Merge branch 'master' into aressem/dont-allow-unresolved-symbols-in-shared-libs-or-executables

21 files changed, 408 insertions, 18 deletions

diff --git a/searchcorespi/src/vespa/searchcorespi/index/CMakeLists.txt b/searchcorespi/src/vespa/searchcorespi/index/CMakeLists.txt
index 65b006f8ea9..84891e37307 100644
--- a/searchcorespi/src/vespa/searchcorespi/index/CMakeLists.txt
+++ b/searchcorespi/src/vespa/searchcorespi/index/CMakeLists.txt
@@ -3,11 +3,13 @@ vespa_add_library(searchcorespi_index OBJECT
     SOURCES
     activediskindexes.cpp
     diskindexcleaner.cpp
+    disk_index_stats.cpp
     eventlogger.cpp
     fusionrunner.cpp
     iindexmanager.cpp
     iindexcollection.cpp
     index_manager_explorer.cpp
+    index_manager_stats.cpp
     indexcollection.cpp
     indexdisklayout.cpp
     indexflushtarget.cpp
@@ -18,6 +20,8 @@ vespa_add_library(searchcorespi_index OBJECT
     indexmanagerconfig.cpp
     indexreadutilities.cpp
     indexsearchable.cpp
+    index_searchable_stats.cpp
+    memory_index_stats.cpp
     indexwriteutilities.cpp
     warmupindexcollection.cpp
     isearchableindexcollection.cpp
diff --git a/searchcorespi/src/vespa/searchcorespi/index/disk_index_stats.cpp b/searchcorespi/src/vespa/searchcorespi/index/disk_index_stats.cpp
new file mode 100644
index 00000000000..f9d5215d6f5
--- /dev/null
+++ b/searchcorespi/src/vespa/searchcorespi/index/disk_index_stats.cpp
@@ -0,0 +1,28 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include <vespa/fastos/fastos.h>
+#include "disk_index_stats.h"
+#include "idiskindex.h"
+
+
+namespace searchcorespi {
+namespace index {
+
+DiskIndexStats::DiskIndexStats()
+    : IndexSearchableStats(),
+      _indexDir()
+{
+}
+
+DiskIndexStats::DiskIndexStats(const IDiskIndex &index)
+    : IndexSearchableStats(index),
+      _indexDir(index.getIndexDir())
+{
+}
+
+DiskIndexStats::~DiskIndexStats()
+{
+}
+
+} // namespace searchcorespi::index
+} // namespace searchcorespi
diff --git a/searchcorespi/src/vespa/searchcorespi/index/disk_index_stats.h b/searchcorespi/src/vespa/searchcorespi/index/disk_index_stats.h
new file mode 100644
index 00000000000..579a840b756
--- /dev/null
+++ b/searchcorespi/src/vespa/searchcorespi/index/disk_index_stats.h
@@ -0,0 +1,26 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+#pragma once
+
+#include "index_searchable_stats.h"
+#include <vespa/vespalib/stllike/string.h>
+
+namespace searchcorespi {
+namespace index {
+
+struct IDiskIndex;
+
+/**
+ * Information about a disk index usable by state explorer.
+ */
+class DiskIndexStats : public IndexSearchableStats {
+    vespalib::string _indexDir;
+public:
+    DiskIndexStats();
+    DiskIndexStats(const IDiskIndex &index);
+    ~DiskIndexStats();
+
+    const vespalib::string &getIndexdir() const { return _indexDir; }
+};
+
+} // namespace searchcorespi::index
+} // namespace searchcorespi
diff --git a/searchcorespi/src/vespa/searchcorespi/index/fakeindexsearchable.h b/searchcorespi/src/vespa/searchcorespi/index/fakeindexsearchable.h
index 0db49c5f2df..00ede178339 100644
--- a/searchcorespi/src/vespa/searchcorespi/index/fakeindexsearchable.h
+++ b/searchcorespi/src/vespa/searchcorespi/index/fakeindexsearchable.h
@@ -37,6 +37,12 @@ public:
     virtual search::SearchableStats getSearchableStats() const {
         return search::SearchableStats();
     }
+
+    virtual search::SerialNum getSerialNum() const override { return 0; }
+    virtual void accept(IndexSearchableVisitor &visitor) const override {
+        (void) visitor;
+    }
+
 };
 
