy_filter(frontend_package);
@@ -378,61 +426,98 @@ yf::SessionShared::BackendInstancePtr yf::SessionShared::BackendClass::create_ba
     ODR_MASK_SET(req->protocolVersion, Z_ProtocolVersion_2);
     ODR_MASK_SET(req->protocolVersion, Z_ProtocolVersion_3);
 
+    if (m_preferredMessageSize)
+        *req->preferredMessageSize = m_preferredMessageSize;
+    if (m_maximumRecordSize)
+        *req->maximumRecordSize = m_maximumRecordSize;
+
     init_package.request() = init_pdu;
 
+    {
+        boost::mutex::scoped_lock lock(m_mutex_backend_class);
+        m_no_init++;
+    }
+
     init_package.move();
 
     boost::mutex::scoped_lock lock(m_mutex_backend_class);
 
     m_named_result_sets = false;
     Z_GDU *gdu = init_package.response().get();
-    if (init_package.session().is_closed())
-    {
-        /* already closed. We don't know why */
-        return null;
-    }
-    else if (gdu && gdu->which == Z_GDU_Z3950 
-             && gdu->u.z3950->which == Z_APDU_initResponse
-             && *gdu->u.z3950->u.initResponse->result)
+
+    if (gdu && gdu->which == Z_GDU_Z3950
+        && gdu->u.z3950->which == Z_APDU_initResponse)
     {
-        /* successful init response */
         Z_InitResponse *res = gdu->u.z3950->u.initResponse;
         m_init_response = gdu->u.z3950;
         if (ODR_MASK_GET(res->options, Z_Options_namedResultSets))
         {
             m_named_result_sets = true;
         }
+        if (*gdu->u.z3950->u.initResponse->result
+            && !init_package.session().is_closed())
+        {
+            bp->m_in_use = true;
+            time(&bp->m_time_last_use);
+            bp->m_sequence_this = 0;
+            bp->m_result_set_sequence = 0;
+            m_backend_list.push_back(bp);
+            m_no_succeeded++;
+            return bp;
+        }
     }
     else
     {
-        /* not init or init rejected */
+        yazpp_1::GDU empty_gdu;
+        m_init_response = empty_gdu;
+    }
+
+    if (!init_package.session().is_closed())
+    {
         init_package.copy_filter(frontend_package);
         init_package.session().close();
         init_package.move();
-        return null;
     }
-    bp->m_in_use = true;
-    time(&bp->m_time_last_use);
-    bp->m_sequence_this = 0;
-    bp->m_result_set_sequence = 0;
-    m_backend_list.push_back(bp);
-
-    return bp;
+    m_no_failed++;
+    return null;
 }
 
 
 yf::SessionShared::BackendClass::BackendClass(const yazpp_1::GDU &init_request,
                                               int resultset_ttl,
                                               int resultset_max,
-                                              int session_ttl)
+                                              int session_ttl,
+                                              Odr_int preferredMessageSize,
+                                              Odr_int maximumRecordSize)
     : m_named_result_sets(false), m_init_request(init_request),
       m_sequence_top(0), m_backend_set_ttl(resultset_ttl),
-      m_backend_expiry_ttl(session_ttl), m_backend_set_max(resultset_max)
+      m_backend_expiry_ttl(session_ttl), m_backend_set_max(resultset_max),
+      m_preferredMessageSize(preferredMessageSize),
+      m_maximumRecordSize(maximumRecordSize),
+      m_no_failed(0), m_no_succeeded(0), m_no_init(0)
 {}
 
