From 599bd6335c27ff2c1a48cc0b3a5ee115d49afcda Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Fri, 12 Jul 2019 20:37:45 +0300
Subject: Speed-up builds page loading

---
 libbrep/build-package.hxx |  2 +-
 libbrep/build.hxx         |  6 +++++-
 libbrep/build.xml         |  8 ++++++++
 mod/mod-builds.cxx        | 27 +++++++++++++++------------
 4 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/libbrep/build-package.hxx b/libbrep/build-package.hxx
index c491b9e..c288f07 100644
--- a/libbrep/build-package.hxx
+++ b/libbrep/build-package.hxx
@@ -71,7 +71,7 @@ namespace brep
 
   // Foreign object that is mapped to a subset of the package object.
   //
-  #pragma db object table("build_package") pointer(shared_ptr) readonly
+  #pragma db object table("build_package") pointer(shared_ptr) readonly session
   class build_package
   {
   public:
diff --git a/libbrep/build.hxx b/libbrep/build.hxx
index ea51c00..a8139a8 100644
--- a/libbrep/build.hxx
+++ b/libbrep/build.hxx
@@ -26,7 +26,7 @@
 //
 #define LIBBREP_BUILD_SCHEMA_VERSION_BASE 7
 
-#pragma db model version(LIBBREP_BUILD_SCHEMA_VERSION_BASE, 8, closed)
+#pragma db model version(LIBBREP_BUILD_SCHEMA_VERSION_BASE, 9, closed)
 
 // We have to keep these mappings at the global scope instead of inside
 // the brep namespace because they need to be also effective in the
@@ -242,6 +242,10 @@ namespace brep
     #pragma db member(toolchain_version) \
       set(this.toolchain_version.init (this.id.toolchain_version, (?)))
 
+    // Speed-up queries with ordering the result by the timestamp.
+    //
+    #pragma db member(timestamp) index
+
     #pragma db member(results) id_column("") value_column("") \
       section(results_section)
 
diff --git a/libbrep/build.xml b/libbrep/build.xml
index 032fd38..2a621b6 100644
--- a/libbrep/build.xml
+++ b/libbrep/build.xml
@@ -1,4 +1,12 @@
 <changelog xmlns="http://www.codesynthesis.com/xmlns/odb/changelog" database="pgsql" schema-name="build" version="1">
+  <changeset version="9">
+    <alter-table name="build">
+      <add-index name="build_timestamp_i">
+        <column name="timestamp"/>
+      </add-index>
+    </alter-table>
+  </changeset>
+
   <changeset version="8"/>
 
   <model version="7">
diff --git a/mod/mod-builds.cxx b/mod/mod-builds.cxx
index 30a18a6..dedabfe 100644
--- a/mod/mod-builds.cxx
+++ b/mod/mod-builds.cxx
@@ -494,13 +494,17 @@ handle (request& rq, response& rs)
     // Specify the portion. Note that we will be querying builds in chunks,
     // not to hold locks for too long.
     //
+    // Also note that for each build we also load the corresponding
+    // package. Nevertheless, we use a fairly large portion to speed-up the
+    // builds traversal but also cache the package objects (see below).
+    //
     size_t offset (0);
 
     // Print package build configurations ordered by the timestamp (later goes
     // first).
     //
     q += "ORDER BY" + query::build::timestamp + "DESC" +
-      "OFFSET" + query::_ref (offset) + "LIMIT 50";
+      "OFFSET" + query::_ref (offset) + "LIMIT 500";
 
     connection_ptr conn (build_db_->connection ());
 
@@ -515,11 +519,12 @@ handle (request& rq, response& rs)
     size_t skip (page * page_configs);
     size_t print (page_configs);
 
-    // Note that adjacent builds may well relate to the same package. We will
-    // use this fact for a cheap optimization, loading the build package only
-    // if it differs from the previous one.
+    // Cache the build package objects that would otherwise be loaded multiple
+    // times for different configuration/toolchain combinations. Note that the
+    // build package is a subset of the package object and normally has a
+    // small memory footprint.
     //
-    shared_ptr<build_package> p;
+    session sn;
 
     for (bool ne (true); ne; )
     {
@@ -541,18 +546,15 @@ handle (request& rq, response& rs)
         {
           shared_ptr<build>& b (pb.build);
 
-          // Prior to loading the package object check if it is already
-          // loaded.
-          //
-          if (p == nullptr || p->id != b->id.package)
-            p = build_db_->load<build_package> (b->id.package);
-
           auto i (build_conf_map_->find (b->configuration.c_str ()));
           assert (i != build_conf_map_->end ());
 
           // Match the configuration against the package build
           // expressions/constraints.
           //
+          shared_ptr<build_package> p (
+            build_db_->load<build_package> (b->id.package));
+
           if (!exclude (p->builds, p->constraints, *i->second))
           {
             if (skip != 0)
@@ -846,7 +848,8 @@ handle (request& rq, response& rs)
       package_query<buildable_package> (params, tn, false /* archived */));
 
     // Specify the portion. Note that we will still be querying packages in
-    // chunks, not to hold locks for too long.
+    // chunks, not to hold locks for too long. For each package we will query
+    // its builds, so let's keep the portion small.
     //
     size_t offset (0);
 
-- 
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