 }  // namespace searchcorespi
diff --git a/searchcorespi/src/vespa/searchcorespi/index/iindexmaintaineroperations.h b/searchcorespi/src/vespa/searchcorespi/index/iindexmaintaineroperations.h
index 2b8a3ac3965..eb5edbf3298 100644
--- a/searchcorespi/src/vespa/searchcorespi/index/iindexmaintaineroperations.h
+++ b/searchcorespi/src/vespa/searchcorespi/index/iindexmaintaineroperations.h
@@ -19,7 +19,7 @@ struct IIndexMaintainerOperations {
     /**
      * Creates a new memory index using the given schema.
      */
-    virtual IMemoryIndex::SP createMemoryIndex(const search::index::Schema &schema) = 0;
+    virtual IMemoryIndex::SP createMemoryIndex(const search::index::Schema &schema, search::SerialNum serialNum) = 0;
 
     /**
      * Loads a disk index from the given directory.
diff --git a/searchcorespi/src/vespa/searchcorespi/index/imemoryindex.h b/searchcorespi/src/vespa/searchcorespi/index/imemoryindex.h
index fabaf730cb7..c8baaf9ca13 100644
--- a/searchcorespi/src/vespa/searchcorespi/index/imemoryindex.h
+++ b/searchcorespi/src/vespa/searchcorespi/index/imemoryindex.h
@@ -61,7 +61,7 @@ struct IMemoryIndex : public searchcorespi::IndexSearchable {
     /**
      * Commits the inserts and removes since the last commit, making them searchable.
      **/
-    virtual void commit(OnWriteDoneType onWriteDone) = 0;
+    virtual void commit(OnWriteDoneType onWriteDone, search::SerialNum serialNum) = 0;
 
     /**
      * Flushes this memory index to disk as a disk index.
diff --git a/searchcorespi/src/vespa/searchcorespi/index/index_manager_explorer.cpp b/searchcorespi/src/vespa/searchcorespi/index/index_manager_explorer.cpp
index f3695f2bd52..959f5ccdc59 100644
--- a/searchcorespi/src/vespa/searchcorespi/index/index_manager_explorer.cpp
+++ b/searchcorespi/src/vespa/searchcorespi/index/index_manager_explorer.cpp
@@ -4,14 +4,41 @@
 #include <vespa/log/log.h>
 LOG_SETUP(".searchcorespi.index.index_manager_explorer");
 #include "index_manager_explorer.h"
+#include "index_manager_stats.h"
 
 #include <vespa/vespalib/data/slime/cursor.h>
 
 using vespalib::slime::Cursor;
 using vespalib::slime::Inserter;
+using search::SearchableStats;
+using searchcorespi::index::DiskIndexStats;
+using searchcorespi::index::MemoryIndexStats;
 
 namespace searchcorespi {
 
+namespace {
+
+void insertDiskIndex(Cursor &arrayCursor, const DiskIndexStats &diskIndex)
+{
+    Cursor &diskIndexCursor = arrayCursor.addObject();
+    const SearchableStats &sstats = diskIndex.getSearchableStats();
+    diskIndexCursor.setLong("serialNum", diskIndex.getSerialNum());
+    diskIndexCursor.setString("indexDir", diskIndex.getIndexdir());
+    diskIndexCursor.setLong("sizeOnDisk", sstats.sizeOnDisk());
+}
+
+void insertMemoryIndex(Cursor &arrayCursor, const MemoryIndexStats &memoryIndex)
+{
+    Cursor &memoryIndexCursor = arrayCursor.addObject();
+    const SearchableStats &sstats = memoryIndex.getSearchableStats();
+    memoryIndexCursor.setLong("serialNum", memoryIndex.getSerialNum());
+    memoryIndexCursor.setLong("docsInMemory", sstats.docsInMemory());
+    memoryIndexCursor.setLong("memoryUsage", sstats.memoryUsage());
+}
+
+}
+
+
 IndexManagerExplorer::IndexManagerExplorer(IIndexManager::SP mgr)
     : _mgr(std::move(mgr))
 {
@@ -20,9 +47,19 @@ IndexManagerExplorer::IndexManagerExplorer(IIndexManager::SP mgr)
 void
 IndexManagerExplorer::get_state(const Inserter &inserter, bool full) const
 {
-    (void) full;
     Cursor &object = inserter.insertObject();
     object.setLong("lastSerialNum", _mgr->getCurrentSerialNum());
+    if (full) {
+        IndexManagerStats stats(*_mgr);
+        Cursor &diskIndexArrayCursor = object.setArray("diskIndexes");
+        for (const auto &diskIndex : stats.getDiskIndexes()) {
+            insertDiskIndex(diskIndexArrayCursor, diskIndex);
+        }
+        Cursor &memoryIndexArrayCursor = object.setArray("memoryIndexes");
+        for (const auto &memoryIndex : stats.getMemoryIndexes()) {
+            insertMemoryIndex(memoryIndexArrayCursor, memoryIndex);
+        }
+    }
 }
 