 yf::SessionShared::BackendClass::~BackendClass()
 {}
 
+void yf::SessionShared::Rep::stat()
+{
+    int no_classes = 0;
+    int no_instances = 0;
+    BackendClassMap::const_iterator it;
+    {
+        boost::mutex::scoped_lock lock(m_mutex_backend_map);
+        for (it = m_backend_map.begin(); it != m_backend_map.end(); it++)
+        {
+            BackendClassPtr bc = it->second;
+            no_classes++;
+            BackendInstanceList::iterator bit = bc->m_backend_list.begin();
+            for (; bit != bc->m_backend_list.end(); bit++)
+                no_instances++;
+        }
+    }
+}
+
 void yf::SessionShared::Rep::init(mp::Package &package, const Z_GDU *gdu,
                                   FrontendPtr frontend)
 {
@@ -450,46 +535,85 @@ void yf::SessionShared::Rep::init(mp::Package &package, const Z_GDU *gdu,
             BackendClassPtr b(new BackendClass(gdu->u.z3950,
                                                m_resultset_ttl,
                                                m_resultset_max,
-                                               m_session_ttl));
+                                               m_session_ttl,
+                                               m_preferredMessageSize,
+                                               m_maximumRecordSize));
             m_backend_map[k] = b;
             frontend->m_backend_class = b;
         }
         else
         {
-            frontend->m_backend_class = it->second;            
+            frontend->m_backend_class = it->second;
         }
     }
     BackendClassPtr bc = frontend->m_backend_class;
-    BackendInstancePtr backend = bc->get_backend(package);
-    
     mp::odr odr;
-    if (!backend)
+
+    // we only need to get init response from "first" target in
+    // backend class - the assumption being that init response is
+    // same for all
+    bool create_first_one = false;
     {
-        Z_APDU *apdu = odr.create_initResponse(gdu->u.z3950, 0, 0);
-        *apdu->u.initResponse->result = 0;
-        package.response() = apdu;
-        package.session().close();
+        boost::mutex::scoped_lock lock(bc->m_mutex_backend_class);
+        if (!bc->m_no_failed && !bc->m_no_succeeded && !bc->m_no_init)
+            create_first_one = true;
+        else
+        {
+            // first for first one to finish
+            while (!bc->m_no_failed && !bc->m_no_succeeded && bc->m_no_init)
+            {
+                bc->m_cond_set_ready.wait(lock);
+            }
+        }
     }
-    else
+    if (create_first_one)
+    {
+        BackendInstancePtr backend = bc->create_backend(package);
+        if (backend)
+            bc->release_backend(backend);
+    }
+    yazpp_1::GDU init_response;
     {
         boost::mutex::scoped_lock lock(bc->m_mutex_backend_class);
-        yazpp_1::GDU init_response = bc->m_init_response;
+
+        init_response = bc->m_init_response;
+    }
+
+    if (init_response.get())
+    {
         Z_GDU *response_gdu = init_response.get();
         mp::util::transfer_referenceId(odr, gdu->u.z3950,
                                        response_gdu->u.z3950);
-
-        Z_Options *server_options =
-            response_gdu->u.z3950->u.initResponse->options;
+        Z_InitResponse *init_res = response_gdu->u.z3950->u.initResponse;
+        Z_Options *server_options = init_res->options;
         Z_Options *client_options = &frontend->m_init_options;
-
         int i;
-        for (i = 0; i<30; i++)
+        for (i = 0; i < 30; i++)
             if (!ODR_MASK_GET(client_options, i))
                 ODR_MASK_CLEAR(server_options, i);
+
+        if (!m_preferredMessageSize ||
+            *init_res->preferredMessageSize > *req->preferredMessageSize)
+            *init_res->preferredMessageSize = *req->preferredMessageSize;
+
+        if (!m_maximumRecordSize ||
+            *init_res->maximumRecordSize > *req->maximumRecordSize)
+            *init_res->maximumRecordSize = *req->maximumRecordSize;
+
         package.response() = init_response;
+        if (!*response_gdu->u.z3950->u.initResponse->result)
+            package.session().close();
+    }
+    else
+    {
+        Z_APDU *apdu =
+            odr.create_initResponse(
+                gdu->u.z3950, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR,
+                "session_shared: target closed connection during init");
+        *apdu->u.initResponse->result = 0;
+        package.response() = apdu;
+        package.session().close();
     }
-    if (backend)
-        bc->release_backend(backend);
 }
 
 void yf::SessionShared::BackendSet::timestamp()
@@ -500,11 +624,22 @@ void yf::SessionShared::BackendSet::timestamp()
 yf::SessionShared::BackendSet::BackendSet(
     const std::string &result_set_id,
     const Databases &databases,
-    const yazpp_1::Yaz_Z_Query &query) :
+    const yazpp_1::Yaz_Z_Query &query,
+    Z_OtherInformation *additionalSearchInfo) :
     m_result_set_id(result_set_id),
-    m_databases(databases), m_result_set_size(0), m_query(query) 
+    m_databases(databases), m_result_set_size(0), m_query(query)
 {
     timestamp();
+    mem_additionalSearchInfo = nmem_create();
+    additionalSearchInfoResponse = 0;
+    additionalSearchInfoRequest =
+        yaz_clone_z_OtherInformation(additionalSearchInfo,
+                                     mem_additionalSearchInfo);
+}
+
+yf::SessionShared::BackendSet::~BackendSet()
+{
+    nmem_destroy(mem_additionalSearchInfo);
 }
 
 static int get_diagnostic(Z_DefaultDiagFormat *r)
@@ -523,11 +658,12 @@ bool yf::SessionShared::BackendSet::search(
     Z_APDU *apdu_req = zget_APDU(odr, Z_APDU_searchRequest);
     Z_SearchRequest *req = apdu_req->u.searchRequest;
 
+    req->additionalSearchInfo = additionalSearchInfoRequest;
     req->resultSetName = odr_strdup(odr, m_result_set_id.c_str());
     req->query = m_query.get_Z_Query();
 
     req->num_databaseNames = m_databases.size();
-    req->databaseNames = (char**) 
+    req->databaseNames = (char**)
         odr_malloc(odr, req->num_databaseNames * sizeof(char *));
     Databases::const_iterator it = m_databases.begin();
     size_t i = 0;
@@ -544,37 +680,45 @@ bool yf::SessionShared::BackendSet::search(
 
