Ticket #266: minmem.patch

tests/api_transdb.cc

@@ -126 +126 @@
 
     return true;
 }
+
+/// Test minimise_memory inside a simple transaction.
+DEFINE_TESTCASE(minmemtransaction1, transactions) {
+    Xapian::WritableDatabase db(get_writable_database("apitest_simpledata"));
+
+    Xapian::doccount docs = db.get_doccount();
+    db.begin_transaction();
+    Xapian::Document doc;
+    doc.set_data("testing");
+    doc.add_term("befuddlement");
+    db.add_document(doc);
+    TEST_EXCEPTION(Xapian::InvalidOperationError, db.begin_transaction());
+    db.minimise_memory();
+    TEST_EQUAL(db.get_doccount(), docs + 1);
+    TEST_EQUAL(db.get_termfreq("befuddlement"), 1);
+    db.commit_transaction();
+    TEST_EQUAL(db.get_doccount(), docs + 1);
+    TEST_EQUAL(db.get_termfreq("befuddlement"), 1);
+
+    return true;
+}
+
+/// Test cancelling a simple transaction after calling minimise_memory.
+DEFINE_TESTCASE(minmemcanceltransaction1, transactions) {
+    Xapian::WritableDatabase db(get_writable_database("apitest_simpledata"));
+
+    Xapian::doccount docs = db.get_doccount();
+    db.begin_transaction();
+    Xapian::Document doc;
+    doc.set_data("testing");
+    doc.add_term("befuddlement");
+    db.add_document(doc);
+    TEST_EXCEPTION(Xapian::InvalidOperationError, db.begin_transaction());
+    TEST_EQUAL(db.get_doccount(), docs + 1);
+    TEST_EQUAL(db.get_termfreq("befuddlement"), 1);
+    db.minimise_memory();
+    db.cancel_transaction();
+    TEST_EQUAL(db.get_doccount(), docs);
+    TEST_EQUAL(db.get_termfreq("befuddlement"), 0);
+
+    return true;
+}

include/xapian/database.h

@@ -5 +5 @@
  * Copyright 2002 Ananova Ltd
  * Copyright 2002,2003,2004,2005,2006,2007,2008,2009,2011 Olly Betts
  * Copyright 2006,2008 Lemur Consulting Ltd
+ * Copyright 2011 Richard Boulton
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
@@ -565 +566 @@
          */
         void flush() { commit(); }
 
+        /** Reduce the amount of memory currently holding buffered changes.
+         *
+         *  This may be used to control the amount of memory used when
+         *  indexing, while still allowing large sets of changes to be applied
+         *  atomically.  Note that it will generally perform a similar amount
+         *  of work to performing a commit(), so as with commit, calling
+         *  mimimise_memory() too often will make indexing take much longer.
+         *
+         *  This may be called whether a transaction is currently in progress
+         *  or not.
+         *
+         *  @exception Xapian::DatabaseError will be thrown if a problem occurs
+         *             while modifying the database.
+         *
+         *  @exception Xapian::DatabaseCorruptError will be thrown if the
+         *             database is in a corrupt state.
+         */
+        void minimise_memory();
+
         /** Begin a transaction.
          *
          *  In Xapian a transaction is a group of modifications to the database

common/database.h

@@ -412 +412 @@
         /** Cancel pending modifications to the database. */
         virtual void cancel();
 
+        /** Reduce the amount of memory currently holding buffered changes.
+         *
+         *  See WritableDatabase::minimise_memory() for more information.
+         */
+        virtual void minimise_memory();
+
         /** Begin a transaction.
          *
          *  See WritableDatabase::begin_transaction() for more information.

api/omdatabase.cc

@@ -785 +785 @@
 }
 
 void
+WritableDatabase::minimise_memory()
+{
+    LOGCALL_VOID(API, "WritableDatabase::minimise_memory", NO_ARGS);
+    if (internal.size() != 1) only_one_subdatabase_allowed();
+    internal[0]->minimise_memory();
+}
+
+void
 WritableDatabase::begin_transaction(bool flushed)
 {
     LOGCALL_VOID(API, "WritableDatabase::begin_transaction", NO_ARGS);

backends/database.cc

@@ -123 +123 @@
 }
 
 void
+Database::Internal::minimise_memory()
+{
+    // Writable databases may override this method.
+}
+
+void
 Database::Internal::begin_transaction(bool flushed)
 {
     if (transaction_state != TRANSACTION_NONE) {

backends/chert/chert_database.cc

@@ -1607 +1607 @@
 }
 
 void
+ChertWritableDatabase::minimise_memory()
+{
+    flush_postlist_changes();
+}
+
+void
 ChertWritableDatabase::add_spelling(const string & word,
                                     Xapian::termcount freqinc) const
 {

backends/chert/chert_database.h

@@ -383 +383 @@
         /** Cancel pending modifications to the database. */
         void cancel();
 
+        /** Minimise buffered changes. */
+        void minimise_memory();
+
         Xapian::docid add_document(const Xapian::Document & document);
         Xapian::docid add_document_(Xapian::docid did, const Xapian::Document & document);
         // Stop the default implementation of delete_document(term) and

backends/brass/brass_database.cc

@@ -1532 +1532 @@
 }
 
 void
+BrassWritableDatabase::minimise_memory()
+{
+    flush_postlist_changes();
+}
+
+void
 BrassWritableDatabase::add_spelling(const string & word,
                                     Xapian::termcount freqinc) const
 {

backends/brass/brass_database.h

@@ -340 +340 @@
         /** Cancel pending modifications to the database. */
         void cancel();
 
+        /** Minimise buffered changes. */
+        void minimise_memory();
+
         Xapian::docid add_document(const Xapian::Document & document);
         Xapian::docid add_document_(Xapian::docid did, const Xapian::Document & document);
         // Stop the default implementation of delete_document(term) and