 } // namespace searchcorespi
diff --git a/searchcorespi/src/vespa/searchcorespi/index/index_manager_stats.cpp b/searchcorespi/src/vespa/searchcorespi/index/index_manager_stats.cpp
new file mode 100644
index 00000000000..035a5698c2f
--- /dev/null
+++ b/searchcorespi/src/vespa/searchcorespi/index/index_manager_stats.cpp
@@ -0,0 +1,61 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include <vespa/fastos/fastos.h>
+#include "index_manager_stats.h"
+#include "iindexmanager.h"
+#include "indexsearchablevisitor.h"
+
+
+namespace searchcorespi {
+
+namespace {
+
+class Visitor : public IndexSearchableVisitor
+{
+public:
+    std::vector<index::DiskIndexStats> _diskIndexes;
+    std::vector<index::MemoryIndexStats> _memoryIndexes;
+
+    Visitor()
+        : _diskIndexes(),
+          _memoryIndexes()
+    {
+    }
+    virtual void visit(const index::IDiskIndex &index) override {
+        _diskIndexes.emplace_back(index);
+    }
+    virtual void visit(const index::IMemoryIndex &index) override {
+        _memoryIndexes.emplace_back(index);
+    }
+
+    void normalize() {
+        std::sort(_diskIndexes.begin(), _diskIndexes.end());
+        std::sort(_memoryIndexes.begin(), _memoryIndexes.end());
+    }
+};
+
+}
+
+IndexManagerStats::IndexManagerStats()
+    : _diskIndexes(),
+      _memoryIndexes()
+{
+}
+
+IndexManagerStats::IndexManagerStats(const IIndexManager &indexManager)
+    : _diskIndexes(),
+      _memoryIndexes()
+{
+    Visitor visitor;
+    IndexSearchable::SP searchable(indexManager.getSearchable());
+    searchable->accept(visitor);
+    visitor.normalize();
+    _diskIndexes = std::move(visitor._diskIndexes);
+    _memoryIndexes = std::move(visitor._memoryIndexes);
+}
+
+IndexManagerStats::~IndexManagerStats()
+{
+}
+
+} // namespace searchcorespi
diff --git a/searchcorespi/src/vespa/searchcorespi/index/index_manager_stats.h b/searchcorespi/src/vespa/searchcorespi/index/index_manager_stats.h
new file mode 100644
index 00000000000..048124b688f
--- /dev/null
+++ b/searchcorespi/src/vespa/searchcorespi/index/index_manager_stats.h
@@ -0,0 +1,30 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+#pragma once
+
+#include "disk_index_stats.h"
+#include "memory_index_stats.h"
+
+namespace searchcorespi {
+
+class IIndexManager;
+
+/**
+ * Information about an index manager usable by state explorer.
+ */
+class IndexManagerStats {
+    std::vector<index::DiskIndexStats> _diskIndexes;
+    std::vector<index::MemoryIndexStats> _memoryIndexes;
+public:
+    IndexManagerStats();
+    IndexManagerStats(const IIndexManager &indexManager);
+    ~IndexManagerStats();
+
+    const std::vector<index::DiskIndexStats> &getDiskIndexes() const {
+        return _diskIndexes;
+    }
+    const std::vector<index::MemoryIndexStats> &getMemoryIndexes() const {
+        return _memoryIndexes;
+    }
+};
+
+} // namespace searchcorespi
diff --git a/searchcorespi/src/vespa/searchcorespi/index/index_searchable_stats.cpp b/searchcorespi/src/vespa/searchcorespi/index/index_searchable_stats.cpp
new file mode 100644
index 00000000000..c5ce5163aac
--- /dev/null
+++ b/searchcorespi/src/vespa/searchcorespi/index/index_searchable_stats.cpp
@@ -0,0 +1,29 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include <vespa/fastos/fastos.h>
+#include "index_searchable_stats.h"
+#include "indexsearchable.h"
+
+
+namespace searchcorespi {
+namespace index {
+
+IndexSearchableStats::IndexSearchableStats()
+    : _serialNum(0),
+      _searchableStats()
+{
+}
+
+IndexSearchableStats::IndexSearchableStats(const IndexSearchable &index)
+    : _serialNum(index.getSerialNum()),
+      _searchableStats(index.getSearchableStats())
+{
+}
+
+bool IndexSearchableStats::operator<(const IndexSearchableStats &rhs) const
+{
+    return _serialNum < rhs._serialNum;
+}
+
+} // namespace searchcorespi::index
+} // namespace searchcorespi
diff --git a/searchcorespi/src/vespa/searchcorespi/index/index_searchable_stats.h b/searchcorespi/src/vespa/searchcorespi/index/index_searchable_stats.h
new file mode 100644
index 00000000000..dd904b3b286
--- /dev/null
+++ b/searchcorespi/src/vespa/searchcorespi/index/index_searchable_stats.h
@@ -0,0 +1,32 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#pragma once
+
+#include <vespa/searchlib/common/serialnum.h>
+#include <vespa/searchlib/util/searchable_stats.h>
+
+namespace searchcorespi {
+
+class IndexSearchable;
+
+namespace index {
+
+/**
+ * Information about a searchable index usable by state explorer.
+ */
+class IndexSearchableStats
+{
+    using SerialNum = search::SerialNum;
+    using SearchableStats = search::SearchableStats;
+    SerialNum _serialNum;
+    SearchableStats _searchableStats;
+public:
+    IndexSearchableStats();
+    IndexSearchableStats(const IndexSearchable &index);
+    bool operator<(const IndexSearchableStats &rhs) const;
+    SerialNum getSerialNum() const { return _serialNum; }
+    const SearchableStats &getSearchableStats() const { return _searchableStats; }
+};
+
+} // namespace searchcorespi::index
+} // namespace searchcorespi
diff --git a/searchcorespi/src/vespa/searchcorespi/index/indexcollection.cpp b/searchcorespi/src/vespa/searchcorespi/index/indexcollection.cpp
index 0284c4a682e..653cf0a28b4 100644
--- a/searchcorespi/src/vespa/searchcorespi/index/indexcollection.cpp
+++ b/searchcorespi/src/vespa/searchcorespi/index/indexcollection.cpp
@@ -9,6 +9,7 @@ LOG_SETUP(".searchcorespi.index.indexcollection");
 #include <vespa/searchlib/queryeval/create_blueprint_visitor_helper.h>
 #include <vespa/searchlib/queryeval/intermediate_blueprints.h>
 #include <vespa/searchlib/queryeval/leaf_blueprints.h>
+#include "indexsearchablevisitor.h"
 