     Z_GDU *gdu = search_package.response().get();
     if (!search_package.session().is_closed()
-        && gdu && gdu->which == Z_GDU_Z3950 
+        && gdu && gdu->which == Z_GDU_Z3950
         && gdu->u.z3950->which == Z_APDU_searchResponse)
     {
         Z_SearchResponse *b_resp = gdu->u.z3950->u.searchResponse;
         *z_records = b_resp->records;
         m_result_set_size = *b_resp->resultCount;
+
+        additionalSearchInfoResponse = yaz_clone_z_OtherInformation(
+            b_resp->additionalSearchInfo, mem_additionalSearchInfo);
         return true;
     }
     Z_APDU *f_apdu = 0;
+    const char *addinfo = "session_shared: "
+        "target closed connection during search";
     if (frontend_apdu->which == Z_APDU_searchRequest)
         f_apdu = odr.create_searchResponse(
-            frontend_apdu, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, 0);
+            frontend_apdu, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, addinfo);
     else if (frontend_apdu->which == Z_APDU_presentRequest)
         f_apdu = odr.create_presentResponse(
-            frontend_apdu, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, 0);
+            frontend_apdu, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, addinfo);
     else
         f_apdu = odr.create_close(
-            frontend_apdu, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, 0);
+            frontend_apdu, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, addinfo);
     frontend_package.response() = f_apdu;
     return false;
 }
 
 void yf::SessionShared::Frontend::override_set(
     BackendInstancePtr &found_backend,
-    std::string &result_set_id)
+    std::string &result_set_id,
+    const Databases &databases,
+    bool out_of_sessions)
 {
     BackendClassPtr bc = m_backend_class;
     BackendInstanceList::const_iterator it = bc->m_backend_list.begin();
     time_t now;
     time(&now);
-    
+
+    size_t max_sets = bc->m_named_result_sets ? bc->m_backend_set_max : 1;
     for (; it != bc->m_backend_list.end(); it++)
     {
         if (!(*it)->m_in_use)
@@ -582,8 +726,11 @@ void yf::SessionShared::Frontend::override_set(
             BackendSetList::iterator set_it = (*it)->m_sets.begin();
             for (; set_it != (*it)->m_sets.end(); set_it++)
             {
-                if (now >= (*set_it)->m_time_last_use &&
-                    now - (*set_it)->m_time_last_use > bc->m_backend_set_ttl)
+                if ((max_sets > 1 || (*set_it)->m_databases == databases)
+                    &&
+                    (out_of_sessions ||
+                     now < (*set_it)->m_time_last_use ||
+                     now - (*set_it)->m_time_last_use >= bc->m_backend_set_ttl))
                 {
                     found_backend = *it;
                     result_set_id = (*set_it)->m_result_set_id;
@@ -593,7 +740,6 @@ void yf::SessionShared::Frontend::override_set(
             }
         }
     }
-    size_t max_sets = bc->m_named_result_sets ? bc->m_backend_set_max : 1;
     for (it = bc->m_backend_list.begin(); it != bc->m_backend_list.end(); it++)
     {
         if (!(*it)->m_in_use && (*it)->m_sets.size() < max_sets)
@@ -602,7 +748,7 @@ void yf::SessionShared::Frontend::override_set(
             if (bc->m_named_result_sets)
             {
                 result_set_id = boost::io::str(
-                    boost::format("%1%") % 
+                    boost::format("%1%") %
                     found_backend->m_result_set_sequence);
                 found_backend->m_result_set_sequence++;
             }
@@ -621,65 +767,96 @@ void yf::SessionShared::Frontend::get_set(mp::Package &package,
                                           BackendSetPtr &found_set)
 {
     bool session_restarted = false;
+    Z_OtherInformation *additionalSearchInfo = 0;
+
+    if (apdu_req->which == Z_APDU_searchRequest)
+        additionalSearchInfo = apdu_req->u.searchRequest->additionalSearchInfo;
 