 using namespace search::queryeval;
 using namespace search::query;
@@ -116,6 +117,25 @@ IndexCollection::getSearchableStats() const
     return stats;
 }
 
+search::SerialNum
+IndexCollection::getSerialNum() const
+{
+    search::SerialNum serialNum = 0;
+    for (auto &source : _sources) {
+        serialNum = std::max(serialNum, source.source_wrapper->getSerialNum());
+    }
+    return serialNum;
+}
+
+
+void
+IndexCollection::accept(IndexSearchableVisitor &visitor) const
+{
+    for (auto &source : _sources) {
+        source.source_wrapper->accept(visitor);
+    }
+}
+
 namespace {
 
 struct Mixer {
diff --git a/searchcorespi/src/vespa/searchcorespi/index/indexcollection.h b/searchcorespi/src/vespa/searchcorespi/index/indexcollection.h
index 223b36fce99..38942abc9dc 100644
--- a/searchcorespi/src/vespa/searchcorespi/index/indexcollection.h
+++ b/searchcorespi/src/vespa/searchcorespi/index/indexcollection.h
@@ -61,6 +61,8 @@ public:
                     const Node &term,
                     const IAttributeContext &attrCtx);
     virtual search::SearchableStats getSearchableStats() const;
+    virtual search::SerialNum getSerialNum() const override;
+    virtual void accept(IndexSearchableVisitor &visitor) const override;
 