 restart:
     std::string result_set_id;
+    bool out_of_sessions = false;
     BackendClassPtr bc = m_backend_class;
     {
         boost::mutex::scoped_lock lock(bc->m_mutex_backend_class);
-        
+
+        if ((int) bc->m_backend_list.size() >= m_p->m_session_max)
+            out_of_sessions = true;
+
         if (m_p->m_optimize_search)
         {
             // look at each backend and see if we have a similar search
             BackendInstanceList::const_iterator it = bc->m_backend_list.begin();
-            for (; it != bc->m_backend_list.end(); it++)
+            while (it != bc->m_backend_list.end())
             {
-                if (!(*it)->m_in_use)
+                bool restart = false;
+                BackendSetList::const_iterator set_it = (*it)->m_sets.begin();
+                for (; set_it != (*it)->m_sets.end(); set_it++)
                 {
-                    BackendSetList::const_iterator set_it = (*it)->m_sets.begin();
-                    for (; set_it != (*it)->m_sets.end(); set_it++)
+                    // for real present request we don't care
+                    // if additionalSearchInfo matches: same records
+                    if ((*set_it)->m_databases == databases
+                        && query.match(&(*set_it)->m_query)
+                        && (apdu_req->which != Z_APDU_searchRequest ||
+                            yaz_compare_z_OtherInformation(
+                                additionalSearchInfo,
+                                (*set_it)->additionalSearchInfoRequest)))
                     {
-                        if ((*set_it)->m_databases == databases
-                            && query.match(&(*set_it)->m_query))
+                        if ((*it)->m_in_use)
+                        {
+                            bc->m_cond_set_ready.wait(lock);
+                            restart = true;
+                            break;
+                        }
+                        else
                         {
                             found_set = *set_it;
                             found_backend = *it;
                             bc->use_backend(found_backend);
-                            found_set->timestamp();
                             // found matching set. No need to search again
                             return;
                         }
                     }
                 }
+                if (restart)
+                    it = bc->m_backend_list.begin();
+                else
+                    it++;
             }
         }
-        override_set(found_backend, result_set_id);
+        override_set(found_backend, result_set_id, databases, out_of_sessions);
         if (found_backend)
             bc->use_backend(found_backend);
     }
     if (!found_backend)
     {
-        // create a new backend set (and new set)
-        found_backend = bc->create_backend(package);
+        // create a new backend set (and new set) if we're not out of sessions
+        if (!out_of_sessions)
+            found_backend = bc->create_backend(package);
 
         if (!found_backend)
         {
             Z_APDU *f_apdu = 0;
             mp::odr odr;
+            const char *addinfo = 0;
+
+            if (out_of_sessions)
+                addinfo = "session_shared: all sessions in use";
+            else
+                addinfo = "session_shared: could not create backend";
             if (apdu_req->which == Z_APDU_searchRequest)
             {
                 f_apdu = odr.create_searchResponse(
-                        apdu_req, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, 0);
+                    apdu_req, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, addinfo);
             }
             else if (apdu_req->which == Z_APDU_presentRequest)
             {
                 f_apdu = odr.create_presentResponse(
-                    apdu_req, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, 0);
+                    apdu_req, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, addinfo);
             }
             else
             {
                 f_apdu = odr.create_close(
-                    apdu_req, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, 0);
+                    apdu_req, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, addinfo);
             }
             package.response() = f_apdu;
             return;
@@ -697,7 +874,13 @@ restart:
 
     // we must search ...
     BackendSetPtr new_set(new BackendSet(result_set_id,
-                                         databases, query));
+                                         databases, query,
+                                         additionalSearchInfo));
+
+    found_set = new_set;
+    found_set->timestamp();
+    found_backend->m_sets.push_back(found_set);
+
     Z_Records *z_records = 0;
 
     Package search_package(found_backend->m_session, package.origin());
@@ -707,7 +890,7 @@ restart:
                          apdu_req, found_backend, &z_records))
     {
         bc->remove_backend(found_backend);
-        return; // search error 
+        return; // search error
     }
 
     if (z_records)
@@ -721,19 +904,20 @@ restart:
         else if (z_records->which == Z_Records_multipleNSD)
         {
             if (z_records->u.multipleNonSurDiagnostics->num_diagRecs >= 1
-                && 
-                
+                &&
+
                 z_records->u.multipleNonSurDiagnostics->diagRecs[0]->which ==
                 Z_DiagRec_defaultFormat)
             {
                 condition = get_diagnostic(
                     z_records->u.multipleNonSurDiagnostics->diagRecs[0]->u.defaultFormat);
-                
+
             }
         }
-        if (!session_restarted &&
+        if (m_p->m_restart && !session_restarted &&
             condition == YAZ_BIB1_TEMPORARY_SYSTEM_ERROR)
         {
+            package.log("session_shared", YLOG_LOG, "restart");
             bc->remove_backend(found_backend);
             session_restarted = true;
             found_backend.reset();
@@ -746,7 +930,7 @@ restart:
             mp::odr odr;
             if (apdu_req->which == Z_APDU_searchRequest)
             {
-                Z_APDU *f_apdu = odr.create_searchResponse(apdu_req, 
+                Z_APDU *f_apdu = odr.create_searchResponse(apdu_req,
                                                            0, 0);
                 Z_SearchResponse *f_resp = f_apdu->u.searchResponse;
                 *f_resp->searchStatus = Z_SearchResponse_none;
@@ -755,62 +939,135 @@ restart:
             }
             if (apdu_req->which == Z_APDU_presentRequest)
             {
-                Z_APDU *f_apdu = odr.create_presentResponse(apdu_req, 
+                Z_APDU *f_apdu = odr.create_presentResponse(apdu_req,
                                                             0, 0);
                 Z_PresentResponse *f_resp = f_apdu->u.presentResponse;
                 f_resp->records = z_records;
                 package.response() = f_apdu;
             }
             bc->release_backend(found_backend);
-            return; // search error 
+            found_set.reset();
+            return; // search error
         }
     }
-    if (!session_restarted && new_set->m_result_set_size < 0)
+    if (m_p->m_restart && !session_restarted && new_set->m_result_set_size < 0)
     {
+        package.log("session_shared", YLOG_LOG, "restart");
         bc->remove_backend(found_backend);
         session_restarted = true;
         found_backend.reset();
         goto restart;
     }
 