     static ISearchableIndexCollection::UP replaceAndRenumber(
             const ISourceSelector::SP & selector,
diff --git a/searchcorespi/src/vespa/searchcorespi/index/indexmaintainer.cpp b/searchcorespi/src/vespa/searchcorespi/index/indexmaintainer.cpp
index 36d42e245e1..3db3875b561 100644
--- a/searchcorespi/src/vespa/searchcorespi/index/indexmaintainer.cpp
+++ b/searchcorespi/src/vespa/searchcorespi/index/indexmaintainer.cpp
@@ -117,6 +117,12 @@ public:
         return _index->createBlueprint(requestContext, fields, term, attrCtx);
     }
     virtual search::SearchableStats getSearchableStats() const { return _index->getSearchableStats(); }
+    virtual search::SerialNum getSerialNum() const override {
+        return _index->getSerialNum();
+    }
+    virtual void accept(IndexSearchableVisitor &visitor) const override {
+        _index->accept(visitor);
+    }
 
     /**
      * Implements IDiskIndex
@@ -293,7 +299,8 @@ IDiskIndex::SP
 IndexMaintainer::flushMemoryIndex(IMemoryIndex &memoryIndex,
                                   uint32_t indexId,
                                   uint32_t docIdLimit,
-                                  SerialNum serialNum)
+                                  SerialNum serialNum,
+                                  FixedSourceSelector::SaveInfo &saveInfo)
 {
     // Called by a flush worker thread
     const string flushDir = getFlushDir(indexId);
@@ -302,6 +309,11 @@ IndexMaintainer::flushMemoryIndex(IMemoryIndex &memoryIndex,
     if (wtSchema.get() != NULL) {
         updateDiskIndexSchema(flushDir, *wtSchema, noSerialNumHigh);
     }
+    IndexWriteUtilities::writeSourceSelector(saveInfo, indexId, getAttrTune(),
+                                             _ctx.getFileHeaderContext(),
+                                             serialNum);
+    IndexWriteUtilities::writeSerialNum(serialNum, flushDir,
+                                        _ctx.getFileHeaderContext());
     return loadDiskIndex(flushDir);
 }
 
@@ -521,14 +533,8 @@ IndexMaintainer::flushMemoryIndex(FlushArgs &args,
     IMemoryIndex &memoryIndex = *args.old_index;
     Schema::SP wtSchema = memoryIndex.getWipeTimeSchema();
     IDiskIndex::SP diskIndex = flushMemoryIndex(memoryIndex, args.old_absolute_id,
-                                                docIdLimit, args.flush_serial_num);
-    IndexWriteUtilities::writeSourceSelector(saveInfo, args.old_absolute_id,
-                                             getAttrTune(), _ctx.getFileHeaderContext(),
-                                             args.flush_serial_num);
-    IndexWriteUtilities::writeSerialNum(args.flush_serial_num,
-                                        getFlushDir(args.old_absolute_id),
-                                        _ctx.getFileHeaderContext());
-
+                                                docIdLimit, args.flush_serial_num,
+                                                saveInfo);
     // Post processing after memory index has been written to disk and
     // opened as disk index.
     args._changeGens = changeGens;
@@ -799,7 +805,7 @@ IndexMaintainer::IndexMaintainer(const IndexMaintainerConfig &config,
       _last_fusion_id(),
       _next_id(),
       _current_index_id(),
-      _current_index(operations.createMemoryIndex(_schema)),
+      _current_index(),
       _current_serial_num(0),
       _flush_serial_num(0),
       _lastFlushTime(),
@@ -848,6 +854,7 @@ IndexMaintainer::IndexMaintainer(const IndexMaintainerConfig &config,
         _selector.reset(getSourceSelector().cloneAndSubtract(ost.str(), id_diff).release());
         assert(_last_fusion_id == _selector->getBaseId());
     }
+    _current_index = operations.createMemoryIndex(_schema, _current_serial_num);
     _current_index_id = getNewAbsoluteId() - _last_fusion_id;
     assert(_current_index_id < ISourceSelector::SOURCE_LIMIT);
     ISearchableIndexCollection::UP sourceList(loadDiskIndexes(spec, ISearchableIndexCollection::UP(new IndexCollection(_selector))));
@@ -874,7 +881,7 @@ IndexMaintainer::initFlush(SerialNum serialNum, searchcorespi::FlushStats * stat
         _current_serial_num = std::max(_current_serial_num, serialNum);
     }
 