+#if 0
     found_set = new_set;
     found_set->timestamp();
     found_backend->m_sets.push_back(found_set);
+#endif
+}
+
+int yf::SessionShared::Frontend::result_set_ref(ODR o,
+                                                const Databases &databases,
+                                                Z_RPNStructure *s,
+                                                std::string &rset)
+{
+    int ret = 0;
+    switch (s->which)
+    {
+    case Z_RPNStructure_simple:
+        if (s->u.simple->which == Z_Operand_resultSetId)
+        {
+            const char *id = s->u.simple->u.resultSetId;
+            rset = id;
+
+            FrontendSets::iterator fset_it = m_frontend_sets.find(id);
+            if (fset_it == m_frontend_sets.end())
+            {
+                ret = YAZ_BIB1_SPECIFIED_RESULT_SET_DOES_NOT_EXIST;
+            }
+            else if (fset_it->second->get_databases() != databases)
+            {
+                ret = YAZ_BIB1_SPECIFIED_RESULT_SET_DOES_NOT_EXIST;
+            }
+            else
+            {
+                yazpp_1::Yaz_Z_Query query = fset_it->second->get_query();
+                Z_Query *q = yaz_copy_Z_Query(query.get_Z_Query(), o);
+                if (q->which == Z_Query_type_1 || q->which == Z_Query_type_101)
+                {
+                    s->which = q->u.type_1->RPNStructure->which;
+                    s->u.simple = q->u.type_1->RPNStructure->u.simple;
+                }
+                else
+                {
+                    ret = YAZ_BIB1_SPECIFIED_RESULT_SET_DOES_NOT_EXIST;
+                }
+            }
+        }
+        break;
+    case Z_RPNStructure_complex:
+        ret = result_set_ref(o, databases, s->u.complex->s1, rset);
+        if (!ret)
+            ret = result_set_ref(o, databases, s->u.complex->s2, rset);
+        break;
+    }
+    return ret;
 }
 
 void yf::SessionShared::Frontend::search(mp::Package &package,
                                          Z_APDU *apdu_req)
 {
     Z_SearchRequest *req = apdu_req->u.searchRequest;
-    FrontendSets::iterator fset_it = 
+    FrontendSets::iterator fset_it =
         m_frontend_sets.find(req->resultSetName);
     if (fset_it != m_frontend_sets.end())
     {
-        // result set already exist 
+        // result set already exist
         // if replace indicator is off: we return diagnostic if
         // result set already exist.
         if (*req->replaceIndicator == 0)
         {
             mp::odr odr;
-            Z_APDU *apdu = 
+            Z_APDU *apdu =
                 odr.create_searchResponse(
                     apdu_req,
                     YAZ_BIB1_RESULT_SET_EXISTS_AND_REPLACE_INDICATOR_OFF,
                     0);
             package.response() = apdu;
-            
             return;
         }
         m_frontend_sets.erase(fset_it);
     }
-    
-    yazpp_1::Yaz_Z_Query query;
-    query.set_Z_Query(req->query);
+
     Databases databases;
     int i;
-    for (i = 0; i<req->num_databaseNames; i++)
+    for (i = 0; i < req->num_databaseNames; i++)
         databases.push_back(req->databaseNames[i]);
 
+
+    yazpp_1::Yaz_Z_Query query;
+    query.set_Z_Query(req->query);
+
+    Z_Query *q = query.get_Z_Query();
+    if (q->which == Z_Query_type_1 || q->which == Z_Query_type_101)
+    {
+        mp::odr odr;
+        std::string rset;
+        int diag = result_set_ref(odr, databases, q->u.type_1->RPNStructure,
+                                  rset);
+        if (diag)
+        {
+            Z_APDU *apdu =
+                odr.create_searchResponse(
+                    apdu_req,
+                    diag,
+                    rset.c_str());
+            package.response() = apdu;
+            return;
+        }
+        query.set_Z_Query(q);
+    }
+
     BackendSetPtr found_set; // null
     BackendInstancePtr found_backend; // null
 
@@ -822,6 +1079,7 @@ void yf::SessionShared::Frontend::search(mp::Package &package,
     Z_APDU *f_apdu = odr.create_searchResponse(apdu_req, 0, 0);
     Z_SearchResponse *f_resp = f_apdu->u.searchResponse;
     *f_resp->resultCount = found_set->m_result_set_size;
+    f_resp->additionalSearchInfo = found_set->additionalSearchInfoResponse;
     package.response() = f_apdu;
 