-    IMemoryIndex::SP new_index(_operations.createMemoryIndex(getSchema()));
+    IMemoryIndex::SP new_index(_operations.createMemoryIndex(getSchema(), _current_serial_num));
     FlushArgs args;
     args.stats = stats;
     scheduleCommit();
@@ -1132,7 +1139,8 @@ IndexMaintainer::commit()
     // only triggered via scheduleCommit()
     assert(_ctx.getThreadingService().index().isCurrentThread());
     LockGuard lock(_index_update_lock);
-    _current_index->commit(std::shared_ptr<search::IDestructorCallback>());
+    _current_index->commit(std::shared_ptr<search::IDestructorCallback>(),
+                           _current_serial_num);
     // caller calls _ctx.getThreadingService().sync()
 }
 
@@ -1142,7 +1150,7 @@ IndexMaintainer::commit(SerialNum serialNum, OnWriteDoneType onWriteDone)
     assert(_ctx.getThreadingService().index().isCurrentThread());
     LockGuard lock(_index_update_lock);
     _current_serial_num = serialNum;
-    _current_index->commit(onWriteDone);
+    _current_index->commit(onWriteDone, serialNum);
 }
 
 void
@@ -1169,7 +1177,7 @@ void
 IndexMaintainer::setSchema(const Schema & schema, const Schema & fusionSchema)
 {
     assert(_ctx.getThreadingService().master().isCurrentThread());
-    IMemoryIndex::SP new_index(_operations.createMemoryIndex(schema));
+    IMemoryIndex::SP new_index(_operations.createMemoryIndex(schema, _current_serial_num));
     SetSchemaArgs args;
 
     args._newSchema = schema;
diff --git a/searchcorespi/src/vespa/searchcorespi/index/indexmaintainer.h b/searchcorespi/src/vespa/searchcorespi/index/indexmaintainer.h
index 417f79fa6ca..39e3d116d44 100644
--- a/searchcorespi/src/vespa/searchcorespi/index/indexmaintainer.h
+++ b/searchcorespi/src/vespa/searchcorespi/index/indexmaintainer.h
@@ -185,7 +185,8 @@ class IndexMaintainer : public IIndexManager,
     flushMemoryIndex(IMemoryIndex &memoryIndex,
                      uint32_t indexId,
                      uint32_t docIdLimit,
-                     SerialNum serialNum);
+                     SerialNum serialNum,
+                     search::FixedSourceSelector::SaveInfo &saveInfo);
 
     ISearchableIndexCollection::UP loadDiskIndexes(const FusionSpec &spec, ISearchableIndexCollection::UP sourceList);
     void replaceSource(uint32_t sourceId, const IndexSearchable::SP &source);
diff --git a/searchcorespi/src/vespa/searchcorespi/index/indexsearchable.h b/searchcorespi/src/vespa/searchcorespi/index/indexsearchable.h
index 2d4d7cd9674..89a7c8d9f07 100644
--- a/searchcorespi/src/vespa/searchcorespi/index/indexsearchable.h
+++ b/searchcorespi/src/vespa/searchcorespi/index/indexsearchable.h
@@ -8,9 +8,12 @@
 #include <vespa/searchlib/queryeval/blueprint.h>
 #include <vespa/searchlib/queryeval/irequestcontext.h>
 #include <vespa/searchlib/util/searchable_stats.h>
+#include <vespa/searchlib/common/serialnum.h>
 
 namespace searchcorespi {
 
+class IndexSearchableVisitor;
+
 /**
  * Abstract class extended by components to expose content that can be
  * searched by a query term. A IndexSearchable component supports searching
@@ -72,6 +75,17 @@ public:
      * Returns the searchable stats for this index searchable.
      */
     virtual search::SearchableStats getSearchableStats() const = 0;
+
+    /*
+     * Returns the serial number for this index searchable.
+     */
+    virtual search::SerialNum getSerialNum() const = 0;
+
+    /*
+     * Calls visitor with properly downcasted argument to differentiate
+     * between different types of indexes (disk index or memory index).
+     */
+    virtual void accept(IndexSearchableVisitor &visitor) const = 0;
 };
 