     FrontendSetPtr fset(new FrontendSet(databases, query));
@@ -836,12 +1094,12 @@ void yf::SessionShared::Frontend::present(mp::Package &package,
     mp::odr odr;
     Z_PresentRequest *req = apdu_req->u.presentRequest;
 
-    FrontendSets::iterator fset_it = 
+    FrontendSets::iterator fset_it =
         m_frontend_sets.find(req->resultSetId);
 
     if (fset_it == m_frontend_sets.end())
     {
-        Z_APDU *apdu = 
+        Z_APDU *apdu =
             odr.create_presentResponse(
                 apdu_req,
                 YAZ_BIB1_SPECIFIED_RESULT_SET_DOES_NOT_EXIST,
@@ -863,23 +1121,28 @@ void yf::SessionShared::Frontend::present(mp::Package &package,
         return;
 
     Z_NamePlusRecordList *npr_res = 0;
-    if (found_set->m_record_cache.lookup(odr, &npr_res, 
-                                         *req->resultSetStartPoint,
-                                         *req->numberOfRecordsRequested,
-                                         req->preferredRecordSyntax,
-                                         req->recordComposition))
+    // record_cache.lookup types are int's. Avoid non-fitting values
+    if (*req->resultSetStartPoint > 0
+        && *req->resultSetStartPoint < INT_MAX
+        && *req->numberOfRecordsRequested > 0
+        && *req->numberOfRecordsRequested < INT_MAX
+        && found_set->m_record_cache.lookup(odr, &npr_res,
+                                            *req->resultSetStartPoint,
+                                            *req->numberOfRecordsRequested,
+                                            req->preferredRecordSyntax,
+                                            req->recordComposition))
     {
         Z_APDU *f_apdu_res = odr.create_presentResponse(apdu_req, 0, 0);
         Z_PresentResponse *f_resp = f_apdu_res->u.presentResponse;
 
-        yaz_log(YLOG_LOG, "Found " ODR_INT_PRINTF "+" ODR_INT_PRINTF 
+        yaz_log(YLOG_LOG, "Found " ODR_INT_PRINTF "+" ODR_INT_PRINTF
                 " records in cache %p",
-                *req->resultSetStartPoint,                      
+                *req->resultSetStartPoint,
                 *req->numberOfRecordsRequested,
-                &found_set->m_record_cache);        
+                &found_set->m_record_cache);
 
         *f_resp->numberOfRecordsReturned = *req->numberOfRecordsRequested;
-        *f_resp->nextResultSetPosition = 
+        *f_resp->nextResultSetPosition =
             *req->resultSetStartPoint + *req->numberOfRecordsRequested;
         // f_resp->presentStatus assumed OK.
         f_resp->records = (Z_Records *) odr_malloc(odr, sizeof(Z_Records));
@@ -891,7 +1154,7 @@ void yf::SessionShared::Frontend::present(mp::Package &package,
     }
 
     found_backend->timestamp();
-                              
+
     Z_APDU *p_apdu = zget_APDU(odr, Z_APDU_presentRequest);
     Z_PresentRequest *p_req = p_apdu->u.presentRequest;
     p_req->preferredRecordSyntax = req->preferredRecordSyntax;
@@ -910,7 +1173,7 @@ void yf::SessionShared::Frontend::present(mp::Package &package,
 
     Z_GDU *gdu = present_package.response().get();
     if (!present_package.session().is_closed()
-        && gdu && gdu->which == Z_GDU_Z3950 
+        && gdu && gdu->which == Z_GDU_Z3950
         && gdu->u.z3950->which == Z_APDU_presentResponse)
     {
         Z_PresentResponse *b_resp = gdu->u.z3950->u.presentResponse;
@@ -926,25 +1189,33 @@ void yf::SessionShared::Frontend::present(mp::Package &package,
 
         if (b_resp->records && b_resp->records->which ==  Z_Records_DBOSD)
         {
-            yaz_log(YLOG_LOG, "Adding " ODR_INT_PRINTF "+" ODR_INT_PRINTF
-                    " records to cache %p",
-                    *req->resultSetStartPoint,                      
-                    *f_resp->numberOfRecordsReturned,
-                    &found_set->m_record_cache);        
-            found_set->m_record_cache.add(
-                odr,
-                b_resp->records->u.databaseOrSurDiagnostics,
-                *req->resultSetStartPoint,                      
-                *f_resp->numberOfRecordsReturned);
+            Z_NamePlusRecordList *npr =
+                b_resp->records->u.databaseOrSurDiagnostics;
+            // record_cache.add types are int's. Avoid non-fitting values
+            if (*req->resultSetStartPoint > 0
+                && npr->num_records + *req->resultSetStartPoint < INT_MAX)
+            {
+#if 0
+                yaz_log(YLOG_LOG, "Adding " ODR_INT_PRINTF "+" ODR_INT_PRINTF
+                        " records to cache %p",
+                        *req->resultSetStartPoint,
+                        *f_resp->numberOfRecordsReturned,
+                        &found_set->m_record_cache);
+#endif
+                found_set->m_record_cache.add(
+                    odr, npr, *req->resultSetStartPoint,
+                    p_req->recordComposition);
+            }
         }
         bc->release_backend(found_backend);
     }
     else
     {
         bc->remove_backend(found_backend);
-        Z_APDU *f_apdu_res = 
+        Z_APDU *f_apdu_res =
             odr.create_presentResponse(
-                apdu_req, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, 0);
+                apdu_req, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR,
+                "session_shared: target closed connection during present");
         package.response() = f_apdu_res;
     }
 }
@@ -958,7 +1229,8 @@ void yf::SessionShared::Frontend::scan(mp::Package &frontend_package,
     {
         mp::odr odr;
         Z_APDU *apdu = odr.create_scanResponse(
-            apdu_req, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR, 0);
+            apdu_req, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR,
+            "session_shared: could not create backend");
         frontend_package.response() = apdu;
     }
     else
@@ -988,7 +1260,7 @@ void yf::SessionShared::Worker::operator() (void)
     m_p->expire();
 }
 
-void yf::SessionShared::BackendClass::expire_class()
+bool yf::SessionShared::BackendClass::expire_instances()
 {
     time_t now;
     time(&now);
@@ -997,20 +1269,13 @@ void yf::SessionShared::BackendClass::expire_class()
     while (bit != m_backend_list.end())
     {
         time_t last_use = (*bit)->m_time_last_use;
-        
+
         if ((*bit)->m_in_use)
         {
             bit++;
         }
-        else if ((now >= last_use && now - last_use > m_backend_expiry_ttl)
-            || (now < last_use))
+        else if (now < last_use || now - last_use > m_backend_expiry_ttl)
         {
-            mp::odr odr;
-            (*bit)->m_close_package->response() = odr.create_close(
-                0, Z_Close_lackOfActivity, 0);
-            (*bit)->m_close_package->session().close();
-            (*bit)->m_close_package->move();
-
             bit = m_backend_list.erase(bit);
         }
         else
@@ -1018,6 +1283,25 @@ void yf::SessionShared::BackendClass::expire_class()
             bit++;
         }
     }
+    if (m_backend_list.empty())
+        return true;
+    return false;
+}
+
+void yf::SessionShared::Rep::expire_classes()
+{
+    boost::mutex::scoped_lock lock(m_mutex_backend_map);
+    BackendClassMap::iterator b_it = m_backend_map.begin();
+    while (b_it != m_backend_map.end())
+    {
+        if (b_it->second->expire_instances())
+        {
+            m_backend_map.erase(b_it);
+            b_it = m_backend_map.begin();
+        }
+        else
+            b_it++;
+    }
 }
 
 void yf::SessionShared::Rep::expire()
@@ -1025,13 +1309,22 @@ void yf::SessionShared::Rep::expire()
     while (true)
     {
         boost::xtime xt;
-        boost::xtime_get(&xt, boost::TIME_UTC);
-        xt.sec += m_session_ttl / 3;
-        boost::thread::sleep(xt);
-        
-        BackendClassMap::const_iterator b_it = m_backend_map.begin();
-        for (; b_it != m_backend_map.end(); b_it++)
-            b_it->second->expire_class();
+        boost::xtime_get(&xt,
+#if BOOST_VERSION >= 105000
+                boost::TIME_UTC_
+#else
+                boost::TIME_UTC
+#endif
+                  );
+        xt.sec += m_session_ttl;
+        {
+            boost::mutex::scoped_lock lock(m_mutex);
+            m_cond_expire_ready.timed_wait(lock, xt);
+            if (close_down)
+                break;
+        }
+        stat();
+        expire_classes();
     }
 }
 
@@ -1041,6 +1334,21 @@ yf::SessionShared::Rep::Rep()
     m_resultset_max = 10;
     m_session_ttl = 90;
     m_optimize_search = true;
+    m_restart = false;
+    m_session_max = 100;
+    m_preferredMessageSize = 0;
+    m_maximumRecordSize = 0;
+    close_down = false;
+}
+
+yf::SessionShared::Rep::~Rep()
+{
+    {
+        boost::mutex::scoped_lock lock(m_mutex);
+        close_down = true;
+        m_cond_expire_ready.notify_all();
+    }
+    m_thrds.join_all();
 }
 
 void yf::SessionShared::Rep::start()
@@ -1074,13 +1382,13 @@ yf::SessionShared::FrontendPtr yf::SessionShared::Rep::get_frontend(mp::Package
     boost::mutex::scoped_lock lock(m_mutex);
 