 } // namespace searchcorespi
diff --git a/searchcorespi/src/vespa/searchcorespi/index/indexsearchablevisitor.h b/searchcorespi/src/vespa/searchcorespi/index/indexsearchablevisitor.h
new file mode 100644
index 00000000000..8238f916c99
--- /dev/null
+++ b/searchcorespi/src/vespa/searchcorespi/index/indexsearchablevisitor.h
@@ -0,0 +1,26 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#pragma once
+
+namespace searchcorespi {
+
+namespace index {
+
+struct IDiskIndex;
+struct IMemoryIndex;
+
+}
+
+/*
+ * Interface for visiting an index searchable containing disk and
+ * memory indexes.
+ */
+class IndexSearchableVisitor
+{
+public:
+    virtual ~IndexSearchableVisitor() { }
+    virtual void visit(const index::IDiskIndex &index) = 0;
+    virtual void visit(const index::IMemoryIndex &index) = 0;
+};
+
+}  // namespace searchcorespi
diff --git a/searchcorespi/src/vespa/searchcorespi/index/memory_index_stats.cpp b/searchcorespi/src/vespa/searchcorespi/index/memory_index_stats.cpp
new file mode 100644
index 00000000000..7805702fd03
--- /dev/null
+++ b/searchcorespi/src/vespa/searchcorespi/index/memory_index_stats.cpp
@@ -0,0 +1,26 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include <vespa/fastos/fastos.h>
+#include "memory_index_stats.h"
+#include "imemoryindex.h"
+
+
+namespace searchcorespi {
+namespace index {
+
+MemoryIndexStats::MemoryIndexStats()
+    : IndexSearchableStats()
+{
+}
+
+MemoryIndexStats::MemoryIndexStats(const IMemoryIndex &index)
+    : IndexSearchableStats(index)
+{
+}
+
+MemoryIndexStats::~MemoryIndexStats()
+{
+}
+
+} // namespace searchcorespi::index
+} // namespace searchcorespi
diff --git a/searchcorespi/src/vespa/searchcorespi/index/memory_index_stats.h b/searchcorespi/src/vespa/searchcorespi/index/memory_index_stats.h
new file mode 100644
index 00000000000..7508ecef3cc
--- /dev/null
+++ b/searchcorespi/src/vespa/searchcorespi/index/memory_index_stats.h
@@ -0,0 +1,22 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+#pragma once
+
+#include "index_searchable_stats.h"
+
+namespace searchcorespi {
+namespace index {
+
+struct IMemoryIndex;
+
+/**
+ * Information about a memory index usable by state explorer.
+ */
+class MemoryIndexStats : public IndexSearchableStats {
+public:
+    MemoryIndexStats();
+    MemoryIndexStats(const IMemoryIndex &index);
+    ~MemoryIndexStats();
+};
+
+} // namespace searchcorespi::index
+} // namespace searchcorespi
diff --git a/searchcorespi/src/vespa/searchcorespi/index/warmupindexcollection.cpp b/searchcorespi/src/vespa/searchcorespi/index/warmupindexcollection.cpp
index c993c79a93e..53a2a4d59ea 100644
--- a/searchcorespi/src/vespa/searchcorespi/index/warmupindexcollection.cpp
+++ b/searchcorespi/src/vespa/searchcorespi/index/warmupindexcollection.cpp
@@ -184,6 +184,22 @@ WarmupIndexCollection::getSearchableStats() const
     return _prev->getSearchableStats();
 }
 
+
+search::SerialNum
+WarmupIndexCollection::getSerialNum() const
+{
+    return std::max(_prev->getSerialNum(), _next->getSerialNum());
+}
+
+
+void
+WarmupIndexCollection::accept(IndexSearchableVisitor &visitor) const
+{
+    _prev->accept(visitor);
+    _next->accept(visitor);
+}
+
+
 void
 WarmupIndexCollection::append(uint32_t id, const IndexSearchable::SP &source)
 {
diff --git a/searchcorespi/src/vespa/searchcorespi/index/warmupindexcollection.h b/searchcorespi/src/vespa/searchcorespi/index/warmupindexcollection.h
index a304b3b9df2..be25b81d498 100644
--- a/searchcorespi/src/vespa/searchcorespi/index/warmupindexcollection.h
+++ b/searchcorespi/src/vespa/searchcorespi/index/warmupindexcollection.h
@@ -49,6 +49,8 @@ public:
                     const Node &term,
                     const IAttributeContext &attrCtx);
     search::SearchableStats getSearchableStats() const override;
+    search::SerialNum getSerialNum() const override;
+    void accept(IndexSearchableVisitor &visitor) const override;
 
     // Implements ISearchableIndexCollection
     void append(uint32_t id, const IndexSearchable::SP &source) override;