     std::map<mp::Session,yf::SessionShared::FrontendPtr>::iterator it;
-    
+
     while(true)
     {
         it = m_clients.find(package.session());
         if (it == m_clients.end())
             break;
-        
+
         if (!it->second->m_in_use)
         {
             it->second->m_in_use = true;
@@ -1098,7 +1406,7 @@ void yf::SessionShared::Rep::release_frontend(mp::Package &package)
 {
     boost::mutex::scoped_lock lock(m_mutex);
     std::map<mp::Session,yf::SessionShared::FrontendPtr>::iterator it;
-    
+
     it = m_clients.find(package.session());
     if (it != m_clients.end())
     {
@@ -1120,7 +1428,7 @@ void yf::SessionShared::process(mp::Package &package) const
     FrontendPtr f = m_p->get_frontend(package);
 
     Z_GDU *gdu = package.request().get();
-    
+
     if (gdu && gdu->which == Z_GDU_Z3950 && gdu->u.z3950->which ==
         Z_APDU_initRequest && !f->m_is_virtual)
     {
@@ -1134,18 +1442,18 @@ void yf::SessionShared::process(mp::Package &package) const
         if (apdu->which == Z_APDU_initRequest)
         {
             mp::odr odr;
-            
+
             package.response() = odr.create_close(
                 apdu,
                 Z_Close_protocolError,
                 "double init");
-            
+
             package.session().close();
         }
         else if (apdu->which == Z_APDU_close)
         {
             mp::odr odr;
-            
+
             package.response() = odr.create_close(
                 apdu,
                 Z_Close_peerAbort, "received close from client");
@@ -1166,11 +1474,11 @@ void yf::SessionShared::process(mp::Package &package) const
         else
         {
             mp::odr odr;
-            
+
             package.response() = odr.create_close(
                 apdu, Z_Close_protocolError,
                 "unsupported APDU in filter_session_shared");
-            
+
             package.session().close();
         }
     }
@@ -1190,11 +1498,11 @@ void yf::SessionShared::configure(const xmlNode *ptr, bool test_only,
             for (attr = ptr->properties; attr; attr = attr->next)
             {
                 if (!strcmp((const char *) attr->name, "ttl"))
-                    m_p->m_resultset_ttl = 
+                    m_p->m_resultset_ttl =
                         mp::xml::get_int(attr->children, 30);
                 else if (!strcmp((const char *) attr->name, "max"))
                 {
-                    m_p->m_resultset_max = 
+                    m_p->m_resultset_max =
                         mp::xml::get_int(attr->children, 10);
                 }
                 else if (!strcmp((const char *) attr->name, "optimizesearch"))
@@ -1202,6 +1510,10 @@ void yf::SessionShared::configure(const xmlNode *ptr, bool test_only,
                     m_p->m_optimize_search =
                         mp::xml::get_bool(attr->children, true);
                 }
+                else if (!strcmp((const char *) attr->name, "restart"))
+                {
+                    m_p->m_restart = mp::xml::get_bool(attr->children, true);
+                }
                 else
                     throw mp::filter::FilterException(
                         "Bad attribute " + std::string((const char *)
@@ -1214,8 +1526,29 @@ void yf::SessionShared::configure(const xmlNode *ptr, bool test_only,
             for (attr = ptr->properties; attr; attr = attr->next)
             {
                 if (!strcmp((const char *) attr->name, "ttl"))
-                    m_p->m_session_ttl = 
-                        mp::xml::get_int(attr->children, 120);
+                    m_p->m_session_ttl =
+                        mp::xml::get_int(attr->children, 90);
+                else if (!strcmp((const char *) attr->name, "max"))
+                    m_p->m_session_max =
+                        mp::xml::get_int(attr->children, 100);
+                else
+                    throw mp::filter::FilterException(
+                        "Bad attribute " + std::string((const char *)
+                                                       attr->name));
+            }
+        }
+        else if (!strcmp((const char *) ptr->name, "init"))
+        {
+            const struct _xmlAttr *attr;
+            for (attr = ptr->properties; attr; attr = attr->next)
+            {
+                if (!strcmp((const char *) attr->name, "maximum-record-size"))
+                    m_p->m_maximumRecordSize =
+                        mp::xml::get_int(attr->children, 0);
+                else if (!strcmp((const char *) attr->name,
+                                 "preferred-message-size"))
+                    m_p->m_preferredMessageSize =
+                        mp::xml::get_int(attr->children, 0);
                 else
                     throw mp::filter::FilterException(
                         "Bad attribute " + std::string((const char *)
@@ -1224,7 +1557,7 @@ void yf::SessionShared::configure(const xmlNode *ptr, bool test_only,
         }
         else
         {
-            throw mp::filter::FilterException("Bad element " 
+            throw mp::filter::FilterException("Bad element "
                                                + std::string((const char *)
                                                              ptr->name));
         }